From 20dbd3ff6c40a6e9a55a29db5b58aa430ca9c280 Mon Sep 17 00:00:00 2001
From: s1fr0 <s1fr0@users.noreply.github.com>
Date: Fri, 3 Jun 2022 19:43:43 +0000
Subject: [PATCH] deploy: c259f4cbaae9ba8ae0dc424aee80887e0fe2693d

---
 tests/v2/test_waku_noise.nim                  | 452 ++++++++++++-
 .../vendor/libbacktrace-upstream/libtool      |   2 +-
 waku/v2/protocol/waku_noise/noise.nim         | 607 +++++++++++++++++-
 3 files changed, 1039 insertions(+), 22 deletions(-)

diff --git a/tests/v2/test_waku_noise.nim b/tests/v2/test_waku_noise.nim
index 7893ef8a6..b2af86d4a 100644
--- a/tests/v2/test_waku_noise.nim
+++ b/tests/v2/test_waku_noise.nim
@@ -209,7 +209,6 @@ procSuite "Waku Noise":
       getNonce(cipherState) == nonce + 1 
       plaintext == decrypted
 
-
     # If a Cipher State has no key set, encryptWithAd should return the plaintext without increasing the nonce
     setCipherStateKey(cipherState, EmptyKey)
     nonce = getNonce(cipherState)
@@ -321,7 +320,7 @@ procSuite "Waku Noise":
     ########################################
 
     # We generate random input key material and we execute mixKey
-    var inputKeyMaterial = randomChaChaPolyKey(rng[])
+    var inputKeyMaterial = randomSeqByte(rng[], rand(1..128))
     mixKey(symmetricState, inputKeyMaterial)
 
     # mixKey changes the Symmetric State's chaining key and encryption key of the embedded Cipher State 
@@ -342,7 +341,7 @@ procSuite "Waku Noise":
     ########################################
 
     # We generate random input key material and we execute mixKeyAndHash
-    inputKeyMaterial = randomChaChaPolyKey(rng[])
+    inputKeyMaterial = randomSeqByte(rng[], rand(1..128))
     mixKeyAndHash(symmetricState, inputKeyMaterial)
 
