diff --git a/account/account.go b/account/account.go
new file mode 100644
index 00000000..fa68167f
--- /dev/null
+++ b/account/account.go
@@ -0,0 +1,19 @@
+package account
+
+import (
+	"bytes"
+	"io"
+)
+
+type Signable interface {
+	WriteSignBytes(w io.Writer, n *int64, err *error)
+}
+
+func SignBytes(o Signable) []byte {
+	buf, n, err := new(bytes.Buffer), new(int64), new(error)
+	o.WriteSignBytes(buf, n, err)
+	if *err != nil {
+		panic(err)
+	}
+	return buf.Bytes()
+}
diff --git a/account/privkey.go b/account/privkey.go
new file mode 100644
index 00000000..92b2d269
--- /dev/null
+++ b/account/privkey.go
@@ -0,0 +1,62 @@
+package account
+
+import (
+	"errors"
+	"io"
+	"reflect"
+
+	"github.com/tendermint/go-ed25519"
+	. "github.com/tendermint/tendermint/binary"
+	. "github.com/tendermint/tendermint/common"
+)
+
+/*
+Each account has an PrivKey which determines access to funds of the account.
+Transaction inputs include Signatures of the account's associated PrivKey.
+*/
+type PrivKey interface {
+	Sign(msg []byte) Signature
+}
+
+const (
+	PrivKeyTypeEd25519 = byte(0x01)
+)
+
+func PrivKeyDecoder(r io.Reader, n *int64, err *error) interface{} {
+	switch t := ReadByte(r, n, err); t {
+	case PrivKeyTypeEd25519:
+		return ReadBinary(&PrivKeyEd25519{}, r, n, err)
+	default:
+		*err = Errorf("Unknown PrivKey type %X", t)
+		return nil
+	}
+}
+
+var _ = RegisterType(&TypeInfo{
+	Type:    reflect.TypeOf((*PrivKey)(nil)).Elem(),
+	Decoder: PrivKeyDecoder,
+})
+
+//-------------------------------------
+
+type PrivKeyEd25519 struct {
+	PubKey  []byte
+	PrivKey []byte
+}
+
+func (key PrivKeyEd25519) TypeByte() byte { return PrivKeyTypeEd25519 }
+
+func (key PrivKeyEd25519) ValidateBasic() error {
+	if len(key.PubKey) != ed25519.PublicKeySize {
+		return errors.New("Invalid PrivKeyEd25519 pubkey size")
+	}
+	if len(key.PrivKey) != ed25519.PrivateKeySize {
+		return errors.New("Invalid PrivKeyEd25519 privkey size")
+	}
+	return nil
+}
+
+func (key PrivKeyEd25519) Sign(msg []byte) Signature {
+	signature := ed25519.SignMessage(msg, key.PrivKey, key.PubKey)
+	return SignatureEd25519{signature}
+}
diff --git a/account/pubkey.go b/account/pubkey.go
new file mode 100644
index 00000000..8f7c3c74
--- /dev/null
+++ b/account/pubkey.go
@@ -0,0 +1,87 @@
+package account
+
+import (
+	"errors"
+	"io"
+	"reflect"
+
+	"github.com/tendermint/go-ed25519"
+	. "github.com/tendermint/tendermint/binary"
+	. "github.com/tendermint/tendermint/common"
+)
+
+/*
+Each account has an PubKey which determines access to funds of the account.
+Transaction inputs include Signatures of the account's associated PubKey.
+*/
+type PubKey interface {
+	Address() []byte
+	VerifyBytes(msg []byte, sig Signature) bool
+}
+
+const (
+	PubKeyTypeUnknown = byte(0x00)
+	PubKeyTypeEd25519 = byte(0x01)
+)
+
+func PubKeyDecoder(r io.Reader, n *int64, err *error) interface{} {
+	switch t := ReadByte(r, n, err); t {
+	case PubKeyTypeUnknown:
+		return PubKeyUnknown{}
+	case PubKeyTypeEd25519:
+		return ReadBinary(&PubKeyEd25519{}, r, n, err)
+	default:
+		*err = Errorf("Unknown PubKey type %X", t)
+		return nil
+	}
+}
+
+var _ = RegisterType(&TypeInfo{
+	Type:    reflect.TypeOf((*PubKey)(nil)).Elem(),
+	Decoder: PubKeyDecoder,
+})
+
+//-------------------------------------
+
+type PubKeyUnknown struct {
+}
+
+func (key PubKeyUnknown) TypeByte() byte { return PubKeyTypeUnknown }
+
+func (key PubKeyUnknown) Address() []byte {
+	panic("PubKeyUnknown has no address")
+}
+
+func (key PubKeyUnknown) VerifyBytes(msg []byte, sig_ Signature) bool {
+	panic("PubKeyUnknown cannot verify messages")
+}
+
+//-------------------------------------
+
+type PubKeyEd25519 struct {
+	PubKey []byte
+}
+
+func (key PubKeyEd25519) TypeByte() byte { return PubKeyTypeEd25519 }
+
+func (key PubKeyEd25519) Address() []byte { return BinaryRipemd160(key.PubKey) }
+
+func (key PubKeyEd25519) ValidateBasic() error {
+	if len(key.PubKey) != ed25519.PublicKeySize {
+		return errors.New("Invalid PubKeyEd25519 key size")
+	}
+	return nil
+}
+
+func (key PubKeyEd25519) VerifyBytes(msg []byte, sig_ Signature) bool {
+	sig, ok := sig_.(SignatureEd25519)
+	if !ok {
+		panic("PubKeyEd25519 expects an SignatureEd25519 signature")
+	}
+	v1 := &ed25519.Verify{
+		Message:   msg,
+		PubKey:    key.PubKey,
+		Signature: []byte(sig.Bytes),
+	}
+	return ed25519.VerifyBatch([]*ed25519.Verify{v1})
+}
diff --git a/account/signature.go b/account/signature.go
new file mode 100644
index 00000000..a4ddf07a
--- /dev/null
+++ b/account/signature.go
@@ -0,0 +1,52 @@
+package account
+
+import (
+	"errors"
+	"io"
+	"reflect"
+
+	"github.com/tendermint/go-ed25519"
+	. "github.com/tendermint/tendermint/binary"
+	. "github.com/tendermint/tendermint/common"
+)
+
+type Signature interface {
+}
+
+const (
+	SignatureTypeEd25519 = byte(0x01)
+)
+
+func SignatureDecoder(r io.Reader, n *int64, err *error) interface{} {
+	switch t := ReadByte(r, n, err); t {
+	case SignatureTypeEd25519:
+		return ReadBinary(&SignatureEd25519{}, r, n, err)
+	default:
+		*err = Errorf("Unknown Signature type %X", t)
+		return nil
+	}
+}
+
+var _ = RegisterType(&TypeInfo{
+	Type:    reflect.TypeOf((*Signature)(nil)).Elem(),
+	Decoder: SignatureDecoder,
+})
+
+//-------------------------------------
+
+type SignatureEd25519 struct {
+	Bytes []byte
+}
+
+func (sig SignatureEd25519) TypeByte() byte { return SignatureTypeEd25519 }
+
+func (sig SignatureEd25519) ValidateBasic() error {
+	if len(sig.Bytes) != ed25519.SignatureSize {
+		return errors.New("Invalid SignatureEd25519 signature size")
+	}
+	return nil
+}
+
+func (sig SignatureEd25519) IsZero() bool {
+	return len(sig.Bytes) == 0
+}
diff --git a/state/account_test.go b/account/signature_test.go
similarity index 97%
rename from state/account_test.go
rename to account/signature_test.go
index 20ce6021..cb379741 100644
--- a/state/account_test.go
+++ b/account/signature_test.go
@@ -1,4 +1,4 @@
-package state
+package account
 
 import (
 	. "github.com/tendermint/tendermint/common"
diff --git a/binary/binary.go b/binary/binary.go
index 338385e2..7f5dd69b 100644
--- a/binary/binary.go
+++ b/binary/binary.go
@@ -1,23 +1,31 @@
 package binary
 
-import "io"
+import (
+	"io"
+	"reflect"
+)
 
-type Binary interface {
-	WriteTo(w io.Writer) (int64, error)
+func ReadBinary(o interface{}, r io.Reader, n *int64, err *error) interface{} {
+	rv, rt := reflect.ValueOf(o), reflect.TypeOf(o)
+	if rv.Kind() == reflect.Ptr {
+		readReflect(rv.Elem(), rt.Elem(), r, n, err)
+		return o
+	} else {
+		ptrRv := reflect.New(rt)
+		readReflect(ptrRv.Elem(), rt, r, n, err)
+		return ptrRv.Elem()
+	}
 }
 
-func WriteBinary(w io.Writer, b Binary, n *int64, err *error) {
-	if *err != nil {
-		return
-	}
-	n_, err_ := b.WriteTo(w)
-	*n += int64(n_)
-	*err = err_
+func WriteBinary(o interface{}, w io.Writer, n *int64, err *error) {
+	rv := reflect.ValueOf(o)
+	rt := reflect.TypeOf(o)
+	writeReflect(rv, rt, w, n, err)
 }
 
 // Write all of bz to w
 // Increment n and set err accordingly.
-func WriteTo(w io.Writer, bz []byte, n *int64, err *error) {
+func WriteTo(bz []byte, w io.Writer, n *int64, err *error) {
 	if *err != nil {
 		return
 	}
@@ -28,7 +36,7 @@ func WriteTo(w io.Writer, bz []byte, n *int64, err *error) {
 
 // Read len(buf) from r
 // Increment n and set err accordingly.
-func ReadFull(r io.Reader, buf []byte, n *int64, err *error) {
+func ReadFull(buf []byte, r io.Reader, n *int64, err *error) {
 	if *err != nil {
 		return
 	}
diff --git a/binary/byteslice.go b/binary/byteslice.go
index e31a5b1e..7f448ced 100644
--- a/binary/byteslice.go
+++ b/binary/byteslice.go
@@ -4,27 +4,27 @@ import (
 	"io"
 )
 
-func WriteByteSlice(w io.Writer, bz []byte, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(bz)), n, err)
-	WriteTo(w, bz, n, err)
+func WriteByteSlice(bz []byte, w io.Writer, n *int64, err *error) {
+	WriteUVarInt(uint(len(bz)), w, n, err)
+	WriteTo(bz, w, n, err)
 }
 
 func ReadByteSlice(r io.Reader, n *int64, err *error) []byte {
-	length := ReadUInt32(r, n, err)
+	length := ReadUVarInt(r, n, err)
 	if *err != nil {
 		return nil
 	}
 	buf := make([]byte, int(length))
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return buf
 }
 
 //-----------------------------------------------------------------------------
 
-func WriteByteSlices(w io.Writer, bzz [][]byte, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(bzz)), n, err)
+func WriteByteSlices(bzz [][]byte, w io.Writer, n *int64, err *error) {
+	WriteUVarInt(uint(len(bzz)), w, n, err)
 	for _, bz := range bzz {
-		WriteByteSlice(w, bz, n, err)
+		WriteByteSlice(bz, w, n, err)
 		if *err != nil {
 			return
 		}
@@ -32,12 +32,12 @@ func WriteByteSlices(w io.Writer, bzz [][]byte, n *int64, err *error) {
 }
 
 func ReadByteSlices(r io.Reader, n *int64, err *error) [][]byte {
-	length := ReadUInt32(r, n, err)
+	length := ReadUVarInt(r, n, err)
 	if *err != nil {
 		return nil
 	}
 	bzz := make([][]byte, length)
-	for i := uint32(0); i < length; i++ {
+	for i := uint(0); i < length; i++ {
 		bz := ReadByteSlice(r, n, err)
 		if *err != nil {
 			return nil
diff --git a/binary/codec.go b/binary/codec.go
index 6dce295a..2f94305d 100644
--- a/binary/codec.go
+++ b/binary/codec.go
@@ -6,10 +6,14 @@ import (
 	"time"
 )
 
-type Codec interface {
-	Encode(o interface{}, w io.Writer, n *int64, err *error)
-	Decode(r io.Reader, n *int64, err *error) interface{}
-	Compare(o1 interface{}, o2 interface{}) int
+type Encoder func(o interface{}, w io.Writer, n *int64, err *error)
+type Decoder func(r io.Reader, n *int64, err *error) interface{}
+type Comparator func(o1 interface{}, o2 interface{}) int
+
+type Codec struct {
+	Encode  Encoder
+	Decode  Decoder
+	Compare Comparator
 }
 
 const (
@@ -29,62 +33,58 @@ const (
 	typeTime      = byte(0x20)
 )
 
-var BasicCodec = basicCodec{}
-
-type basicCodec struct{}
-
-func (bc basicCodec) Encode(o interface{}, w io.Writer, n *int64, err *error) {
+func BasicCodecEncoder(o interface{}, w io.Writer, n *int64, err *error) {
 	switch o.(type) {
 	case nil:
 		panic("nil type unsupported")
 	case byte:
-		WriteByte(w, typeByte, n, err)
-		WriteByte(w, o.(byte), n, err)
+		WriteByte(typeByte, w, n, err)
+		WriteByte(o.(byte), w, n, err)
 	case int8:
-		WriteByte(w, typeInt8, n, err)
-		WriteInt8(w, o.(int8), n, err)
+		WriteByte(typeInt8, w, n, err)
+		WriteInt8(o.(int8), w, n, err)
 	//case uint8:
-	//	WriteByte(w, typeUInt8, n, err)
-	//	WriteUInt8(w, o.(uint8), n, err)
+	//	WriteByte( typeUInt8, w, n, err)
+	//	WriteUInt8( o.(uint8), w, n, err)
 	case int16:
-		WriteByte(w, typeInt16, n, err)
-		WriteInt16(w, o.(int16), n, err)
+		WriteByte(typeInt16, w, n, err)
+		WriteInt16(o.(int16), w, n, err)
 	case uint16:
-		WriteByte(w, typeUInt16, n, err)
-		WriteUInt16(w, o.(uint16), n, err)
+		WriteByte(typeUInt16, w, n, err)
+		WriteUInt16(o.(uint16), w, n, err)
 	case int32:
-		WriteByte(w, typeInt32, n, err)
-		WriteInt32(w, o.(int32), n, err)
+		WriteByte(typeInt32, w, n, err)
+		WriteInt32(o.(int32), w, n, err)
 	case uint32:
-		WriteByte(w, typeUInt32, n, err)
-		WriteUInt32(w, o.(uint32), n, err)
+		WriteByte(typeUInt32, w, n, err)
+		WriteUInt32(o.(uint32), w, n, err)
 	case int64:
-		WriteByte(w, typeInt64, n, err)
-		WriteInt64(w, o.(int64), n, err)
+		WriteByte(typeInt64, w, n, err)
+		WriteInt64(o.(int64), w, n, err)
 	case uint64:
-		WriteByte(w, typeUInt64, n, err)
-		WriteUInt64(w, o.(uint64), n, err)
+		WriteByte(typeUInt64, w, n, err)
+		WriteUInt64(o.(uint64), w, n, err)
 	case int:
-		WriteByte(w, typeVarInt, n, err)
-		WriteVarInt(w, o.(int), n, err)
+		WriteByte(typeVarInt, w, n, err)
+		WriteVarInt(o.(int), w, n, err)
 	case uint:
-		WriteByte(w, typeUVarInt, n, err)
-		WriteUVarInt(w, o.(uint), n, err)
+		WriteByte(typeUVarInt, w, n, err)
+		WriteUVarInt(o.(uint), w, n, err)
 	case string:
-		WriteByte(w, typeString, n, err)
-		WriteString(w, o.(string), n, err)
+		WriteByte(typeString, w, n, err)
+		WriteString(o.(string), w, n, err)
 	case []byte:
-		WriteByte(w, typeByteSlice, n, err)
-		WriteByteSlice(w, o.([]byte), n, err)
+		WriteByte(typeByteSlice, w, n, err)
+		WriteByteSlice(o.([]byte), w, n, err)
 	case time.Time:
-		WriteByte(w, typeTime, n, err)
-		WriteTime(w, o.(time.Time), n, err)
+		WriteByte(typeTime, w, n, err)
+		WriteTime(o.(time.Time), w, n, err)
 	default:
 		panic("Unsupported type")
 	}
 }
 
-func (bc basicCodec) Decode(r io.Reader, n *int64, err *error) (o interface{}) {
+func BasicCodecDecoder(r io.Reader, n *int64, err *error) (o interface{}) {
 	type_ := ReadByte(r, n, err)
 	switch type_ {
 	case typeByte:
@@ -121,7 +121,7 @@ func (bc basicCodec) Decode(r io.Reader, n *int64, err *error) (o interface{}) {
 	return o
 }
 
-func (bc basicCodec) Compare(o1 interface{}, o2 interface{}) int {
+func BasicCodecComparator(o1 interface{}, o2 interface{}) int {
 	switch o1.(type) {
 	case byte:
 		return int(o1.(byte) - o2.(byte))
@@ -154,3 +154,9 @@ func (bc basicCodec) Compare(o1 interface{}, o2 interface{}) int {
 		panic("Unsupported type")
 	}
 }
+
+var BasicCodec = Codec{
+	Encode:  BasicCodecEncoder,
+	Decode:  BasicCodecDecoder,
+	Compare: BasicCodecComparator,
+}
diff --git a/binary/int.go b/binary/int.go
index 42445e18..23372302 100644
--- a/binary/int.go
+++ b/binary/int.go
@@ -8,20 +8,20 @@ import (
 
 // Byte
 
-func WriteByte(w io.Writer, b byte, n *int64, err *error) {
-	WriteTo(w, []byte{b}, n, err)
+func WriteByte(b byte, w io.Writer, n *int64, err *error) {
+	WriteTo([]byte{b}, w, n, err)
 }
 
 func ReadByte(r io.Reader, n *int64, err *error) byte {
 	buf := make([]byte, 1)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return buf[0]
 }
 
 // Int8
 
-func WriteInt8(w io.Writer, i int8, n *int64, err *error) {
-	WriteByte(w, byte(i), n, err)
+func WriteInt8(i int8, w io.Writer, n *int64, err *error) {
+	WriteByte(byte(i), w, n, err)
 }
 
 func ReadInt8(r io.Reader, n *int64, err *error) int8 {
@@ -30,8 +30,8 @@ func ReadInt8(r io.Reader, n *int64, err *error) int8 {
 
 // UInt8
 
-func WriteUInt8(w io.Writer, i uint8, n *int64, err *error) {
-	WriteByte(w, byte(i), n, err)
+func WriteUInt8(i uint8, w io.Writer, n *int64, err *error) {
+	WriteByte(byte(i), w, n, err)
 }
 
 func ReadUInt8(r io.Reader, n *int64, err *error) uint8 {
@@ -40,40 +40,40 @@ func ReadUInt8(r io.Reader, n *int64, err *error) uint8 {
 
 // Int16
 
-func WriteInt16(w io.Writer, i int16, n *int64, err *error) {
+func WriteInt16(i int16, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 2)
 	binary.LittleEndian.PutUint16(buf, uint16(i))
 	*n += 2
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadInt16(r io.Reader, n *int64, err *error) int16 {
 	buf := make([]byte, 2)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return int16(binary.LittleEndian.Uint16(buf))
 }
 
 // UInt16
 
-func WriteUInt16(w io.Writer, i uint16, n *int64, err *error) {
+func WriteUInt16(i uint16, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 2)
 	binary.LittleEndian.PutUint16(buf, uint16(i))
 	*n += 2
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadUInt16(r io.Reader, n *int64, err *error) uint16 {
 	buf := make([]byte, 2)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return uint16(binary.LittleEndian.Uint16(buf))
 }
 
 // []UInt16
 
-func WriteUInt16s(w io.Writer, iz []uint16, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(iz)), n, err)
+func WriteUInt16s(iz []uint16, w io.Writer, n *int64, err *error) {
+	WriteUInt32(uint32(len(iz)), w, n, err)
 	for _, i := range iz {
-		WriteUInt16(w, i, n, err)
+		WriteUInt16(i, w, n, err)
 		if *err != nil {
 			return
 		}
@@ -98,71 +98,71 @@ func ReadUInt16s(r io.Reader, n *int64, err *error) []uint16 {
 
 // Int32
 
-func WriteInt32(w io.Writer, i int32, n *int64, err *error) {
+func WriteInt32(i int32, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 4)
 	binary.LittleEndian.PutUint32(buf, uint32(i))
 	*n += 4
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadInt32(r io.Reader, n *int64, err *error) int32 {
 	buf := make([]byte, 4)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return int32(binary.LittleEndian.Uint32(buf))
 }
 
 // UInt32
 
-func WriteUInt32(w io.Writer, i uint32, n *int64, err *error) {
+func WriteUInt32(i uint32, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 4)
 	binary.LittleEndian.PutUint32(buf, uint32(i))
 	*n += 4
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadUInt32(r io.Reader, n *int64, err *error) uint32 {
 	buf := make([]byte, 4)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return uint32(binary.LittleEndian.Uint32(buf))
 }
 
 // Int64
 
-func WriteInt64(w io.Writer, i int64, n *int64, err *error) {
+func WriteInt64(i int64, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 8)
 	binary.LittleEndian.PutUint64(buf, uint64(i))
 	*n += 8
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadInt64(r io.Reader, n *int64, err *error) int64 {
 	buf := make([]byte, 8)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return int64(binary.LittleEndian.Uint64(buf))
 }
 
 // UInt64
 
-func WriteUInt64(w io.Writer, i uint64, n *int64, err *error) {
+func WriteUInt64(i uint64, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 8)
 	binary.LittleEndian.PutUint64(buf, uint64(i))
 	*n += 8
-	WriteTo(w, buf, n, err)
+	WriteTo(buf, w, n, err)
 }
 
 func ReadUInt64(r io.Reader, n *int64, err *error) uint64 {
 	buf := make([]byte, 8)
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return uint64(binary.LittleEndian.Uint64(buf))
 }
 
 // VarInt
 
-func WriteVarInt(w io.Writer, i int, n *int64, err *error) {
+func WriteVarInt(i int, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 9)
 	n_ := int64(binary.PutVarint(buf, int64(i)))
 	*n += n_
-	WriteTo(w, buf[:n_], n, err)
+	WriteTo(buf[:n_], w, n, err)
 }
 
 func ReadVarInt(r io.Reader, n *int64, err *error) int {
@@ -174,11 +174,11 @@ func ReadVarInt(r io.Reader, n *int64, err *error) int {
 
 // UVarInt
 
-func WriteUVarInt(w io.Writer, i uint, n *int64, err *error) {
+func WriteUVarInt(i uint, w io.Writer, n *int64, err *error) {
 	buf := make([]byte, 9)
 	n_ := int64(binary.PutUvarint(buf, uint64(i)))
 	*n += n_
-	WriteTo(w, buf[:n_], n, err)
+	WriteTo(buf[:n_], w, n, err)
 }
 
 func ReadUVarInt(r io.Reader, n *int64, err *error) uint {
diff --git a/binary/reflect.go b/binary/reflect.go
new file mode 100644
index 00000000..56981df3
--- /dev/null
+++ b/binary/reflect.go
@@ -0,0 +1,198 @@
+package binary
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+)
+
+type TypeInfo struct {
+	Type    reflect.Type // The type
+	Encoder Encoder      // Optional custom encoder function
+	Decoder Decoder      // Optional custom decoder function
+}
+
+// If a type implements TypeByte, the byte is included
+// as the first byte for encoding.  This is used to encode
+// interfaces/union types.  In this case the decoding should
+// be done manually with a switch statement, and so the
+// reflection-based decoder provided here does not expect this
+// prefix byte.
+// See the reactor implementations for use-cases.
+type HasTypeByte interface {
+	TypeByte() byte
+}
+
+var typeInfos = map[reflect.Type]*TypeInfo{}
+
+func RegisterType(info *TypeInfo) bool {
+
+	// Register the type info
+	typeInfos[info.Type] = info
+
+	// Also register the underlying struct's info, if info.Type is a pointer.
+	if info.Type.Kind() == reflect.Ptr {
+		rt := info.Type.Elem()
+		typeInfos[rt] = info
+	}
+
+	return true
+}
+
+func readReflect(rv reflect.Value, rt reflect.Type, r io.Reader, n *int64, err *error) {
+
+	// First, create a new struct if rv is nil pointer.
+	if rt.Kind() == reflect.Ptr && rv.IsNil() {
+		newRv := reflect.New(rt.Elem())
+		rv.Set(newRv)
+		rv = newRv
+	}
+
+	// Dereference pointer
+	// Still addressable, thus settable!
+	if rv.Kind() == reflect.Ptr {
+		rv, rt = rv.Elem(), rt.Elem()
+	}
+
+	// Custom decoder
+	typeInfo := typeInfos[rt]
+	if typeInfo != nil && typeInfo.Decoder != nil {
+		decoded := typeInfo.Decoder(r, n, err)
+		decodedRv := reflect.Indirect(reflect.ValueOf(decoded))
+		rv.Set(decodedRv)
+		return
+	}
+
+	switch rt.Kind() {
+	case reflect.Slice:
+		elemRt := rt.Elem()
+		if elemRt.Kind() == reflect.Uint8 {
+			// Special case: Byteslices
+			byteslice := ReadByteSlice(r, n, err)
+			rv.Set(reflect.ValueOf(byteslice))
+		} else {
+			// Read length
+			length := int(ReadUVarInt(r, n, err))
+			sliceRv := reflect.MakeSlice(rt, length, length)
+			// Read elems
+			for i := 0; i < length; i++ {
+				elemRv := sliceRv.Index(i)
+				readReflect(elemRv, elemRt, r, n, err)
+			}
+			rv.Set(sliceRv)
+		}
+
+	case reflect.Struct:
+		numFields := rt.NumField()
+		for i := 0; i < numFields; i++ {
+			field := rt.Field(i)
+			if field.Anonymous {
+				continue
+			}
+			fieldRv := rv.Field(i)
+			readReflect(fieldRv, field.Type, r, n, err)
+		}
+
+	case reflect.String:
+		str := ReadString(r, n, err)
+		rv.SetString(str)
+
+	case reflect.Uint64:
+		num := ReadUInt64(r, n, err)
+		rv.SetUint(uint64(num))
+
+	case reflect.Uint32:
+		num := ReadUInt32(r, n, err)
+		rv.SetUint(uint64(num))
+
+	case reflect.Uint16:
+		num := ReadUInt16(r, n, err)
+		rv.SetUint(uint64(num))
+
+	case reflect.Uint8:
+		num := ReadUInt8(r, n, err)
+		rv.SetUint(uint64(num))
+
+	case reflect.Uint:
+		num := ReadUVarInt(r, n, err)
+		rv.SetUint(uint64(num))
+
+	default:
+		panic(fmt.Sprintf("Unknown field type %v", rt.Kind()))
+	}
+}
+
+func writeReflect(rv reflect.Value, rt reflect.Type, w io.Writer, n *int64, err *error) {
+
+	// Custom encoder
+	typeInfo := typeInfos[rt]
+	if typeInfo != nil && typeInfo.Encoder != nil {
+		typeInfo.Encoder(rv.Interface(), w, n, err)
+		return
+	}
+
+	// Dereference pointer or interface
+	if rt.Kind() == reflect.Ptr {
+		rt = rt.Elem()
+		rv = rv.Elem()
+	} else if rt.Kind() == reflect.Interface {
+		rv = rv.Elem()
+		rt = rv.Type()
+	}
+
+	// Write TypeByte prefix
+	if rt.Implements(reflect.TypeOf((*HasTypeByte)(nil)).Elem()) {
+		WriteByte(rv.Interface().(HasTypeByte).TypeByte(), w, n, err)
+	}
+
+	switch rt.Kind() {
+	case reflect.Slice:
+		elemRt := rt.Elem()
+		if elemRt.Kind() == reflect.Uint8 {
+			// Special case: Byteslices
+			byteslice := rv.Interface().([]byte)
+			WriteByteSlice(byteslice, w, n, err)
+		} else {
+			// Write length
+			length := rv.Len()
+			WriteUVarInt(uint(length), w, n, err)
+			// Write elems
+			for i := 0; i < length; i++ {
+				elemRv := rv.Index(i)
+				writeReflect(elemRv, elemRt, w, n, err)
+			}
+		}
+
+	case reflect.Struct:
+		numFields := rt.NumField()
+		for i := 0; i < numFields; i++ {
+			field := rt.Field(i)
+			if field.Anonymous {
+				continue
+			}
+			fieldRv := rv.Field(i)
+			writeReflect(fieldRv, field.Type, w, n, err)
+		}
+
+	case reflect.String:
+		WriteString(rv.String(), w, n, err)
+
+	case reflect.Uint64:
+		WriteUInt64(rv.Uint(), w, n, err)
+
+	case reflect.Uint32:
+		WriteUInt32(uint32(rv.Uint()), w, n, err)
+
+	case reflect.Uint16:
+		WriteUInt16(uint16(rv.Uint()), w, n, err)
+
+	case reflect.Uint8:
+		WriteUInt8(uint8(rv.Uint()), w, n, err)
+
+	case reflect.Uint:
+		WriteUVarInt(uint(rv.Uint()), w, n, err)
+
+	default:
+		panic(fmt.Sprintf("Unknown field type %v", rt.Kind()))
+	}
+}
diff --git a/binary/string.go b/binary/string.go
index 3ad25d0d..6968ad44 100644
--- a/binary/string.go
+++ b/binary/string.go
@@ -4,9 +4,9 @@ import "io"
 
