diff --git a/src/@types/handshake.ts b/src/@types/handshake.ts
new file mode 100644
index 0000000..265f769
--- /dev/null
+++ b/src/@types/handshake.ts
@@ -0,0 +1,39 @@
+import {bytes, bytes32, uint32, uint64} from "./basic";
+import {KeyPair} from "./libp2p";
+
+export type Hkdf = [bytes, bytes, bytes];
+
+export interface MessageBuffer {
+  ne: bytes32;
+  ns: bytes;
+  ciphertext: bytes;
+}
+
+export type CipherState = {
+  k: bytes32;
+  n: uint32;
+}
+
+export type SymmetricState = {
+  cs: CipherState;
+  ck: bytes32;  // chaining key
+  h: bytes32; // handshake hash
+}
+
+export type HandshakeState = {
+  ss: SymmetricState;
+  s: KeyPair;
+  e?: KeyPair;
+  rs: bytes32;
+  re: bytes32;
+  psk: bytes32;
+}
+
+export type NoiseSession = {
+  hs: HandshakeState;
+  h?: bytes32;
+  cs1?: CipherState;
+  cs2?: CipherState;
+  mc: uint64;
+  i: boolean;
+}
diff --git a/src/encoder.ts b/src/encoder.ts
index 6c4cf75..e4e2c30 100644
--- a/src/encoder.ts
+++ b/src/encoder.ts
@@ -1,18 +1,18 @@
 import {Buffer} from "buffer";
 import {bytes} from "./@types/basic";
-import {MessageBuffer} from "./xx";
+import {MessageBuffer} from "./@types/handshake";
 
-export const int16BEEncode = (value, target, offset) => {
+export const uint16BEEncode = (value, target, offset) => {
   target = target || Buffer.allocUnsafe(2);
   return target.writeUInt16BE(value, offset);
 };
-int16BEEncode.bytes = 2;
+uint16BEEncode.bytes = 2;
 
-export const int16BEDecode = data => {
+export const uint16BEDecode = data => {
   if (data.length < 2) throw RangeError('Could not decode int16BE');
   return data.readUInt16BE(0);
 };
-int16BEDecode.bytes = 2;
+uint16BEDecode.bytes = 2;
 
 export function encodeMessageBuffer(message: MessageBuffer): bytes {
   return Buffer.concat([message.ne, message.ns, message.ciphertext]);
diff --git a/src/handshake.ts b/src/handshake.ts
index cb76381..b2d96dc 100644
--- a/src/handshake.ts
+++ b/src/handshake.ts
@@ -1,8 +1,9 @@
 import { Buffer } from "buffer";
 