     # mixKeyAndHash executes a mixKey and a mixHash using the input key material
@@ -413,3 +412,450 @@ procSuite "Waku Noise":
       getNonce(cs1) == 0.uint64
       getNonce(cs2) == 0.uint64
       getKey(cs1) != getKey(cs2)
+
+  test "Noise XX Handhshake and message encryption (extended test)":
+
+    let hsPattern = NoiseHandshakePatterns["XX"]
+
+    # We initialize Alice's and Bob's Handshake State
+    let aliceStaticKey = genKeyPair(rng[])
+    var aliceHS = initialize(hsPattern = hsPattern, staticKey = aliceStaticKey, initiator = true)
+
+    let bobStaticKey = genKeyPair(rng[])
+    var bobHS = initialize(hsPattern = hsPattern, staticKey = bobStaticKey)
+    
+    var 
+      sentTransportMessage: seq[byte]
+      aliceStep, bobStep: HandshakeStepResult 
+    
+    # Here the handshake starts
+    # Write and read calls alternate between Alice and Bob: the handhshake progresses by alternatively calling stepHandshake for each user
+
+    ###############
+    # 1st step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # By being the handshake initiator, Alice writes a Waku2 payload v2 containing her handshake message 
+    # and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 2nd step
+    ###############
+    
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # At this step, Bob writes and returns a payload
+    bobStep = stepHandshake(rng[], bobHS, transportMessage = sentTransportMessage).get()
+
+    # While Alice reads and returns the (decrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, readPayloadV2 = bobStep.payload2).get()
+    
+    check: 
+      aliceStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 3rd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32) 
+
+    # Similarly as in first step, Alice writes a Waku2 payload containing the handshake message and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check: 
+      bobStep.transportMessage == sentTransportMessage
+
+    # Note that for this handshake pattern, no more message patterns are left for processing 
+    # Another call to stepHandshake would return an empty HandshakeStepResult
+    # We test that extra calls to stepHandshake do not affect parties' handshake states
+    # and that the intermediate HandshakeStepResult are empty
+    let prevAliceHS = aliceHS
+    let prevBobHS = bobHS
+    
+    let bobStep1 = stepHandshake(rng[], bobHS, transportMessage = sentTransportMessage).get()
+    let aliceStep1 = stepHandshake(rng[], aliceHS, readPayloadV2 = bobStep1.payload2).get()
+    let aliceStep2 = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+    let bobStep2 = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep2.payload2).get()
+   
+    check:
+      aliceStep1 == default(HandshakeStepResult)
+      aliceStep2 == default(HandshakeStepResult)
+      bobStep1 == default(HandshakeStepResult)
+      bobStep2 == default(HandshakeStepResult)
+      aliceHS == prevAliceHS 
+      bobHS == prevBobHS 
+
+    #########################
+    # After Handshake
+    #########################
+
+    # We finalize the handshake to retrieve the Inbound/Outbound symmetric states
+    var aliceHSResult, bobHSResult: HandshakeResult
+
+    aliceHSResult = finalizeHandshake(aliceHS)
+    bobHSResult = finalizeHandshake(bobHS)
+
+    # We test read/write of random messages exchanged between Alice and Bob
+    var 
+      payload2: PayloadV2
+      message: seq[byte]
+      readMessage: seq[byte]
+
+    for _ in 0..10:
+
+      # Alice writes to Bob
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(aliceHSResult, message)
+      readMessage = readMessage(bobHSResult, payload2).get()
+      
+      check: 
+        message == readMessage
+      
+      # Bob writes to Alice
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(bobHSResult, message)
+      readMessage = readMessage(aliceHSResult, payload2).get()
+      
+      check:
+        message == readMessage
+
+  test "Noise XXpsk0 Handhshake and message encryption (short test)":
+
+    let hsPattern = NoiseHandshakePatterns["XXpsk0"]
+
+    # We generate a random psk
+    let psk = randomSeqByte(rng[], 32)
+    
+    # We initialize Alice's and Bob's Handshake State
+    let aliceStaticKey = genKeyPair(rng[])
+    var aliceHS = initialize(hsPattern = hsPattern, staticKey = aliceStaticKey, psk = psk, initiator = true)
+
+    let bobStaticKey = genKeyPair(rng[])
+    var bobHS = initialize(hsPattern = hsPattern, staticKey = bobStaticKey, psk = psk)
+    
+    var 
+      sentTransportMessage: seq[byte]
+      aliceStep, bobStep: HandshakeStepResult 
+    