 // String
 
-func WriteString(w io.Writer, s string, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(s)), n, err)
-	WriteTo(w, []byte(s), n, err)
+func WriteString(s string, w io.Writer, n *int64, err *error) {
+	WriteUInt32(uint32(len(s)), w, n, err)
+	WriteTo([]byte(s), w, n, err)
 }
 
 func ReadString(r io.Reader, n *int64, err *error) string {
@@ -15,6 +15,6 @@ func ReadString(r io.Reader, n *int64, err *error) string {
 		return ""
 	}
 	buf := make([]byte, int(length))
-	ReadFull(r, buf, n, err)
+	ReadFull(buf, r, n, err)
 	return string(buf)
 }
diff --git a/binary/time.go b/binary/time.go
index 8cc36f86..9c678046 100644
--- a/binary/time.go
+++ b/binary/time.go
@@ -7,8 +7,8 @@ import (
 
 // Time
 
-func WriteTime(w io.Writer, t time.Time, n *int64, err *error) {
-	WriteInt64(w, t.UnixNano(), n, err)
+func WriteTime(t time.Time, w io.Writer, n *int64, err *error) {
+	WriteInt64(t.UnixNano(), w, n, err)
 }
 
 func ReadTime(r io.Reader, n *int64, err *error) time.Time {
diff --git a/binary/util.go b/binary/util.go
index e80c7a0b..e1b0c7d8 100644
--- a/binary/util.go
+++ b/binary/util.go
@@ -2,36 +2,46 @@ package binary
 
 import (
 	"bytes"
+	"code.google.com/p/go.crypto/ripemd160"
 	"crypto/sha256"
 )
 
-func BinaryBytes(b Binary) []byte {
-	buf := bytes.NewBuffer(nil)
-	_, err := b.WriteTo(buf)
-	if err != nil {
+func BinaryBytes(o interface{}) []byte {
+	w, n, err := new(bytes.Buffer), new(int64), new(error)
+	WriteBinary(o, w, n, err)
+	if *err != nil {
 		panic(err)
 	}
-	return buf.Bytes()
+	return w.Bytes()
 }
 
 // NOTE: does not care about the type, only the binary representation.
-func BinaryEqual(a, b Binary) bool {
+func BinaryEqual(a, b interface{}) bool {
 	aBytes := BinaryBytes(a)
 	bBytes := BinaryBytes(b)
 	return bytes.Equal(aBytes, bBytes)
 }
 
 // NOTE: does not care about the type, only the binary representation.
-func BinaryCompare(a, b Binary) int {
+func BinaryCompare(a, b interface{}) int {
 	aBytes := BinaryBytes(a)
 	bBytes := BinaryBytes(b)
 	return bytes.Compare(aBytes, bBytes)
 }
 
-func BinaryHash(b Binary) []byte {
-	hasher := sha256.New()
-	_, err := b.WriteTo(hasher)
-	if err != nil {
+func BinarySha256(o interface{}) []byte {
+	hasher, n, err := sha256.New(), new(int64), new(error)
+	WriteBinary(o, hasher, n, err)
+	if *err != nil {
+		panic(err)
+	}
+	return hasher.Sum(nil)
+}
+
+func BinaryRipemd160(o interface{}) []byte {
+	hasher, n, err := ripemd160.New(), new(int64), new(error)
+	WriteBinary(o, hasher, n, err)
+	if *err != nil {
 		panic(err)
 	}
 	return hasher.Sum(nil)
diff --git a/blocks/block.go b/blocks/block.go
index 253cecec..9591b86c 100644
--- a/blocks/block.go
+++ b/blocks/block.go
@@ -5,10 +5,10 @@ import (
 	"crypto/sha256"
 	"errors"
 	"fmt"
-	"io"
 	"strings"
 	"time"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
 	. "github.com/tendermint/tendermint/config"
@@ -24,23 +24,8 @@ type Block struct {
 	hash []byte
 }
 
-func ReadBlock(r io.Reader, n *int64, err *error) *Block {
-	return &Block{
-		Header:     ReadHeader(r, n, err),
-		Validation: ReadValidation(r, n, err),
-		Data:       ReadData(r, n, err),
-	}
-}
-
-func (b *Block) WriteTo(w io.Writer) (n int64, err error) {
-	WriteBinary(w, b.Header, &n, &err)
-	WriteBinary(w, b.Validation, &n, &err)
-	WriteBinary(w, b.Data, &n, &err)
-	return
-}
-
 // Basic validation that doesn't involve state data.
-func (b *Block) ValidateBasic(lastBlockHeight uint32, lastBlockHash []byte,
+func (b *Block) ValidateBasic(lastBlockHeight uint, lastBlockHash []byte,
 	lastBlockParts PartSetHeader, lastBlockTime time.Time) error {
 	if b.Network != Config.Network {
 		return errors.New("Invalid block network")
@@ -115,7 +100,7 @@ func (b *Block) Description() string {
 
 type Header struct {
 	Network        string
-	Height         uint32
+	Height         uint
 	Time           time.Time
 	Fees           uint64
 	LastBlockHash  []byte
@@ -126,37 +111,11 @@ type Header struct {
 	hash []byte
 }
 
-func ReadHeader(r io.Reader, n *int64, err *error) *Header {
-	if *err != nil {
-		return nil
-	}
-	return &Header{
-		Network:        ReadString(r, n, err),
-		Height:         ReadUInt32(r, n, err),
-		Time:           ReadTime(r, n, err),
-		Fees:           ReadUInt64(r, n, err),
-		LastBlockHash:  ReadByteSlice(r, n, err),
-		LastBlockParts: ReadPartSetHeader(r, n, err),
-		StateHash:      ReadByteSlice(r, n, err),
-	}
-}
-
-func (h *Header) WriteTo(w io.Writer) (n int64, err error) {
-	WriteString(w, h.Network, &n, &err)
-	WriteUInt32(w, h.Height, &n, &err)
-	WriteTime(w, h.Time, &n, &err)
-	WriteUInt64(w, h.Fees, &n, &err)
-	WriteByteSlice(w, h.LastBlockHash, &n, &err)
-	WriteBinary(w, h.LastBlockParts, &n, &err)
-	WriteByteSlice(w, h.StateHash, &n, &err)
-	return
-}
-
 func (h *Header) Hash() []byte {
 	if h.hash == nil {
-		hasher := sha256.New()
-		_, err := h.WriteTo(hasher)
-		if err != nil {
+		hasher, n, err := sha256.New(), new(int64), new(error)
+		WriteBinary(h, hasher, n, err)
+		if *err != nil {
 			panic(err)
 		}
 		h.hash = hasher.Sum(nil)
@@ -186,30 +145,35 @@ func (h *Header) StringWithIndent(indent string) string {
 
 //-----------------------------------------------------------------------------
 
+type Commit struct {
+	// It's not strictly needed here, but consider adding address here for convenience
+	Round     uint
+	Signature SignatureEd25519
+}
+
+func (commit Commit) IsZero() bool {
+	return commit.Round == 0 && commit.Signature.IsZero()
+}
+
+func (commit Commit) String() string {
+	return fmt.Sprintf("Commit{R:%v %X}", commit.Round, Fingerprint(commit.Signature.Bytes))
+}
+
+//-------------------------------------
+
 type Validation struct {
-	Commits []RoundSignature
+	Commits []Commit
 
 	// Volatile
 	hash     []byte
 	bitArray BitArray
 }
 
-func ReadValidation(r io.Reader, n *int64, err *error) *Validation {
-	return &Validation{
-		Commits: ReadRoundSignatures(r, n, err),
-	}
-}
-
-func (v *Validation) WriteTo(w io.Writer) (n int64, err error) {
-	WriteRoundSignatures(w, v.Commits, &n, &err)
-	return
-}
-
 func (v *Validation) Hash() []byte {
 	if v.hash == nil {
-		bs := make([]Binary, len(v.Commits))
+		bs := make([]interface{}, len(v.Commits))
 		for i, commit := range v.Commits {
-			bs[i] = Binary(commit)
+			bs[i] = commit
 		}
 		v.hash = merkle.HashFromBinaries(bs)
 	}
@@ -231,8 +195,8 @@ func (v *Validation) StringWithIndent(indent string) string {
 func (v *Validation) BitArray() BitArray {
 	if v.bitArray.IsZero() {
 		v.bitArray = NewBitArray(uint(len(v.Commits)))
-		for i, rsig := range v.Commits {
-			v.bitArray.SetIndex(uint(i), !rsig.IsZero())
+		for i, commit := range v.Commits {
+			v.bitArray.SetIndex(uint(i), !commit.IsZero())
 		}
 	}
 	return v.bitArray
@@ -247,28 +211,11 @@ type Data struct {
 	hash []byte
 }
 
-func ReadData(r io.Reader, n *int64, err *error) *Data {
-	numTxs := ReadUInt32(r, n, err)
-	txs := make([]Tx, 0, numTxs)
-	for i := uint32(0); i < numTxs; i++ {
-		txs = append(txs, ReadTx(r, n, err))
-	}
-	return &Data{Txs: txs}
-}
-
-func (data *Data) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt32(w, uint32(len(data.Txs)), &n, &err)
-	for _, tx := range data.Txs {
-		WriteBinary(w, tx, &n, &err)
-	}
-	return
-}
-
 func (data *Data) Hash() []byte {
 	if data.hash == nil {
-		bs := make([]Binary, len(data.Txs))
+		bs := make([]interface{}, len(data.Txs))
 		for i, tx := range data.Txs {
-			bs[i] = Binary(tx)
+			bs[i] = tx
 		}
 		data.hash = merkle.HashFromBinaries(bs)
 	}
@@ -278,7 +225,7 @@ func (data *Data) Hash() []byte {
 func (data *Data) StringWithIndent(indent string) string {
 	txStrings := make([]string, len(data.Txs))
 	for i, tx := range data.Txs {
-		txStrings[i] = tx.String()
+		txStrings[i] = fmt.Sprintf("Tx:%v", tx)
 	}
 	return fmt.Sprintf(`Data{
 %s  %v
diff --git a/blocks/block_test.go b/blocks/block_test.go
deleted file mode 100644
index 15723c87..00000000
--- a/blocks/block_test.go
+++ /dev/null
@@ -1,126 +0,0 @@
-package blocks
-
-import (
-	"bytes"
-	. "github.com/tendermint/tendermint/binary"
-	. "github.com/tendermint/tendermint/common"
-	"testing"
-)
-
-func randSig() Signature {
-	return Signature{RandUInt64Exp(), RandBytes(32)}
-}
-
-func randRoundSig() RoundSignature {
-	return RoundSignature{RandUInt16(), randSig()}
-}
-
-func randBaseTx() BaseTx {
-	return BaseTx{0, RandUInt64Exp(), randSig()}
-}
-
-func randBlock() *Block {
-	// Account Txs
-	sendTx := &SendTx{
-		BaseTx: randBaseTx(),
-		To:     RandUInt64Exp(),
-		Amount: RandUInt64Exp(),
-	}
-	nameTx := &NameTx{
-		BaseTx: randBaseTx(),
-		Name:   string(RandBytes(12)),
-		PubKey: RandBytes(32),
-	}
-
-	// Validation Txs
-	bondTx := &BondTx{
-		BaseTx: randBaseTx(),
-		//UnbondTo: RandUInt64Exp(),
-	}
-	unbondTx := &UnbondTx{
-		BaseTx: randBaseTx(),
-	}
-	dupeoutTx := &DupeoutTx{
-		VoteA: Vote{
-			Height:    RandUInt32Exp(),
-			Round:     RandUInt16Exp(),
-			Type:      VoteTypePrevote,
-			BlockHash: RandBytes(32),
-			Signature: randSig(),
-		},
-		VoteB: Vote{
-			Height:    RandUInt32Exp(),
-			Round:     RandUInt16Exp(),
-			Type:      VoteTypePrevote,
-			BlockHash: RandBytes(32),
-			Signature: randSig(),
-		},
-	}
-
-	// Block
-	block := &Block{
-		Header: &Header{
-			Network:       "Tendermint",
-			Height:        RandUInt32Exp(),
-			Fees:          RandUInt64Exp(),
-			Time:          RandTime(),
-			LastBlockHash: RandBytes(32),
-			StateHash:     RandBytes(32),
-		},
-		Validation: &Validation{
-			Commits: []RoundSignature{randRoundSig(), randRoundSig()},
-		},
-		Data: &Data{
-			Txs: []Tx{sendTx, nameTx, bondTx, unbondTx, dupeoutTx},
-		},
-	}
-	return block
-}
-
-func TestBlock(t *testing.T) {
-
-	block := randBlock()
-	// Mutate the block and ensure that the hash changed.
-	lastHash := block.Hash()
-	expectChange := func(mutateFn func(b *Block), message string) {
-		// mutate block
-		mutateFn(block)
-		// nuke hashes
-		block.hash = nil
-		block.Header.hash = nil
-		block.Validation.hash = nil
-		block.Data.hash = nil
-		// compare
-		if bytes.Equal(lastHash, block.Hash()) {
-			t.Error(message)
-		} else {
-			lastHash = block.Hash()
-		}
-	}
-	expectChange(func(b *Block) { b.Header.Network = "blah" }, "Expected hash to depend on Network")
-	expectChange(func(b *Block) { b.Header.Height += 1 }, "Expected hash to depend on Height")
-	expectChange(func(b *Block) { b.Header.Fees += 1 }, "Expected hash to depend on Fees")
-	expectChange(func(b *Block) { b.Header.Time = RandTime() }, "Expected hash to depend on Time")
-	expectChange(func(b *Block) { b.Header.LastBlockHash = RandBytes(32) }, "Expected hash to depend on LastBlockHash")
-	expectChange(func(b *Block) { b.Header.StateHash = RandBytes(32) }, "Expected hash to depend on StateHash")
-	expectChange(func(b *Block) { b.Validation.Commits[0].Round += 1 }, "Expected hash to depend on Validation Commit")
-	expectChange(func(b *Block) { b.Validation.Commits[0].SignerId += 1 }, "Expected hash to depend on Validation Commit")
-	expectChange(func(b *Block) { b.Validation.Commits[0].Bytes = RandBytes(32) }, "Expected hash to depend on Validation Commit")
-	expectChange(func(b *Block) { b.Data.Txs[0].(*SendTx).Signature.SignerId += 1 }, "Expected hash to depend on tx Signature")
-	expectChange(func(b *Block) { b.Data.Txs[0].(*SendTx).Amount += 1 }, "Expected hash to depend on send tx Amount")
-
-	// Write the block, read it in again, check hash.
-	block1 := randBlock()
-	block1Bytes := BinaryBytes(block1)
-	var n int64
-	var err error
-	block2 := ReadBlock(bytes.NewReader(block1Bytes), &n, &err)
-	if err != nil {
-		t.Errorf("Reading block failed: %v", err)
-	}
-	if !bytes.Equal(block1.Hash(), block2.Hash()) {
-		t.Errorf("Expected write/read to preserve original hash")
-		t.Logf("\nBlock1:\n%v", block1)
-		t.Logf("\nBlock2:\n%v", block2)
-	}
-}
diff --git a/blocks/codec_test.go b/blocks/codec_test.go
deleted file mode 100644
index 32c10769..00000000
--- a/blocks/codec_test.go
+++ /dev/null
@@ -1,162 +0,0 @@
-package blocks
-
-import (
-	"bytes"
-	"encoding/gob"
-	"encoding/json"
-	"testing"
-	"time"
-
-	"github.com/ugorji/go/codec"
-	"github.com/vmihailenco/msgpack"
-)
-
-func BenchmarkTestCustom(b *testing.B) {
-	b.StopTimer()
-
-	h := &Header{
-		Network:       "Header",
-		Height:        123,
-		Fees:          123,
-		Time:          time.Unix(123, 0),
-		LastBlockHash: []byte("prevhash"),
-		StateHash:     []byte("statehash"),
-	}
-
-	buf := bytes.NewBuffer(nil)
-
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		buf.Reset()
-		h.WriteTo(buf)
-		var n int64
-		var err error
-		h2 := ReadHeader(buf, &n, &err)
-		if h2.Network != "Header" {
-			b.Fatalf("wrong name")
-		}
-	}
-}
-
-type HHeader struct {
-	Network       string `json:"N"`
-	Height        uint64 `json:"H"`
-	Fees          uint64 `json:"F"`
-	Time          uint64 `json:"T"`
-	LastBlockHash []byte `json:"PH"`
-	StateHash     []byte `json:"SH"`
-}
-
-func BenchmarkTestJSON(b *testing.B) {
-	b.StopTimer()
-
-	h := &HHeader{
-		Network:       "Header",
-		Height:        123,
-		Fees:          123,
-		Time:          123,
-		LastBlockHash: []byte("prevhash"),
-		StateHash:     []byte("statehash"),
-	}
-	h2 := &HHeader{}
-
-	buf := bytes.NewBuffer(nil)
-	enc := json.NewEncoder(buf)
-	dec := json.NewDecoder(buf)
-
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		buf.Reset()
-		enc.Encode(h)
-		dec.Decode(h2)
-		if h2.Network != "Header" {
-			b.Fatalf("wrong name")
-		}
-	}
-}
-
-func BenchmarkTestGob(b *testing.B) {
-	b.StopTimer()
-
-	h := &Header{
-		Network:       "Header",
-		Height:        123,
-		Fees:          123,
-		Time:          time.Unix(123, 0),
-		LastBlockHash: []byte("prevhash"),
-		StateHash:     []byte("statehash"),
-	}
-	h2 := &Header{}
-
-	buf := bytes.NewBuffer(nil)
-	enc := gob.NewEncoder(buf)
-	dec := gob.NewDecoder(buf)
-
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		buf.Reset()
-		enc.Encode(h)
-		dec.Decode(h2)
-		if h2.Network != "Header" {
-			b.Fatalf("wrong name")
-		}
-	}
-}
-
-func BenchmarkTestMsgPack(b *testing.B) {
-	b.StopTimer()
-
-	h := &Header{
-		Network:       "Header",
-		Height:        123,
-		Fees:          123,
-		Time:          time.Unix(123, 0),
-		LastBlockHash: []byte("prevhash"),
-		StateHash:     []byte("statehash"),
-	}
-	h2 := &Header{}
-
-	buf := bytes.NewBuffer(nil)
-	enc := msgpack.NewEncoder(buf)
-	dec := msgpack.NewDecoder(buf)
-
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		buf.Reset()
-		enc.Encode(h)
-		dec.Decode(h2)
-		if h2.Network != "Header" {
-			b.Fatalf("wrong name")
-		}
-	}
-}
-
-func BenchmarkTestMsgPack2(b *testing.B) {
-	b.StopTimer()
-
-	h := &Header{
-		Network:       "Header",
-		Height:        123,
-		Fees:          123,
-		Time:          time.Unix(123, 0),
-		LastBlockHash: []byte("prevhash"),
-		StateHash:     []byte("statehash"),
-	}
-	h2 := &Header{}
-	var mh codec.MsgpackHandle
-	handle := &mh
-
-	buf := bytes.NewBuffer(nil)
-	enc := codec.NewEncoder(buf, handle)
-	dec := codec.NewDecoder(buf, handle)
-
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		buf.Reset()
-		enc.Encode(h)
-		dec.Decode(h2)
-		if h2.Network != "Header" {
-			b.Fatalf("wrong name")
-		}
-	}
-}
diff --git a/blocks/part_set.go b/blocks/part_set.go
index 7254a38f..a43ec0c3 100644
--- a/blocks/part_set.go
+++ b/blocks/part_set.go
@@ -9,7 +9,6 @@ import (
 	"strings"
 	"sync"
 
-	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/merkle"
 )
@@ -24,7 +23,7 @@ var (
 )
 
 type Part struct {
-	Index uint16
+	Index uint
 	Trail [][]byte
 	Bytes []byte
 
@@ -32,21 +31,6 @@ type Part struct {
 	hash []byte
 }
 
-func ReadPart(r io.Reader, n *int64, err *error) *Part {
-	return &Part{
-		Index: ReadUInt16(r, n, err),
-		Trail: ReadByteSlices(r, n, err),
-		Bytes: ReadByteSlice(r, n, err),
-	}
-}
-
-func (part *Part) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt16(w, part.Index, &n, &err)
-	WriteByteSlices(w, part.Trail, &n, &err)
-	WriteByteSlice(w, part.Bytes, &n, &err)
-	return
-}
-
 func (part *Part) Hash() []byte {
 	if part.hash != nil {
 		return part.hash
@@ -84,23 +68,10 @@ func (part *Part) StringWithIndent(indent string) string {
 //-------------------------------------
 
 type PartSetHeader struct {
-	Total uint16
+	Total uint
 	Hash  []byte
 }
 
-func ReadPartSetHeader(r io.Reader, n *int64, err *error) PartSetHeader {
-	return PartSetHeader{
-		Total: ReadUInt16(r, n, err),
-		Hash:  ReadByteSlice(r, n, err),
-	}
-}
-
-func (psh PartSetHeader) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt16(w, psh.Total, &n, &err)
-	WriteByteSlice(w, psh.Hash, &n, &err)
-	return
-}
-
 func (psh PartSetHeader) String() string {
 	return fmt.Sprintf("PartSet{T:%v %X}", psh.Total, Fingerprint(psh.Hash))
 }
@@ -116,13 +87,13 @@ func (psh PartSetHeader) Equals(other PartSetHeader) bool {
 //-------------------------------------
 
 type PartSet struct {
-	total uint16
+	total uint
 	hash  []byte
 
 	mtx           sync.Mutex
 	parts         []*Part
 	partsBitArray BitArray
-	count         uint16
+	count         uint
 }
 
 // Returns an immutable, full PartSet.
@@ -135,7 +106,7 @@ func NewPartSetFromData(data []byte) *PartSet {
 	partsBitArray := NewBitArray(uint(total))
 	for i := 0; i < total; i++ {
 		part := &Part{
-			Index: uint16(i),
+			Index: uint(i),
 			Bytes: data[i*partSize : MinInt(len(data), (i+1)*partSize)],
 		}
 		parts[i] = part
@@ -148,11 +119,11 @@ func NewPartSetFromData(data []byte) *PartSet {
 		parts[i].Trail = trails[i].Flatten()
 	}
 	return &PartSet{
-		total:         uint16(total),
+		total:         uint(total),
 		hash:          rootTrail.Hash,
 		parts:         parts,
 		partsBitArray: partsBitArray,
-		count:         uint16(total),
+		count:         uint(total),
 	}
 }
 
@@ -207,14 +178,14 @@ func (ps *PartSet) HashesTo(hash []byte) bool {
 	return bytes.Equal(ps.hash, hash)
 }
 
-func (ps *PartSet) Count() uint16 {
+func (ps *PartSet) Count() uint {
 	if ps == nil {
 		return 0
 	}
 	return ps.count
 }
 
-func (ps *PartSet) Total() uint16 {
+func (ps *PartSet) Total() uint {
 	if ps == nil {
 		return 0
 	}
@@ -247,7 +218,7 @@ func (ps *PartSet) AddPart(part *Part) (bool, error) {
 	return true, nil
 }
 
-func (ps *PartSet) GetPart(index uint16) *Part {
+func (ps *PartSet) GetPart(index uint) *Part {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 	return ps.parts[index]
diff --git a/blocks/part_set_test.go b/blocks/part_set_test.go
index 60e929f7..22c7e219 100644
--- a/blocks/part_set_test.go
+++ b/blocks/part_set_test.go
@@ -27,7 +27,7 @@ func TestBasicPartSet(t *testing.T) {
 	// Test adding parts to a new partSet.
 	partSet2 := NewPartSetFromHeader(partSet.Header())
 
-	for i := uint16(0); i < partSet.Total(); i++ {
+	for i := uint(0); i < partSet.Total(); i++ {
 		part := partSet.GetPart(i)
 		//t.Logf("\n%v", part)
 		added, err := partSet2.AddPart(part)
diff --git a/blocks/signature.go b/blocks/signature.go
deleted file mode 100644
index 6f90ffd4..00000000
--- a/blocks/signature.go
+++ /dev/null
@@ -1,111 +0,0 @@
-package blocks
-
-import (
-	"fmt"
-	"io"
-
-	. "github.com/tendermint/tendermint/binary"
-	. "github.com/tendermint/tendermint/common"
-)
-
-type Signable interface {
-	Binary
-	GetSignature() Signature
-	SetSignature(Signature)
-}
-
-//-----------------------------------------------------------------------------
-
-type Signature struct {
-	SignerId uint64
-	Bytes    []byte
-}
-
-func ReadSignature(r io.Reader, n *int64, err *error) Signature {
-	return Signature{
-		SignerId: ReadUInt64(r, n, err),
-		Bytes:    ReadByteSlice(r, n, err),
-	}
-}
-
-func (sig Signature) IsZero() bool {
-	return len(sig.Bytes) == 0
-}
-
-func (sig Signature) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt64(w, sig.SignerId, &n, &err)
-	WriteByteSlice(w, sig.Bytes, &n, &err)
-	return
-}
-
-func (sig Signature) String() string {
-	return fmt.Sprintf("Signature{Id:%v %X}", sig.SignerId, Fingerprint(sig.Bytes))
-}
-
-//-------------------------------------
-
-func ReadSignatures(r io.Reader, n *int64, err *error) (sigs []Signature) {
-	length := ReadUInt32(r, n, err)
-	for i := uint32(0); i < length; i++ {
-		sigs = append(sigs, ReadSignature(r, n, err))
-	}
-	return
-}
-
-func WriteSignatures(w io.Writer, sigs []Signature, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(sigs)), n, err)
-	for _, sig := range sigs {
-		WriteBinary(w, sig, n, err)
-		if *err != nil {
-			return
-		}
-	}
-}
-
-//-----------------------------------------------------------------------------
-
-type RoundSignature struct {
-	Round uint16
-	Signature
-}
-
-func ReadRoundSignature(r io.Reader, n *int64, err *error) RoundSignature {
-	return RoundSignature{
-		ReadUInt16(r, n, err),
-		ReadSignature(r, n, err),
-	}
-}
-
-func (rsig RoundSignature) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt16(w, rsig.Round, &n, &err)
-	WriteBinary(w, rsig.Signature, &n, &err)
-	return
-}
-
-func (rsig RoundSignature) IsZero() bool {
-	return rsig.Round == 0 && rsig.SignerId == 0 && len(rsig.Bytes) == 0
-}
-
-func (rsig RoundSignature) String() string {
-	return fmt.Sprintf("RoundSignature{R:%v Id:%v %X}", rsig.Round, rsig.SignerId, Fingerprint(rsig.Bytes))
-}
-
-//-------------------------------------
-
-func ReadRoundSignatures(r io.Reader, n *int64, err *error) (rsigs []RoundSignature) {
-	length := ReadUInt32(r, n, err)
-	for i := uint32(0); i < length; i++ {
-		rsigs = append(rsigs, ReadRoundSignature(r, n, err))
-	}
-	return
-}
-
-func WriteRoundSignatures(w io.Writer, rsigs []RoundSignature, n *int64, err *error) {
-	WriteUInt32(w, uint32(len(rsigs)), n, err)
-	for _, rsig := range rsigs {
-		WriteBinary(w, rsig, n, err)
-		if *err != nil {
-			return
-		}
-	}
-}
diff --git a/blocks/store.go b/blocks/store.go
index 67bba864..53aadcf0 100644
--- a/blocks/store.go
+++ b/blocks/store.go
@@ -2,8 +2,8 @@ package blocks
 
 import (
 	"bytes"
-	"encoding/binary"
 	"encoding/json"
+	"fmt"
 	"io"
 
 	. "github.com/tendermint/tendermint/binary"
@@ -17,7 +17,7 @@ import (
 Simple low level store for blocks, which is actually stored as separte parts (wire format).
 */
 type BlockStore struct {
-	height uint32
+	height uint
 	db     db_.DB
 }
 
@@ -30,7 +30,7 @@ func NewBlockStore(db db_.DB) *BlockStore {
 }
 
 // Height() returns the last known contiguous block height.
-func (bs *BlockStore) Height() uint32 {
+func (bs *BlockStore) Height() uint {
 	return bs.height
 }
 
@@ -42,49 +42,49 @@ func (bs *BlockStore) GetReader(key []byte) io.Reader {
 	return bytes.NewReader(bytez)
 }
 
-func (bs *BlockStore) LoadBlock(height uint32) *Block {
+func (bs *BlockStore) LoadBlock(height uint) *Block {
 	var n int64
 	var err error
-	meta := ReadBlockMeta(bs.GetReader(calcBlockMetaKey(height)), &n, &err)
+	meta := ReadBinary(&BlockMeta{}, bs.GetReader(calcBlockMetaKey(height)), &n, &err).(*BlockMeta)
 	if err != nil {
 		Panicf("Error reading block meta: %v", err)
 	}
 	bytez := []byte{}
-	for i := uint16(0); i < meta.Parts.Total; i++ {
+	for i := uint(0); i < meta.Parts.Total; i++ {
 		part := bs.LoadBlockPart(height, i)
 		bytez = append(bytez, part.Bytes...)
 	}
-	block := ReadBlock(bytes.NewReader(bytez), &n, &err)
+	block := ReadBinary(&Block{}, bytes.NewReader(bytez), &n, &err).(*Block)
 	if err != nil {
 		Panicf("Error reading block: %v", err)
 	}
 	return block
 }
 
