Add ascii armor support

symmetric.go

@@ -0,0 +1,51 @@
+package crypto
+
+import (
+	"errors"
+
+	. "github.com/tendermint/go-common"
+	"golang.org/x/crypto/nacl/secretbox"
+)
+
+const nonceLen = 24
+const secretLen = 32
+
+// secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase))
+// The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext.
+// NOTE: call crypto.MixEntropy() first.
+func EncryptSymmetric(plaintext []byte, secret []byte) (ciphertext []byte) {
+	if len(secret) != secretLen {
+		PanicSanity(Fmt("Secret must be 32 bytes long, got len %v", len(secret)))
+	}
+	nonce := CRandBytes(nonceLen)
+	nonceArr := [nonceLen]byte{}
+	copy(nonceArr[:], nonce)
+	secretArr := [secretLen]byte{}
+	copy(secretArr[:], secret)
+	ciphertext = make([]byte, nonceLen+secretbox.Overhead+len(plaintext))
+	copy(ciphertext, nonce)
+	secretbox.Seal(ciphertext[nonceLen:nonceLen], plaintext, &nonceArr, &secretArr)
+	return ciphertext
+}
+
+// secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase))
+// The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext.
+func DecryptSymmetric(ciphertext []byte, secret []byte) (plaintext []byte, err error) {
+	if len(secret) != secretLen {
+		PanicSanity(Fmt("Secret must be 32 bytes long, got len %v", len(secret)))
+	}
+	if len(ciphertext) <= secretbox.Overhead+nonceLen {
+		return nil, errors.New("Ciphertext is too short")
+	}
+	nonce := ciphertext[:nonceLen]
+	nonceArr := [nonceLen]byte{}
+	copy(nonceArr[:], nonce)
+	secretArr := [secretLen]byte{}
+	copy(secretArr[:], secret)
+	plaintext = make([]byte, len(ciphertext)-nonceLen-secretbox.Overhead)
+	_, ok := secretbox.Open(plaintext[:0], ciphertext[nonceLen:], &nonceArr, &secretArr)
+	if !ok {
+		return nil, errors.New("Ciphertext decryption failed")
+	}
+	return plaintext, nil
+}