-import { bytes, bytes32 } from "./@types/basic";
-import { NoiseSession, XXHandshake } from "./xx";
+import { XXHandshake } from "./handshakes/xx";
 import { KeyPair, PeerId } from "./@types/libp2p";
+import { bytes, bytes32 } from "./@types/basic";
+import { NoiseSession } from "./@types/handshake";
 import {
   createHandshakePayload,
   getHandshakePayload,
diff --git a/src/handshakes/abstract-handshake.ts b/src/handshakes/abstract-handshake.ts
new file mode 100644
index 0000000..486dd96
--- /dev/null
+++ b/src/handshakes/abstract-handshake.ts
@@ -0,0 +1,171 @@
+import {Buffer} from "buffer";
+import { AEAD, x25519, SHA256 } from 'bcrypto';
+
+import {bytes, bytes32, uint32} from "../@types/basic";
+import {CipherState, MessageBuffer, SymmetricState} from "../@types/handshake";
+import {getHkdf} from "../utils";
+
+export const MIN_NONCE = 0;
+
+export abstract class AbstractHandshake {
+  public encryptWithAd(cs: CipherState, ad: bytes, plaintext: bytes): bytes {
+    const e = this.encrypt(cs.k, cs.n, ad, plaintext);
+    this.setNonce(cs, this.incrementNonce(cs.n));
+
+    return e;
+  }
+
+  public decryptWithAd(cs: CipherState, ad: bytes, ciphertext: bytes): bytes {
+    const plaintext = this.decrypt(cs.k, cs.n, ad, ciphertext);
+    this.setNonce(cs, this.incrementNonce(cs.n));
+
+    return plaintext;
+  }
+
+
+  // Cipher state related
+  protected hasKey(cs: CipherState): boolean {
+    return !this.isEmptyKey(cs.k);
+  }
+
+  protected setNonce(cs: CipherState, nonce: uint32): void {
+    cs.n = nonce;
+  }
+
+  protected createEmptyKey(): bytes32 {
+    return Buffer.alloc(32);
+  }
+
+  protected isEmptyKey(k: bytes32): boolean {
+    const emptyKey = this.createEmptyKey();
+    return emptyKey.equals(k);
+  }
+
+  protected incrementNonce(n: uint32): uint32 {
+    return n + 1;
+  }
+
+  protected nonceToBytes(n: uint32): bytes {
+    const nonce = Buffer.alloc(12);
+    nonce.writeUInt32LE(n, 4);
+
+    return nonce;
+  }
+
+  protected encrypt(k: bytes32, n: uint32, ad: bytes, plaintext: bytes): bytes {
+    const nonce = this.nonceToBytes(n);
+    const ctx = new AEAD();
+
+    ctx.init(k, nonce);
+    ctx.aad(ad);
+    ctx.encrypt(plaintext);
+
+    // Encryption is done on the sent reference
+    return plaintext;
+  }
+
+  protected encryptAndHash(ss: SymmetricState, plaintext: bytes): bytes {
+    let ciphertext;
+    if (this.hasKey(ss.cs)) {
+      ciphertext = this.encryptWithAd(ss.cs, ss.h, plaintext);
+    } else {
+      ciphertext = plaintext;
+    }
+
+    this.mixHash(ss, ciphertext);
+    return ciphertext;
+  }
+
+  protected decrypt(k: bytes32, n: uint32, ad: bytes, ciphertext: bytes): bytes {
+    const nonce = this.nonceToBytes(n);
+    const ctx = new AEAD();
+
+    ctx.init(k, nonce);
+    ctx.aad(ad);
+    ctx.decrypt(ciphertext);
+
+    // Decryption is done on the sent reference
+    return ciphertext;
+  }
+
+  protected decryptAndHash(ss: SymmetricState, ciphertext: bytes): bytes {
+    let plaintext;
+    if (this.hasKey(ss.cs)) {
+      plaintext = this.decryptWithAd(ss.cs, ss.h, ciphertext);
+    } else {
+      plaintext = ciphertext;
+    }
+
+    this.mixHash(ss, ciphertext);
+    return plaintext;
+  }
+
+  protected dh(privateKey: bytes32, publicKey: bytes32): bytes32 {
+    const derived = x25519.derive(publicKey, privateKey);
+    const result = Buffer.alloc(32);
+    derived.copy(result);
+    return result;
+  }
+
+  protected mixHash(ss: SymmetricState, data: bytes): void {
+    ss.h = this.getHash(ss.h, data);
+  }
+
+  protected getHash(a: bytes, b: bytes): bytes32 {
+    return SHA256.digest(Buffer.from([...a, ...b]));
+  }
+
+  protected mixKey(ss: SymmetricState, ikm: bytes32): void {
+    const [ ck, tempK ] = getHkdf(ss.ck, ikm);
+    ss.cs = this.initializeKey(tempK) as CipherState;
+    ss.ck = ck;
+  }
+
+  protected initializeKey(k: bytes32): CipherState {
+    const n = MIN_NONCE;
+    return { k, n };
+  }
+
+  // Symmetric state related
+
+  protected initializeSymmetric(protocolName: string): SymmetricState {
+    const protocolNameBytes: bytes = Buffer.from(protocolName, 'utf-8');
+    const h = this.hashProtocolName(protocolNameBytes);
+
+    const ck = h;
+    const key = this.createEmptyKey();
+    const cs: CipherState = this.initializeKey(key);
+
+    return { cs, ck, h };
+  }
+
+  protected hashProtocolName(protocolName: bytes): bytes32 {
+    if (protocolName.length <= 32) {
+      const h = Buffer.alloc(32);
+      protocolName.copy(h);
+      return h;
+    } else {
+      return this.getHash(protocolName, Buffer.alloc(0));
+    }
+  }
+
+  protected split(ss: SymmetricState) {
+    const [ tempk1, tempk2 ] = getHkdf(ss.ck, Buffer.alloc(0));
+    const cs1 = this.initializeKey(tempk1);
+    const cs2 = this.initializeKey(tempk2);
+
+    return { cs1, cs2 };
+  }
+
+  protected writeMessageRegular(cs: CipherState, payload: bytes): MessageBuffer {
+    const ciphertext = this.encryptWithAd(cs, Buffer.alloc(0), payload);
+    const ne = this.createEmptyKey();
+    const ns = Buffer.alloc(0);
+
+    return { ne, ns, ciphertext };
+  }
+
+  protected readMessageRegular(cs: CipherState, message: MessageBuffer): bytes {
+    return this.decryptWithAd(cs, Buffer.alloc(0), message.ciphertext);
+  }
+}
diff --git a/src/handshakes/ik.ts b/src/handshakes/ik.ts
new file mode 100644
index 0000000..f7c04ff
--- /dev/null
+++ b/src/handshakes/ik.ts
@@ -0,0 +1,172 @@
+import {Buffer} from "buffer";
+import {BN} from "bn.js";
+
+import {HandshakeState, MessageBuffer, NoiseSession} from "../@types/handshake";
+import {bytes, bytes32} from "../@types/basic";
+import {generateKeypair, getHkdf, isValidPublicKey} from "../utils";
+import {AbstractHandshake} from "./abstract-handshake";