+    # Here the handshake starts
+    # Write and read calls alternate between Alice and Bob: the handhshake progresses by alternatively calling stepHandshake for each user
+
+    ###############
+    # 1st step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+    
+    # By being the handshake initiator, Alice writes a Waku2 payload v2 containing her handshake message 
+    # and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 2nd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # At this step, Bob writes and returns a payload
+    bobStep = stepHandshake(rng[], bobHS, transportMessage = sentTransportMessage).get()
+
+    # While Alice reads and returns the (decrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, readPayloadV2 = bobStep.payload2).get()
+    
+    check: 
+      aliceStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 3rd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # Similarly as in first step, Alice writes a Waku2 payload containing the handshake message and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transportMessage alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    # Note that for this handshake pattern, no more message patterns are left for processing 
+   
+    #########################
+    # After Handshake
+    #########################
+
+    # We finalize the handshake to retrieve the Inbound/Outbound Symmetric States
+    var aliceHSResult, bobHSResult: HandshakeResult
+
+    aliceHSResult = finalizeHandshake(aliceHS)
+    bobHSResult = finalizeHandshake(bobHS)
+
+    # We test read/write of random messages exchanged between Alice and Bob
+    var 
+      payload2: PayloadV2
+      message: seq[byte]
+      readMessage: seq[byte]
+
+    for _ in 0..10:
+
+      # Alice writes to Bob
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(aliceHSResult, message)
+      readMessage = readMessage(bobHSResult, payload2).get()
+      
+      check: 
+        message == readMessage
+      
+      # Bob writes to Alice
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(bobHSResult, message)
+      readMessage = readMessage(aliceHSResult, payload2).get()
+      
+      check:
+        message == readMessage
+
+  test "Noise K1K1 Handhshake and message encryption (short test)":
+
+    let hsPattern = NoiseHandshakePatterns["K1K1"]
+
+    # We initialize Alice's and Bob's Handshake State
+    let aliceStaticKey = genKeyPair(rng[])
+    let bobStaticKey = genKeyPair(rng[])
+
+    # This handshake has the following pre-message pattern:
+    # -> s
+    # <- s
+    #   ...
+    # So we define accordingly the sequence of the pre-message public keys
+    let preMessagePKs: seq[NoisePublicKey] = @[toNoisePublicKey(getPublicKey(aliceStaticKey)), toNoisePublicKey(getPublicKey(bobStaticKey))]
+
+    var aliceHS = initialize(hsPattern = hsPattern, staticKey = aliceStaticKey, preMessagePKs = preMessagePKs, initiator = true)
+    var bobHS = initialize(hsPattern = hsPattern, staticKey = bobStaticKey, preMessagePKs = preMessagePKs)
+    
+    var 
+      sentTransportMessage: seq[byte]
+      aliceStep, bobStep: HandshakeStepResult 
+    
+    # Here the handshake starts
+    # Write and read calls alternate between Alice and Bob: the handhshake progresses by alternatively calling stepHandshake for each user
+
+    ###############
+    # 1st step
+    ###############
+
+    # We generate a random transport message  
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # By being the handshake initiator, Alice writes a Waku2 payload v2 containing her handshake message 
+    # and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 2nd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+ 
+    # At this step, Bob writes and returns a payload
+    bobStep = stepHandshake(rng[], bobHS, transportMessage = sentTransportMessage).get()
+
+    # While Alice reads and returns the (decrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, readPayloadV2 = bobStep.payload2).get()
+    
+    check:
+      aliceStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 3rd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # Similarly as in first step, Alice writes a Waku2 payload containing the handshake_message and the (encrypted) transportMessage
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transportMessage alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    # Note that for this handshake pattern, no more message patterns are left for processing 
+    
+    #########################
+    # After Handshake
+    #########################
+
+    # We finalize the handshake to retrieve the Inbound/Outbound Symmetric States