-func (bs *BlockStore) LoadBlockPart(height uint32, index uint16) *Part {
+func (bs *BlockStore) LoadBlockPart(height uint, index uint) *Part {
 	var n int64
 	var err error
-	part := ReadPart(bs.GetReader(calcBlockPartKey(height, index)), &n, &err)
+	part := ReadBinary(&Part{}, bs.GetReader(calcBlockPartKey(height, index)), &n, &err).(*Part)
 	if err != nil {
 		Panicf("Error reading block part: %v", err)
 	}
 	return part
 }
 
-func (bs *BlockStore) LoadBlockMeta(height uint32) *BlockMeta {
+func (bs *BlockStore) LoadBlockMeta(height uint) *BlockMeta {
 	var n int64
 	var err error
-	meta := ReadBlockMeta(bs.GetReader(calcBlockMetaKey(height)), &n, &err)
+	meta := ReadBinary(&BlockMeta{}, bs.GetReader(calcBlockMetaKey(height)), &n, &err).(*BlockMeta)
 	if err != nil {
 		Panicf("Error reading block meta: %v", err)
 	}
 	return meta
 }
 
-func (bs *BlockStore) LoadBlockValidation(height uint32) *Validation {
+func (bs *BlockStore) LoadBlockValidation(height uint) *Validation {
 	var n int64
 	var err error
-	validation := ReadValidation(bs.GetReader(calcBlockValidationKey(height)), &n, &err)
+	validation := ReadBinary(&Validation{}, bs.GetReader(calcBlockValidationKey(height)), &n, &err).(*Validation)
 	if err != nil {
 		Panicf("Error reading validation: %v", err)
 	}
@@ -108,7 +108,7 @@ func (bs *BlockStore) SaveBlock(block *Block, blockParts *PartSet) {
 	metaBytes := BinaryBytes(meta)
 	bs.db.Set(calcBlockMetaKey(height), metaBytes)
 	// Save block parts
-	for i := uint16(0); i < blockParts.Total(); i++ {
+	for i := uint(0); i < blockParts.Total(); i++ {
 		bs.saveBlockPart(height, i, blockParts.GetPart(i))
 	}
 	// Save block validation (duplicate and separate)
@@ -120,7 +120,7 @@ func (bs *BlockStore) SaveBlock(block *Block, blockParts *PartSet) {
 	bs.height = height
 }
 
-func (bs *BlockStore) saveBlockPart(height uint32, index uint16, part *Part) {
+func (bs *BlockStore) saveBlockPart(height uint, index uint, part *Part) {
 	if height != bs.height+1 {
 		Panicf("BlockStore can only save contiguous blocks. Wanted %v, got %v", bs.height+1, height)
 	}
@@ -136,40 +136,18 @@ type BlockMeta struct {
 	Header *Header       // The block's Header
 }
 
-func ReadBlockMeta(r io.Reader, n *int64, err *error) *BlockMeta {
-	return &BlockMeta{
-		Hash:   ReadByteSlice(r, n, err),
-		Parts:  ReadPartSetHeader(r, n, err),
-		Header: ReadHeader(r, n, err),
-	}
-}
-
-func (bm *BlockMeta) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByteSlice(w, bm.Hash, &n, &err)
-	WriteBinary(w, bm.Parts, &n, &err)
-	WriteBinary(w, bm.Header, &n, &err)
-	return
-}
-
 //-----------------------------------------------------------------------------
 
-func calcBlockMetaKey(height uint32) []byte {
-	buf := [5]byte{'H'}
-	binary.BigEndian.PutUint32(buf[1:5], height)
-	return buf[:]
+func calcBlockMetaKey(height uint) []byte {
+	return []byte(fmt.Sprintf("H:%v", height))
 }
 
-func calcBlockPartKey(height uint32, partIndex uint16) []byte {
-	buf := [7]byte{'P'}
-	binary.BigEndian.PutUint32(buf[1:5], height)
-	binary.BigEndian.PutUint16(buf[5:7], partIndex)
-	return buf[:]
+func calcBlockPartKey(height uint, partIndex uint) []byte {
+	return []byte(fmt.Sprintf("P:%v:%v", height, partIndex))
 }
 
-func calcBlockValidationKey(height uint32) []byte {
-	buf := [5]byte{'V'}
-	binary.BigEndian.PutUint32(buf[1:5], height)
-	return buf[:]
+func calcBlockValidationKey(height uint) []byte {
+	return []byte(fmt.Sprintf("V:%v", height))
 }
 
 //-----------------------------------------------------------------------------
@@ -177,7 +155,7 @@ func calcBlockValidationKey(height uint32) []byte {
 var blockStoreKey = []byte("blockStore")
 
 type BlockStoreJSON struct {
-	Height uint32
+	Height uint
 }
 
 func (bsj BlockStoreJSON) Save(db db_.DB) {
diff --git a/blocks/tx.go b/blocks/tx.go
index 96063e8e..edbdd8ff 100644
--- a/blocks/tx.go
+++ b/blocks/tx.go
@@ -1,35 +1,33 @@
 package blocks
 
 import (
-	"fmt"
+	"errors"
 	"io"
+	"reflect"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
 )
 
 /*
+Tx (Transaction) is an atomic operation on the ledger state.
+
 Account Txs:
-1. Send			Send coins to account
-2. Name			Associate account with a name
+1. SendTx			Send coins to address
 
 Validation Txs:
-3. Bond         New validator posts a bond
-4. Unbond       Validator leaves
-5. Dupeout      Validator dupes out (signs twice)
+1. BondTx         New validator posts a bond
+2. UnbondTx       Validator leaves
+3. DupeoutTx      Validator dupes out (equivocates)
 */
-
 type Tx interface {
-	Signable
-	GetSequence() uint
-	GetFee() uint64
-	String() string
+	WriteSignBytes(w io.Writer, n *int64, err *error)
 }
 
 const (
 	// Account transactions
 	TxTypeSend = byte(0x01)
-	TxTypeName = byte(0x02)
 
 	// Validation transactions
 	TxTypeBond    = byte(0x11)
@@ -37,174 +35,150 @@ const (
 	TxTypeDupeout = byte(0x13)
 )
 
-func ReadTx(r io.Reader, n *int64, err *error) Tx {
+var (
+	ErrTxInvalidAddress    = errors.New("Error invalid address")
+	ErrTxDuplicateAddress  = errors.New("Error duplicate address")
+	ErrTxInvalidAmount     = errors.New("Error invalid amount")
+	ErrTxInsufficientFunds = errors.New("Error insufficient funds")
+	ErrTxInvalidSignature  = errors.New("Error invalid signature")
+	ErrTxInvalidSequence   = errors.New("Error invalid sequence")
+)
+
+func TxDecoder(r io.Reader, n *int64, err *error) interface{} {
 	switch t := ReadByte(r, n, err); t {
 	case TxTypeSend:
-		return &SendTx{
-			BaseTx: ReadBaseTx(r, n, err),
-			To:     ReadUInt64(r, n, err),
-			Amount: ReadUInt64(r, n, err),
-		}
-	case TxTypeName:
-		return &NameTx{
-			BaseTx: ReadBaseTx(r, n, err),
-			Name:   ReadString(r, n, err),
-			PubKey: ReadByteSlice(r, n, err),
-		}
+		return ReadBinary(&SendTx{}, r, n, err)
 	case TxTypeBond:
-		return &BondTx{
-			BaseTx: ReadBaseTx(r, n, err),
-			//UnbondTo: ReadUInt64(r, n, err),
-		}
+		return ReadBinary(&BondTx{}, r, n, err)
 	case TxTypeUnbond:
-		return &UnbondTx{
-			BaseTx: ReadBaseTx(r, n, err),
-		}
+		return ReadBinary(&UnbondTx{}, r, n, err)
 	case TxTypeDupeout:
-		return &DupeoutTx{
-			BaseTx: ReadBaseTx(r, n, err),
-			VoteA:  *ReadVote(r, n, err),
-			VoteB:  *ReadVote(r, n, err),
-		}
+		return ReadBinary(&DupeoutTx{}, r, n, err)
 	default:
 		*err = Errorf("Unknown Tx type %X", t)
 		return nil
 	}
 }
 
+var _ = RegisterType(&TypeInfo{
+	Type:    reflect.TypeOf((*Tx)(nil)).Elem(),
+	Decoder: TxDecoder,
+})
+
 //-----------------------------------------------------------------------------
 
-type BaseTx struct {
-	Sequence  uint
-	Fee       uint64
-	Signature Signature
+type TxInput struct {
+	Address   []byte           // Hash of the PubKey
+	Amount    uint64           // Must not exceed account balance
+	Sequence  uint             // Must be 1 greater than the last committed TxInput
+	Signature Signature // Depends on the PubKey type and the whole Tx
 }
 
-func ReadBaseTx(r io.Reader, n *int64, err *error) BaseTx {
-	return BaseTx{
-		Sequence:  ReadUVarInt(r, n, err),
-		Fee:       ReadUInt64(r, n, err),
-		Signature: ReadSignature(r, n, err),
+func (txIn *TxInput) ValidateBasic() error {
+	if len(txIn.Address) != 20 {
+		return ErrTxInvalidAddress
 	}
+	if txIn.Amount == 0 {
+		return ErrTxInvalidAmount
+	}
+	return nil
 }
 
-func (tx BaseTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUVarInt(w, tx.Sequence, &n, &err)
-	WriteUInt64(w, tx.Fee, &n, &err)
-	WriteBinary(w, tx.Signature, &n, &err)
-	return
+func (txIn *TxInput) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteByteSlice(txIn.Address, w, n, err)
+	WriteUInt64(txIn.Amount, w, n, err)
+	WriteUVarInt(txIn.Sequence, w, n, err)
 }
 
-func (tx *BaseTx) GetSequence() uint {
-	return tx.Sequence
+//-----------------------------------------------------------------------------
+
+type TxOutput struct {
+	Address []byte // Hash of the PubKey
+	Amount  uint64 // The sum of all outputs must not exceed the inputs.
 }
 
-func (tx *BaseTx) GetSignature() Signature {
-	return tx.Signature
+func (txOut *TxOutput) ValidateBasic() error {
+	if len(txOut.Address) != 20 {
+		return ErrTxInvalidAddress
+	}
+	if txOut.Amount == 0 {
+		return ErrTxInvalidAmount
+	}
+	return nil
 }
 
-func (tx *BaseTx) GetFee() uint64 {
-	return tx.Fee
-}
-
-func (tx *BaseTx) SetSignature(sig Signature) {
-	tx.Signature = sig
-}
-
-func (tx *BaseTx) String() string {
-	return fmt.Sprintf("{S:%v F:%v Sig:%X}", tx.Sequence, tx.Fee, tx.Signature)
+func (txOut *TxOutput) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteByteSlice(txOut.Address, w, n, err)
+	WriteUInt64(txOut.Amount, w, n, err)
 }
 
 //-----------------------------------------------------------------------------
 
 type SendTx struct {
-	BaseTx
-	To     uint64
-	Amount uint64
+	Inputs  []*TxInput
+	Outputs []*TxOutput
 }
 
-func (tx *SendTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, TxTypeSend, &n, &err)
-	WriteBinary(w, tx.BaseTx, &n, &err)
-	WriteUInt64(w, tx.To, &n, &err)
-	WriteUInt64(w, tx.Amount, &n, &err)
-	return
-}
+func (tx *SendTx) TypeByte() byte { return TxTypeSend }
 
-func (tx *SendTx) String() string {
-	return fmt.Sprintf("SendTx{%v To:%v Amount:%v}", tx.BaseTx, tx.To, tx.Amount)
-}
-
-//-----------------------------------------------------------------------------
-
-type NameTx struct {
-	BaseTx
-	Name   string
-	PubKey []byte
-}
-
-func (tx *NameTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, TxTypeName, &n, &err)
-	WriteBinary(w, tx.BaseTx, &n, &err)
-	WriteString(w, tx.Name, &n, &err)
-	WriteByteSlice(w, tx.PubKey, &n, &err)
-	return
-}
-
-func (tx *NameTx) String() string {
-	return fmt.Sprintf("NameTx{%v Name:%v PubKey:%X}", tx.BaseTx, tx.Name, tx.PubKey)
+func (tx *SendTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteUVarInt(uint(len(tx.Inputs)), w, n, err)
+	for _, in := range tx.Inputs {
+		in.WriteSignBytes(w, n, err)
+	}
+	WriteUVarInt(uint(len(tx.Outputs)), w, n, err)
+	for _, out := range tx.Outputs {
+		out.WriteSignBytes(w, n, err)
+	}
 }
 
 //-----------------------------------------------------------------------------
 
 type BondTx struct {
-	BaseTx
-	//UnbondTo uint64
+	PubKey   PubKeyEd25519
+	Inputs   []*TxInput
+	UnbondTo []*TxOutput
 }
 
-func (tx *BondTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, TxTypeBond, &n, &err)
-	WriteBinary(w, tx.BaseTx, &n, &err)
-	//WriteUInt64(w, tx.UnbondTo, &n, &err)
-	return
-}
+func (tx *BondTx) TypeByte() byte { return TxTypeBond }
 
-func (tx *BondTx) String() string {
-	return fmt.Sprintf("BondTx{%v}", tx.BaseTx)
+func (tx *BondTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteBinary(tx.PubKey, w, n, err)
+	WriteUVarInt(uint(len(tx.Inputs)), w, n, err)
+	for _, in := range tx.Inputs {
+		in.WriteSignBytes(w, n, err)
+	}
+	WriteUVarInt(uint(len(tx.UnbondTo)), w, n, err)
+	for _, out := range tx.UnbondTo {
+		out.WriteSignBytes(w, n, err)
+	}
 }
 
 //-----------------------------------------------------------------------------
 
 type UnbondTx struct {
-	BaseTx
+	Address   []byte
+	Height    uint
+	Signature SignatureEd25519
 }
 
-func (tx *UnbondTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, TxTypeUnbond, &n, &err)
-	WriteBinary(w, tx.BaseTx, &n, &err)
-	return
-}
+func (tx *UnbondTx) TypeByte() byte { return TxTypeUnbond }
 
-func (tx *UnbondTx) String() string {
-	return fmt.Sprintf("UnbondTx{%v}", tx.BaseTx)
+func (tx *UnbondTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteByteSlice(tx.Address, w, n, err)
+	WriteUVarInt(tx.Height, w, n, err)
 }
 
 //-----------------------------------------------------------------------------
 
 type DupeoutTx struct {
-	BaseTx
-	VoteA Vote
-	VoteB Vote
+	Address []byte
+	VoteA   Vote
+	VoteB   Vote
 }
 
-func (tx *DupeoutTx) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, TxTypeDupeout, &n, &err)
-	WriteBinary(w, tx.BaseTx, &n, &err)
-	WriteBinary(w, &tx.VoteA, &n, &err)
-	WriteBinary(w, &tx.VoteB, &n, &err)
-	return
-}
+func (tx *DupeoutTx) TypeByte() byte { return TxTypeDupeout }
 
-func (tx *DupeoutTx) String() string {
-	return fmt.Sprintf("DupeoutTx{%v VoteA:%v VoteB:%v}", tx.BaseTx, tx.VoteA, tx.VoteB)
+func (tx *DupeoutTx) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	panic("DupeoutTx has no sign bytes")
 }
diff --git a/blocks/vote.go b/blocks/vote.go
index c44ffd27..c4f892aa 100644
--- a/blocks/vote.go
+++ b/blocks/vote.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
 )
@@ -23,53 +24,34 @@ var (
 	ErrVoteConflictingSignature = errors.New("Conflicting round vote signature")
 )
 
-// Represents a prevote, precommit, or commit vote for proposals.
+// Represents a prevote, precommit, or commit vote for proposals from validators.
+// Commit votes get aggregated into the next block's Validaiton.
+// See the whitepaper for details.
 type Vote struct {
-	Height     uint32
-	Round      uint16
+	Height     uint
+	Round      uint
 	Type       byte
 	BlockHash  []byte        // empty if vote is nil.
 	BlockParts PartSetHeader // zero if vote is nil.
-	Signature
+	Signature  SignatureEd25519
 }
 
-func ReadVote(r io.Reader, n *int64, err *error) *Vote {
-	return &Vote{
-		Height:     ReadUInt32(r, n, err),
-		Round:      ReadUInt16(r, n, err),
-		Type:       ReadByte(r, n, err),
-		BlockHash:  ReadByteSlice(r, n, err),
-		BlockParts: ReadPartSetHeader(r, n, err),
-		Signature:  ReadSignature(r, n, err),
-	}
+func (vote *Vote) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteUVarInt(vote.Height, w, n, err)
+	WriteUVarInt(vote.Round, w, n, err)
+	WriteByte(vote.Type, w, n, err)
+	WriteByteSlice(vote.BlockHash, w, n, err)
+	WriteBinary(vote.BlockParts, w, n, err)
 }
 
-func (v *Vote) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt32(w, v.Height, &n, &err)
-	WriteUInt16(w, v.Round, &n, &err)
-	WriteByte(w, v.Type, &n, &err)
-	WriteByteSlice(w, v.BlockHash, &n, &err)
-	WriteBinary(w, v.BlockParts, &n, &err)
-	WriteBinary(w, v.Signature, &n, &err)
-	return
+func (vote *Vote) Copy() *Vote {
+	voteCopy := *vote
+	return &voteCopy
 }
 
-func (v *Vote) GetSignature() Signature {
-	return v.Signature
-}
-
-func (v *Vote) SetSignature(sig Signature) {
-	v.Signature = sig
-}
-
-func (v *Vote) Copy() *Vote {
-	vCopy := *v
-	return &vCopy
-}
-
-func (v *Vote) String() string {
+func (vote *Vote) String() string {
 	var typeString string
-	switch v.Type {
+	switch vote.Type {
 	case VoteTypePrevote:
 		typeString = "Prevote"
 	case VoteTypePrecommit:
@@ -80,5 +62,5 @@ func (v *Vote) String() string {
 		panic("Unknown vote type")
 	}
 
-	return fmt.Sprintf("%v{%v/%v %X#%v %v}", typeString, v.Height, v.Round, Fingerprint(v.BlockHash), v.BlockParts, v.Signature)
+	return fmt.Sprintf("%v{%v/%v %X#%v %v}", typeString, vote.Height, vote.Round, Fingerprint(vote.BlockHash), vote.BlockParts, vote.Signature)
 }
diff --git a/cmd/daemon.go b/cmd/daemon.go
index 6e9022fc..dce8c47a 100644
--- a/cmd/daemon.go
+++ b/cmd/daemon.go
@@ -33,20 +33,18 @@ func NewNode() *Node {
 	stateDB := db_.NewMemDB() // TODO configurable db.
 	state := state_.LoadState(stateDB)
 	if state == nil {
-		state = state_.GenesisStateFromFile(stateDB, config.RootDir+"/genesis.json")
+		state = state_.GenesisStateFromFile(stateDB, config.GenesisFile())
 		state.Save()
 	}
 
-	// Get PrivAccount
+	// Get PrivValidator
 	var privValidator *consensus.PrivValidator
-	if _, err := os.Stat(config.RootDir + "/private.json"); err == nil {
-		privAccount := state_.PrivAccountFromFile(config.RootDir + "/private.json")
-		privValidatorDB := db_.NewMemDB() // TODO configurable db.
-		privValidator = consensus.NewPrivValidator(privValidatorDB, privAccount)
+	if _, err := os.Stat(config.PrivValidatorFile()); err == nil {
+		privValidator = consensus.LoadPrivValidator()
 	}
 
 	// Get PEXReactor
-	book := p2p.NewAddrBook(config.RootDir + "/addrbook.json")
+	book := p2p.NewAddrBook(config.AddrBookFile())
 	pexReactor := p2p.NewPEXReactor(book)
 
 	// Get MempoolReactor
diff --git a/cmd/gen_account.go b/cmd/gen_account.go
index e2355dbb..371e7cf5 100644
--- a/cmd/gen_account.go
+++ b/cmd/gen_account.go
@@ -4,13 +4,15 @@ import (
 	"encoding/base64"
 	"fmt"
 
-	"github.com/tendermint/tendermint/state"
+	. "github.com/tendermint/tendermint/binary"
+	"github.com/tendermint/tendermint/wallet"
 )
 
 func gen_account() {
 
+	// TODO: uh, write better logic.
 	// Generate private account
-	privAccount := state.GenPrivAccount()
+	privAccount := wallet.GenPrivAccount()
 
 	fmt.Printf(`Generated account:
 Account Public Key:  %X
@@ -19,7 +21,7 @@ Account Private Key: %X
             (base64) %v
 `,
 		privAccount.PubKey,
-		base64.StdEncoding.EncodeToString(privAccount.PubKey),
+		base64.StdEncoding.EncodeToString(BinaryBytes(privAccount.PubKey)),
 		privAccount.PrivKey,
-		base64.StdEncoding.EncodeToString(privAccount.PrivKey))
+		base64.StdEncoding.EncodeToString(BinaryBytes(privAccount.PrivKey)))
 }
diff --git a/cmd/gen_validator.go b/cmd/gen_validator.go
new file mode 100644
index 00000000..14d822fd
--- /dev/null
+++ b/cmd/gen_validator.go
@@ -0,0 +1,23 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/tendermint/tendermint/config"
+	"github.com/tendermint/tendermint/consensus"
+)
+
+func gen_validator() {
+
+	// If already exists, bail out.
+	filename := config.PrivValidatorFile()
+	if _, err := os.Stat(filename); !os.IsNotExist(err) {
+		fmt.Printf("Cannot generate new validator, file already exists at %v\n", filename)
+	}
+
+	// Generate private validator
+	privValidator := consensus.GenPrivValidator()
+	privValidator.Save()
+	fmt.Printf("Generated a new validator at %v\n", filename)
+}
diff --git a/cmd/main.go b/cmd/main.go
index b804c0c3..161ab4c7 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -19,6 +19,7 @@ func main() {
 Commands:
     daemon        Run the tendermint node daemon
     gen_account   Generate new account keypair
+    gen_validator Generate new validator keypair
 	
 tendermint --help for command options`)
 		return
@@ -29,5 +30,7 @@ tendermint --help for command options`)
 		daemon()
 	case "gen_account":
 		gen_account()
+	case "gen_validator":
+		gen_validator()
 	}
 }
diff --git a/common/bit_array.go b/common/bit_array.go
index 3d46184f..86ef2e4d 100644
--- a/common/bit_array.go
+++ b/common/bit_array.go
@@ -2,11 +2,8 @@ package common
 
 import (
 	"fmt"
-	"io"
 	"math/rand"
 	"strings"
-
-	. "github.com/tendermint/tendermint/binary"
 )
 
 // Not goroutine safe
@@ -19,47 +16,6 @@ func NewBitArray(bits uint) BitArray {
 	return BitArray{bits, make([]uint64, (bits+63)/64)}
 }
 
-func ReadBitArray(r io.Reader, n *int64, err *error) BitArray {
-	bits := ReadUVarInt(r, n, err)
-	if bits == 0 {
-		return BitArray{}
-	}
-	elemsWritten := ReadUVarInt(r, n, err)
-	if *err != nil {
-		return BitArray{}
-	}
-	bA := NewBitArray(bits)
-	for i := uint(0); i < elemsWritten; i++ {
-		bA.elems[i] = ReadUInt64(r, n, err)
-		if *err != nil {
-			return BitArray{}
-		}
-	}
-	return bA
-}
-
-func (bA BitArray) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUVarInt(w, bA.bits, &n, &err)
-	if bA.bits == 0 {
-		return
-	}
-	// Count the last element > 0.
-	elemsToWrite := 0
-	for i, elem := range bA.elems {
-		if elem > 0 {
-			elemsToWrite = i + 1
-		}
-	}
-	WriteUVarInt(w, uint(elemsToWrite), &n, &err)
-	for i, elem := range bA.elems {
-		if i >= elemsToWrite {
-			break
-		}
-		WriteUInt64(w, elem, &n, &err)
-	}
-	return
-}
-
 func (bA BitArray) Size() uint {
 	return bA.bits
 }
diff --git a/config/config.go b/config/config.go
index 0785237f..b8743e41 100644
--- a/config/config.go
+++ b/config/config.go
@@ -12,8 +12,22 @@ import (
 	"strings"
 )
 
-var RootDir string
-var Config Config_
+var rootDir string
+
+func init() {
+	rootDir = os.Getenv("TMROOT")
+	if rootDir == "" {
+		rootDir = os.Getenv("HOME") + "/.tendermint"
+	}
+}
+
+func ConfigFile() string        { return rootDir + "/config.json" }
+func GenesisFile() string       { return rootDir + "/genesis.json" }
+func AddrBookFile() string      { return rootDir + "/addrbook.json" }
+func PrivValidatorFile() string { return rootDir + "/priv_validator.json" }
+func DataDir() string           { return rootDir + "/data" }
+
+var Config ConfigType
 
 func setFlags(printHelp *bool) {
 	flag.BoolVar(printHelp, "help", false, "Print this help message.")
@@ -22,11 +36,7 @@ func setFlags(printHelp *bool) {
 }
 
 func ParseFlags() {
-	RootDir = os.Getenv("TMROOT")
-	if RootDir == "" {
-		RootDir = os.Getenv("HOME") + "/.tendermint"
-	}
-	configFile := RootDir + "/config.json"
+	configFile := ConfigFile()
 
 	// try to read configuration. if missing, write default
 	configBytes, err := ioutil.ReadFile(configFile)
@@ -38,7 +48,7 @@ func ParseFlags() {
 	}
 
 	// try to parse configuration. on error, die
-	Config = Config_{}
+	Config = ConfigType{}
 	err = json.Unmarshal(configBytes, &Config)
 	if err != nil {
 		log.Panicf("Invalid configuration file %s: %v", configFile, err)
@@ -61,13 +71,13 @@ func ParseFlags() {
 //-----------------------------------------------------------------------------j
 // Default configuration
 
-var defaultConfig = Config_{
+var defaultConfig = ConfigType{
 	Network:  "tendermint_testnet0",
 	LAddr:    "0.0.0.0:0",
 	SeedNode: "",
 	Db: DbConfig{
 		Type: "level",
-		Dir:  RootDir + "/data",
+		Dir:  DataDir(),
 	},
 	Alert: AlertConfig{},
 	SMTP:  SMTPConfig{},
@@ -79,7 +89,7 @@ var defaultConfig = Config_{
 //-----------------------------------------------------------------------------j
 // Configuration types
 
-type Config_ struct {
+type ConfigType struct {
 	Network  string
 	LAddr    string
 	SeedNode string
@@ -118,7 +128,7 @@ type RPCConfig struct {
 
 //-----------------------------------------------------------------------------j
 
-func (cfg *Config_) validate() error {
+func (cfg *ConfigType) validate() error {
 	if cfg.Network == "" {
 		cfg.Network = defaultConfig.Network
 	}
@@ -134,7 +144,7 @@ func (cfg *Config_) validate() error {
 	return nil
 }
 
-func (cfg *Config_) bytes() []byte {
+func (cfg *ConfigType) bytes() []byte {
 	configBytes, err := json.MarshalIndent(cfg, "", "\t")
 	if err != nil {
 		panic(err)
@@ -142,7 +152,7 @@ func (cfg *Config_) bytes() []byte {
 	return configBytes
 }
 
-func (cfg *Config_) write(configFile string) {
+func (cfg *ConfigType) write(configFile string) {
 	if strings.Index(configFile, "/") != -1 {
 		err := os.MkdirAll(filepath.Dir(configFile), 0700)
 		if err != nil {
diff --git a/consensus/pol.go b/consensus/pol.go
index 174cc22b..96e2d010 100644
--- a/consensus/pol.go
+++ b/consensus/pol.go
@@ -2,111 +2,81 @@ package consensus
 
 import (
 	"fmt"
-	"io"
 
-	. "github.com/tendermint/tendermint/binary"
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/blocks"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/state"
 )
 
+// Each signature of a POL (proof-of-lock, see whitepaper) is
+// either a prevote or a commit.
+// Commits require an additional round which is strictly less than
+// the POL round.  Prevote rounds are equal to the POL round.
+type POLVoteSignature struct {
+	Round     uint
+	Signature SignatureEd25519
+}
+
 // Proof of lock.
 // +2/3 of validators' prevotes for a given blockhash (or nil)
 type POL struct {
-	Height     uint32
-	Round      uint16
-	BlockHash  []byte           // Could be nil, which makes this a proof of unlock.
-	BlockParts PartSetHeader    // When BlockHash is nil, this is zero.
-	Votes      []Signature      // Vote signatures for height/round/hash
-	Commits    []RoundSignature // Commit signatures for height/hash
-}
-
-func ReadPOL(r io.Reader, n *int64, err *error) *POL {
-	return &POL{
-		Height:     ReadUInt32(r, n, err),
-		Round:      ReadUInt16(r, n, err),
-		BlockHash:  ReadByteSlice(r, n, err),
-		BlockParts: ReadPartSetHeader(r, n, err),
-		Votes:      ReadSignatures(r, n, err),
-		Commits:    ReadRoundSignatures(r, n, err),
-	}
-}
-
-func (pol *POL) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt32(w, pol.Height, &n, &err)
-	WriteUInt16(w, pol.Round, &n, &err)
-	WriteByteSlice(w, pol.BlockHash, &n, &err)
-	WriteBinary(w, pol.BlockParts, &n, &err)
-	WriteSignatures(w, pol.Votes, &n, &err)
-	WriteRoundSignatures(w, pol.Commits, &n, &err)
-	return
+	Height     uint
+	Round      uint
+	BlockHash  []byte             // Could be nil, which makes this a proof of unlock.
+	BlockParts PartSetHeader      // When BlockHash is nil, this is zero.
+	Votes      []POLVoteSignature // Prevote and commit signatures in ValidatorSet order.
 }
 