+import {KeyPair} from "../@types/libp2p";
+
+
+export class IKHandshake extends AbstractHandshake {
+  public initSession(initiator: boolean, prologue: bytes32, s: KeyPair, rs: bytes32): NoiseSession {
+    const psk = this.createEmptyKey();
+
+    let hs;
+    if (initiator) {
+      hs = this.initializeInitiator(prologue, s, rs, psk);
+    } else {
+      hs = this.initializeResponder(prologue, s, rs, psk);
+    }
+
+    return {
+      hs,
+      i: initiator,
+      mc: new BN(0),
+    };
+  }
+
+  public sendMessage(session: NoiseSession, message: bytes): MessageBuffer {
+    let messageBuffer: MessageBuffer;
+    if (session.mc.eqn(0)) {
+      messageBuffer = this.writeMessageA(session.hs, message);
+    } else if (session.mc.eqn(1)) {
+      const { messageBuffer: mb, h, cs1, cs2 } = this.writeMessageB(session.hs, message);
+      messageBuffer = mb;
+      session.h = h;
+      session.cs1 = cs1;
+      session.cs2 = cs2;
+    } else if (session.mc.gtn(1)) {
+      if (session.i) {
+        if (!session.cs1) {
+          throw new Error("CS1 (cipher state) is not defined")
+        }
+
+        messageBuffer = this.writeMessageRegular(session.cs1, message);
+      } else {
+        if (!session.cs2) {
+          throw new Error("CS2 (cipher state) is not defined")
+        }
+
+        messageBuffer = this.writeMessageRegular(session.cs2, message);
+      }
+    } else {
+      throw new Error("Session invalid.")
+    }
+
+    session.mc = session.mc.add(new BN(1));
+    return messageBuffer;
+  }
+
+  public recvMessage(session: NoiseSession, message: MessageBuffer): bytes {
+    let plaintext: bytes;
+    if (session.mc.eqn(0)) {
+      plaintext = this.readMessageA(session.hs, message);
+    } else if (session.mc.eqn(1)) {
+      const { plaintext: pt, h, cs1, cs2 } = this.readMessageB(session.hs, message);
+      plaintext = pt;
+      session.h = h;
+      session.cs1 = cs1;
+      session.cs2 = cs2;
+      delete session.hs;
+    } else if (session.mc.gtn(1)) {
+      if (session.i) {
+        if (!session.cs2) {
+          throw new Error("CS1 (cipher state) is not defined")
+        }
+        plaintext = this.readMessageRegular(session.cs2, message);
+      } else {
+        if (!session.cs1) {
+          throw new Error("CS1 (cipher state) is not defined")
+        }
+        plaintext = this.readMessageRegular(session.cs1, message);
+      }
+    } else {
+      throw new Error("Session invalid.");
+    }
+
+    session.mc = session.mc.add(new BN(1));
+    return plaintext;
+  }
+
+  private writeMessageA(hs: HandshakeState, payload: bytes): MessageBuffer {
+    hs.e = generateKeypair();
+    const ne = hs.e.publicKey;
+    this.mixHash(hs.ss, ne);
+    this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.rs));
+    const spk = Buffer.from(hs.s.publicKey);
+    const ns = this.encryptAndHash(hs.ss, spk);
+
+    this.mixKey(hs.ss, this.dh(hs.s.privateKey, hs.rs));
+    const ciphertext = this.encryptAndHash(hs.ss, payload);
+
+    return { ne, ns, ciphertext };
+  }
+
+  private writeMessageB(hs: HandshakeState, payload: bytes) {
+    hs.e = generateKeypair();
+    const ne = hs.e.publicKey;
+    this.mixHash(hs.ss, ne);
+
+    this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.re));
+    this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.rs));
+    const ciphertext = this.encryptAndHash(hs.ss, payload);
+    const ns = this.createEmptyKey();
+    const messageBuffer: MessageBuffer = {ne, ns, ciphertext};
+    const { cs1, cs2 } = this.split(hs.ss);
+
+    return { messageBuffer, cs1, cs2, h: hs.ss.h }
+  }
+
+  private readMessageA(hs: HandshakeState, message: MessageBuffer): bytes {
+    if (isValidPublicKey(message.ne)) {
+      hs.re = message.ne;
+    }
+
+    this.mixHash(hs.ss, hs.re);
+    this.mixKey(hs.ss, this.dh(hs.s.privateKey, hs.re));
+    const ns = this.decryptAndHash(hs.ss, message.ns);
+    if (ns.length === 32 && isValidPublicKey(message.ns)) {
+      hs.rs = ns;
+    }
+    this.mixKey(hs.ss, this.dh(hs.s.privateKey, hs.rs));
+    return this.decryptAndHash(hs.ss, message.ciphertext);
+  }
+
+  private readMessageB(hs: HandshakeState, message: MessageBuffer) {
+    if (isValidPublicKey(message.ne)) {
+      hs.re = message.ne;
+    }
+
+    this.mixHash(hs.ss, hs.re);
+    if (!hs.e) {
+      throw new Error("Handshake state should contain ephemeral key by now.");
+    }
+    this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.re));
+    this.mixKey(hs.ss, this.dh(hs.s.privateKey, hs.re));
+    const plaintext = this.decryptAndHash(hs.ss, message.ciphertext);
+    const { cs1, cs2 } = this.split(hs.ss);
+
+    return { h: hs.ss.h, plaintext, cs1, cs2 };
+  }
+
+  private initializeInitiator(prologue: bytes32, s: KeyPair, rs: bytes32, psk: bytes32): HandshakeState {
+    const name = "Noise_IK_25519_ChaChaPoly_SHA256";
+    const ss = this.initializeSymmetric(name);
+    this.mixHash(ss, prologue);
+    this.mixHash(ss, rs);
+    const re = Buffer.alloc(32);
+
+    return { ss, s, rs, re, psk };
+  }
+
+  private initializeResponder(prologue: bytes32, s: KeyPair, rs: bytes32, psk: bytes32): HandshakeState {
+    const name = "Noise_IK_25519_ChaChaPoly_SHA256";
+    const ss = this.initializeSymmetric(name);
+    this.mixHash(ss, prologue);
+    this.mixHash(ss, s.publicKey);
+    const re = Buffer.alloc(32);
+
+    return { ss, s, rs, re, psk };
+  }
+}
diff --git a/src/xx.ts b/src/handshakes/xx.ts
similarity index 50%
rename from src/xx.ts
rename to src/handshakes/xx.ts
index d4b479a..3b8b0a9 100644
--- a/src/xx.ts
+++ b/src/handshakes/xx.ts
@@ -1,54 +1,14 @@
 import { Buffer } from 'buffer';
-import { AEAD, x25519, HKDF, SHA256 } from 'bcrypto';
 import { BN } from 'bn.js';
 