+    var aliceHSResult, bobHSResult: HandshakeResult
+
+    aliceHSResult = finalizeHandshake(aliceHS)
+    bobHSResult = finalizeHandshake(bobHS)
+
+    # We test read/write of random messages between Alice and Bob
+    var 
+      payload2: PayloadV2
+      message: seq[byte]
+      readMessage: seq[byte]
+
+    for _ in 0..10:
+
+      # Alice writes to Bob
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(aliceHSResult, message)
+      readMessage = readMessage(bobHSResult, payload2).get()
+      
+      check: 
+        message == readMessage
+      
+      # Bob writes to Alice
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(bobHSResult, message)
+      readMessage = readMessage(aliceHSResult, payload2).get()
+      
+      check:
+        message == readMessage
+
+
+  test "Noise XK1 Handhshake and message encryption (short test)":
+
+    let hsPattern = NoiseHandshakePatterns["XK1"]
+
+    # We initialize Alice's and Bob's Handshake State
+    let aliceStaticKey = genKeyPair(rng[])
+    let bobStaticKey = genKeyPair(rng[])
+
+    # This handshake has the following pre-message pattern:
+    # <- s
+    #   ...
+    # So we define accordingly the sequence of the pre-message public keys
+    let preMessagePKs: seq[NoisePublicKey] = @[toNoisePublicKey(getPublicKey(bobStaticKey))]
+
+    var aliceHS = initialize(hsPattern = hsPattern, staticKey = aliceStaticKey, preMessagePKs = preMessagePKs, initiator = true)
+    var bobHS = initialize(hsPattern = hsPattern, staticKey = bobStaticKey, preMessagePKs = preMessagePKs)
+    
+    var 
+      sentTransportMessage: seq[byte]
+      aliceStep, bobStep: HandshakeStepResult 
+    
+    # Here the handshake starts
+    # Write and read calls alternate between Alice and Bob: the handhshake progresses by alternatively calling stepHandshake for each user
+
+    ###############
+    # 1st step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # By being the handshake initiator, Alice writes a Waku2 payload v2 containing her handshake message 
+    # and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 2nd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # At this step, Bob writes and returns a payload
+    bobStep = stepHandshake(rng[], bobHS, transportMessage = sentTransportMessage).get()
+
+    # While Alice reads and returns the (decrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, readPayloadV2 = bobStep.payload2).get()
+    
+    check:
+      aliceStep.transportMessage == sentTransportMessage
+
+    ###############
+    # 3rd step
+    ###############
+
+    # We generate a random transport message
+    sentTransportMessage = randomSeqByte(rng[], 32)
+
+    # Similarly as in first step, Alice writes a Waku2 payload containing the handshake message and the (encrypted) transport message
+    aliceStep = stepHandshake(rng[], aliceHS, transportMessage = sentTransportMessage).get()
+
+    # Bob reads Alice's payloads, and returns the (decrypted) transport message Alice sent to him
+    bobStep = stepHandshake(rng[], bobHS, readPayloadV2 = aliceStep.payload2).get()
+    
+    check:
+      bobStep.transportMessage == sentTransportMessage
+
+    # Note that for this handshake pattern, no more message patterns are left for processing 
+        
+    #########################
+    # After Handshake
+    #########################
+
+    # We finalize the handshake to retrieve the Inbound/Outbound Symmetric States
+    var aliceHSResult, bobHSResult: HandshakeResult
+
+    aliceHSResult = finalizeHandshake(aliceHS)
+    bobHSResult = finalizeHandshake(bobHS)
+
+    # We test read/write of random messages exchanged between Alice and Bob
+    var 
+      payload2: PayloadV2
+      message: seq[byte]
+      readMessage: seq[byte]
+
+    for _ in 0..10:
+
+      # Alice writes to Bob
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(aliceHSResult, message)
+      readMessage = readMessage(bobHSResult, payload2).get()
+      
+      check: 
+        message == readMessage
+      
+      # Bob writes to Alice
+      message = randomSeqByte(rng[], 32)
+      payload2 = writeMessage(bobHSResult, message)
+      readMessage = readMessage(aliceHSResult, payload2).get()
+      
+      check:
+        message == readMessage
diff --git a/vendor/nim-libbacktrace/vendor/libbacktrace-upstream/libtool b/vendor/nim-libbacktrace/vendor/libbacktrace-upstream/libtool
index fc5b7e3de..95d456335 100755
--- a/vendor/nim-libbacktrace/vendor/libbacktrace-upstream/libtool
+++ b/vendor/nim-libbacktrace/vendor/libbacktrace-upstream/libtool
@@ -2,7 +2,7 @@
 