 // Returns whether +2/3 have voted/committed for BlockHash.
-func (pol *POL) Verify(vset *state.ValidatorSet) error {
+func (pol *POL) Verify(valSet *state.ValidatorSet) error {
+
+	if uint(len(pol.Votes)) != valSet.Size() {
+		return Errorf("Invalid POL votes count: Expected %v, got %v",
+			valSet.Size(), len(pol.Votes))
+	}
 
 	talliedVotingPower := uint64(0)
-	voteDoc := BinaryBytes(&Vote{
+	prevoteDoc := SignBytes(&Vote{
 		Height: pol.Height, Round: pol.Round, Type: VoteTypePrevote,
 		BlockHash:  pol.BlockHash,
 		BlockParts: pol.BlockParts,
 	})
-	seenValidators := map[uint64]struct{}{}
+	seenValidators := map[string]struct{}{}
 
-	for _, sig := range pol.Votes {
+	for idx, sig := range pol.Votes {
+		voteDoc := prevoteDoc
+		_, val := valSet.GetByIndex(uint(idx))
+
+		// Commit signature?
+		if sig.Round < pol.Round {
+			voteDoc = SignBytes(&Vote{
+				Height: pol.Height, Round: sig.Round, Type: VoteTypeCommit,
+				BlockHash:  pol.BlockHash,
+				BlockParts: pol.BlockParts,
+			})
+		} else if sig.Round > pol.Round {
+			return Errorf("Invalid commit round %v for POL %v", sig.Round, pol)
+		}
 
 		// Validate
-		if _, seen := seenValidators[sig.SignerId]; seen {
+		if _, seen := seenValidators[string(val.Address)]; seen {
 			return Errorf("Duplicate validator for vote %v for POL %v", sig, pol)
 		}
-		_, val := vset.GetById(sig.SignerId)
-		if val == nil {
-			return Errorf("Invalid validator for vote %v for POL %v", sig, pol)
-		}
-		if !val.VerifyBytes(voteDoc, sig) {
+		if !val.PubKey.VerifyBytes(voteDoc, sig.Signature.Bytes) {
 			return Errorf("Invalid signature for vote %v for POL %v", sig, pol)
 		}
 
 		// Tally
-		seenValidators[val.Id] = struct{}{}
+		seenValidators[string(val.Address)] = struct{}{}
 		talliedVotingPower += val.VotingPower
 	}
 
-	for _, rsig := range pol.Commits {
-		round := rsig.Round
-		sig := rsig.Signature
-
-		// Validate
-		if _, seen := seenValidators[sig.SignerId]; seen {
-			return Errorf("Duplicate validator for commit %v for POL %v", sig, pol)
-		}
-		_, val := vset.GetById(sig.SignerId)
-		if val == nil {
-			return Errorf("Invalid validator for commit %v for POL %v", sig, pol)
-		}
-		if round >= pol.Round {
-			return Errorf("Invalid commit round %v for POL %v", round, pol)
-		}
-
-		commitDoc := BinaryBytes(&Vote{
-			Height: pol.Height, Round: round, Type: VoteTypeCommit,
-			BlockHash:  pol.BlockHash,
-			BlockParts: pol.BlockParts,
-		})
-		if !val.VerifyBytes(commitDoc, sig) {
-			return Errorf("Invalid signature for commit %v for POL %v", sig, pol)
-		}
-
-		// Tally
-		seenValidators[val.Id] = struct{}{}
-		talliedVotingPower += val.VotingPower
-	}
-
-	if talliedVotingPower > vset.TotalVotingPower()*2/3 {
+	if talliedVotingPower > valSet.TotalVotingPower()*2/3 {
 		return nil
 	} else {
 		return Errorf("Invalid POL, insufficient voting power %v, needed %v",
-			talliedVotingPower, (vset.TotalVotingPower()*2/3 + 1))
+			talliedVotingPower, (valSet.TotalVotingPower()*2/3 + 1))
 	}
 
 }
diff --git a/consensus/priv_validator.go b/consensus/priv_validator.go
index a7f19e9f..bf851516 100644
--- a/consensus/priv_validator.go
+++ b/consensus/priv_validator.go
@@ -1,30 +1,166 @@
 package consensus
 
+// TODO: This logic is crude. Should be more transactional.
+
 import (
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+
+	. "github.com/tendermint/tendermint/account"
+	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
-	db_ "github.com/tendermint/tendermint/db"
-	"github.com/tendermint/tendermint/state"
+	. "github.com/tendermint/tendermint/common"
+	. "github.com/tendermint/tendermint/config"
+
+	"github.com/tendermint/go-ed25519"
 )
 
-//-----------------------------------------------------------------------------
+const (
+	stepNone      = 0 // Used to distinguish the initial state
+	stepPropose   = 1
+	stepPrevote   = 2
+	stepPrecommit = 3
+	stepCommit    = 4
+)
 
-type PrivValidator struct {
-	db db_.DB
-	state.PrivAccount
-}
-
-func NewPrivValidator(db db_.DB, priv *state.PrivAccount) *PrivValidator {
-	return &PrivValidator{db, *priv}
-}
-
-// Double signing results in a panic.
-func (pv *PrivValidator) Sign(o Signable) {
-	switch o.(type) {
-	case *Proposal:
-		//TODO: prevent double signing && test.
-		pv.PrivAccount.Sign(o.(*Proposal))
-	case *Vote:
-		//TODO: prevent double signing && test.
-		pv.PrivAccount.Sign(o.(*Vote))
+func voteToStep(vote *Vote) uint8 {
+	switch vote.Type {
+	case VoteTypePrevote:
+		return stepPrevote
+	case VoteTypePrecommit:
+		return stepPrecommit
+	case VoteTypeCommit:
+		return stepCommit
+	default:
+		panic("Unknown vote type")
+	}
+}
+
+type PrivValidator struct {
+	Address    []byte
+	PubKey     PubKeyEd25519
+	PrivKey    PrivKeyEd25519
+	LastHeight uint
+	LastRound  uint
+	LastStep   uint8
+}
+
+// Generates a new validator with private key.
+func GenPrivValidator() *PrivValidator {
+	privKeyBytes := CRandBytes(32)
+	pubKeyBytes := ed25519.MakePubKey(privKeyBytes)
+	pubKey := PubKeyEd25519{pubKeyBytes}
+	privKey := PrivKeyEd25519{pubKeyBytes, privKeyBytes}
+	return &PrivValidator{
+		Address:    pubKey.Address(),
+		PubKey:     pubKey,
+		PrivKey:    privKey,
+		LastHeight: 0,
+		LastRound:  0,
+		LastStep:   stepNone,
+	}
+}
+
+type PrivValidatorJSON struct {
+	Address    string
+	PubKey     string
+	PrivKey    string
+	LastHeight uint
+	LastRound  uint
+	LastStep   uint8
+}
+
+func LoadPrivValidator() *PrivValidator {
+	privValJSONBytes, err := ioutil.ReadFile(PrivValidatorFile())
+	if err != nil {
+		panic(err)
+	}
+	privValJSON := PrivValidatorJSON{}
+	err = json.Unmarshal(privValJSONBytes, &privValJSON)
+	if err != nil {
+		panic(err)
+	}
+	address, err := base64.StdEncoding.DecodeString(privValJSON.Address)
+	if err != nil {
+		panic(err)
+	}
+	pubKeyBytes, err := base64.StdEncoding.DecodeString(privValJSON.PubKey)
+	if err != nil {
+		panic(err)
+	}
+	privKeyBytes, err := base64.StdEncoding.DecodeString(privValJSON.PrivKey)
+	if err != nil {
+		panic(err)
+	}
+	n := new(int64)
+	privVal := &PrivValidator{
+		Address:    address,
+		PubKey:     ReadBinary(PubKeyEd25519{}, bytes.NewReader(pubKeyBytes), n, &err).(PubKeyEd25519),
+		PrivKey:    ReadBinary(PrivKeyEd25519{}, bytes.NewReader(privKeyBytes), n, &err).(PrivKeyEd25519),
+		LastHeight: privValJSON.LastHeight,
+		LastRound:  privValJSON.LastRound,
+		LastStep:   privValJSON.LastStep,
+	}
+	if err != nil {
+		panic(err)
+	}
+	return privVal
+}
+
+func (privVal *PrivValidator) Save() {
+	privValJSON := PrivValidatorJSON{
+		Address:    base64.StdEncoding.EncodeToString(privVal.Address),
+		PubKey:     base64.StdEncoding.EncodeToString(BinaryBytes(privVal.PubKey)),
+		PrivKey:    base64.StdEncoding.EncodeToString(BinaryBytes(privVal.PrivKey)),
+		LastHeight: privVal.LastHeight,
+		LastRound:  privVal.LastRound,
+		LastStep:   privVal.LastStep,
+	}
+	privValJSONBytes, err := json.Marshal(privValJSON)
+	if err != nil {
+		panic(err)
+	}
+	err = ioutil.WriteFile(PrivValidatorFile(), privValJSONBytes, 0700)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (privVal *PrivValidator) SignVote(vote *Vote) SignatureEd25519 {
+	if privVal.LastHeight < vote.Height ||
+		privVal.LastHeight == vote.Height && privVal.LastRound < vote.Round ||
+		privVal.LastHeight == vote.Height && privVal.LastRound == vote.Round && privVal.LastStep < voteToStep(vote) {
+
+		// Persist height/round/step
+		privVal.LastHeight = vote.Height
+		privVal.LastRound = vote.Round
+		privVal.LastStep = voteToStep(vote)
+		privVal.Save()
+
+		// Sign
+		return privVal.PrivKey.Sign(SignBytes(vote)).(SignatureEd25519)
+	} else {
+		panic(fmt.Sprintf("Attempt of duplicate signing of vote: Height %v, Round %v, Type %v", vote.Height, vote.Round, vote.Type))
+	}
+}
+
+func (privVal *PrivValidator) SignProposal(proposal *Proposal) SignatureEd25519 {
+	if privVal.LastHeight < proposal.Height ||
+		privVal.LastHeight == proposal.Height && privVal.LastRound < proposal.Round ||
+		privVal.LastHeight == 0 && privVal.LastRound == 0 && privVal.LastStep == stepNone {
+
+		// Persist height/round/step
+		privVal.LastHeight = proposal.Height
+		privVal.LastRound = proposal.Round
+		privVal.LastStep = stepPropose
+		privVal.Save()
+
+		// Sign
+		return privVal.PrivKey.Sign(SignBytes(proposal)).(SignatureEd25519)
+	} else {
+		panic(fmt.Sprintf("Attempt of duplicate signing of proposal: Height %v, Round %v, Type %v", proposal.Height, proposal.Round))
 	}
 }
diff --git a/consensus/proposal.go b/consensus/proposal.go
index 0c52af60..cc64c310 100644
--- a/consensus/proposal.go
+++ b/consensus/proposal.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
 )
@@ -15,15 +16,14 @@ var (
 )
 
 type Proposal struct {
-	Height     uint32
-	Round      uint16
+	Height     uint
+	Round      uint
 	BlockParts PartSetHeader
 	POLParts   PartSetHeader
-	Signature  Signature
+	Signature  SignatureEd25519
 }
 
-func NewProposal(height uint32, round uint16, blockParts, polParts PartSetHeader) *Proposal {
-
+func NewProposal(height uint, round uint, blockParts, polParts PartSetHeader) *Proposal {
 	return &Proposal{
 		Height:     height,
 		Round:      round,
@@ -32,34 +32,14 @@ func NewProposal(height uint32, round uint16, blockParts, polParts PartSetHeader
 	}
 }
 
-func ReadProposal(r io.Reader, n *int64, err *error) *Proposal {
-	return &Proposal{
-		Height:     ReadUInt32(r, n, err),
-		Round:      ReadUInt16(r, n, err),
-		BlockParts: ReadPartSetHeader(r, n, err),
-		POLParts:   ReadPartSetHeader(r, n, err),
-		Signature:  ReadSignature(r, n, err),
-	}
-}
-
-func (p *Proposal) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt32(w, p.Height, &n, &err)
-	WriteUInt16(w, p.Round, &n, &err)
-	WriteBinary(w, p.BlockParts, &n, &err)
-	WriteBinary(w, p.POLParts, &n, &err)
-	WriteBinary(w, p.Signature, &n, &err)
-	return
-}
-
-func (p *Proposal) GetSignature() Signature {
-	return p.Signature
-}
-
-func (p *Proposal) SetSignature(sig Signature) {
-	p.Signature = sig
-}
-
 func (p *Proposal) String() string {
 	return fmt.Sprintf("Proposal{%v/%v %v %v %v}", p.Height, p.Round,
 		p.BlockParts, p.POLParts, p.Signature)
 }
+
+func (p *Proposal) WriteSignBytes(w io.Writer, n *int64, err *error) {
+	WriteUVarInt(p.Height, w, n, err)
+	WriteUVarInt(p.Round, w, n, err)
+	WriteBinary(p.BlockParts, w, n, err)
+	WriteBinary(p.POLParts, w, n, err)
+}
diff --git a/consensus/reactor.go b/consensus/reactor.go
index e009036e..fe0f2e56 100644
--- a/consensus/reactor.go
+++ b/consensus/reactor.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -123,9 +122,9 @@ func (conR *ConsensusReactor) Receive(chId byte, peer *p2p.Peer, msgBytes []byte
 			msg := msg_.(*NewRoundStepMessage)
 			ps.ApplyNewRoundStepMessage(msg, rs)
 
-		case *CommitMessage:
-			msg := msg_.(*CommitMessage)
-			ps.ApplyCommitMessage(msg)
+		case *CommitStepMessage:
+			msg := msg_.(*CommitStepMessage)
+			ps.ApplyCommitStepMessage(msg)
 
 		case *HasVoteMessage:
 			msg := msg_.(*HasVoteMessage)
@@ -160,10 +159,17 @@ func (conR *ConsensusReactor) Receive(chId byte, peer *p2p.Peer, msgBytes []byte
 
 	case VoteCh:
 		switch msg_.(type) {
-		case *Vote:
-			vote := msg_.(*Vote)
-			added, index, err := conR.conS.AddVote(vote)
+		case *VoteMessage:
+			voteMessage := msg_.(*VoteMessage)
+			vote := voteMessage.Vote
+			if rs.Height != vote.Height {
+				return // Wrong height. Not necessarily a bad peer.
+			}
+			validatorIndex := voteMessage.ValidatorIndex
+			address, _ := rs.Validators.GetByIndex(validatorIndex)
+			added, index, err := conR.conS.AddVote(address, vote)
 			if err != nil {
+				// Probably an invalid signature. Bad peer.
 				log.Warning("Error attempting to add vote: %v", err)
 			}
 			// Initialize Prevotes/Precommits/Commits if needed
@@ -220,14 +226,14 @@ func (conR *ConsensusReactor) broadcastNewRoundStepRoutine() {
 				Height: rs.Height,
 				Round:  rs.Round,
 				Step:   rs.Step,
-				SecondsSinceStartTime: uint32(timeElapsed.Seconds()),
+				SecondsSinceStartTime: uint(timeElapsed.Seconds()),
 			}
 			conR.sw.Broadcast(StateCh, msg)
 		}
 
-		// If the step is commit, then also broadcast a CommitMessage.
+		// If the step is commit, then also broadcast a CommitStepMessage.
 		if rs.Step == RoundStepCommit {
-			msg := &CommitMessage{
+			msg := &CommitStepMessage{
 				Height:        rs.Height,
 				BlockParts:    rs.ProposalBlockParts.Header(),
 				BlockBitArray: rs.ProposalBlockParts.BitArray(),
@@ -259,10 +265,10 @@ OUTER_LOOP:
 					Height: rs.Height,
 					Round:  rs.Round,
 					Type:   partTypeProposalBlock,
-					Part:   rs.ProposalBlockParts.GetPart(uint16(index)),
+					Part:   rs.ProposalBlockParts.GetPart(index),
 				}
 				peer.Send(DataCh, msg)
-				ps.SetHasProposalBlockPart(rs.Height, rs.Round, uint16(index))
+				ps.SetHasProposalBlockPart(rs.Height, rs.Round, index)
 				continue OUTER_LOOP
 			}
 		}
@@ -289,10 +295,10 @@ OUTER_LOOP:
 					Height: rs.Height,
 					Round:  rs.Round,
 					Type:   partTypeProposalPOL,
-					Part:   rs.ProposalPOLParts.GetPart(uint16(index)),
+					Part:   rs.ProposalPOLParts.GetPart(index),
 				}
 				peer.Send(DataCh, msg)
-				ps.SetHasProposalPOLPart(rs.Height, rs.Round, uint16(index))
+				ps.SetHasProposalPOLPart(rs.Height, rs.Round, index)
 				continue OUTER_LOOP
 			}
 		}
@@ -320,7 +326,7 @@ OUTER_LOOP:
 			if ok {
 				vote := voteSet.GetByIndex(index)
 				// NOTE: vote may be a commit.
-				msg := p2p.TypedMessage{msgTypeVote, vote}
+				msg := &VoteMessage{index, vote}
 				peer.Send(VoteCh, msg)
 				ps.SetHasVote(vote, index)
 				return true
@@ -399,7 +405,7 @@ OUTER_LOOP:
 					BlockParts: header.LastBlockParts,
 					Signature:  rsig.Signature,
 				}
-				msg := p2p.TypedMessage{msgTypeVote, vote}
+				msg := &VoteMessage{index, vote}
 				peer.Send(VoteCh, msg)
 				ps.SetHasVote(vote, index)
 				continue OUTER_LOOP
@@ -416,8 +422,8 @@ OUTER_LOOP:
 
 // Read only when returned by PeerState.GetRoundState().
 type PeerRoundState struct {
-	Height                uint32        // Height peer is at
-	Round                 uint16        // Round peer is at
+	Height                uint          // Height peer is at
+	Round                 uint          // Round peer is at
 	Step                  RoundStep     // Step peer is at
 	StartTime             time.Time     // Estimated start of round 0 at this height
 	Proposal              bool          // True if peer has proposal for this round
@@ -474,7 +480,7 @@ func (ps *PeerState) SetHasProposal(proposal *Proposal) {
 	ps.ProposalPOLBitArray = NewBitArray(uint(proposal.POLParts.Total))
 }
 
-func (ps *PeerState) SetHasProposalBlockPart(height uint32, round uint16, index uint16) {
+func (ps *PeerState) SetHasProposalBlockPart(height uint, round uint, index uint) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
@@ -485,7 +491,7 @@ func (ps *PeerState) SetHasProposalBlockPart(height uint32, round uint16, index
 	ps.ProposalBlockBitArray.SetIndex(uint(index), true)
 }
 
-func (ps *PeerState) SetHasProposalPOLPart(height uint32, round uint16, index uint16) {
+func (ps *PeerState) SetHasProposalPOLPart(height uint, round uint, index uint) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
@@ -496,7 +502,7 @@ func (ps *PeerState) SetHasProposalPOLPart(height uint32, round uint16, index ui
 	ps.ProposalPOLBitArray.SetIndex(uint(index), true)
 }
 
-func (ps *PeerState) EnsureVoteBitArrays(height uint32, numValidators uint) {
+func (ps *PeerState) EnsureVoteBitArrays(height uint, numValidators uint) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
@@ -521,7 +527,7 @@ func (ps *PeerState) SetHasVote(vote *Vote, index uint) {
 	ps.setHasVote(vote.Height, vote.Round, vote.Type, index)
 }
 
-func (ps *PeerState) setHasVote(height uint32, round uint16, type_ byte, index uint) {
+func (ps *PeerState) setHasVote(height uint, round uint, type_ byte, index uint) {
 	if ps.Height == height+1 && type_ == VoteTypeCommit {
 		// Special case for LastCommits.
 		ps.LastCommits.SetIndex(index, true)
@@ -583,7 +589,7 @@ func (ps *PeerState) ApplyNewRoundStepMessage(msg *NewRoundStepMessage, rs *Roun
 	}
 }
 
-func (ps *PeerState) ApplyCommitMessage(msg *CommitMessage) {
+func (ps *PeerState) ApplyCommitStepMessage(msg *CommitStepMessage) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
@@ -614,15 +620,13 @@ func (ps *PeerState) ApplyHasVoteMessage(msg *HasVoteMessage) {
 // Messages
 
 const (
-	msgTypeUnknown = byte(0x00)
-	// Messages for communicating state changes
+	msgTypeUnknown      = byte(0x00)
 	msgTypeNewRoundStep = byte(0x01)
-	msgTypeCommit       = byte(0x02)
-	// Messages of data
-	msgTypeProposal = byte(0x11)
-	msgTypePart     = byte(0x12) // both block & POL
-	msgTypeVote     = byte(0x13)
-	msgTypeHasVote  = byte(0x14)
+	msgTypeCommitStep   = byte(0x02)
+	msgTypeProposal     = byte(0x11)
+	msgTypePart         = byte(0x12) // both block & POL
+	msgTypeVote         = byte(0x13)
+	msgTypeHasVote      = byte(0x14)
 )
 
 // TODO: check for unnecessary extra bytes at the end.
@@ -634,18 +638,18 @@ func decodeMessage(bz []byte) (msgType byte, msg interface{}) {
 	switch msgType {
 	// Messages for communicating state changes
 	case msgTypeNewRoundStep:
-		msg = readNewRoundStepMessage(r, n, err)
-	case msgTypeCommit:
-		msg = readCommitMessage(r, n, err)
+		msg = ReadBinary(&NewRoundStepMessage{}, r, n, err)
+	case msgTypeCommitStep:
+		msg = ReadBinary(&CommitStepMessage{}, r, n, err)
 	// Messages of data
 	case msgTypeProposal:
-		msg = ReadProposal(r, n, err)
+		msg = ReadBinary(&Proposal{}, r, n, err)
 	case msgTypePart:
-		msg = readPartMessage(r, n, err)
+		msg = ReadBinary(&PartMessage{}, r, n, err)
 	case msgTypeVote:
-		msg = ReadVote(r, n, err)
+		msg = ReadBinary(&VoteMessage{}, r, n, err)
 	case msgTypeHasVote:
-		msg = readHasVoteMessage(r, n, err)
+		msg = ReadBinary(&HasVoteMessage{}, r, n, err)
 	default:
 		msg = nil
 	}
@@ -655,29 +659,13 @@ func decodeMessage(bz []byte) (msgType byte, msg interface{}) {
 //-------------------------------------
 
 type NewRoundStepMessage struct {
-	Height                uint32
-	Round                 uint16
+	Height                uint
+	Round                 uint
 	Step                  RoundStep
-	SecondsSinceStartTime uint32
+	SecondsSinceStartTime uint
 }
 
-func readNewRoundStepMessage(r io.Reader, n *int64, err *error) *NewRoundStepMessage {
-	return &NewRoundStepMessage{
-		Height: ReadUInt32(r, n, err),
-		Round:  ReadUInt16(r, n, err),
-		Step:   RoundStep(ReadUInt8(r, n, err)),
-		SecondsSinceStartTime: ReadUInt32(r, n, err),
-	}
-}
-
-func (m *NewRoundStepMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeNewRoundStep, &n, &err)
-	WriteUInt32(w, m.Height, &n, &err)
-	WriteUInt16(w, m.Round, &n, &err)
-	WriteUInt8(w, uint8(m.Step), &n, &err)
-	WriteUInt32(w, m.SecondsSinceStartTime, &n, &err)
-	return
-}
+func (m *NewRoundStepMessage) TypeByte() byte { return msgTypeNewRoundStep }
 
 func (m *NewRoundStepMessage) String() string {
 	return fmt.Sprintf("[NewRoundStep %v/%v/%X]", m.Height, m.Round, m.Step)
@@ -685,30 +673,16 @@ func (m *NewRoundStepMessage) String() string {
 
 //-------------------------------------
 
-type CommitMessage struct {
-	Height        uint32
+type CommitStepMessage struct {
+	Height        uint
 	BlockParts    PartSetHeader
 	BlockBitArray BitArray
 }
 
-func readCommitMessage(r io.Reader, n *int64, err *error) *CommitMessage {
-	return &CommitMessage{
-		Height:        ReadUInt32(r, n, err),
-		BlockParts:    ReadPartSetHeader(r, n, err),
-		BlockBitArray: ReadBitArray(r, n, err),
-	}
-}
+func (m *CommitStepMessage) TypeByte() byte { return msgTypeCommitStep }
 
-func (m *CommitMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeCommit, &n, &err)
-	WriteUInt32(w, m.Height, &n, &err)
-	WriteBinary(w, m.BlockParts, &n, &err)
-	WriteBinary(w, m.BlockBitArray, &n, &err)
-	return
-}
-
-func (m *CommitMessage) String() string {
-	return fmt.Sprintf("[Commit %v %v %v]", m.Height, m.BlockParts, m.BlockBitArray)
+func (m *CommitStepMessage) String() string {
+	return fmt.Sprintf("[CommitStep %v %v %v]", m.Height, m.BlockParts, m.BlockBitArray)
 }
 
 //-------------------------------------
@@ -719,29 +693,13 @@ const (
 )
 
 type PartMessage struct {
-	Height uint32
-	Round  uint16
+	Height uint
+	Round  uint
 	Type   byte
 	Part   *Part
 }
 
-func readPartMessage(r io.Reader, n *int64, err *error) *PartMessage {
-	return &PartMessage{
-		Height: ReadUInt32(r, n, err),
-		Round:  ReadUInt16(r, n, err),
-		Type:   ReadByte(r, n, err),
-		Part:   ReadPart(r, n, err),
-	}
-}
-
-func (m *PartMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypePart, &n, &err)
-	WriteUInt32(w, m.Height, &n, &err)
-	WriteUInt16(w, m.Round, &n, &err)
-	WriteByte(w, m.Type, &n, &err)
-	WriteBinary(w, m.Part, &n, &err)
-	return
-}
+func (m *PartMessage) TypeByte() byte { return msgTypePart }
 
 func (m *PartMessage) String() string {
 	return fmt.Sprintf("[Part %v/%v T:%X %v]", m.Height, m.Round, m.Type, m.Part)
@@ -749,30 +707,27 @@ func (m *PartMessage) String() string {
 
 //-------------------------------------
 
+type VoteMessage struct {
+	ValidatorIndex uint
+	Vote           *Vote
+}
+
+func (m *VoteMessage) TypeByte() byte { return msgTypeVote }
+
+func (m *VoteMessage) String() string {
+	return fmt.Sprintf("[Vote ValidatorIndex:%v Vote:%v]", m.ValidatorIndex, m.Vote)
+}
+
+//-------------------------------------
+
 type HasVoteMessage struct {
-	Height uint32
-	Round  uint16
+	Height uint
+	Round  uint
 	Type   byte
 	Index  uint
 }
 
-func readHasVoteMessage(r io.Reader, n *int64, err *error) *HasVoteMessage {
-	return &HasVoteMessage{
-		Height: ReadUInt32(r, n, err),
-		Round:  ReadUInt16(r, n, err),
-		Type:   ReadByte(r, n, err),
-		Index:  ReadUVarInt(r, n, err),
-	}
-}
-
-func (m *HasVoteMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeHasVote, &n, &err)
-	WriteUInt32(w, m.Height, &n, &err)
-	WriteUInt16(w, m.Round, &n, &err)
-	WriteByte(w, m.Type, &n, &err)
-	WriteUVarInt(w, m.Index, &n, &err)
-	return
-}
+func (m *HasVoteMessage) TypeByte() byte { return msgTypeHasVote }
 
 func (m *HasVoteMessage) String() string {
 	return fmt.Sprintf("[HasVote %v/%v T:%X]", m.Height, m.Round, m.Type)
diff --git a/consensus/state.go b/consensus/state.go
index 1c2ee777..7dee95ed 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -52,6 +52,7 @@ Consensus State Machine Overview:
 package consensus
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"math"
@@ -59,6 +60,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
 	. "github.com/tendermint/tendermint/common"
@@ -82,7 +84,7 @@ const (
 	RoundActionPrevote     = RoundActionType(0xA1) // Prevote and goto RoundStepPrevote
 	RoundActionPrecommit   = RoundActionType(0xA2) // Precommit and goto RoundStepPrecommit
 	RoundActionTryCommit   = RoundActionType(0xC0) // Goto RoundStepCommit, or RoundStepPropose for next round.
-	RoundActionCommit      = RoundActionType(0xC1) // Goto RoundStepCommit
+	RoundActionCommit      = RoundActionType(0xC1) // Goto RoundStepCommit upon +2/3 commits
 	RoundActionTryFinalize = RoundActionType(0xC2) // Maybe goto RoundStepPropose for next round.
 
 	roundDuration0         = 60 * time.Second   // The first round is 60 seconds long.
@@ -97,8 +99,8 @@ var (
 )
 
 type RoundAction struct {
-	Height uint32          // The block height for which consensus is reaching for.
-	Round  uint16          // The round number at given height.
+	Height uint            // The block height for which consensus is reaching for.
+	Round  uint            // The round number at given height.
 	Action RoundActionType // Action to perform.
 }
 