-import { bytes32, uint32, uint64, bytes } from './@types/basic'
-import { KeyPair } from './@types/libp2p'
-import { generateKeypair } from './utils';
+import { bytes32, bytes } from '../@types/basic'
+import { KeyPair } from '../@types/libp2p'
+import {generateKeypair, getHkdf, isValidPublicKey} from '../utils';
+import { HandshakeState, MessageBuffer, NoiseSession } from "../@types/handshake";
+import {AbstractHandshake} from "./abstract-handshake";
 
-export interface MessageBuffer {
-  ne: bytes32;
-  ns: bytes;
-  ciphertext: bytes;
-}
-
-type CipherState = {
-  k: bytes32;
-  n: uint32;
-}
-
-type SymmetricState = {
-  cs: CipherState;
-  ck: bytes32;  // chaining key
-  h: bytes32; // handshake hash
-}
-
-type HandshakeState = {
-  ss: SymmetricState;
-  s: KeyPair;
-  e?: KeyPair;
-  rs: bytes32;
-  re: bytes32;
-  psk: bytes32;
-}
-
-export type NoiseSession = {
-  hs: HandshakeState;
-  h?: bytes32;
-  cs1?: CipherState;
-  cs2?: CipherState;
-  mc: uint64;
-  i: boolean;
-}
-export type Hkdf = [bytes, bytes, bytes];
-
-const minNonce = 0;
-
-export class XXHandshake {
-  private createEmptyKey(): bytes32 {
-    return Buffer.alloc(32);
-  }
 