 # libtool - Provide generalized library-building support services.
 # Generated automatically by config.status (libbacktrace) version-unused
-# Libtool was configured on host fv-az133-170:
+# Libtool was configured on host fv-az124-778:
 # NOTE: Changes made to this file will be lost: look at ltmain.sh.
 #
 #   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005,
diff --git a/waku/v2/protocol/waku_noise/noise.nim b/waku/v2/protocol/waku_noise/noise.nim
index e41c746e7..fa57ad021 100644
--- a/waku/v2/protocol/waku_noise/noise.nim
+++ b/waku/v2/protocol/waku_noise/noise.nim
@@ -152,13 +152,21 @@ type
     msgPatternIdx: uint8
     psk: seq[byte]
 
+  # While processing messages patterns, users either:
+  # - read (decrypt) the other party's (encrypted) transport message
+  # - write (encrypt) a message, sent through a PayloadV2
+  # These two intermediate results are stored in the HandshakeStepResult data structure
+  HandshakeStepResult* = object
+    payload2*: PayloadV2
+    transportMessage*: seq[byte]
+
   # When a handshake is complete, the HandhshakeResult will contain the two 
   # Cipher States used to encrypt/decrypt outbound/inbound messages
   # The recipient static key rs and handshake hash values h are stored to address some possible future applications (channel-binding, session management, etc.).
   # However, are not required by Noise specifications and are thus optional
-  HandshakeResult = object
-    csInbound: CipherState
+  HandshakeResult* = object
     csOutbound: CipherState
+    csInbound: CipherState
     # Optional fields:
     rs: EllipticCurveKey
     h: MDigest[256]
@@ -195,7 +203,7 @@ type
 const
 