@@ -106,8 +108,8 @@ type RoundAction struct {
 
 // Immutable when returned from ConsensusState.GetRoundState()
 type RoundState struct {
-	Height             uint32 // Height we are working on
-	Round              uint16
+	Height             uint // Height we are working on
+	Round              uint
 	Step               RoundStep
 	StartTime          time.Time
 	CommitTime         time.Time // Time when +2/3 commits were found
@@ -347,7 +349,6 @@ ACTION_LOOP:
 			if rs.Precommits.HasTwoThirdsMajority() {
 				// Enter RoundStepCommit and commit.
 				cs.RunActionCommit(rs.Height)
-				cs.queueAction(RoundAction{rs.Height, rs.Round, RoundActionTryFinalize})
 				continue ACTION_LOOP
 			} else {
 				// Could not commit, move onto next round.
@@ -363,7 +364,6 @@ ACTION_LOOP:
 			}
 			// Enter RoundStepCommit and commit.
 			cs.RunActionCommit(rs.Height)
-			cs.queueAction(RoundAction{rs.Height, rs.Round, RoundActionTryFinalize})
 			continue ACTION_LOOP
 
 		case RoundActionTryFinalize:
@@ -435,7 +435,7 @@ func (cs *ConsensusState) updateToState(state *state.State) {
 }
 
 // After the call cs.Step becomes RoundStepNewRound.
-func (cs *ConsensusState) setupNewRound(round uint16) {
+func (cs *ConsensusState) setupNewRound(round uint) {
 	// Sanity check
 	if round == 0 {
 		panic("setupNewRound() should never be called for round 0")
@@ -470,7 +470,7 @@ func (cs *ConsensusState) SetPrivValidator(priv *PrivValidator) {
 //-----------------------------------------------------------------------------
 
 // Set up the round to desired round and set step to RoundStepNewRound
-func (cs *ConsensusState) SetupNewRound(height uint32, desiredRound uint16) bool {
+func (cs *ConsensusState) SetupNewRound(height uint, desiredRound uint) bool {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 	if cs.Height != height {
@@ -485,7 +485,7 @@ func (cs *ConsensusState) SetupNewRound(height uint32, desiredRound uint16) bool
 	return true
 }
 
-func (cs *ConsensusState) RunActionPropose(height uint32, round uint16) {
+func (cs *ConsensusState) RunActionPropose(height uint, round uint) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 	if cs.Height != height || cs.Round != round {
@@ -497,7 +497,7 @@ func (cs *ConsensusState) RunActionPropose(height uint32, round uint16) {
 	}()
 
 	// Nothing to do if it's not our turn.
-	if cs.PrivValidator == nil || cs.Validators.Proposer().Id != cs.PrivValidator.Id {
+	if cs.PrivValidator == nil || !bytes.Equal(cs.Validators.Proposer().Address, cs.PrivValidator.Address) {
 		return
 	}
 
@@ -560,7 +560,7 @@ func (cs *ConsensusState) RunActionPropose(height uint32, round uint16) {
 
 	// Make proposal
 	proposal := NewProposal(cs.Height, cs.Round, blockParts.Header(), polParts.Header())
-	cs.PrivValidator.Sign(proposal)
+	proposal.Signature = cs.PrivValidator.SignProposal(proposal)
 
 	// Set fields
 	cs.Proposal = proposal
@@ -572,7 +572,7 @@ func (cs *ConsensusState) RunActionPropose(height uint32, round uint16) {
 
 // Prevote for LockedBlock if we're locked, or ProposealBlock if valid.
 // Otherwise vote nil.
-func (cs *ConsensusState) RunActionPrevote(height uint32, round uint16) {
+func (cs *ConsensusState) RunActionPrevote(height uint, round uint) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 	if cs.Height != height || cs.Round != round {
@@ -612,7 +612,7 @@ func (cs *ConsensusState) RunActionPrevote(height uint32, round uint16) {
 
 // Lock & Precommit the ProposalBlock if we have enough prevotes for it,
 // or unlock an existing lock if +2/3 of prevotes were nil.
-func (cs *ConsensusState) RunActionPrecommit(height uint32, round uint16) {
+func (cs *ConsensusState) RunActionPrecommit(height uint, round uint) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 	if cs.Height != height || cs.Round != round {
@@ -668,7 +668,11 @@ func (cs *ConsensusState) RunActionPrecommit(height uint32, round uint16) {
 }
 
 // Enter commit step. See the diagram for details.
-func (cs *ConsensusState) RunActionCommit(height uint32) {
+// There are two ways to enter this step:
+// * After the Precommit step with +2/3 precommits, or,
+// * Upon +2/3 commits regardless of current step
+// Either way this action is run at most once per round.
+func (cs *ConsensusState) RunActionCommit(height uint) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 	if cs.Height != height {
@@ -679,6 +683,7 @@ func (cs *ConsensusState) RunActionCommit(height uint32) {
 		cs.newStepCh <- cs.getRoundState()
 	}()
 
+	// Sanity check.
 	// There are two ways to enter:
 	// 1. +2/3 precommits at the end of RoundStepPrecommit
 	// 2. +2/3 commits at any time
@@ -712,15 +717,20 @@ func (cs *ConsensusState) RunActionCommit(height uint32) {
 		}
 	} else {
 		// We have the block, so save/stage/sign-commit-vote.
+		cs.saveCommitVoteBlock(cs.ProposalBlock, cs.ProposalBlockParts)
+	}
 
-		cs.processBlockForCommit(cs.ProposalBlock, cs.ProposalBlockParts)
+	// If we have the block AND +2/3 commits, queue RoundActionTryFinalize.
+	// Round will immediately become finalized.
+	if cs.ProposalBlock.HashesTo(hash) && cs.Commits.HasTwoThirdsMajority() {
+		cs.queueAction(RoundAction{cs.Height, cs.Round, RoundActionTryFinalize})
 	}
 
 }
 
 // Returns true if Finalize happened, which increments height && sets
 // the step to RoundStepNewHeight (or RoundStepNewRound, but probably not).
-func (cs *ConsensusState) TryFinalizeCommit(height uint32) bool {
+func (cs *ConsensusState) TryFinalizeCommit(height uint) bool {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 
@@ -754,6 +764,7 @@ func (cs *ConsensusState) TryFinalizeCommit(height uint32) bool {
 			return true
 		} else {
 			// Prevent zombies.
+			// TODO: Does this ever happen?
 			Panicf("+2/3 committed an invalid block: %v", err)
 		}
 	}
@@ -782,7 +793,7 @@ func (cs *ConsensusState) SetProposal(proposal *Proposal) error {
 	}
 
 	// Verify signature
-	if !cs.Validators.Proposer().Verify(proposal) {
+	if !cs.Validators.Proposer().PubKey.VerifyBytes(SignBytes(proposal), proposal.Signature) {
 		return ErrInvalidProposalSignature
 	}
 
@@ -794,7 +805,7 @@ func (cs *ConsensusState) SetProposal(proposal *Proposal) error {
 
 // NOTE: block is not necessarily valid.
 // NOTE: This function may increment the height.
-func (cs *ConsensusState) AddProposalBlockPart(height uint32, round uint16, part *Part) (added bool, err error) {
+func (cs *ConsensusState) AddProposalBlockPart(height uint, round uint, part *Part) (added bool, err error) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 
@@ -815,8 +826,11 @@ func (cs *ConsensusState) AddProposalBlockPart(height uint32, round uint16, part
 	if added && cs.ProposalBlockParts.IsComplete() {
 		var n int64
 		var err error
-		cs.ProposalBlock = ReadBlock(cs.ProposalBlockParts.GetReader(), &n, &err)
-		cs.queueAction(RoundAction{cs.Height, cs.Round, RoundActionTryFinalize})
+		cs.ProposalBlock = ReadBinary(&Block{}, cs.ProposalBlockParts.GetReader(), &n, &err).(*Block)
+		// If we're already in the commit step, try to finalize round.
+		if cs.Step == RoundStepCommit {
+			cs.queueAction(RoundAction{cs.Height, cs.Round, RoundActionTryFinalize})
+		}
 		// XXX If POL is valid, consider unlocking.
 		return true, err
 	}
@@ -824,7 +838,7 @@ func (cs *ConsensusState) AddProposalBlockPart(height uint32, round uint16, part
 }
 
 // NOTE: POL is not necessarily valid.
-func (cs *ConsensusState) AddProposalPOLPart(height uint32, round uint16, part *Part) (added bool, err error) {
+func (cs *ConsensusState) AddProposalPOLPart(height uint, round uint, part *Part) (added bool, err error) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 
@@ -844,21 +858,21 @@ func (cs *ConsensusState) AddProposalPOLPart(height uint32, round uint16, part *
 	if added && cs.ProposalPOLParts.IsComplete() {
 		var n int64
 		var err error
-		cs.ProposalPOL = ReadPOL(cs.ProposalPOLParts.GetReader(), &n, &err)
+		cs.ProposalPOL = ReadBinary(&POL{}, cs.ProposalPOLParts.GetReader(), &n, &err).(*POL)
 		return true, err
 	}
 	return true, nil
 }
 
-func (cs *ConsensusState) AddVote(vote *Vote) (added bool, index uint, err error) {
+func (cs *ConsensusState) AddVote(address []byte, vote *Vote) (added bool, index uint, err error) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
 
-	return cs.addVote(vote)
+	return cs.addVote(address, vote)
 }
 
 // TODO: Maybe move this out of here?
-func (cs *ConsensusState) LoadHeaderValidation(height uint32) (*Header, *Validation) {
+func (cs *ConsensusState) LoadHeaderValidation(height uint) (*Header, *Validation) {
 	meta := cs.blockStore.LoadBlockMeta(height)
 	if meta == nil {
 		return nil, nil
@@ -869,21 +883,21 @@ func (cs *ConsensusState) LoadHeaderValidation(height uint32) (*Header, *Validat
 
 //-----------------------------------------------------------------------------
 
-func (cs *ConsensusState) addVote(vote *Vote) (added bool, index uint, err error) {
+func (cs *ConsensusState) addVote(address []byte, vote *Vote) (added bool, index uint, err error) {
 	switch vote.Type {
 	case VoteTypePrevote:
 		// Prevotes checks for height+round match.
-		return cs.Prevotes.Add(vote)
+		return cs.Prevotes.Add(address, vote)
 	case VoteTypePrecommit:
 		// Precommits checks for height+round match.
-		return cs.Precommits.Add(vote)
+		return cs.Precommits.Add(address, vote)
 	case VoteTypeCommit:
 		if vote.Height == cs.Height {
 			// No need to check if vote.Round < cs.Round ...
 			// Prevotes && Precommits already checks that.
-			cs.Prevotes.Add(vote)
-			cs.Precommits.Add(vote)
-			added, index, err = cs.Commits.Add(vote)
+			cs.Prevotes.Add(address, vote)
+			cs.Precommits.Add(address, vote)
+			added, index, err = cs.Commits.Add(address, vote)
 			if added && cs.Commits.HasTwoThirdsMajority() && cs.CommitTime.IsZero() {
 				cs.CommitTime = time.Now()
 				log.Debug("Set CommitTime to %v", cs.CommitTime)
@@ -896,7 +910,7 @@ func (cs *ConsensusState) addVote(vote *Vote) (added bool, index uint, err error
 			return added, index, err
 		}
 		if vote.Height+1 == cs.Height {
-			return cs.LastCommits.Add(vote)
+			return cs.LastCommits.Add(address, vote)
 		}
 		return false, 0, nil
 	default:
@@ -930,7 +944,7 @@ func (cs *ConsensusState) stageBlock(block *Block, blockParts *PartSet) error {
 }
 
 func (cs *ConsensusState) signAddVote(type_ byte, hash []byte, header PartSetHeader) *Vote {
-	if cs.PrivValidator == nil || !cs.Validators.HasId(cs.PrivValidator.Id) {
+	if cs.PrivValidator == nil || !cs.Validators.HasAddress(cs.PrivValidator.Address) {
 		return nil
 	}
 	vote := &Vote{
@@ -940,12 +954,12 @@ func (cs *ConsensusState) signAddVote(type_ byte, hash []byte, header PartSetHea
 		BlockHash:  hash,
 		BlockParts: header,
 	}
-	cs.PrivValidator.Sign(vote)
-	cs.addVote(vote)
+	vote.Signature = cs.PrivValidator.SignVote(vote)
+	cs.addVote(cs.PrivValidator.Address, vote)
 	return vote
 }
 
-func (cs *ConsensusState) processBlockForCommit(block *Block, blockParts *PartSet) {
+func (cs *ConsensusState) saveCommitVoteBlock(block *Block, blockParts *PartSet) {
 
 	// The proposal must be valid.
 	if err := cs.stageBlock(block, blockParts); err != nil {
@@ -969,19 +983,19 @@ func (cs *ConsensusState) processBlockForCommit(block *Block, blockParts *PartSe
 //-----------------------------------------------------------------------------
 
 // total duration of given round
-func calcRoundDuration(round uint16) time.Duration {
+func calcRoundDuration(round uint) time.Duration {
 	return roundDuration0 + roundDurationDelta*time.Duration(round)
 }
 
 // startTime is when round zero started.
-func calcRoundStartTime(round uint16, startTime time.Time) time.Time {
+func calcRoundStartTime(round uint, startTime time.Time) time.Time {
 	return startTime.Add(roundDuration0*time.Duration(round) +
 		roundDurationDelta*(time.Duration((int64(round)*int64(round)-int64(round))/2)))
 }
 
 // calculates the current round given startTime of round zero.
 // NOTE: round is zero if startTime is in the future.
-func calcRound(startTime time.Time) uint16 {
+func calcRound(startTime time.Time) uint {
 	now := time.Now()
 	if now.Before(startTime) {
 		return 0
@@ -997,18 +1011,18 @@ func calcRound(startTime time.Time) uint16 {
 	if math.IsNaN(R) {
 		panic("Could not calc round, should not happen")
 	}
-	if R > math.MaxInt16 {
+	if R > math.MaxInt32 {
 		Panicf("Could not calc round, round overflow: %v", R)
 	}
 	if R < 0 {
 		return 0
 	}
-	return uint16(R)
+	return uint(R)
 }
 
 // convenience
 // NOTE: elapsedRatio can be negative if startTime is in the future.
-func calcRoundInfo(startTime time.Time) (round uint16, roundStartTime time.Time, roundDuration time.Duration,
+func calcRoundInfo(startTime time.Time) (round uint, roundStartTime time.Time, roundDuration time.Duration,
 	roundElapsed time.Duration, elapsedRatio float64) {
 	round = calcRound(startTime)
 	roundStartTime = calcRoundStartTime(round, startTime)
diff --git a/consensus/test.go b/consensus/test.go
index 8112c802..56348ba8 100644
--- a/consensus/test.go
+++ b/consensus/test.go
@@ -6,23 +6,27 @@ import (
 
 // Common test methods
 
-func makeValidator(id uint64, votingPower uint64) (*state.Validator, *state.PrivAccount) {
-	privAccount := state.GenPrivAccount()
-	privAccount.Id = id
+func makeValidator(votingPower uint64) (*state.Validator, *PrivValidator) {
+	privValidator := GenPrivValidator()
 	return &state.Validator{
-		Account:     privAccount.Account,
-		VotingPower: votingPower,
-	}, privAccount
+		Address:          privValidator.Address,
+		PubKey:           privValidator.PubKey,
+		BondHeight:       0,
+		UnbondHeight:     0,
+		LastCommitHeight: 0,
+		VotingPower:      votingPower,
+		Accum:            0,
+	}, privValidator
 }
 
-func makeVoteSet(height uint32, round uint16, type_ byte, numValidators int, votingPower uint64) (*VoteSet, *state.ValidatorSet, []*state.PrivAccount) {
+func makeVoteSet(height uint, round uint, type_ byte, numValidators int, votingPower uint64) (*VoteSet, *state.ValidatorSet, []*PrivValidator) {
 	vals := make([]*state.Validator, numValidators)
-	privAccounts := make([]*state.PrivAccount, numValidators)
+	privValidators := make([]*PrivValidator, numValidators)
 	for i := 0; i < numValidators; i++ {
-		val, privAccount := makeValidator(uint64(i), votingPower)
+		val, privValidator := makeValidator(votingPower)
 		vals[i] = val
-		privAccounts[i] = privAccount
+		privValidators[i] = privValidator
 	}
 	valSet := state.NewValidatorSet(vals)
-	return NewVoteSet(height, round, type_, valSet), valSet, privAccounts
+	return NewVoteSet(height, round, type_, valSet), valSet, privValidators
 }
diff --git a/consensus/vote_set.go b/consensus/vote_set.go
index d6b94fdf..73bfc83c 100644
--- a/consensus/vote_set.go
+++ b/consensus/vote_set.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 	"sync"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
 	. "github.com/tendermint/tendermint/common"
@@ -16,17 +17,16 @@ import (
 // for a predefined vote type.
 // Note that there three kinds of votes: prevotes, precommits, and commits.
 // A commit of prior rounds can be added added in lieu of votes/precommits.
-// TODO: test majority calculations etc.
-// NOTE: assumes that the sum total of voting power does not exceed MaxUInt64.
+// NOTE: Assumes that the sum total of voting power does not exceed MaxUInt64.
 type VoteSet struct {
-	height uint32
-	round  uint16
+	height uint
+	round  uint
 	type_  byte
 
 	mtx           sync.Mutex
-	vset          *state.ValidatorSet
-	votes         map[uint64]*Vote
-	votesBitArray BitArray
+	valSet        *state.ValidatorSet
+	votes         []*Vote           // validator index -> vote
+	votesBitArray BitArray          // validator index -> has vote?
 	votesByBlock  map[string]uint64 // string(blockHash)+string(blockParts) -> vote sum.
 	totalVotes    uint64
 	maj23Hash     []byte
@@ -35,7 +35,7 @@ type VoteSet struct {
 }
 
 // Constructs a new VoteSet struct used to accumulate votes for each round.
-func NewVoteSet(height uint32, round uint16, type_ byte, vset *state.ValidatorSet) *VoteSet {
+func NewVoteSet(height uint, round uint, type_ byte, valSet *state.ValidatorSet) *VoteSet {
 	if height == 0 {
 		panic("Cannot make VoteSet for height == 0, doesn't make sense.")
 	}
@@ -46,55 +46,55 @@ func NewVoteSet(height uint32, round uint16, type_ byte, vset *state.ValidatorSe
 		height:        height,
 		round:         round,
 		type_:         type_,
-		vset:          vset,
-		votes:         make(map[uint64]*Vote, vset.Size()),
-		votesBitArray: NewBitArray(vset.Size()),
+		valSet:        valSet,
+		votes:         make([]*Vote, valSet.Size()),
+		votesBitArray: NewBitArray(valSet.Size()),
 		votesByBlock:  make(map[string]uint64),
 		totalVotes:    0,
 	}
 }
 
-func (vs *VoteSet) Size() uint {
-	if vs == nil {
+func (voteSet *VoteSet) Size() uint {
+	if voteSet == nil {
 		return 0
 	} else {
-		return vs.vset.Size()
+		return voteSet.valSet.Size()
 	}
 }
 
 // True if added, false if not.
 // Returns ErrVote[UnexpectedStep|InvalidAccount|InvalidSignature|InvalidBlockHash|ConflictingSignature]
 // NOTE: vote should not be mutated after adding.
-func (vs *VoteSet) Add(vote *Vote) (bool, uint, error) {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
+func (voteSet *VoteSet) Add(address []byte, vote *Vote) (bool, uint, error) {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
 
-	// Make sure the step matches. (or that vote is commit && round < vs.round)
-	if vote.Height != vs.height ||
-		(vote.Type != VoteTypeCommit && vote.Round != vs.round) ||
-		(vote.Type != VoteTypeCommit && vote.Type != vs.type_) ||
-		(vote.Type == VoteTypeCommit && vs.type_ != VoteTypeCommit && vote.Round >= vs.round) {
+	// Make sure the step matches. (or that vote is commit && round < voteSet.round)
+	if vote.Height != voteSet.height ||
+		(vote.Type != VoteTypeCommit && vote.Round != voteSet.round) ||
+		(vote.Type != VoteTypeCommit && vote.Type != voteSet.type_) ||
+		(vote.Type == VoteTypeCommit && voteSet.type_ != VoteTypeCommit && vote.Round >= voteSet.round) {
 		return false, 0, ErrVoteUnexpectedStep
 	}
 
 	// Ensure that signer is a validator.
-	_, val := vs.vset.GetById(vote.SignerId)
+	valIndex, val := voteSet.valSet.GetByAddress(address)
 	if val == nil {
 		return false, 0, ErrVoteInvalidAccount
 	}
 
 	// Check signature.
-	if !val.Verify(vote) {
+	if !val.PubKey.VerifyBytes(SignBytes(vote), vote.Signature) {
 		// Bad signature.
 		return false, 0, ErrVoteInvalidSignature
 	}
 
-	return vs.addVote(vote)
+	return voteSet.addVote(valIndex, vote)
 }
 
-func (vs *VoteSet) addVote(vote *Vote) (bool, uint, error) {
+func (voteSet *VoteSet) addVote(valIndex uint, vote *Vote) (bool, uint, error) {
 	// If vote already exists, return false.
-	if existingVote, ok := vs.votes[vote.SignerId]; ok {
+	if existingVote := voteSet.votes[valIndex]; existingVote != nil {
 		if bytes.Equal(existingVote.BlockHash, vote.BlockHash) {
 			return false, 0, nil
 		} else {
@@ -103,170 +103,154 @@ func (vs *VoteSet) addVote(vote *Vote) (bool, uint, error) {
 	}
 
 	// Add vote.
-	vs.votes[vote.SignerId] = vote
-	voterIndex, val := vs.vset.GetById(vote.SignerId)
+	_, val := voteSet.valSet.GetByIndex(valIndex)
 	if val == nil {
-		return false, 0, ErrVoteInvalidAccount
+		panic(fmt.Sprintf("Missing validator for index %v", valIndex))
 	}
-	vs.votesBitArray.SetIndex(uint(voterIndex), true)
+	voteSet.votes[valIndex] = vote
+	voteSet.votesBitArray.SetIndex(valIndex, true)
 	blockKey := string(vote.BlockHash) + string(BinaryBytes(vote.BlockParts))
-	totalBlockHashVotes := vs.votesByBlock[blockKey] + val.VotingPower
-	vs.votesByBlock[blockKey] = totalBlockHashVotes
-	vs.totalVotes += val.VotingPower
+	totalBlockHashVotes := voteSet.votesByBlock[blockKey] + val.VotingPower
+	voteSet.votesByBlock[blockKey] = totalBlockHashVotes
+	voteSet.totalVotes += val.VotingPower
 
 	// If we just nudged it up to two thirds majority, add it.
-	if totalBlockHashVotes > vs.vset.TotalVotingPower()*2/3 &&
-		(totalBlockHashVotes-val.VotingPower) <= vs.vset.TotalVotingPower()*2/3 {
-		vs.maj23Hash = vote.BlockHash
-		vs.maj23Parts = vote.BlockParts
-		vs.maj23Exists = true
+	if totalBlockHashVotes > voteSet.valSet.TotalVotingPower()*2/3 &&
+		(totalBlockHashVotes-val.VotingPower) <= voteSet.valSet.TotalVotingPower()*2/3 {
+		voteSet.maj23Hash = vote.BlockHash
+		voteSet.maj23Parts = vote.BlockParts
+		voteSet.maj23Exists = true
 	}
 
-	return true, voterIndex, nil
+	return true, valIndex, nil
 }
 
 // Assumes that commits VoteSet is valid.
-func (vs *VoteSet) AddFromCommits(commits *VoteSet) {
-	commitVotes := commits.AllVotes()
-	for _, commit := range commitVotes {
-		if commit.Round < vs.round {
-			vs.addVote(commit)
+func (voteSet *VoteSet) AddFromCommits(commits *VoteSet) {
+	for valIndex, commit := range commits.votes {
+		if commit.Round < voteSet.round {
+			voteSet.addVote(uint(valIndex), commit)
 		}
 	}
 }
 
-func (vs *VoteSet) BitArray() BitArray {
-	if vs == nil {
+func (voteSet *VoteSet) BitArray() BitArray {
+	if voteSet == nil {
 		return BitArray{}
 	}
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	return vs.votesBitArray.Copy()
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	return voteSet.votesBitArray.Copy()
 }
 
-func (vs *VoteSet) GetByIndex(index uint) *Vote {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
+func (voteSet *VoteSet) GetByIndex(valIndex uint) *Vote {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	return voteSet.votes[valIndex]
+}
 
-	id, val := vs.vset.GetByIndex(index)
+func (voteSet *VoteSet) GetByAddress(address []byte) *Vote {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	valIndex, val := voteSet.valSet.GetByAddress(address)
 	if val == nil {
-		panic("GetByIndex(index) returned nil")
+		panic("GetByAddress(address) returned nil")
 	}
-
-	return vs.votes[id]
+	return voteSet.votes[valIndex]
 }
 
-func (vs *VoteSet) GetById(id uint64) *Vote {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	return vs.votes[id]
-}
-
-func (vs *VoteSet) AllVotes() []*Vote {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	votes := []*Vote{}
-	for _, vote := range vs.votes {
-		votes = append(votes, vote)
-	}
-	return votes
-}
-
-func (vs *VoteSet) HasTwoThirdsMajority() bool {
-	if vs == nil {
+func (voteSet *VoteSet) HasTwoThirdsMajority() bool {
+	if voteSet == nil {
 		return false
 	}
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	return vs.maj23Exists
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	return voteSet.maj23Exists
 }
 
 // Returns either a blockhash (or nil) that received +2/3 majority.
 // If there exists no such majority, returns (nil, false).
-func (vs *VoteSet) TwoThirdsMajority() (hash []byte, parts PartSetHeader, ok bool) {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	if vs.maj23Exists {
-		return vs.maj23Hash, vs.maj23Parts, true
+func (voteSet *VoteSet) TwoThirdsMajority() (hash []byte, parts PartSetHeader, ok bool) {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	if voteSet.maj23Exists {
+		return voteSet.maj23Hash, voteSet.maj23Parts, true
 	} else {
 		return nil, PartSetHeader{}, false
 	}
 }
 
-func (vs *VoteSet) MakePOL() *POL {
-	if vs.type_ != VoteTypePrevote {
+func (voteSet *VoteSet) MakePOL() *POL {
+	if voteSet.type_ != VoteTypePrevote {
 		panic("Cannot MakePOL() unless VoteSet.Type is VoteTypePrevote")
 	}
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	if !vs.maj23Exists {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	if !voteSet.maj23Exists {
 		return nil
 	}
 	pol := &POL{
-		Height:     vs.height,
-		Round:      vs.round,
-		BlockHash:  vs.maj23Hash,
-		BlockParts: vs.maj23Parts,
+		Height:     voteSet.height,
+		Round:      voteSet.round,
+		BlockHash:  voteSet.maj23Hash,
+		BlockParts: voteSet.maj23Parts,
+		Votes:      make([]POLVoteSignature, voteSet.valSet.Size()),
 	}
-	for _, vote := range vs.votes {
-		if !bytes.Equal(vote.BlockHash, vs.maj23Hash) {
+	for valIndex, vote := range voteSet.votes {
+		if !bytes.Equal(vote.BlockHash, voteSet.maj23Hash) {
 			continue
 		}
-		if !vote.BlockParts.Equals(vs.maj23Parts) {
+		if !vote.BlockParts.Equals(voteSet.maj23Parts) {
 			continue
 		}
-		if vote.Type == VoteTypePrevote {
-			pol.Votes = append(pol.Votes, vote.Signature)
-		} else if vote.Type == VoteTypeCommit {
-			pol.Commits = append(pol.Commits, RoundSignature{vote.Round, vote.Signature})
-		} else {
-			Panicf("Unexpected vote type %X", vote.Type)
+		pol.Votes[valIndex] = POLVoteSignature{
+			Round:     vote.Round,
+			Signature: vote.Signature,
 		}
 	}
 	return pol
 }
 
-func (vs *VoteSet) MakeValidation() *Validation {
-	if vs.type_ != VoteTypeCommit {
+func (voteSet *VoteSet) MakeValidation() *Validation {
+	if voteSet.type_ != VoteTypeCommit {
 		panic("Cannot MakeValidation() unless VoteSet.Type is VoteTypeCommit")
 	}
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
-	if len(vs.maj23Hash) == 0 {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
+	if len(voteSet.maj23Hash) == 0 {
 		panic("Cannot MakeValidation() unless a blockhash has +2/3")
 	}
-	rsigs := make([]RoundSignature, vs.vset.Size())
-	vs.vset.Iterate(func(index uint, val *state.Validator) bool {
-		vote := vs.votes[val.Id]
-
+	commits := make([]Commit, voteSet.valSet.Size())
+	voteSet.valSet.Iterate(func(valIndex uint, val *state.Validator) bool {
+		vote := voteSet.votes[valIndex]
 		if vote == nil {
 			return false
 		}
-		if !bytes.Equal(vote.BlockHash, vs.maj23Hash) {
+		if !bytes.Equal(vote.BlockHash, voteSet.maj23Hash) {
 			return false
 		}
-		if !vote.BlockParts.Equals(vs.maj23Parts) {
+		if !vote.BlockParts.Equals(voteSet.maj23Parts) {
 			return false
 		}
-		rsigs[index] = RoundSignature{vote.Round, vote.Signature}
+		commits[valIndex] = Commit{vote.Round, vote.Signature}
 		return false
 	})
 	return &Validation{
-		Commits: rsigs,
+		Commits: commits,
 	}
 }
 