+export class XXHandshake extends AbstractHandshake {
   private initializeInitiator(prologue: bytes32, s: KeyPair, rs: bytes32, psk: bytes32): HandshakeState {
     const name = "Noise_XX_25519_ChaChaPoly_SHA256";
     const ss = this.initializeSymmetric(name);
@@ -67,162 +27,6 @@ export class XXHandshake {
     return { ss, s, rs, psk, re };
   }
 
-  private incrementNonce(n: uint32): uint32 {
-    return n + 1;
-  }
-
-  private dh(privateKey: bytes32, publicKey: bytes32): bytes32 {
-    const derived = x25519.derive(publicKey, privateKey);
-    const result = Buffer.alloc(32);
-    derived.copy(result);
-    return result;
-  }
-
-  private nonceToBytes(n: uint32): bytes {
-    const nonce = Buffer.alloc(12);
-    nonce.writeUInt32LE(n, 4);
-
-    return nonce;
-  }
-
-  private encrypt(k: bytes32, n: uint32, ad: bytes, plaintext: bytes): bytes {
-    const nonce = this.nonceToBytes(n);
-    const ctx = new AEAD();
-
-    ctx.init(k, nonce);
-    ctx.aad(ad);
-    ctx.encrypt(plaintext);
-
-    // Encryption is done on the sent reference
-    return plaintext;
-  }
-
-  private decrypt(k: bytes32, n: uint32, ad: bytes, ciphertext: bytes): bytes {
-    const nonce = this.nonceToBytes(n);
-    const ctx = new AEAD();
-
-    ctx.init(k, nonce);
-    ctx.aad(ad);
-    ctx.decrypt(ciphertext);
-
-    // Decryption is done on the sent reference
-    return ciphertext;
-  }
-
-  private isEmptyKey(k: bytes32): boolean {
-    const emptyKey = this.createEmptyKey();
-    return emptyKey.equals(k);
-  }
-
-  // Cipher state related
-  private initializeKey(k: bytes32): CipherState {
-    const n = minNonce;
-    return { k, n };
-  }
-
-  private hasKey(cs: CipherState): boolean {
-    return !this.isEmptyKey(cs.k);
-  }
-
-  private setNonce(cs: CipherState, nonce: uint32): void {
-    cs.n = nonce;
-  }
-
-  public encryptWithAd(cs: CipherState, ad: bytes, plaintext: bytes): bytes {
-    const e = this.encrypt(cs.k, cs.n, ad, plaintext);
-    this.setNonce(cs, this.incrementNonce(cs.n));
-
-    return e;
-  }
-
-  public decryptWithAd(cs: CipherState, ad: bytes, ciphertext: bytes): bytes {
-    const plaintext = this.decrypt(cs.k, cs.n, ad, ciphertext);
-    this.setNonce(cs, this.incrementNonce(cs.n));
-
-    return plaintext;
-  }
-
-  // Symmetric state related
-
-  private initializeSymmetric(protocolName: string): SymmetricState {
-    const protocolNameBytes: bytes = Buffer.from(protocolName, 'utf-8');
-    const h = this.hashProtocolName(protocolNameBytes);
-
-    const ck = h;
-    const key = this.createEmptyKey();
-    const cs: CipherState = this.initializeKey(key);
-
-    return { cs, ck, h };
-  }
-
-  private mixKey(ss: SymmetricState, ikm: bytes32): void {
-    const [ ck, tempK ] = this.getHkdf(ss.ck, ikm);
-    ss.cs = this.initializeKey(tempK) as CipherState;
-    ss.ck = ck;
-  }
-
-  private hashProtocolName(protocolName: bytes): bytes32 {
-    if (protocolName.length <= 32) {
-      const h = Buffer.alloc(32);
-      protocolName.copy(h);
-      return h;
-    } else {
-      return this.getHash(protocolName, Buffer.alloc(0));
-    }
-  }
-
-  public getHkdf(ck: bytes32, ikm: bytes): Hkdf {
-    const info = Buffer.alloc(0);
-    const prk = HKDF.extract(SHA256, ikm, ck);
-    const okm = HKDF.expand(SHA256, prk, info, 96);
-
-    const k1 = okm.slice(0, 32);
-    const k2 = okm.slice(32, 64);
-    const k3 = okm.slice(64, 96);
-
-    return [ k1, k2, k3 ];
-  }
-
-  private mixHash(ss: SymmetricState, data: bytes) {
-    ss.h = this.getHash(ss.h, data);
-  }
-
-  private getHash(a: bytes, b: bytes): bytes32 {
-    return SHA256.digest(Buffer.from([...a, ...b]));
-  }
-
-  private encryptAndHash(ss: SymmetricState, plaintext: bytes): bytes {
-    let ciphertext;
-    if (this.hasKey(ss.cs)) {
-      ciphertext = this.encryptWithAd(ss.cs, ss.h, plaintext);
-    } else {
-      ciphertext = plaintext;
-    }
-
-    this.mixHash(ss, ciphertext);
-    return ciphertext;
-  }
-
-  private decryptAndHash(ss: SymmetricState, ciphertext: bytes): bytes {
-    let plaintext;
-    if (this.hasKey(ss.cs)) {
-      plaintext = this.decryptWithAd(ss.cs, ss.h, ciphertext);
-    } else {
-      plaintext = ciphertext;
-    }
-
-    this.mixHash(ss, ciphertext);
-    return plaintext;
-  }
-
-  private split (ss: SymmetricState) {
-    const [ tempk1, tempk2 ] = this.getHkdf(ss.ck, Buffer.alloc(0));
-    const cs1 = this.initializeKey(tempk1);
-    const cs2 = this.initializeKey(tempk2);
-
-    return { cs1, cs2 };
-  }
-
   private writeMessageA(hs: HandshakeState, payload: bytes): MessageBuffer {
     const ns = Buffer.alloc(0);
     hs.e = generateKeypair();
@@ -262,16 +66,8 @@ export class XXHandshake {
     return { h: hs.ss.h, messageBuffer, cs1, cs2 };
   }
 