   # The empty pre message patterns
-  EmptyPreMessagePattern: seq[PreMessagePattern] = @[]
+  EmptyPreMessage: seq[PreMessagePattern] = @[]
 
   # Supported Noise handshake patterns as defined in https://rfc.vac.dev/spec/35/#specification
   NoiseHandshakePatterns*  = {
@@ -215,14 +223,14 @@ const
                               ),
 
     "XX":     HandshakePattern(name: "Noise_XX_25519_ChaChaPoly_SHA256",
-                               preMessagePatterns: EmptyPreMessagePattern, 
+                               preMessagePatterns: EmptyPreMessage, 
                                messagePatterns:    @[   MessagePattern(direction: D_r, tokens: @[T_e]),
                                                         MessagePattern(direction: D_l, tokens: @[T_e, T_ee, T_s, T_es]),
                                                         MessagePattern(direction: D_r, tokens: @[T_s, T_se])]
                               ),
 
     "XXpsk0": HandshakePattern(name: "Noise_XXpsk0_25519_ChaChaPoly_SHA256",
-                               preMessagePatterns: EmptyPreMessagePattern, 
+                               preMessagePatterns: EmptyPreMessage, 
                                messagePatterns:     @[  MessagePattern(direction: D_r, tokens: @[T_psk, T_e]),
                                                         MessagePattern(direction: D_l, tokens: @[T_e, T_ee, T_s, T_es]),
                                                         MessagePattern(direction: D_r, tokens: @[T_s, T_se])]
@@ -278,8 +286,8 @@ proc print*(self: HandshakePattern)
     if self.name != "":
       stdout.write self.name, ":\n"
       stdout.flushFile()
-    #We iterate over pre message patterns, if any
-    if self.preMessagePatterns != EmptyPreMessagePattern:
+    # We iterate over pre message patterns, if any
+    if self.preMessagePatterns != EmptyPreMessage:
       for pattern in self.preMessagePatterns:
           stdout.write "  ", pattern.direction
           var first = true
@@ -293,7 +301,7 @@ proc print*(self: HandshakePattern)
           stdout.flushFile()
       stdout.write "    ...\n"
       stdout.flushFile()
-    #We iterate over message patterns
+    # We iterate over message patterns
     for pattern in self.messagePatterns:
       stdout.write "  ", pattern.direction
       var first = true
@@ -339,7 +347,6 @@ proc dh*(private: EllipticCurveKey, public: EllipticCurveKey): EllipticCurveKey
 
   return output
 
-
 #################################################################
 
 # Noise state machine primitives
@@ -506,7 +513,7 @@ proc init*(_: type[SymmetricState], hsPattern: HandshakePattern): SymmetricState
 