-func (vs *VoteSet) String() string {
-	return vs.StringWithIndent("")
+func (voteSet *VoteSet) String() string {
+	return voteSet.StringWithIndent("")
 }
 
-func (vs *VoteSet) StringWithIndent(indent string) string {
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
+func (voteSet *VoteSet) StringWithIndent(indent string) string {
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
 
-	voteStrings := make([]string, len(vs.votes))
+	voteStrings := make([]string, len(voteSet.votes))
 	counter := 0
-	for _, vote := range vs.votes {
+	for _, vote := range voteSet.votes {
 		voteStrings[counter] = vote.String()
 		counter++
 	}
@@ -275,18 +259,18 @@ func (vs *VoteSet) StringWithIndent(indent string) string {
 %s  %v
 %s  %v
 %s}`,
-		indent, vs.height, vs.round, vs.type_,
+		indent, voteSet.height, voteSet.round, voteSet.type_,
 		indent, strings.Join(voteStrings, "\n"+indent+"  "),
-		indent, vs.votesBitArray,
+		indent, voteSet.votesBitArray,
 		indent)
 }
 
-func (vs *VoteSet) Description() string {
-	if vs == nil {
+func (voteSet *VoteSet) Description() string {
+	if voteSet == nil {
 		return "nil-VoteSet"
 	}
-	vs.mtx.Lock()
-	defer vs.mtx.Unlock()
+	voteSet.mtx.Lock()
+	defer voteSet.mtx.Unlock()
 	return fmt.Sprintf(`VoteSet{H:%v R:%v T:%v %v}`,
-		vs.height, vs.round, vs.type_, vs.votesBitArray)
+		voteSet.height, voteSet.round, voteSet.type_, voteSet.votesBitArray)
 }
diff --git a/db/db.go b/db/db.go
index d44f4078..122f88a9 100644
--- a/db/db.go
+++ b/db/db.go
@@ -3,4 +3,7 @@ package db
 type DB interface {
 	Get([]byte) []byte
 	Set([]byte, []byte)
+	SetSync([]byte, []byte)
+	Delete([]byte)
+	DeleteSync([]byte)
 }
diff --git a/db/level_db.go b/db/level_db.go
index e6956404..aa9a222d 100644
--- a/db/level_db.go
+++ b/db/level_db.go
@@ -3,6 +3,7 @@ package db
 import (
 	"fmt"
 	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/opt"
 	"path"
 )
 
@@ -20,13 +21,6 @@ func NewLevelDB(name string) (*LevelDB, error) {
 	return database, nil
 }
 
-func (db *LevelDB) Set(key []byte, value []byte) {
-	err := db.db.Put(key, value, nil)
-	if err != nil {
-		panic(err)
-	}
-}
-
 func (db *LevelDB) Get(key []byte) []byte {
 	res, err := db.db.Get(key, nil)
 	if err != nil {
@@ -35,6 +29,20 @@ func (db *LevelDB) Get(key []byte) []byte {
 	return res
 }
 
+func (db *LevelDB) Set(key []byte, value []byte) {
+	err := db.db.Put(key, value, nil)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (db *LevelDB) SetSync(key []byte, value []byte) {
+	err := db.db.Put(key, value, &opt.WriteOptions{Sync: true})
+	if err != nil {
+		panic(err)
+	}
+}
+
 func (db *LevelDB) Delete(key []byte) {
 	err := db.db.Delete(key, nil)
 	if err != nil {
@@ -42,6 +50,13 @@ func (db *LevelDB) Delete(key []byte) {
 	}
 }
 
+func (db *LevelDB) DeleteSync(key []byte) {
+	err := db.db.Delete(key, &opt.WriteOptions{Sync: true})
+	if err != nil {
+		panic(err)
+	}
+}
+
 func (db *LevelDB) Db() *leveldb.DB {
 	return db.db
 }
diff --git a/db/mem_db.go b/db/mem_db.go
index 3824872e..9b9b0d20 100644
--- a/db/mem_db.go
+++ b/db/mem_db.go
@@ -13,18 +13,26 @@ func NewMemDB() *MemDB {
 	return database
 }
 
-func (db *MemDB) Set(key []byte, value []byte) {
-	db.db[string(key)] = value
-}
-
 func (db *MemDB) Get(key []byte) []byte {
 	return db.db[string(key)]
 }
 
+func (db *MemDB) Set(key []byte, value []byte) {
+	db.db[string(key)] = value
+}
+
+func (db *MemDB) SetSync(key []byte, value []byte) {
+	db.db[string(key)] = value
+}
+
 func (db *MemDB) Delete(key []byte) {
 	delete(db.db, string(key))
 }
 
+func (db *MemDB) DeleteSync(key []byte) {
+	delete(db.db, string(key))
+}
+
 func (db *MemDB) Print() {
 	for key, value := range db.db {
 		fmt.Printf("[%X]:\t[%X]\n", []byte(key), value)
diff --git a/mempool/mempool.go b/mempool/mempool.go
index 284f0458..631890f6 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -59,14 +59,14 @@ func (mem *Mempool) ResetForBlockAndState(block *Block, state *state.State) {
 	// First, create a lookup map of txns in new block.
 	blockTxsMap := make(map[string]struct{})
 	for _, tx := range block.Data.Txs {
-		txHash := BinaryHash(tx)
+		txHash := BinarySha256(tx)
 		blockTxsMap[string(txHash)] = struct{}{}
 	}
 
 	// Next, filter all txs from mem.txs that are in blockTxsMap
 	txs := []Tx{}
 	for _, tx := range mem.txs {
-		txHash := BinaryHash(tx)
+		txHash := BinarySha256(tx)
 		if _, ok := blockTxsMap[string(txHash)]; ok {
 			continue
 		} else {
diff --git a/mempool/reactor.go b/mempool/reactor.go
index 05d7278d..7a2b620c 100644
--- a/mempool/reactor.go
+++ b/mempool/reactor.go
@@ -3,7 +3,6 @@ package mempool
 import (
 	"bytes"
 	"fmt"
-	"io"
 	"sync/atomic"
 
 	. "github.com/tendermint/tendermint/binary"
@@ -119,12 +118,10 @@ const (
 // TODO: check for unnecessary extra bytes at the end.
 func decodeMessage(bz []byte) (msgType byte, msg interface{}) {
 	n, err := new(int64), new(error)
-	// log.Debug("decoding msg bytes: %X", bz)
 	msgType = bz[0]
 	switch msgType {
 	case msgTypeTx:
-		msg = readTxMessage(bytes.NewReader(bz[1:]), n, err)
-	// case ...:
+		msg = ReadBinary(&TxMessage{}, bytes.NewReader(bz[1:]), n, err)
 	default:
 		msg = nil
 	}
@@ -137,17 +134,7 @@ type TxMessage struct {
 	Tx Tx
 }
 
-func readTxMessage(r io.Reader, n *int64, err *error) *TxMessage {
-	return &TxMessage{
-		Tx: ReadTx(r, n, err),
-	}
-}
-
-func (m *TxMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeTx, &n, &err)
-	WriteBinary(w, m.Tx, &n, &err)
-	return
-}
+func (m *TxMessage) TypeByte() byte { return msgTypeTx }
 
 func (m *TxMessage) String() string {
 	return fmt.Sprintf("[TxMessage %v]", m.Tx)
diff --git a/merkle/iavl_node.go b/merkle/iavl_node.go
index dad7d38c..feece084 100644
--- a/merkle/iavl_node.go
+++ b/merkle/iavl_node.go
@@ -253,8 +253,8 @@ func (node *IAVLNode) remove(t *IAVLTree, key interface{}) (
 // NOTE: sets hashes recursively
 func (node *IAVLNode) writeToCountHashes(t *IAVLTree, w io.Writer) (n int64, hashCount uint64, err error) {
 	// height & size & key
-	WriteUInt8(w, node.height, &n, &err)
-	WriteUInt64(w, node.size, &n, &err)
+	WriteUInt8(node.height, w, &n, &err)
+	WriteUInt64(node.size, w, &n, &err)
 	t.keyCodec.Encode(node.key, w, &n, &err)
 	if err != nil {
 		return
@@ -273,7 +273,7 @@ func (node *IAVLNode) writeToCountHashes(t *IAVLTree, w io.Writer) (n int64, has
 		if node.leftHash == nil {
 			panic("node.leftHash was nil in save")
 		}
-		WriteByteSlice(w, node.leftHash, &n, &err)
+		WriteByteSlice(node.leftHash, w, &n, &err)
 		// right
 		if node.rightNode != nil {
 			rightHash, rightCount := node.rightNode.hashWithCount(t)
@@ -283,7 +283,7 @@ func (node *IAVLNode) writeToCountHashes(t *IAVLTree, w io.Writer) (n int64, has
 		if node.rightHash == nil {
 			panic("node.rightHash was nil in save")
 		}
-		WriteByteSlice(w, node.rightHash, &n, &err)
+		WriteByteSlice(node.rightHash, w, &n, &err)
 	}
 	return
 }
diff --git a/merkle/simple_tree.go b/merkle/simple_tree.go
index b3a6331c..5433dbfd 100644
--- a/merkle/simple_tree.go
+++ b/merkle/simple_tree.go
@@ -35,8 +35,8 @@ func HashFromTwoHashes(left []byte, right []byte) []byte {
 	var n int64
 	var err error
 	var hasher = sha256.New()
-	WriteByteSlice(hasher, left, &n, &err)
-	WriteByteSlice(hasher, right, &n, &err)
+	WriteByteSlice(left, hasher, &n, &err)
+	WriteByteSlice(right, hasher, &n, &err)
 	if err != nil {
 		panic(err)
 	}
@@ -58,16 +58,15 @@ func HashFromHashes(hashes [][]byte) []byte {
 }
 
 // Convenience for HashFromHashes.
-func HashFromBinaries(items []Binary) []byte {
+func HashFromBinaries(items []interface{}) []byte {
 	hashes := [][]byte{}
 	for _, item := range items {
-		hasher := sha256.New()
-		_, err := item.WriteTo(hasher)
-		if err != nil {
+		hasher, n, err := sha256.New(), new(int64), new(error)
+		WriteBinary(item, hasher, n, err)
+		if *err != nil {
 			panic(err)
 		}
-		hash := hasher.Sum(nil)
-		hashes = append(hashes, hash)
+		hashes = append(hashes, hasher.Sum(nil))
 	}
 	return HashFromHashes(hashes)
 }
diff --git a/p2p/connection.go b/p2p/connection.go
index dfaf0e72..925babd5 100644
--- a/p2p/connection.go
+++ b/p2p/connection.go
@@ -17,7 +17,7 @@ import (
 )
 
 const (
-	numBatchPackets           = 10
+	numBatchMsgPackets        = 10
 	minReadBufferSize         = 1024
 	minWriteBufferSize        = 1024
 	flushThrottleMS           = 50
@@ -35,7 +35,7 @@ type errorCbFunc func(interface{})
 
 /*
 A MConnection wraps a network connection and handles buffering and multiplexing.
-Binary messages are sent with ".Send(channelId, msg)".
+<essages are sent with ".Send(channelId, msg)".
 Inbound message bytes are handled with an onReceive callback function.
 */
 type MConnection struct {
@@ -158,7 +158,7 @@ func (c *MConnection) stopForError(r interface{}) {
 }
 
 // Queues a message to be sent to channel.
-func (c *MConnection) Send(chId byte, msg Binary) bool {
+func (c *MConnection) Send(chId byte, msg interface{}) bool {
 	if atomic.LoadUint32(&c.stopped) == 1 {
 		return false
 	}
@@ -185,7 +185,7 @@ func (c *MConnection) Send(chId byte, msg Binary) bool {
 
 // Queues a message to be sent to channel.
 // Nonblocking, returns true if successful.
-func (c *MConnection) TrySend(chId byte, msg Binary) bool {
+func (c *MConnection) TrySend(chId byte, msg interface{}) bool {
 	if atomic.LoadUint32(&c.stopped) == 1 {
 		return false
 	}
@@ -242,18 +242,18 @@ FOR_LOOP:
 				channel.updateStats()
 			}
 		case <-c.pingTimer.Ch:
-			WriteByte(c.bufWriter, packetTypePing, &n, &err)
+			WriteByte(packetTypePing, c.bufWriter, &n, &err)
 			c.sendMonitor.Update(int(n))
 			c.flush()
 		case <-c.pong:
-			WriteByte(c.bufWriter, packetTypePong, &n, &err)
+			WriteByte(packetTypePing, c.bufWriter, &n, &err)
 			c.sendMonitor.Update(int(n))
 			c.flush()
 		case <-c.quit:
 			break FOR_LOOP
 		case <-c.send:
-			// Send some packets
-			eof := c.sendSomePackets()
+			// Send some msgPackets
+			eof := c.sendSomeMsgPackets()
 			if !eof {
 				// Keep sendRoutine awake.
 				select {
@@ -278,15 +278,15 @@ FOR_LOOP:
 
 // Returns true if messages from channels were exhausted.
 // Blocks in accordance to .sendMonitor throttling.
-func (c *MConnection) sendSomePackets() bool {
+func (c *MConnection) sendSomeMsgPackets() bool {
 	// Block until .sendMonitor says we can write.
 	// Once we're ready we send more than we asked for,
 	// but amortized it should even out.
-	c.sendMonitor.Limit(maxPacketSize, atomic.LoadInt64(&c.sendRate), true)
+	c.sendMonitor.Limit(maxMsgPacketSize, atomic.LoadInt64(&c.sendRate), true)
 
-	// Now send some packets.
-	for i := 0; i < numBatchPackets; i++ {
-		if c.sendPacket() {
+	// Now send some msgPackets.
+	for i := 0; i < numBatchMsgPackets; i++ {
+		if c.sendMsgPacket() {
 			return true
 		}
 	}
@@ -294,8 +294,8 @@ func (c *MConnection) sendSomePackets() bool {
 }
 
 // Returns true if messages from channels were exhausted.
-func (c *MConnection) sendPacket() bool {
-	// Choose a channel to create a packet from.
+func (c *MConnection) sendMsgPacket() bool {
+	// Choose a channel to create a msgPacket from.
 	// The chosen channel will be the one whose recentlySent/priority is the least.
 	var leastRatio float32 = math.MaxFloat32
 	var leastChannel *Channel
@@ -316,13 +316,13 @@ func (c *MConnection) sendPacket() bool {
 	if leastChannel == nil {
 		return true
 	} else {
-		// log.Debug("Found a packet to send")
+		// log.Debug("Found a msgPacket to send")
 	}
 
-	// Make & send a packet from this channel
-	n, err := leastChannel.writePacketTo(c.bufWriter)
+	// Make & send a msgPacket from this channel
+	n, err := leastChannel.writeMsgPacketTo(c.bufWriter)
 	if err != nil {
-		log.Warning("Failed to write packet. Error: %v", err)
+		log.Warning("Failed to write msgPacket. Error: %v", err)
 		c.stopForError(err)
 		return true
 	}
@@ -331,7 +331,7 @@ func (c *MConnection) sendPacket() bool {
 	return false
 }
 
-// recvRoutine reads packets and reconstructs the message using the channels' "recving" buffer.
+// recvRoutine reads msgPackets and reconstructs the message using the channels' "recving" buffer.
 // After a whole message has been assembled, it's pushed to onReceive().
 // Blocks depending on how the connection is throttled.
 func (c *MConnection) recvRoutine() {
@@ -340,7 +340,7 @@ func (c *MConnection) recvRoutine() {
 FOR_LOOP:
 	for {
 		// Block until .recvMonitor says we can read.
-		c.recvMonitor.Limit(maxPacketSize, atomic.LoadInt64(&c.recvRate), true)
+		c.recvMonitor.Limit(maxMsgPacketSize, atomic.LoadInt64(&c.recvRate), true)
 
 		// Read packet type
 		var n int64
@@ -359,7 +359,7 @@ FOR_LOOP:
 		if log.IsEnabledFor(logging.DEBUG) {
 			numBytes := c.bufReader.Buffered()
 			bytes, err := c.bufReader.Peek(MinInt(numBytes, 100))
-			if err != nil {
+			if err == nil {
 				log.Debug("recvRoutine packet type %X, peeked: %X", pktType, bytes)
 			}
 		}
@@ -371,10 +371,11 @@ FOR_LOOP:
 			c.pong <- struct{}{}
 		case packetTypePong:
 			// do nothing
-		case packetTypeMessage:
-			pkt, n, err := readPacketSafe(c.bufReader)
-			c.recvMonitor.Update(int(n))
-			if err != nil {
+		case packetTypeMsg:
+			pkt, n, err := msgPacket{}, new(int64), new(error)
+			ReadBinary(&pkt, c.bufReader, n, err)
+			c.recvMonitor.Update(int(*n))
+			if *err != nil {
 				if atomic.LoadUint32(&c.stopped) != 1 {
 					log.Info("%v failed @ recvRoutine", c)
 					c.Stop()
@@ -385,7 +386,7 @@ FOR_LOOP:
 			if !ok || channel == nil {
 				Panicf("Unknown channel %X", pkt.ChannelId)
 			}
-			msgBytes := channel.recvPacket(pkt)
+			msgBytes := channel.recvMsgPacket(pkt)
 			if msgBytes != nil {
 				c.onReceive(pkt.ChannelId, msgBytes)
 			}
@@ -394,7 +395,7 @@ FOR_LOOP:
 		}
 
 		// TODO: shouldn't this go in the sendRoutine?
-		// Better to send a packet when *we* haven't sent anything for a while.
+		// Better to send a ping packet when *we* haven't sent anything for a while.
 		c.pingTimer.Reset()
 	}
 
@@ -471,8 +472,8 @@ func (ch *Channel) canSend() bool {
 	return ch.loadSendQueueSize() < defaultSendQueueCapacity
 }
 
-// Returns true if any packets are pending to be sent.
-// Call before calling nextPacket()
+// Returns true if any msgPackets are pending to be sent.
+// Call before calling nextMsgPacket()
 // Goroutine-safe
 func (ch *Channel) isSendPending() bool {
 	if len(ch.sending) == 0 {
@@ -484,38 +485,37 @@ func (ch *Channel) isSendPending() bool {
 	return true
 }
 
-// Creates a new packet to send.
+// Creates a new msgPacket to send.
 // Not goroutine-safe
-func (ch *Channel) nextPacket() packet {
-	packet := packet{}
+func (ch *Channel) nextMsgPacket() msgPacket {
+	packet := msgPacket{}
 	packet.ChannelId = byte(ch.id)
-	packet.Bytes = ch.sending[:MinInt(maxPacketSize, len(ch.sending))]
-	if len(ch.sending) <= maxPacketSize {
+	packet.Bytes = ch.sending[:MinInt(maxMsgPacketSize, len(ch.sending))]
+	if len(ch.sending) <= maxMsgPacketSize {
 		packet.EOF = byte(0x01)
 		ch.sending = nil
 		atomic.AddUint32(&ch.sendQueueSize, ^uint32(0)) // decrement sendQueueSize
 	} else {
 		packet.EOF = byte(0x00)
-		ch.sending = ch.sending[MinInt(maxPacketSize, len(ch.sending)):]
+		ch.sending = ch.sending[MinInt(maxMsgPacketSize, len(ch.sending)):]
 	}
 	return packet
 }
 
-// Writes next packet to w.
+// Writes next msgPacket to w.
 // Not goroutine-safe
-func (ch *Channel) writePacketTo(w io.Writer) (n int64, err error) {
-	packet := ch.nextPacket()
-	WriteByte(w, packetTypeMessage, &n, &err)
-	WriteBinary(w, packet, &n, &err)
+func (ch *Channel) writeMsgPacketTo(w io.Writer) (n int64, err error) {
+	packet := ch.nextMsgPacket()
+	WriteBinary(packet, w, &n, &err)
 	if err != nil {
 		ch.recentlySent += n
 	}
 	return
 }
 
-// Handles incoming packets. Returns a msg bytes if msg is complete.
+// Handles incoming msgPackets. Returns a msg bytes if msg is complete.
 // Not goroutine-safe
-func (ch *Channel) recvPacket(pkt packet) []byte {
+func (ch *Channel) recvMsgPacket(pkt msgPacket) []byte {
 	ch.recving = append(ch.recving, pkt.Bytes...)
 	if pkt.EOF == byte(0x01) {
 		msgBytes := ch.recving
@@ -536,36 +536,23 @@ func (ch *Channel) updateStats() {
 //-----------------------------------------------------------------------------
 
 const (
-	maxPacketSize     = 1024
-	packetTypePing    = byte(0x00)
-	packetTypePong    = byte(0x01)
-	packetTypeMessage = byte(0x10)
+	maxMsgPacketSize = 1024
+	packetTypePing   = byte(0x00)
+	packetTypePong   = byte(0x01)
+	packetTypeMsg    = byte(0x10)
 )
 
-// Messages in channels are chopped into smaller packets for multiplexing.
-type packet struct {
+// Messages in channels are chopped into smaller msgPackets for multiplexing.
+type msgPacket struct {
 	ChannelId byte
 	EOF       byte // 1 means message ends here.
 	Bytes     []byte
 }
 
-func (p packet) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, p.ChannelId, &n, &err)
-	WriteByte(w, p.EOF, &n, &err)
-	WriteByteSlice(w, p.Bytes, &n, &err)
-	return
-}
+func (p msgPacket) TypeByte() byte { return packetTypeMsg }
 
-func (p packet) String() string {
-	return fmt.Sprintf("Packet{%X:%X}", p.ChannelId, p.Bytes)
-}
-
-func readPacketSafe(r io.Reader) (pkt packet, n int64, err error) {
-	chId := ReadByte(r, &n, &err)
-	eof := ReadByte(r, &n, &err)
-	bytes := ReadByteSlice(r, &n, &err)
-	pkt = packet{chId, eof, bytes}
-	return
+func (p msgPacket) String() string {
+	return fmt.Sprintf("MsgPacket{%X:%X}", p.ChannelId, p.Bytes)
 }
 
 //-----------------------------------------------------------------------------
@@ -574,19 +561,9 @@ func readPacketSafe(r io.Reader) (pkt packet, n int64, err error) {
 // Reading requires a custom decoder that switches on the first type byte of a byteslice.
 type TypedMessage struct {
 	Type byte
-	Msg  Binary
-}
-
-func (tm TypedMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, tm.Type, &n, &err)
-	WriteBinary(w, tm.Msg, &n, &err)
-	return
+	Msg  interface{}
 }
 
 func (tm TypedMessage) String() string {
 	return fmt.Sprintf("TMsg{%X:%v}", tm.Type, tm.Msg)
 }
-
-func (tm TypedMessage) Bytes() []byte {
-	return BinaryBytes(tm)
-}
diff --git a/p2p/log.go b/p2p/log.go
index c68c453d..fc3a2c08 100644
--- a/p2p/log.go
+++ b/p2p/log.go
@@ -8,7 +8,7 @@ var log = logging.MustGetLogger("p2p")
 
 func init() {
 	logging.SetFormatter(logging.MustStringFormatter("[%{level:.1s}] %{message}"))
-	logging.SetLevel(logging.WARNING, "p2p")
+	logging.SetLevel(logging.DEBUG, "p2p")
 }
 
 func SetP2PLogger(l *logging.Logger) {
diff --git a/p2p/netaddress.go b/p2p/netaddress.go
index c3e3c6d7..d2369fd9 100644
--- a/p2p/netaddress.go
+++ b/p2p/netaddress.go
@@ -5,13 +5,10 @@
 package p2p
 
 import (
-	"io"
+	"fmt"
 	"net"
 	"strconv"
 	"time"
-
-	. "github.com/tendermint/tendermint/binary"
-	. "github.com/tendermint/tendermint/common"
 )
 
 /* NetAddress */
@@ -26,7 +23,7 @@ type NetAddress struct {
 func NewNetAddress(addr net.Addr) *NetAddress {
 	tcpAddr, ok := addr.(*net.TCPAddr)
 	if !ok {
-		Panicf("Only TCPAddrs are supported. Got: %v", addr)
+		panic(fmt.Sprintf("Only TCPAddrs are supported. Got: %v", addr))
 	}
 	ip := tcpAddr.IP
 	port := uint16(tcpAddr.Port)
@@ -47,12 +44,6 @@ func NewNetAddressString(addr string) *NetAddress {
 	return na
 }
 
-func ReadNetAddress(r io.Reader, n *int64, err *error) *NetAddress {
-	ipBytes := ReadByteSlice(r, n, err)
-	port := ReadUInt16(r, n, err)
-	return NewNetAddressIPPort(net.IP(ipBytes), port)
-}
-
 func NewNetAddressIPPort(ip net.IP, port uint16) *NetAddress {
 	na := &NetAddress{
 		IP:   ip,
@@ -65,12 +56,6 @@ func NewNetAddressIPPort(ip net.IP, port uint16) *NetAddress {
 	return na
 }
 
-func (na *NetAddress) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByteSlice(w, na.IP.To16(), &n, &err)
-	WriteUInt16(w, na.Port, &n, &err)
-	return
-}
-
 func (na *NetAddress) Equals(other interface{}) bool {
 	if o, ok := other.(*NetAddress); ok {
 		return na.String() == o.String()
diff --git a/p2p/peer.go b/p2p/peer.go
index be0608cf..ff69e8ac 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -72,14 +72,14 @@ func (p *Peer) IsOutbound() bool {
 	return p.outbound
 }
 
-func (p *Peer) Send(chId byte, msg Binary) bool {
+func (p *Peer) Send(chId byte, msg interface{}) bool {
 	if atomic.LoadUint32(&p.stopped) == 1 {
 		return false
 	}
 	return p.mconn.Send(chId, msg)
 }
 
-func (p *Peer) TrySend(chId byte, msg Binary) bool {
+func (p *Peer) TrySend(chId byte, msg interface{}) bool {
 	if atomic.LoadUint32(&p.stopped) == 1 {
 		return false
 	}
@@ -94,7 +94,7 @@ func (p *Peer) CanSend(chId byte) bool {
 }
 
 func (p *Peer) WriteTo(w io.Writer) (n int64, err error) {
-	WriteString(w, p.Key, &n, &err)
+	WriteString(p.Key, w, &n, &err)
 	return
 }
 
diff --git a/p2p/pex_reactor.go b/p2p/pex_reactor.go
index 85b94ffb..e8c16728 100644
--- a/p2p/pex_reactor.go
+++ b/p2p/pex_reactor.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io"
 	"sync/atomic"
 	"time"
 
@@ -97,17 +96,17 @@ func (pexR *PEXReactor) Receive(chId byte, src *Peer, msgBytes []byte) {
 		// src requested some peers.
 		// TODO: prevent abuse.
 		addrs := pexR.book.GetSelection()
-		msg := &pexRddrsMessage{Addrs: addrs}
+		msg := &pexAddrsMessage{Addrs: addrs}
 		queued := src.TrySend(PexCh, msg)
 		if !queued {
 			// ignore
 		}
-	case *pexRddrsMessage:
+	case *pexAddrsMessage:
 		// We received some peer addresses from src.
 		// TODO: prevent abuse.
 		// (We don't want to get spammed with bad peers)
 		srcAddr := src.RemoteAddress()
-		for _, addr := range msg.(*pexRddrsMessage).Addrs {
+		for _, addr := range msg.(*pexAddrsMessage).Addrs {
 			pexR.book.AddAddress(addr, srcAddr)
 		}
 	default:
@@ -122,7 +121,7 @@ func (pexR *PEXReactor) RequestPEX(peer *Peer) {
 }
 
 func (pexR *PEXReactor) SendAddrs(peer *Peer, addrs []*NetAddress) {
-	peer.Send(PexCh, &pexRddrsMessage{Addrs: addrs})
+	peer.Send(PexCh, &pexAddrsMessage{Addrs: addrs})
 }
 
 // Ensures that sufficient peers are connected. (continuous)
@@ -193,8 +192,7 @@ func (pexR *PEXReactor) ensurePeers() {
 }
 
 //-----------------------------------------------------------------------------
-
-/* Messages */
+// Messages
 
 const (
 	msgTypeUnknown = byte(0x00)
@@ -211,7 +209,7 @@ func decodeMessage(bz []byte) (msg interface{}) {
 	case msgTypeRequest:
 		return &pexRequestMessage{}
 	case msgTypeAddrs:
-		return readPexAddrsMessage(bytes.NewReader(bz[1:]), &n, &err)
+		return ReadBinary(&pexAddrsMessage{}, bytes.NewReader(bz[1:]), &n, &err)
 	default:
 		return nil
 	}
@@ -223,10 +221,7 @@ A pexRequestMessage requests additional peer addresses.
 type pexRequestMessage struct {
 }
 
-func (m *pexRequestMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeRequest, &n, &err)
-	return
-}
+func (m *pexRequestMessage) TypeByte() byte { return msgTypeRequest }
 
 func (m *pexRequestMessage) String() string {
 	return "[pexRequest]"
@@ -235,31 +230,12 @@ func (m *pexRequestMessage) String() string {
 /*
 A message with announced peer addresses.
 */
-type pexRddrsMessage struct {
+type pexAddrsMessage struct {
 	Addrs []*NetAddress
 }
 
-func readPexAddrsMessage(r io.Reader, n *int64, err *error) *pexRddrsMessage {
-	numAddrs := int(ReadUInt32(r, n, err))
-	addrs := []*NetAddress{}
-	for i := 0; i < numAddrs; i++ {
-		addr := ReadNetAddress(r, n, err)
-		addrs = append(addrs, addr)
-	}
-	return &pexRddrsMessage{
-		Addrs: addrs,
-	}
-}
+func (m *pexAddrsMessage) TypeByte() byte { return msgTypeAddrs }
 