-  private writeMessageRegular(cs: CipherState, payload: bytes): MessageBuffer {
-    const ciphertext = this.encryptWithAd(cs, Buffer.alloc(0), payload);
-    const ne = this.createEmptyKey();
-    const ns = Buffer.alloc(0);
-
-    return { ne, ns, ciphertext };
-  }
-
   private readMessageA(hs: HandshakeState, message: MessageBuffer): bytes {
-    if (x25519.publicKeyVerify(message.ne)) {
+    if (isValidPublicKey(message.ne)) {
       hs.re = message.ne;
     }
 
@@ -280,7 +76,7 @@ export class XXHandshake {
   }
 
   private readMessageB(hs: HandshakeState, message: MessageBuffer): bytes {
-    if (x25519.publicKeyVerify(message.ne)) {
+    if (isValidPublicKey(message.ne)) {
       hs.re = message.ne;
     }
 
@@ -290,7 +86,7 @@ export class XXHandshake {
     }
     this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.re));
     const ns = this.decryptAndHash(hs.ss, message.ns);
-    if (ns.length === 32 && x25519.publicKeyVerify(message.ns)) {
+    if (ns.length === 32 && isValidPublicKey(message.ns)) {
       hs.rs = ns;
     }
     this.mixKey(hs.ss, this.dh(hs.e.privateKey, hs.rs));
@@ -299,7 +95,7 @@ export class XXHandshake {
 
   private readMessageC(hs: HandshakeState, message: MessageBuffer) {
     const ns = this.decryptAndHash(hs.ss, message.ns);
-    if (ns.length === 32 && x25519.publicKeyVerify(message.ns)) {
+    if (ns.length === 32 && isValidPublicKey(message.ns)) {
       hs.rs = ns;
     }
 
@@ -314,10 +110,6 @@ export class XXHandshake {
     return { h: hs.ss.h, plaintext, cs1, cs2 };
   }
 