 # MixKey as per Noise specification http://www.noiseprotocol.org/noise.html#the-symmetricstate-object
 # Updates a Symmetric state chaining key and symmetric state
-proc mixKey*(ss: var SymmetricState, inputKeyMaterial: ChaChaPolyKey) =
+proc mixKey*(ss: var SymmetricState, inputKeyMaterial: openArray[byte]) =
   # We derive two keys using HKDF
   var tempKeys: array[2, ChaChaPolyKey]
   sha256.hkdf(ss.ck, inputKeyMaterial, [], tempKeys)
@@ -626,7 +633,7 @@ proc encrypt*(
   # Since ChaChaPoly's library "encrypt" primitive directly changes the input plaintext to the ciphertext,
   # we copy the plaintext into the ciphertext variable and we pass the latter to encrypt
   ciphertext.data.add plaintext
-  #TODO: add padding
+  # TODO: add padding
   # ChaChaPoly.encrypt takes as input: the key (k), the nonce (nonce), a data structure for storing the computed authorization tag (tag), 
   # the plaintext (overwritten to ciphertext) (data), the associated data (ad)
   ChaChaPoly.encrypt(state.k, state.nonce, ciphertext.tag, ciphertext.data, state.ad)
@@ -653,7 +660,7 @@ proc decrypt*(
   # ChaChaPoly.decrypt takes as input: the key (k), the nonce (nonce), a data structure for storing the computed authorization tag (tag), 
   # the ciphertext (overwritten to plaintext) (data), the associated data (ad)
   ChaChaPoly.decrypt(state.k, state.nonce, tagOut, plaintext, state.ad)
-  #TODO: add unpadding
+  # TODO: add unpadding
   trace "decrypt", tagIn = tagIn, tagOut = tagOut, nonce = state.nonce
   # We check if the authorization tag computed while decrypting is the same as the input tag
   if tagIn != tagOut:
@@ -687,11 +694,11 @@ proc randomChaChaPolyCipherState*(rng: var BrHmacDrbgContext): ChaChaPolyCipherS
 proc `==`(k1, k2: NoisePublicKey): bool =
   return (k1.flag == k2.flag) and (k1.pk == k2.pk)
   
-# Converts a (public, private) Elliptic Curve keypair to an unencrypted Noise public key (only public part)
-proc keyPairToNoisePublicKey*(keyPair: KeyPair): NoisePublicKey =
+# Converts a public Elliptic Curve key to an unencrypted Noise public key
+proc toNoisePublicKey*(publicKey: EllipticCurveKey): NoisePublicKey =
   var noisePublicKey: NoisePublicKey
   noisePublicKey.flag = 0
-  noisePublicKey.pk = getBytes(keyPair.publicKey)
+  noisePublicKey.pk = getBytes(publicKey)
   return noisePublicKey
 
 # Generates a random Noise public key
@@ -803,7 +810,7 @@ proc randomPayloadV2*(rng: var BrHmacDrbgContext): PayloadV2 =
 # The output can be then passed to the payload field of a WakuMessage https://rfc.vac.dev/spec/14/
 proc serializePayloadV2*(self: PayloadV2): Result[seq[byte], cstring] =
 
-  #We collect public keys contained in the handshake message
+  # We collect public keys contained in the handshake message
   var
     # According to https://rfc.vac.dev/spec/35/, the maximum size for the handshake message is 256 bytes, that is 
     # the handshake message length can be represented with 1 byte only. (its length can be stored in 1 byte)
@@ -873,7 +880,6 @@ proc deserializePayloadV2*(payload: seq[byte]): Result[PayloadV2, cstring]
   var handshakeMessageLen = payload[i].uint64
   if handshakeMessageLen > uint8.high.uint64:
     debug "Payload malformed: too many public keys contained in the handshake message"
-    #raise newException(NoiseMalformedHandshake, "Too many public keys in handshake message")
     return err("Too many public keys in handshake message")
 
   i += 1
@@ -917,4 +923,569 @@ proc deserializePayloadV2*(payload: seq[byte]): Result[PayloadV2, cstring]
   payload2.transportMessage = payload[i..i+transportMessageLen-1]
   i += transportMessageLen
 