-func (m *pexRddrsMessage) WriteTo(w io.Writer) (n int64, err error) {
-	WriteByte(w, msgTypeAddrs, &n, &err)
-	WriteUInt32(w, uint32(len(m.Addrs)), &n, &err)
-	for _, addr := range m.Addrs {
-		WriteBinary(w, addr, &n, &err)
-	}
-	return
-}
-
-func (m *pexRddrsMessage) String() string {
-	return fmt.Sprintf("[pexRddrs %v]", m.Addrs)
+func (m *pexAddrsMessage) String() string {
+	return fmt.Sprintf("[pexAddrs %v]", m.Addrs)
 }
diff --git a/p2p/switch.go b/p2p/switch.go
index 13009338..6b8967fb 100644
--- a/p2p/switch.go
+++ b/p2p/switch.go
@@ -2,11 +2,11 @@ package p2p
 
 import (
 	"errors"
+	"fmt"
 	"net"
 	"sync/atomic"
 	"time"
 
-	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/common"
 )
 
@@ -67,7 +67,7 @@ func NewSwitch(reactors []Reactor) *Switch {
 		for _, chDesc := range reactorChannels {
 			chId := chDesc.Id
 			if reactorsByCh[chId] != nil {
-				Panicf("Channel %X has multiple reactors %v & %v", chId, reactorsByCh[chId], reactor)
+				panic(fmt.Sprintf("Channel %X has multiple reactors %v & %v", chId, reactorsByCh[chId], reactor))
 			}
 			chDescs = append(chDescs, chDesc)
 			reactorsByCh[chId] = reactor
@@ -165,7 +165,7 @@ func (sw *Switch) IsDialing(addr *NetAddress) bool {
 }
 
 // XXX: This is wrong, we can't just ignore failures on TrySend.
-func (sw *Switch) Broadcast(chId byte, msg Binary) (numSuccess, numFailure int) {
+func (sw *Switch) Broadcast(chId byte, msg interface{}) (numSuccess, numFailure int) {
 	if atomic.LoadUint32(&sw.stopped) == 1 {
 		return
 	}
diff --git a/p2p/switch_test.go b/p2p/switch_test.go
index 0b9f00d3..f195f83b 100644
--- a/p2p/switch_test.go
+++ b/p2p/switch_test.go
@@ -2,7 +2,6 @@ package p2p
 
 import (
 	"bytes"
-	"io"
 	"sync"
 	"testing"
 	"time"
@@ -10,15 +9,6 @@ import (
 	. "github.com/tendermint/tendermint/binary"
 )
 
-type String string
-
-func (s String) WriteTo(w io.Writer) (n int64, err error) {
-	WriteString(w, string(s), &n, &err)
-	return
-}
-
-//-----------------------------------------------------------------------------
-
 type PeerMessage struct {
 	PeerKey string
 	Bytes   []byte
@@ -137,16 +127,16 @@ func TestSwitches(t *testing.T) {
 		t.Errorf("Expected exactly 1 peer in s2, got %v", s2.Peers().Size())
 	}
 
-	ch0Msg := String("channel zero")
-	ch1Msg := String("channel one")
-	ch2Msg := String("channel two")
+	ch0Msg := "channel zero"
+	ch1Msg := "channel one"
+	ch2Msg := "channel two"
 
 	s1.Broadcast(byte(0x00), ch0Msg)
 	s1.Broadcast(byte(0x01), ch1Msg)
 	s1.Broadcast(byte(0x02), ch2Msg)
 
 	// Wait for things to settle...
-	time.Sleep(100 * time.Millisecond)
+	time.Sleep(5000 * time.Millisecond)
 
 	// Check message on ch0
 	ch0Msgs := s2.Reactors()[0].(*TestReactor).msgsReceived[byte(0x00)]
@@ -206,7 +196,7 @@ func BenchmarkSwitches(b *testing.B) {
 	// Send random message from one channel to another
 	for i := 0; i < b.N; i++ {
 		chId := byte(i % 4)
-		nS, nF := s1.Broadcast(chId, String("test data"))
+		nS, nF := s1.Broadcast(chId, "test data")
 		numSuccess += nS
 		numFailure += nF
 	}
diff --git a/rpc/http_params.go b/rpc/http_params.go
index 1ad23f2a..dfd192da 100644
--- a/rpc/http_params.go
+++ b/rpc/http_params.go
@@ -1,7 +1,6 @@
 package rpc
 
 import (
-	"fmt"
 	"net/http"
 	"regexp"
 	"strconv"
diff --git a/state/account.go b/state/account.go
index 307bd810..703ed4a0 100644
--- a/state/account.go
+++ b/state/account.go
@@ -1,177 +1,47 @@
 package state
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 
-	"github.com/tendermint/go-ed25519"
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
-	. "github.com/tendermint/tendermint/blocks"
-	. "github.com/tendermint/tendermint/common"
-)
-
-const (
-	AccountStatusNominal   = byte(0x00)
-	AccountStatusBonded    = byte(0x01)
-	AccountStatusUnbonding = byte(0x02)
-	AccountStatusDupedOut  = byte(0x03)
 )
 
 type Account struct {
-	Id     uint64 // Numeric id of account, incrementing.
-	PubKey []byte
-}
-
-func ReadAccount(r io.Reader, n *int64, err *error) Account {
-	return Account{
-		Id:     ReadUInt64(r, n, err),
-		PubKey: ReadByteSlice(r, n, err),
-	}
-}
-
-func (account Account) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUInt64(w, account.Id, &n, &err)
-	WriteByteSlice(w, account.PubKey, &n, &err)
-	return
-}
-
-func (account Account) VerifyBytes(msg []byte, sig Signature) bool {
-	if sig.SignerId != account.Id {
-		panic("account.id doesn't match sig.signerid")
-	}
-	if len(sig.Bytes) == 0 {
-		panic("signature is empty")
-	}
-	v1 := &ed25519.Verify{
-		Message:   msg,
-		PubKey:    account.PubKey,
-		Signature: sig.Bytes,
-	}
-	ok := ed25519.VerifyBatch([]*ed25519.Verify{v1})
-	return ok
-}
-
-func (account Account) Verify(o Signable) bool {
-	sig := o.GetSignature()
-	o.SetSignature(Signature{}) // clear
-	msg := BinaryBytes(o)
-	o.SetSignature(sig) // restore
-	return account.VerifyBytes(msg, sig)
-}
-
-func (account Account) String() string {
-	return fmt.Sprintf("Account{%v:%X}", account.Id, account.PubKey[:6])
-}
-
-//-----------------------------------------------------------------------------
-
-type AccountDetail struct {
-	Account
+	Address  []byte
+	PubKey   PubKey
 	Sequence uint
 	Balance  uint64
-	Status   byte
 }
 
-func ReadAccountDetail(r io.Reader, n *int64, err *error) *AccountDetail {
-	return &AccountDetail{
-		Account:  ReadAccount(r, n, err),
-		Sequence: ReadUVarInt(r, n, err),
-		Balance:  ReadUInt64(r, n, err),
-		Status:   ReadByte(r, n, err),
+func NewAccount(address []byte, pubKey PubKey) *Account {
+	return &Account{
+		Address:  address,
+		PubKey:   pubKey,
+		Sequence: uint(0),
+		Balance:  uint64(0),
 	}
 }
 
-func (accDet *AccountDetail) WriteTo(w io.Writer) (n int64, err error) {
-	WriteBinary(w, accDet.Account, &n, &err)
-	WriteUVarInt(w, accDet.Sequence, &n, &err)
-	WriteUInt64(w, accDet.Balance, &n, &err)
-	WriteByte(w, accDet.Status, &n, &err)
-	return
+func (account *Account) Copy() *Account {
+	accountCopy := *account
+	return &accountCopy
 }
 
-func (accDet *AccountDetail) String() string {
-	return fmt.Sprintf("AccountDetail{%v:%X Sequence:%v Balance:%v Status:%X}",
-		accDet.Id, accDet.PubKey, accDet.Sequence, accDet.Balance, accDet.Status)
+func (account *Account) String() string {
+	return fmt.Sprintf("Account{%X:%v}", account.Address, account.PubKey)
 }
 
-func (accDet *AccountDetail) Copy() *AccountDetail {
-	accDetCopy := *accDet
-	return &accDetCopy
+func AccountEncoder(o interface{}, w io.Writer, n *int64, err *error) {
+	WriteBinary(o.(*Account), w, n, err)
 }
 
-//-------------------------------------
-
-var AccountDetailCodec = accountDetailCodec{}
-
-type accountDetailCodec struct{}
-
-func (abc accountDetailCodec) Encode(accDet interface{}, w io.Writer, n *int64, err *error) {
-	WriteBinary(w, accDet.(*AccountDetail), n, err)
+func AccountDecoder(r io.Reader, n *int64, err *error) interface{} {
+	return ReadBinary(&Account{}, r, n, err)
 }
 
-func (abc accountDetailCodec) Decode(r io.Reader, n *int64, err *error) interface{} {
-	return ReadAccountDetail(r, n, err)
-}
-
-func (abc accountDetailCodec) Compare(o1 interface{}, o2 interface{}) int {
-	panic("AccountDetailCodec.Compare not implemented")
-}
-
-//-----------------------------------------------------------------------------
-
-type PrivAccount struct {
-	Account
-	PrivKey []byte
-}
-
-// Generates a new account with private key.
-// The Account.Id is empty since it isn't in the blockchain.
-func GenPrivAccount() *PrivAccount {
-	privKey := CRandBytes(32)
-	pubKey := ed25519.MakePubKey(privKey)
-	return &PrivAccount{
-		Account: Account{
-			Id:     uint64(0),
-			PubKey: pubKey,
-		},
-		PrivKey: privKey,
-	}
-}
-
-// The Account.Id is empty since it isn't in the blockchain.
-func PrivAccountFromJSON(jsonBlob []byte) (privAccount *PrivAccount) {
-	err := json.Unmarshal(jsonBlob, &privAccount)
-	if err != nil {
-		Panicf("Couldn't read PrivAccount: %v", err)
-	}
-	return
-}
-
-// The Account.Id is empty since it isn't in the blockchain.
-func PrivAccountFromFile(file string) *PrivAccount {
-	jsonBlob, err := ioutil.ReadFile(file)
-	if err != nil {
-		Panicf("Couldn't read PrivAccount from file: %v", err)
-	}
-	return PrivAccountFromJSON(jsonBlob)
-}
-
-func (pa *PrivAccount) SignBytes(msg []byte) Signature {
-	signature := ed25519.SignMessage(msg, pa.PrivKey, pa.PubKey)
-	sig := Signature{
-		SignerId: pa.Id,
-		Bytes:    signature,
-	}
-	return sig
-}
-
-func (pa *PrivAccount) Sign(o Signable) {
-	if !o.GetSignature().IsZero() {
-		panic("Cannot sign: already signed")
-	}
-	msg := BinaryBytes(o)
-	sig := pa.SignBytes(msg)
-	o.SetSignature(sig)
+var AccountCodec = Codec{
+	Encode: AccountEncoder,
+	Decode: AccountDecoder,
 }
diff --git a/state/genesis.go b/state/genesis.go
index 75130e8f..a16be769 100644
--- a/state/genesis.go
+++ b/state/genesis.go
@@ -13,8 +13,9 @@ import (
 )
 
 type GenesisDoc struct {
-	GenesisTime    time.Time
-	AccountDetails []*AccountDetail
+	GenesisTime time.Time
+	Accounts    []*Account
+	Validators  []*Validator
 }
 
 func GenesisDocFromJSON(jsonBlob []byte) (genState *GenesisDoc) {
@@ -31,47 +32,32 @@ func GenesisStateFromFile(db db_.DB, genDocFile string) *State {
 		Panicf("Couldn't read GenesisDoc file: %v", err)
 	}
 	genDoc := GenesisDocFromJSON(jsonBlob)
-	return GenesisStateFromDoc(db, genDoc)
+	return GenesisState(db, genDoc)
 }
 
-func GenesisStateFromDoc(db db_.DB, genDoc *GenesisDoc) *State {
-	return GenesisState(db, genDoc.GenesisTime, genDoc.AccountDetails)
-}
-
-func GenesisState(db db_.DB, genesisTime time.Time, accDets []*AccountDetail) *State {
-
-	if genesisTime.IsZero() {
-		genesisTime = time.Now()
-	}
-
-	// TODO: Use "uint64Codec" instead of BasicCodec
-	accountDetails := merkle.NewIAVLTree(BasicCodec, AccountDetailCodec, defaultAccountDetailsCacheCapacity, db)
-	validators := []*Validator{}
-
-	for _, accDet := range accDets {
-		accountDetails.Set(accDet.Id, accDet)
-		if accDet.Status == AccountStatusBonded {
-			validators = append(validators, &Validator{
-				Account:     accDet.Account,
-				BondHeight:  0,
-				VotingPower: accDet.Balance,
-				Accum:       0,
-			})
-		}
-	}
-
-	if len(validators) == 0 {
+func GenesisState(db db_.DB, genDoc *GenesisDoc) *State {
+	if len(genDoc.Validators) == 0 {
 		panic("Must have some validators")
 	}
 
+	if genDoc.GenesisTime.IsZero() {
+		genDoc.GenesisTime = time.Now()
+	}
+
+	// Make accounts state tree
+	accounts := merkle.NewIAVLTree(BasicCodec, AccountCodec, defaultAccountsCacheCapacity, db)
+	for _, acc := range genDoc.Accounts {
+		accounts.Set(acc.Address, acc)
+	}
+
 	return &State{
 		DB:                  db,
 		LastBlockHeight:     0,
 		LastBlockHash:       nil,
 		LastBlockParts:      PartSetHeader{},
-		LastBlockTime:       genesisTime,
-		BondedValidators:    NewValidatorSet(validators),
+		LastBlockTime:       genDoc.GenesisTime,
+		BondedValidators:    NewValidatorSet(genDoc.Validators),
 		UnbondingValidators: NewValidatorSet(nil),
-		accountDetails:      accountDetails,
+		accounts:            accounts,
 	}
 }
diff --git a/state/state.go b/state/state.go
index e8feebd3..295de836 100644
--- a/state/state.go
+++ b/state/state.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"time"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
 	. "github.com/tendermint/tendermint/common"
@@ -14,17 +15,11 @@ import (
 )
 
 var (
-	ErrStateInvalidAccountId      = errors.New("Error State invalid account id")
-	ErrStateInvalidSignature      = errors.New("Error State invalid signature")
-	ErrStateInvalidSequenceNumber = errors.New("Error State invalid sequence number")
-	ErrStateInvalidAccountState   = errors.New("Error State invalid account state")
-	ErrStateInsufficientFunds     = errors.New("Error State insufficient funds")
-
-	stateKey                           = []byte("stateKey")
-	minBondAmount                      = uint64(1)             // TODO adjust
-	defaultAccountDetailsCacheCapacity = 1000                  // TODO adjust
-	unbondingPeriodBlocks              = uint32(60 * 24 * 365) // TODO probably better to make it time based.
-	validatorTimeoutBlocks             = uint32(10)            // TODO adjust
+	stateKey                     = []byte("stateKey")
+	minBondAmount                = uint64(1)           // TODO adjust
+	defaultAccountsCacheCapacity = 1000                // TODO adjust
+	unbondingPeriodBlocks        = uint(60 * 24 * 365) // TODO probably better to make it time based.
+	validatorTimeoutBlocks       = uint(10)            // TODO adjust
 )
 
 //-----------------------------------------------------------------------------
@@ -43,13 +38,14 @@ func (txErr InvalidTxError) Error() string {
 // NOTE: not goroutine-safe.
 type State struct {
 	DB                  db_.DB
-	LastBlockHeight     uint32
+	LastBlockHeight     uint
 	LastBlockHash       []byte
 	LastBlockParts      PartSetHeader
 	LastBlockTime       time.Time
 	BondedValidators    *ValidatorSet
 	UnbondingValidators *ValidatorSet
-	accountDetails      merkle.Tree // Shouldn't be accessed directly.
+	accounts            merkle.Tree // Shouldn't be accessed directly.
+	validatorInfos      merkle.Tree // Shouldn't be accessed directly.
 }
 
 func LoadState(db db_.DB) *State {
@@ -58,20 +54,21 @@ func LoadState(db db_.DB) *State {
 	if len(buf) == 0 {
 		return nil
 	} else {
-		reader := bytes.NewReader(buf)
-		var n int64
-		var err error
-		s.LastBlockHeight = ReadUInt32(reader, &n, &err)
-		s.LastBlockHash = ReadByteSlice(reader, &n, &err)
-		s.LastBlockParts = ReadPartSetHeader(reader, &n, &err)
-		s.LastBlockTime = ReadTime(reader, &n, &err)
-		s.BondedValidators = ReadValidatorSet(reader, &n, &err)
-		s.UnbondingValidators = ReadValidatorSet(reader, &n, &err)
-		accountDetailsHash := ReadByteSlice(reader, &n, &err)
-		s.accountDetails = merkle.NewIAVLTree(BasicCodec, AccountDetailCodec, defaultAccountDetailsCacheCapacity, db)
-		s.accountDetails.Load(accountDetailsHash)
-		if err != nil {
-			panic(err)
+		r, n, err := bytes.NewReader(buf), new(int64), new(error)
+		s.LastBlockHeight = ReadUVarInt(r, n, err)
+		s.LastBlockHash = ReadByteSlice(r, n, err)
+		s.LastBlockParts = ReadBinary(PartSetHeader{}, r, n, err).(PartSetHeader)
+		s.LastBlockTime = ReadTime(r, n, err)
+		s.BondedValidators = ReadBinary(&ValidatorSet{}, r, n, err).(*ValidatorSet)
+		s.UnbondingValidators = ReadBinary(&ValidatorSet{}, r, n, err).(*ValidatorSet)
+		accountsHash := ReadByteSlice(r, n, err)
+		s.accounts = merkle.NewIAVLTree(BasicCodec, AccountCodec, defaultAccountsCacheCapacity, db)
+		s.accounts.Load(accountsHash)
+		validatorInfosHash := ReadByteSlice(r, n, err)
+		s.validatorInfos = merkle.NewIAVLTree(BasicCodec, ValidatorInfoCodec, 0, db)
+		s.validatorInfos.Load(validatorInfosHash)
+		if *err != nil {
+			panic(*err)
 		}
 		// TODO: ensure that buf is completely read.
 	}
@@ -80,19 +77,18 @@ func LoadState(db db_.DB) *State {
 
 // Save this state into the db.
 func (s *State) Save() {
-	s.accountDetails.Save()
-	var buf bytes.Buffer
-	var n int64
-	var err error
-	WriteUInt32(&buf, s.LastBlockHeight, &n, &err)
-	WriteByteSlice(&buf, s.LastBlockHash, &n, &err)
-	WriteBinary(&buf, s.LastBlockParts, &n, &err)
-	WriteTime(&buf, s.LastBlockTime, &n, &err)
-	WriteBinary(&buf, s.BondedValidators, &n, &err)
-	WriteBinary(&buf, s.UnbondingValidators, &n, &err)
-	WriteByteSlice(&buf, s.accountDetails.Hash(), &n, &err)
-	if err != nil {
-		panic(err)
+	s.accounts.Save()
+	buf, n, err := new(bytes.Buffer), new(int64), new(error)
+	WriteUVarInt(s.LastBlockHeight, buf, n, err)
+	WriteByteSlice(s.LastBlockHash, buf, n, err)
+	WriteBinary(s.LastBlockParts, buf, n, err)
+	WriteTime(s.LastBlockTime, buf, n, err)
+	WriteBinary(s.BondedValidators, buf, n, err)
+	WriteBinary(s.UnbondingValidators, buf, n, err)
+	WriteByteSlice(s.accounts.Hash(), buf, n, err)
+	WriteByteSlice(s.validatorInfos.Hash(), buf, n, err)
+	if *err != nil {
+		panic(*err)
 	}
 	s.DB.Set(stateKey, buf.Bytes())
 }
@@ -106,185 +102,312 @@ func (s *State) Copy() *State {
 		LastBlockTime:       s.LastBlockTime,
 		BondedValidators:    s.BondedValidators.Copy(),
 		UnbondingValidators: s.UnbondingValidators.Copy(),
-		accountDetails:      s.accountDetails.Copy(),
+		accounts:            s.accounts.Copy(),
+		validatorInfos:      s.validatorInfos.Copy(),
+	}
+}
+
+func (s *State) GetOrMakeAccounts(ins []*TxInput, outs []*TxOutput) (map[string]*Account, error) {
+	accounts := map[string]*Account{}
+	for _, in := range ins {
+		// Account shouldn't be duplicated
+		if _, ok := accounts[string(in.Address)]; ok {
+			return nil, ErrTxDuplicateAddress
+		}
+		account := s.GetAccount(in.Address)
+		if account == nil {
+			return nil, ErrTxInvalidAddress
+		}
+		accounts[string(in.Address)] = account
+	}
+	for _, out := range outs {
+		// Account shouldn't be duplicated
+		if _, ok := accounts[string(out.Address)]; ok {
+			return nil, ErrTxDuplicateAddress
+		}
+		account := s.GetAccount(out.Address)
+		// output account may be nil (new)
+		if account == nil {
+			account = NewAccount(out.Address, PubKeyUnknown{})
+		}
+		accounts[string(out.Address)] = account
+	}
+	return accounts, nil
+}
+
+func (s *State) ValidateInputs(accounts map[string]*Account, signBytes []byte, ins []*TxInput) (total uint64, err error) {
+	for _, in := range ins {
+		account := accounts[string(in.Address)]
+		if account == nil {
+			panic("ValidateInputs() expects account in accounts")
+		}
+		// Check TxInput basic
+		if err := in.ValidateBasic(); err != nil {
+			return 0, err
+		}
+		// Check amount
+		if account.Balance < in.Amount {
+			return 0, ErrTxInsufficientFunds
+		}
+		// Check signatures
+		if !account.PubKey.VerifyBytes(signBytes, in.Signature) {
+			return 0, ErrTxInvalidSignature
+		}
+		// Check sequences
+		if account.Sequence+1 != in.Sequence {
+			return 0, ErrTxInvalidSequence
+		}
+		// Good. Add amount to total
+		total += in.Amount
+	}
+	return total, nil
+}
+
+func (s *State) ValidateOutputs(outs []*TxOutput) (total uint64, err error) {
+	for _, out := range outs {
+		// Check TxOutput basic
+		if err := out.ValidateBasic(); err != nil {
+			return 0, err
+		}
+		// Good. Add amount to total
+		total += out.Amount
+	}
+	return total, nil
+}
+
+func (s *State) AdjustByInputs(accounts map[string]*Account, ins []*TxInput) {
+	for _, in := range ins {
+		account := accounts[string(in.Address)]
+		if account == nil {
+			panic("AdjustByInputs() expects account in accounts")
+		}
+		if account.Balance < in.Amount {
+			panic("AdjustByInputs() expects sufficient funds")
+		}
+		account.Balance -= in.Amount
+	}
+}
+
+func (s *State) AdjustByOutputs(accounts map[string]*Account, outs []*TxOutput) {
+	for _, out := range outs {
+		account := accounts[string(out.Address)]
+		if account == nil {
+			panic("AdjustByInputs() expects account in accounts")
+		}
+		account.Balance += out.Amount
 	}
 }
 
 // If the tx is invalid, an error will be returned.
 // Unlike AppendBlock(), state will not be altered.
-func (s *State) ExecTx(tx Tx) error {
-	accDet := s.GetAccountDetail(tx.GetSignature().SignerId)
-	if accDet == nil {
-		return ErrStateInvalidAccountId
-	}
-	// Check signature
-	if !accDet.Verify(tx) {
-		return ErrStateInvalidSignature
-	}
-	// Check and update sequence
-	if tx.GetSequence() <= accDet.Sequence {
-		return ErrStateInvalidSequenceNumber
-	} else {
-		// TODO consider prevSequence for tx chaining.
-		accDet.Sequence = tx.GetSequence()
-	}
-	// Subtract fee from balance.
-	if accDet.Balance < tx.GetFee() {
-		return ErrStateInsufficientFunds
-	} else {
-		accDet.Balance -= tx.GetFee()
-	}
+func (s *State) ExecTx(tx_ Tx) error {
+
+	// TODO: do something with fees
+	fees := uint64(0)
+
 	// Exec tx
-	switch tx.(type) {
+	switch tx_.(type) {
 	case *SendTx:
-		stx := tx.(*SendTx)
-		toAccDet := s.GetAccountDetail(stx.To)
-		// Accounts must be nominal
-		if accDet.Status != AccountStatusNominal {
-			return ErrStateInvalidAccountState
+		tx := tx_.(*SendTx)
+		accounts, err := s.GetOrMakeAccounts(tx.Inputs, tx.Outputs)
+		if err != nil {
+			return err
 		}
-		if toAccDet.Status != AccountStatusNominal {
-			return ErrStateInvalidAccountState
+		signBytes := SignBytes(tx)
+		inTotal, err := s.ValidateInputs(accounts, signBytes, tx.Inputs)
+		if err != nil {
+			return err
 		}
-		// Check account balance
-		if accDet.Balance < stx.Amount {
-			return ErrStateInsufficientFunds
+		outTotal, err := s.ValidateOutputs(tx.Outputs)
+		if err != nil {
+			return err
 		}
-		// Check existence of destination account
-		if toAccDet == nil {
-			return ErrStateInvalidAccountId
+		if outTotal > inTotal {
+			return ErrTxInsufficientFunds
 		}
-		// Good!
-		accDet.Balance -= stx.Amount
-		toAccDet.Balance += stx.Amount
-		s.SetAccountDetail(accDet)
-		s.SetAccountDetail(toAccDet)
+		fee := inTotal - outTotal
+		fees += fee
+
+		// Good! Adjust accounts
+		s.AdjustByInputs(accounts, tx.Inputs)
+		s.AdjustByOutputs(accounts, tx.Outputs)
+		s.SetAccounts(accounts)
 		return nil
-	//case *NameTx
+
 	case *BondTx:
-		//btx := tx.(*BondTx)
-		// Account must be nominal
-		if accDet.Status != AccountStatusNominal {
-			return ErrStateInvalidAccountState
+		tx := tx_.(*BondTx)
+		accounts, err := s.GetOrMakeAccounts(tx.Inputs, tx.UnbondTo)
+		if err != nil {
+			return err
 		}
-		// Check account balance
-		if accDet.Balance < minBondAmount {
-			return ErrStateInsufficientFunds
+		signBytes := SignBytes(tx)
+		inTotal, err := s.ValidateInputs(accounts, signBytes, tx.Inputs)
+		if err != nil {
+			return err
 		}
-		// Good!
-		accDet.Status = AccountStatusBonded
-		s.SetAccountDetail(accDet)
+		if err := tx.PubKey.ValidateBasic(); err != nil {
+			return err
+		}
+		outTotal, err := s.ValidateOutputs(tx.UnbondTo)
+		if err != nil {
+			return err
+		}
+		if outTotal > inTotal {
+			return ErrTxInsufficientFunds
+		}
+		fee := inTotal - outTotal
+		fees += fee
+
+		// Good! Adjust accounts
+		s.AdjustByInputs(accounts, tx.Inputs)
+		s.SetAccounts(accounts)
+		// Add ValidatorInfo
+		updated := s.SetValidatorInfo(&ValidatorInfo{
+			Address:         tx.PubKey.Address(),
+			PubKey:          tx.PubKey,
+			UnbondTo:        tx.UnbondTo,
+			FirstBondHeight: s.LastBlockHeight + 1,
+		})
+		if !updated {
+			panic("Failed to add validator info")
+		}
+		// Add Validator
 		added := s.BondedValidators.Add(&Validator{
-			Account:     accDet.Account,
-			BondHeight:  s.LastBlockHeight,
-			VotingPower: accDet.Balance,
+			Address:     tx.PubKey.Address(),
+			PubKey:      tx.PubKey,
+			BondHeight:  s.LastBlockHeight + 1,
+			VotingPower: inTotal,
 			Accum:       0,
 		})
 		if !added {
 			panic("Failed to add validator")
 		}
 		return nil
+
 	case *UnbondTx:
-		//utx := tx.(*UnbondTx)
-		// Account must be bonded.
-		if accDet.Status != AccountStatusBonded {
-			return ErrStateInvalidAccountState
+		tx := tx_.(*UnbondTx)
+
+		// The validator must be active
+		_, val := s.BondedValidators.GetByAddress(tx.Address)
+		if val == nil {
+			return ErrTxInvalidAddress
 		}
+
+		// Verify the signature
+		signBytes := SignBytes(tx)
+		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
+			return ErrTxInvalidSignature
+		}
+
+		// tx.Height must be greater than val.LastCommitHeight
+		if tx.Height < val.LastCommitHeight {
+			return errors.New("Invalid bond height")
+		}
+
 		// Good!
-		s.unbondValidator(accDet.Id, accDet)
-		s.SetAccountDetail(accDet)
+		s.unbondValidator(val)
 		return nil
+
 	case *DupeoutTx:
-		{
-			// NOTE: accDet is the one who created this transaction.
-			// Subtract any fees, save, and forget.
-			s.SetAccountDetail(accDet)
-			accDet = nil
-		}
-		dtx := tx.(*DupeoutTx)
+		tx := tx_.(*DupeoutTx)
+
 		// Verify the signatures
-		if dtx.VoteA.SignerId != dtx.VoteB.SignerId {
-			return ErrStateInvalidSignature
-		}
-		accused := s.GetAccountDetail(dtx.VoteA.SignerId)
-		if !accused.Verify(&dtx.VoteA) || !accused.Verify(&dtx.VoteB) {
-			return ErrStateInvalidSignature
+		_, accused := s.BondedValidators.GetByAddress(tx.Address)
+		voteASignBytes := SignBytes(&tx.VoteA)
+		voteBSignBytes := SignBytes(&tx.VoteB)
+		if !accused.PubKey.VerifyBytes(voteASignBytes, tx.VoteA.Signature) ||
+			!accused.PubKey.VerifyBytes(voteBSignBytes, tx.VoteB.Signature) {
+			return ErrTxInvalidSignature
 		}
+
 		// Verify equivocation
-		if dtx.VoteA.Height != dtx.VoteB.Height {
-			return errors.New("DupeoutTx height must be the same.")
+		// TODO: in the future, just require one vote from a previous height that
+		// doesn't exist on this chain.
+		if tx.VoteA.Height != tx.VoteB.Height {
+			return errors.New("DupeoutTx heights don't match")
 		}
-		if dtx.VoteA.Type == VoteTypeCommit && dtx.VoteA.Round < dtx.VoteB.Round {
+		if tx.VoteA.Type == VoteTypeCommit && tx.VoteA.Round < tx.VoteB.Round {
 			// Check special case.
 			// Validators should not sign another vote after committing.
 		} else {
-			if dtx.VoteA.Round != dtx.VoteB.Round {
+			if tx.VoteA.Round != tx.VoteB.Round {
 				return errors.New("DupeoutTx rounds don't match")
 			}
-			if dtx.VoteA.Type != dtx.VoteB.Type {
+			if tx.VoteA.Type != tx.VoteB.Type {
 				return errors.New("DupeoutTx types don't match")
 			}
-			if bytes.Equal(dtx.VoteA.BlockHash, dtx.VoteB.BlockHash) {
-				return errors.New("DupeoutTx blockhash shouldn't match")
+			if bytes.Equal(tx.VoteA.BlockHash, tx.VoteB.BlockHash) {
+				return errors.New("DupeoutTx blockhashes shouldn't match")
 			}
 		}
+
 		// Good! (Bad validator!)
-		if accused.Status == AccountStatusBonded {
-			_, removed := s.BondedValidators.Remove(accused.Id)
-			if !removed {
-				panic("Failed to remove accused validator")
-			}
-		} else if accused.Status == AccountStatusUnbonding {
-			_, removed := s.UnbondingValidators.Remove(accused.Id)
-			if !removed {
-				panic("Failed to remove accused validator")
-			}
-		} else {
-			panic("Couldn't find accused validator")
-		}
-		accused.Status = AccountStatusDupedOut
-		updated := s.SetAccountDetail(accused)
-		if !updated {
-			panic("Failed to update accused validator account")
-		}
+		s.destroyValidator(accused)
 		return nil
+
 	default:
 		panic("Unknown Tx type")
 	}
 }
 