-  private readMessageRegular(cs: CipherState, message: MessageBuffer): bytes {
-    return this.decryptWithAd(cs, Buffer.alloc(0), message.ciphertext);
-  }
-
   public initSession(initiator: boolean, prologue: bytes32, s: KeyPair): NoiseSession {
     const psk = this.createEmptyKey();
     const rs = Buffer.alloc(32); // no static key yet
@@ -348,6 +140,7 @@ export class XXHandshake {
       session.h = h;
       session.cs1 = cs1;
       session.cs2 = cs2;
+      delete session.hs;
     } else if (session.mc.gtn(2)) {
       if (session.i) {
         if (!session.cs1) {
diff --git a/src/noise.ts b/src/noise.ts
index 83b313e..068ade3 100644
--- a/src/noise.ts
+++ b/src/noise.ts
@@ -8,7 +8,7 @@ import lp from 'it-length-prefixed';
 
 import { Handshake } from "./handshake";
 import { generateKeypair } from "./utils";
-import { int16BEDecode, int16BEEncode } from "./encoder";
+import { uint16BEDecode, uint16BEEncode } from "./encoder";
 import { decryptStream, encryptStream } from "./crypto";
 import { bytes } from "./@types/basic";
 import { NoiseConnection, PeerId, KeyPair, SecureOutbound } from "./@types/libp2p";
@@ -108,9 +108,9 @@ export class Noise implements NoiseConnection {
       secure, // write to wrapper
       ensureBuffer, // ensure any type of data is converted to buffer
       encryptStream(handshake), // data is encrypted
-      lp.encode({ lengthEncoder: int16BEEncode }), // prefix with message length
+      lp.encode({ lengthEncoder: uint16BEEncode }), // prefix with message length
       network, // send to the remote peer
-      lp.decode({ lengthDecoder: int16BEDecode }), // read message length prefix
+      lp.decode({ lengthDecoder: uint16BEDecode }), // read message length prefix
       ensureBuffer, // ensure any type of data is converted to buffer
       decryptStream(handshake), // decrypt the incoming data
       secure // pipe to the wrapper
diff --git a/src/utils.ts b/src/utils.ts
index 65b7939..005f826 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,11 +1,12 @@
-import { x25519, ed25519 } from 'bcrypto';
+import { x25519, ed25519, HKDF, SHA256 } from 'bcrypto';
 import protobuf from "protobufjs";
 import { Buffer } from "buffer";
 import PeerId from "peer-id";
 import * as crypto from 'libp2p-crypto';
 
 import { KeyPair } from "./@types/libp2p";
-import { bytes } from "./@types/basic";
+import {bytes, bytes32} from "./@types/basic";
+import {Hkdf} from "./@types/handshake";
 