-// accDet optional
-func (s *State) unbondValidator(accountId uint64, accDet *AccountDetail) {
-	if accDet == nil {
-		accDet = s.GetAccountDetail(accountId)
-	}
-	accDet.Status = AccountStatusUnbonding
-	s.SetAccountDetail(accDet)
-	val, removed := s.BondedValidators.Remove(accDet.Id)
+func (s *State) unbondValidator(val *Validator) {
+	// Move validator to UnbondingValidators
+	val, removed := s.BondedValidators.Remove(val.Address)
 	if !removed {
-		panic("Failed to remove validator")
+		panic("Couldn't remove validator for unbonding")
 	}
 	val.UnbondHeight = s.LastBlockHeight
 	added := s.UnbondingValidators.Add(val)
 	if !added {
-		panic("Failed to add validator")
+		panic("Couldn't add validator for unbonding")
 	}
 }
 
-func (s *State) releaseValidator(accountId uint64) {
-	accDet := s.GetAccountDetail(accountId)
-	if accDet.Status != AccountStatusUnbonding {
-		panic("Cannot release validator")
+func (s *State) releaseValidator(val *Validator) {
+	// Update validatorInfo
+	valInfo := s.GetValidatorInfo(val.Address)
+	if valInfo == nil {
+		panic("Couldn't find validatorInfo for release")
 	}
-	accDet.Status = AccountStatusNominal
-	// TODO: move balance to designated address, UnbondTo.
-	s.SetAccountDetail(accDet)
-	_, removed := s.UnbondingValidators.Remove(accountId)
+	valInfo.ReleasedHeight = s.LastBlockHeight + 1
+	s.SetValidatorInfo(valInfo)
+
+	// Send coins back to UnbondTo outputs
+	accounts, err := s.GetOrMakeAccounts(nil, valInfo.UnbondTo)
+	if err != nil {
+		panic("Couldn't get or make unbondTo accounts")
+	}
+	s.AdjustByOutputs(accounts, valInfo.UnbondTo)
+	s.SetAccounts(accounts)
+
+	// Remove validator from UnbondingValidators
+	_, removed := s.UnbondingValidators.Remove(val.Address)
 	if !removed {
-		panic("Couldn't release validator")
+		panic("Couldn't remove validator for release")
 	}
 }
 
+func (s *State) destroyValidator(val *Validator) {
+	// Update validatorInfo
+	valInfo := s.GetValidatorInfo(val.Address)
+	if valInfo == nil {
+		panic("Couldn't find validatorInfo for release")
+	}
+	valInfo.DestroyedHeight = s.LastBlockHeight + 1
+	valInfo.DestroyedAmount = val.VotingPower
+	s.SetValidatorInfo(valInfo)
+
+	// Remove validator
+	_, removed := s.BondedValidators.Remove(val.Address)
+	if !removed {
+		_, removed := s.UnbondingValidators.Remove(val.Address)
+		if !removed {
+			panic("Couldn't remove validator for destruction")
+		}
+	}
+
+}
+
 // "checkStateHash": If false, instead of checking the resulting
 // state.Hash() against block.StateHash, it *sets* the block.StateHash.
 // (used for constructing a new proposal)
@@ -308,23 +431,18 @@ func (s *State) AppendBlock(block *Block, blockPartsHeader PartSetHeader, checkS
 		}
 		var sumVotingPower uint64
 		s.BondedValidators.Iterate(func(index uint, val *Validator) bool {
-			rsig := block.Validation.Commits[index]
-			if rsig.IsZero() {
+			commit := block.Validation.Commits[index]
+			if commit.IsZero() {
 				return false
 			} else {
-				if rsig.SignerId != val.Id {
-					err = errors.New("Invalid validation order")
-					return true
-				}
 				vote := &Vote{
 					Height:     block.Height - 1,
-					Round:      rsig.Round,
+					Round:      commit.Round,
 					Type:       VoteTypeCommit,
 					BlockHash:  block.LastBlockHash,
 					BlockParts: block.LastBlockParts,
-					Signature:  rsig.Signature,
 				}
-				if val.Verify(vote) {
+				if val.PubKey.VerifyBytes(SignBytes(vote), commit.Signature) {
 					sumVotingPower += val.VotingPower
 					return false
 				} else {
@@ -351,10 +469,13 @@ func (s *State) AppendBlock(block *Block, blockPartsHeader PartSetHeader, checkS
 	}
 
 	// Update Validator.LastCommitHeight as necessary.
-	for _, rsig := range block.Validation.Commits {
-		_, val := s.BondedValidators.GetById(rsig.SignerId)
+	for i, commit := range block.Validation.Commits {
+		if commit.IsZero() {
+			continue
+		}
+		_, val := s.BondedValidators.GetByIndex(uint(i))
 		if val == nil {
-			return ErrStateInvalidSignature
+			return ErrTxInvalidSignature
 		}
 		val.LastCommitHeight = block.Height - 1
 		updated := s.BondedValidators.Update(val)
@@ -373,7 +494,7 @@ func (s *State) AppendBlock(block *Block, blockPartsHeader PartSetHeader, checkS
 		return false
 	})
 	for _, val := range toRelease {
-		s.releaseValidator(val.Id)
+		s.releaseValidator(val)
 	}
 
 	// If any validators haven't signed in a while,
@@ -386,7 +507,7 @@ func (s *State) AppendBlock(block *Block, blockPartsHeader PartSetHeader, checkS
 		return false
 	})
 	for _, val := range toTimeout {
-		s.unbondValidator(val.Id, nil)
+		s.unbondValidator(val)
 	}
 
 	// Increment validator AccumPowers
@@ -415,21 +536,39 @@ func (s *State) AppendBlock(block *Block, blockPartsHeader PartSetHeader, checkS
 	return nil
 }
 
-// The returned AccountDetail is a copy, so mutating it
+// The returned Account is a copy, so mutating it
 // has no side effects.
-func (s *State) GetAccountDetail(accountId uint64) *AccountDetail {
-	_, accDet := s.accountDetails.Get(accountId)
-	if accDet == nil {
+func (s *State) GetAccount(address []byte) *Account {
+	_, account := s.accounts.Get(address)
+	if account == nil {
 		return nil
 	}
-	return accDet.(*AccountDetail).Copy()
+	return account.(*Account).Copy()
+}
+
+// The accounts are copied before setting, so mutating it
+// afterwards has no side effects.
+func (s *State) SetAccounts(accounts map[string]*Account) {
+	for _, account := range accounts {
+		s.accounts.Set(account.Address, account.Copy())
+	}
+}
+
+// The returned ValidatorInfo is a copy, so mutating it
+// has no side effects.
+func (s *State) GetValidatorInfo(address []byte) *ValidatorInfo {
+	_, valInfo := s.validatorInfos.Get(address)
+	if valInfo == nil {
+		return nil
+	}
+	return valInfo.(*ValidatorInfo).Copy()
 }
 
 // Returns false if new, true if updated.
-// The accDet is copied before setting, so mutating it
+// The valInfo is copied before setting, so mutating it
 // afterwards has no side effects.
-func (s *State) SetAccountDetail(accDet *AccountDetail) (updated bool) {
-	return s.accountDetails.Set(accDet.Id, accDet.Copy())
+func (s *State) SetValidatorInfo(valInfo *ValidatorInfo) (updated bool) {
+	return s.validatorInfos.Set(valInfo.Address, valInfo.Copy())
 }
 
 // Returns a hash that represents the state data,
@@ -438,7 +577,7 @@ func (s *State) Hash() []byte {
 	hashables := []merkle.Hashable{
 		s.BondedValidators,
 		s.UnbondingValidators,
-		s.accountDetails,
+		s.accounts,
 	}
 	return merkle.HashFromHashables(hashables)
 }
diff --git a/state/validator.go b/state/validator.go
index c49aa097..0ba00f82 100644
--- a/state/validator.go
+++ b/state/validator.go
@@ -1,34 +1,61 @@
 package state
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 
+	. "github.com/tendermint/tendermint/account"
 	. "github.com/tendermint/tendermint/binary"
+	. "github.com/tendermint/tendermint/blocks"
 )
 
-// Holds state for a Validator at a given height+round.
-// Meant to be discarded every round of the consensus protocol.
-// TODO consider moving this to another common types package.
-type Validator struct {
-	Account
-	BondHeight       uint32
-	UnbondHeight     uint32
-	LastCommitHeight uint32
-	VotingPower      uint64
-	Accum            int64
+// Persistent static data for each Validator
+type ValidatorInfo struct {
+	Address         []byte
+	PubKey          PubKeyEd25519
+	UnbondTo        []*TxOutput
+	FirstBondHeight uint
+
+	// If destroyed:
+	DestroyedHeight uint
+	DestroyedAmount uint64
+
+	// If released:
+	ReleasedHeight uint
 }
 
-// Used to persist the state of ConsensusStateControl.
-func ReadValidator(r io.Reader, n *int64, err *error) *Validator {
-	return &Validator{
-		Account:          ReadAccount(r, n, err),
-		BondHeight:       ReadUInt32(r, n, err),
-		UnbondHeight:     ReadUInt32(r, n, err),
-		LastCommitHeight: ReadUInt32(r, n, err),
-		VotingPower:      ReadUInt64(r, n, err),
-		Accum:            ReadInt64(r, n, err),
-	}
+func (valInfo *ValidatorInfo) Copy() *ValidatorInfo {
+	valInfoCopy := *valInfo
+	return &valInfoCopy
+}
+
+func ValidatorInfoEncoder(o interface{}, w io.Writer, n *int64, err *error) {
+	WriteBinary(o.(*ValidatorInfo), w, n, err)
+}
+
+func ValidatorInfoDecoder(r io.Reader, n *int64, err *error) interface{} {
+	return ReadBinary(&ValidatorInfo{}, r, n, err)
+}
+
+var ValidatorInfoCodec = Codec{
+	Encode: ValidatorInfoEncoder,
+	Decode: ValidatorInfoDecoder,
+}
+
+//-----------------------------------------------------------------------------
+
+// Volatile state for each Validator
+// Also persisted with the state, but fields change
+// every height|round so they don't go in merkle.Tree
+type Validator struct {
+	Address          []byte
+	PubKey           PubKeyEd25519
+	BondHeight       uint
+	UnbondHeight     uint
+	LastCommitHeight uint
+	VotingPower      uint64
+	Accum            int64
 }
 
 // Creates a new copy of the validator so we can mutate accum.
@@ -37,17 +64,6 @@ func (v *Validator) Copy() *Validator {
 	return &vCopy
 }
 
-// Used to persist the state of ConsensusStateControl.
-func (v *Validator) WriteTo(w io.Writer) (n int64, err error) {
-	WriteBinary(w, v.Account, &n, &err)
-	WriteUInt32(w, v.BondHeight, &n, &err)
-	WriteUInt32(w, v.UnbondHeight, &n, &err)
-	WriteUInt32(w, v.LastCommitHeight, &n, &err)
-	WriteUInt64(w, v.VotingPower, &n, &err)
-	WriteInt64(w, v.Accum, &n, &err)
-	return
-}
-
 // Returns the one with higher Accum.
 func (v *Validator) CompareAccum(other *Validator) *Validator {
 	if v == nil {
@@ -58,9 +74,9 @@ func (v *Validator) CompareAccum(other *Validator) *Validator {
 	} else if v.Accum < other.Accum {
 		return other
 	} else {
-		if v.Id < other.Id {
+		if bytes.Compare(v.Address, other.Address) < 0 {
 			return v
-		} else if v.Id > other.Id {
+		} else if bytes.Compare(v.Address, other.Address) > 0 {
 			return other
 		} else {
 			panic("Cannot compare identical validators")
@@ -69,8 +85,9 @@ func (v *Validator) CompareAccum(other *Validator) *Validator {
 }
 
 func (v *Validator) String() string {
-	return fmt.Sprintf("Validator{%v %v-%v-%v VP:%v A:%v}",
-		v.Account,
+	return fmt.Sprintf("Validator{%X %v %v-%v-%v VP:%v A:%v}",
+		v.Address,
+		v.PubKey,
 		v.BondHeight,
 		v.LastCommitHeight,
 		v.UnbondHeight,
@@ -79,7 +96,7 @@ func (v *Validator) String() string {
 }
 
 func (v *Validator) Hash() []byte {
-	return BinaryHash(v)
+	return BinarySha256(v)
 }
 
 //-------------------------------------
@@ -89,11 +106,11 @@ var ValidatorCodec = validatorCodec{}
 type validatorCodec struct{}
 
 func (vc validatorCodec) Encode(o interface{}, w io.Writer, n *int64, err *error) {
-	WriteBinary(w, o.(*Validator), n, err)
+	WriteBinary(o.(*Validator), w, n, err)
 }
 
 func (vc validatorCodec) Decode(r io.Reader, n *int64, err *error) interface{} {
-	return ReadValidator(r, n, err)
+	return ReadBinary(&Validator{}, r, n, err)
 }
 
 func (vc validatorCodec) Compare(o1 interface{}, o2 interface{}) int {
diff --git a/state/validator_set.go b/state/validator_set.go
index 9bb1ad94..b0e4b898 100644
--- a/state/validator_set.go
+++ b/state/validator_set.go
@@ -1,12 +1,11 @@
 package state
 
 import (
+	"bytes"
 	"fmt"
-	"io"
 	"sort"
 	"strings"
 
-	. "github.com/tendermint/tendermint/binary"
 	"github.com/tendermint/tendermint/merkle"
 )
 
@@ -20,7 +19,7 @@ func (vs ValidatorSlice) Len() int {
 }
 
 func (vs ValidatorSlice) Less(i, j int) bool {
-	return vs[i].Id < vs[j].Id
+	return bytes.Compare(vs[i].Address, vs[j].Address) == -1
 }
 
 func (vs ValidatorSlice) Swap(i, j int) {
@@ -31,10 +30,17 @@ func (vs ValidatorSlice) Swap(i, j int) {
 
 //-------------------------------------
 
-// Not goroutine-safe.
-// TODO: consider validator Accum overflow?
+// ValidatorSet represent a set of *Validator at a given height.
+// The validators can be fetched by address or index.
+// The index is in order of .Address, so the index are the same
+// for all rounds of a given blockchain height.
+// On the other hand, the .AccumPower of each validator and
+// the designated .Proposer() of a set changes every round,
+// upon calling .IncrementAccum().
+// NOTE: Not goroutine-safe.
+// NOTE: All get/set to validators should copy the value for safety.
+// TODO: consider validator Accum overflow
 // TODO: replace validators []*Validator with github.com/jaekwon/go-ibbs?
-// NOTE: all get/set to validators should copy the value for safety.
 type ValidatorSet struct {
 	validators []*Validator
 
@@ -54,169 +60,149 @@ func NewValidatorSet(vals []*Validator) *ValidatorSet {
 	}
 }
 
-func ReadValidatorSet(r io.Reader, n *int64, err *error) *ValidatorSet {
-	size := ReadUVarInt(r, n, err)
-	validators := []*Validator{}
-	for i := uint(0); i < size; i++ {
-		validator := ReadValidator(r, n, err)
-		validators = append(validators, validator)
-	}
-	sort.Sort(ValidatorSlice(validators))
-	return NewValidatorSet(validators)
-}
-
-func (vset *ValidatorSet) WriteTo(w io.Writer) (n int64, err error) {
-	WriteUVarInt(w, uint(len(vset.validators)), &n, &err)
-	vset.Iterate(func(index uint, val *Validator) bool {
-		WriteBinary(w, val, &n, &err)
-		return false
-	})
-	return
-}
-
-func (vset *ValidatorSet) IncrementAccum() {
+func (valSet *ValidatorSet) IncrementAccum() {
 	// Decrement from previous proposer
-	oldProposer := vset.Proposer()
-	oldProposer.Accum -= int64(vset.TotalVotingPower())
-	vset.Update(oldProposer)
+	oldProposer := valSet.Proposer()
+	oldProposer.Accum -= int64(valSet.TotalVotingPower())
+	valSet.Update(oldProposer)
 	var newProposer *Validator
 	// Increment accum and find new proposer
 	// NOTE: updates validators in place.
-	for _, val := range vset.validators {
+	for _, val := range valSet.validators {
 		val.Accum += int64(val.VotingPower)
 		newProposer = newProposer.CompareAccum(val)
 	}
-	vset.proposer = newProposer
+	valSet.proposer = newProposer
 }
 
-func (vset *ValidatorSet) Copy() *ValidatorSet {
-	validators := make([]*Validator, len(vset.validators))
-	for i, val := range vset.validators {
+func (valSet *ValidatorSet) Copy() *ValidatorSet {
+	validators := make([]*Validator, len(valSet.validators))
+	for i, val := range valSet.validators {
 		// NOTE: must copy, since IncrementAccum updates in place.
 		validators[i] = val.Copy()
 	}
 	return &ValidatorSet{
 		validators:       validators,
-		proposer:         vset.proposer,
-		totalVotingPower: vset.totalVotingPower,
+		proposer:         valSet.proposer,
+		totalVotingPower: valSet.totalVotingPower,
 	}
 }
 
-func (vset *ValidatorSet) HasId(id uint64) bool {
-	idx := sort.Search(len(vset.validators), func(i int) bool {
-		return id <= vset.validators[i].Id
+func (valSet *ValidatorSet) HasAddress(address []byte) bool {
+	idx := sort.Search(len(valSet.validators), func(i int) bool {
+		return bytes.Compare(address, valSet.validators[i].Address) <= 0
 	})
-	return idx != len(vset.validators) && vset.validators[idx].Id == id
+	return idx != len(valSet.validators) && bytes.Compare(valSet.validators[idx].Address, address) == 0
 }
 
-func (vset *ValidatorSet) GetById(id uint64) (index uint, val *Validator) {
-	idx := sort.Search(len(vset.validators), func(i int) bool {
-		return id <= vset.validators[i].Id
+func (valSet *ValidatorSet) GetByAddress(address []byte) (index uint, val *Validator) {
+	idx := sort.Search(len(valSet.validators), func(i int) bool {
+		return bytes.Compare(address, valSet.validators[i].Address) <= 0
 	})
-	if idx != len(vset.validators) && vset.validators[idx].Id == id {
-		return uint(idx), vset.validators[idx].Copy()
+	if idx != len(valSet.validators) && bytes.Compare(valSet.validators[idx].Address, address) == 0 {
+		return uint(idx), valSet.validators[idx].Copy()
 	} else {
 		return 0, nil
 	}
 }
 
-func (vset *ValidatorSet) GetByIndex(index uint) (id uint64, val *Validator) {
-	val = vset.validators[index]
-	return val.Id, val.Copy()
+func (valSet *ValidatorSet) GetByIndex(index uint) (address []byte, val *Validator) {
+	val = valSet.validators[index]
+	return val.Address, val.Copy()
 }
 
-func (vset *ValidatorSet) Size() uint {
-	return uint(len(vset.validators))
+func (valSet *ValidatorSet) Size() uint {
+	return uint(len(valSet.validators))
 }
 
-func (vset *ValidatorSet) TotalVotingPower() uint64 {
-	if vset.totalVotingPower == 0 {
-		for _, val := range vset.validators {
-			vset.totalVotingPower += val.VotingPower
+func (valSet *ValidatorSet) TotalVotingPower() uint64 {
+	if valSet.totalVotingPower == 0 {
+		for _, val := range valSet.validators {
+			valSet.totalVotingPower += val.VotingPower
 		}
 	}
-	return vset.totalVotingPower
+	return valSet.totalVotingPower
 }
 
-func (vset *ValidatorSet) Proposer() (proposer *Validator) {
-	if vset.proposer == nil {
-		for _, val := range vset.validators {
-			vset.proposer = vset.proposer.CompareAccum(val)
+func (valSet *ValidatorSet) Proposer() (proposer *Validator) {
+	if valSet.proposer == nil {
+		for _, val := range valSet.validators {
+			valSet.proposer = valSet.proposer.CompareAccum(val)
 		}
 	}
-	return vset.proposer.Copy()
+	return valSet.proposer.Copy()
 }
 
-func (vset *ValidatorSet) Hash() []byte {
-	if len(vset.validators) == 0 {
+func (valSet *ValidatorSet) Hash() []byte {
+	if len(valSet.validators) == 0 {
 		return nil
 	}
-	hashables := make([]merkle.Hashable, len(vset.validators))
-	for i, val := range vset.validators {
+	hashables := make([]merkle.Hashable, len(valSet.validators))
+	for i, val := range valSet.validators {
 		hashables[i] = val
 	}
 	return merkle.HashFromHashables(hashables)
 }
 
-func (vset *ValidatorSet) Add(val *Validator) (added bool) {
+func (valSet *ValidatorSet) Add(val *Validator) (added bool) {
 	val = val.Copy()
-	idx := sort.Search(len(vset.validators), func(i int) bool {
-		return val.Id <= vset.validators[i].Id
+	idx := sort.Search(len(valSet.validators), func(i int) bool {
+		return bytes.Compare(val.Address, valSet.validators[i].Address) <= 0
 	})
-	if idx == len(vset.validators) {
-		vset.validators = append(vset.validators, val)
+	if idx == len(valSet.validators) {
+		valSet.validators = append(valSet.validators, val)
 		// Invalidate cache
-		vset.proposer = nil
-		vset.totalVotingPower = 0
+		valSet.proposer = nil
+		valSet.totalVotingPower = 0
 		return true
-	} else if vset.validators[idx].Id == val.Id {
+	} else if bytes.Compare(valSet.validators[idx].Address, val.Address) == 0 {
 		return false
 	} else {
-		newValidators := append(vset.validators[:idx], val)
-		newValidators = append(newValidators, vset.validators[idx:]...)
-		vset.validators = newValidators
+		newValidators := append(valSet.validators[:idx], val)
+		newValidators = append(newValidators, valSet.validators[idx:]...)
+		valSet.validators = newValidators
 		// Invalidate cache
-		vset.proposer = nil
-		vset.totalVotingPower = 0
+		valSet.proposer = nil
+		valSet.totalVotingPower = 0
 		return true
 	}
 }
 
-func (vset *ValidatorSet) Update(val *Validator) (updated bool) {
-	index, sameVal := vset.GetById(val.Id)
+func (valSet *ValidatorSet) Update(val *Validator) (updated bool) {
+	index, sameVal := valSet.GetByAddress(val.Address)
 	if sameVal == nil {
 		return false
 	} else {
-		vset.validators[index] = val.Copy()
+		valSet.validators[index] = val.Copy()
 		// Invalidate cache
-		vset.proposer = nil
-		vset.totalVotingPower = 0
+		valSet.proposer = nil
+		valSet.totalVotingPower = 0
 		return true
 	}
 }
 
-func (vset *ValidatorSet) Remove(id uint64) (val *Validator, removed bool) {
-	idx := sort.Search(len(vset.validators), func(i int) bool {
-		return id <= vset.validators[i].Id
+func (valSet *ValidatorSet) Remove(address []byte) (val *Validator, removed bool) {
+	idx := sort.Search(len(valSet.validators), func(i int) bool {
+		return bytes.Compare(address, valSet.validators[i].Address) <= 0
 	})
-	if idx == len(vset.validators) || vset.validators[idx].Id != id {
+	if idx == len(valSet.validators) || bytes.Compare(valSet.validators[idx].Address, address) != 0 {
 		return nil, false
 	} else {
-		removedVal := vset.validators[idx]
-		newValidators := vset.validators[:idx]
-		if idx+1 < len(vset.validators) {
-			newValidators = append(newValidators, vset.validators[idx+1:]...)
+		removedVal := valSet.validators[idx]
+		newValidators := valSet.validators[:idx]
+		if idx+1 < len(valSet.validators) {
+			newValidators = append(newValidators, valSet.validators[idx+1:]...)
 		}
-		vset.validators = newValidators
+		valSet.validators = newValidators
 		// Invalidate cache
-		vset.proposer = nil
-		vset.totalVotingPower = 0
+		valSet.proposer = nil
+		valSet.totalVotingPower = 0
 		return removedVal, true
 	}
 }
 
-func (vset *ValidatorSet) Iterate(fn func(index uint, val *Validator) bool) {
-	for i, val := range vset.validators {
+func (valSet *ValidatorSet) Iterate(fn func(index uint, val *Validator) bool) {
+	for i, val := range valSet.validators {
 		stop := fn(uint(i), val.Copy())
 		if stop {
 			break
@@ -224,13 +210,13 @@ func (vset *ValidatorSet) Iterate(fn func(index uint, val *Validator) bool) {
 	}
 }
 
-func (vset *ValidatorSet) String() string {
-	return vset.StringWithIndent("")
+func (valSet *ValidatorSet) String() string {
+	return valSet.StringWithIndent("")
 }
 
-func (vset *ValidatorSet) StringWithIndent(indent string) string {
+func (valSet *ValidatorSet) StringWithIndent(indent string) string {
 	valStrings := []string{}
-	vset.Iterate(func(index uint, val *Validator) bool {
+	valSet.Iterate(func(index uint, val *Validator) bool {
 		valStrings = append(valStrings, val.String())
 		return false
 	})
@@ -239,7 +225,7 @@ func (vset *ValidatorSet) StringWithIndent(indent string) string {
 %s  Validators:
 %s    %v
 %s}`,
-		indent, vset.Proposer().String(),
+		indent, valSet.Proposer().String(),
 		indent,
 		indent, strings.Join(valStrings, "\n"+indent+"    "),
 		indent)
diff --git a/wallet/priv_account.go b/wallet/priv_account.go
new file mode 100644
index 00000000..db95e725
--- /dev/null
+++ b/wallet/priv_account.go
@@ -0,0 +1,28 @@
+package wallet
+
+import (
+	"github.com/tendermint/go-ed25519"
+
+	. "github.com/tendermint/tendermint/account"
+	. "github.com/tendermint/tendermint/common"
+)
+
+type PrivAccount struct {
+	PubKey  PubKey
+	PrivKey PrivKey
+}
+
+// Generates a new account with private key.
+func GenPrivAccount() *PrivAccount {
+	privKey := CRandBytes(32)
+	pubKey := ed25519.MakePubKey(privKey)
+	return &PrivAccount{
+		PubKeyEd25519{
+			PubKey: pubKey,
+		},
+		PrivKeyEd25519{
+			PubKey:  pubKey,
+			PrivKey: privKey,
+		},
+	}
+}