 export async function loadPayloadProto () {
   const payloadProtoBuf = await protobuf.load("protos/payload.proto");
@@ -88,3 +89,19 @@ export async function verifySignedPayload(noiseStaticKey: bytes, plaintext: byte
     throw new Error("Static key doesn't match to peer that signed payload!");
   }
 }
+
+export function getHkdf(ck: bytes32, ikm: bytes): Hkdf {
+  const info = Buffer.alloc(0);
+  const prk = HKDF.extract(SHA256, ikm, ck);
+  const okm = HKDF.expand(SHA256, prk, info, 96);
+
+  const k1 = okm.slice(0, 32);
+  const k2 = okm.slice(32, 64);
+  const k3 = okm.slice(64, 96);
+
+  return [ k1, k2, k3 ];
+}
+
+export function isValidPublicKey(pk: bytes): boolean {
+  return x25519.publicKeyVerify(pk);
+}
diff --git a/test/handshakes/ik.test.ts b/test/handshakes/ik.test.ts
new file mode 100644
index 0000000..6a4bf8e
--- /dev/null
+++ b/test/handshakes/ik.test.ts
@@ -0,0 +1,67 @@
+import {Buffer} from "buffer";
+import {IKHandshake} from "../../src/handshakes/ik";
+import {KeyPair} from "../../src/@types/libp2p";
+import {createHandshakePayload, generateKeypair, getHandshakePayload} from "../../src/utils";
+import {assert, expect} from "chai";
+import {generateEd25519Keys} from "../utils";
+
+describe("Index", () => {
+  const prologue = Buffer.from("/noise", "utf-8");
+
+  it("Test complete IK handshake", async () => {
+    try {
+      const ikI = new IKHandshake();
+      const ikR = new IKHandshake();
+
+      // Generate static noise keys
+      const kpInitiator: KeyPair = await generateKeypair();
+      const kpResponder: KeyPair = await generateKeypair();
+
+      // Generate libp2p keys
+      const libp2pInitKeys = await generateEd25519Keys();
+      const libp2pRespKeys = await generateEd25519Keys();
+
+      // Create sessions
+      const initiatorSession = await ikI.initSession(true, prologue, kpInitiator, kpResponder.publicKey);
+      const responderSession = await ikR.initSession(false, prologue, kpResponder, Buffer.alloc(32));
+
+      /* Stage 0 */
+
+      // initiator creates payload
+      const initSignedPayload = await libp2pInitKeys.sign(getHandshakePayload(kpInitiator.publicKey));
+      const libp2pInitPrivKey = libp2pInitKeys.marshal().slice(0, 32);
+      const libp2pInitPubKey = libp2pInitKeys.marshal().slice(32, 64);
+      const payloadInitEnc = await createHandshakePayload(libp2pInitPubKey, libp2pInitPrivKey, initSignedPayload);
+
+      // initiator sends message
+      const message = Buffer.concat([Buffer.alloc(0), payloadInitEnc]);
+      const messageBuffer = ikI.sendMessage(initiatorSession, message);
+
+      expect(messageBuffer.ne.length).not.equal(0);
+
+      // responder receives message
+      const plaintext = ikR.recvMessage(responderSession, messageBuffer);
+
+      /* Stage 1 */
+
+      // responder creates payload
+      const libp2pRespPrivKey = libp2pRespKeys.marshal().slice(0, 32);
+      const libp2pRespPubKey = libp2pRespKeys.marshal().slice(32, 64);
+      const respSignedPayload = await libp2pRespKeys.sign(getHandshakePayload(kpResponder.publicKey));
+      const payloadRespEnc = await createHandshakePayload(libp2pRespPubKey, libp2pRespPrivKey, respSignedPayload);
+
+      const message1 = Buffer.concat([message, payloadRespEnc]);
+      const messageBuffer2 = ikR.sendMessage(responderSession, message1);
+
+      // initiator receives message
+      const plaintext2 = ikI.recvMessage(initiatorSession, messageBuffer2);
+
+      assert(initiatorSession.cs1.k.equals(responderSession.cs1.k));
+      assert(initiatorSession.cs2.k.equals(responderSession.cs2.k));
+
+    } catch (e) {
+      console.log(e);
+      assert(false, e.message);
+    }
+  });
+});
diff --git a/test/xx.test.ts b/test/handshakes/xx.test.ts
similarity index 95%
rename from test/xx.test.ts
rename to test/handshakes/xx.test.ts
index 1eca6b4..b6d93f4 100644
--- a/test/xx.test.ts
+++ b/test/handshakes/xx.test.ts
@@ -1,10 +1,10 @@
 import { expect, assert } from "chai";
 import { Buffer } from 'buffer';
 
-import { XXHandshake } from "../src/xx";
-import { KeyPair } from "../src/@types/libp2p";
-import { generateEd25519Keys } from "./utils";
-import {createHandshakePayload, generateKeypair, getHandshakePayload} from "../src/utils";
+import { XXHandshake } from "../../src/handshakes/xx";
+import { KeyPair } from "../../src/@types/libp2p";
+import { generateEd25519Keys } from "../utils";
+import {createHandshakePayload, generateKeypair, getHandshakePayload, getHkdf} from "../../src/utils";
 
 describe("Index", () => {
   const prologue = Buffer.from("/noise", "utf-8");
@@ -29,7 +29,7 @@ describe("Index", () => {
     const ck = Buffer.alloc(32);
     ckBytes.copy(ck);
 
-    const [k1, k2, k3] = xx.getHkdf(ck, ikm);
+    const [k1, k2, k3] = getHkdf(ck, ikm);
     expect(k1.toString('hex')).to.equal('cc5659adff12714982f806e2477a8d5ddd071def4c29bb38777b7e37046f6914');
     expect(k2.toString('hex')).to.equal('a16ada915e551ab623f38be674bb4ef15d428ae9d80688899c9ef9b62ef208fa');
     expect(k3.toString('hex')).to.equal('ff67bf9727e31b06efc203907e6786667d2c7a74ac412b4d31a80ba3fd766f68');
diff --git a/test/noise.test.ts b/test/noise.test.ts
index d6a8dd2..6594473 100644
--- a/test/noise.test.ts
+++ b/test/noise.test.ts
@@ -13,7 +13,7 @@ import {
   signPayload
 } from "../src/utils";
 import { decodeMessageBuffer, encodeMessageBuffer } from "../src/encoder";
-import {XXHandshake} from "../src/xx";
+import {XXHandshake} from "../src/handshakes/xx";
 import {Buffer} from "buffer";
 import {getKeyPairFromPeerId} from "./utils";