-  return ok(payload2)
\ No newline at end of file
+  return ok(payload2)
+
+
+#################################################################
+
+# Handshake Processing
+
+#################################
+## Utilities
+#################################
+
+# Based on the message handshake direction and if the user is or not the initiator, returns a boolean tuple telling if the user
+# has to read or write the next handshake message
+proc getReadingWritingState(hs: HandshakeState, direction: MessageDirection): (bool, bool) =
+
+  var reading, writing : bool
+
+  if hs.initiator and direction == D_r:
+    # I'm Alice and direction is ->
+    reading = false
+    writing = true
+  elif hs.initiator and direction == D_l:
+    # I'm Alice and direction is <-
+    reading = true
+    writing = false
+  elif not hs.initiator and direction == D_r:
+    # I'm Bob and direction is ->
+    reading = true
+    writing = false
+  elif not hs.initiator and direction == D_l:
+    # I'm Bob and direction is <-
+    reading = false
+    writing = true
+
+  return (reading, writing)
+
+# Checks if a pre-message is valid according to Noise specifications 
+# http://www.noiseprotocol.org/noise.html#handshake-patterns
+proc isValid(msg: seq[PreMessagePattern]): bool =
+
+  var isValid: bool = true
+
+  # Non-empty pre-messages can only have patterns "e", "s", "e,s" in each direction
+  let allowedPatterns: seq[PreMessagePattern] = @[ PreMessagePattern(direction: D_r, tokens: @[T_s]),
+                                                   PreMessagePattern(direction: D_r, tokens: @[T_e]),
+                                                   PreMessagePattern(direction: D_r, tokens: @[T_e, T_s]),
+                                                   PreMessagePattern(direction: D_l, tokens: @[T_s]),
+                                                   PreMessagePattern(direction: D_l, tokens: @[T_e]),
+                                                   PreMessagePattern(direction: D_l, tokens: @[T_e, T_s])
+                                                 ]
+
+  # We check if pre message patterns are allowed
+  for pattern in msg:
+    if not (pattern in allowedPatterns):
+      isValid = false
+      break
+
+  return isValid
+
+#################################
+# Handshake messages processing procedures
+#################################
+
+# Processes pre-message patterns
+proc processPreMessagePatternTokens*(hs: var HandshakeState, inPreMessagePKs: seq[NoisePublicKey] = @[])
+  {.raises: [Defect, NoiseMalformedHandshake, NoiseHandshakeError, NoisePublicKeyError].} =
+
+  var 
+    # I make a copy of the input pre-message public keys, so that I can easily delete processed ones without using iterators/counters
+    preMessagePKs = inPreMessagePKs
+    # Here we store currently processed pre message public key
+    currPK : NoisePublicKey
+
+  # We retrieve the pre-message patterns to process, if any
+  # If none, there's nothing to do
+  if hs.handshakePattern.preMessagePatterns == EmptyPreMessage:
+    return
+
+  # If not empty, we check that pre-message is valid according to Noise specifications
+  if isValid(hs.handshakePattern.preMessagePatterns) == false:
+    raise newException(NoiseMalformedHandshake, "Invalid pre-message in handshake")
+
+  # We iterate over each pattern contained in the pre-message
+  for messagePattern in hs.handshakePattern.preMessagePatterns:
+    let
+      direction = messagePattern.direction
+      tokens = messagePattern.tokens
+    
+    # We get if the user is reading or writing the current pre-message pattern
+    var (reading, writing) = getReadingWritingState(hs , direction)
+    
+    # We process each message pattern token
+    for token in tokens:
+
+      # We process the pattern token
+      case token
+      of T_e:
+
+        # We expect an ephemeral key, so we attempt to read it (next PK to process will always be at index 0 of preMessagePKs)
+        if preMessagePKs.len > 0:
+          currPK = preMessagePKs[0]
+        else:
+          raise newException(NoiseHandshakeError, "Noise pre-message read e, expected a public key")
+
+        # If user is reading the "e" token
+        if reading:
+          trace "noise pre-message read e"
+
+          # We check if current key is encrypted or not. We assume pre-message public keys are all unencrypted on users' end
+          if currPK.flag == 0.uint8:
+
+            # Sets re and calls MixHash(re.public_key).
+            hs.re = intoCurve25519Key(currPK.pk)
+            hs.ss.mixHash(hs.re)
+
+          else:
+            raise newException(NoisePublicKeyError, "Noise read e, incorrect encryption flag for pre-message public key")
+   
+        # If user is writing the "e" token
+        elif writing:
+   
+          trace "noise pre-message write e"
+
+          # When writing, the user is sending a public key, 
+          # We check that the public part corresponds to the set local key and we call MixHash(e.public_key).
+          if hs.e.publicKey == intoCurve25519Key(currPK.pk):
+            hs.ss.mixHash(hs.e.publicKey)
+          else:
+            raise newException(NoisePublicKeyError, "Noise pre-message e key doesn't correspond to locally set e key pair")
+
+        # Noise specification: section 9.2
+        # In non-PSK handshakes, the "e" token in a pre-message pattern or message pattern always results 
+        # in a call to MixHash(e.public_key). 
+        # In a PSK handshake, all of these calls are followed by MixKey(e.public_key).
+        if "psk" in hs.handshakePattern.name:
+          hs.ss.mixKey(currPK.pk)
+
+        # We delete processed public key 
+        preMessagePKs.delete(0)
+
+      of T_s:
+
+        # We expect a static key, so we attempt to read it (next PK to process will always be at index of preMessagePKs)
+        if preMessagePKs.len > 0:
+          currPK = preMessagePKs[0]
+        else:
+          raise newException(NoiseHandshakeError, "Noise pre-message read s, expected a public key")
+
+        # If user is reading the "s" token
+        if reading:
+          trace "noise pre-message read s"
+
+          # We check if current key is encrypted or not. We assume pre-message public keys are all unencrypted on users' end
+          if currPK.flag == 0.uint8:
+
+            # Sets re and calls MixHash(re.public_key).
+            hs.rs = intoCurve25519Key(currPK.pk)
+            hs.ss.mixHash(hs.rs)
+
+          else:
+            raise newException(NoisePublicKeyError, "Noise read s, incorrect encryption flag for pre-message public key")
+
+        # If user is writing the "s" token
+        elif writing:
+   
+          trace "noise pre-message write s"
+
+          # If writing, it means that the user is sending a public key, 
+          # We check that the public part corresponds to the set local key and we call MixHash(s.public_key).
+          if hs.s.publicKey == intoCurve25519Key(currPK.pk):
+            hs.ss.mixHash(hs.s.publicKey)
+          else:
+            raise newException(NoisePublicKeyError, "Noise pre-message s key doesn't correspond to locally set s key pair")
+
+        # Noise specification: section 9.2
+        # In non-PSK handshakes, the "e" token in a pre-message pattern or message pattern always results 
+        # in a call to MixHash(e.public_key). 
+        # In a PSK handshake, all of these calls are followed by MixKey(e.public_key).
+        if "psk" in hs.handshakePattern.name:
+          hs.ss.mixKey(currPK.pk)
+
+        # We delete processed public key 
+        preMessagePKs.delete(0)
+
+      else:
+
+        raise newException(NoiseMalformedHandshake, "Invalid Token for pre-message pattern")
+
+# This procedure encrypts/decrypts the implicit payload attached at the end of every message pattern
+proc processMessagePatternPayload(hs: var HandshakeState, transportMessage: seq[byte]): seq[byte]
+  {.raises: [Defect, NoiseDecryptTagError, NoiseNonceMaxError].} =
+
+  var payload: seq[byte]
+
+  # We retrieve current message pattern (direction + tokens) to process
+  let direction = hs.handshakePattern.messagePatterns[hs.msgPatternIdx].direction
+
+  # We get if the user is reading or writing the input handshake message
+  var (reading, writing) = getReadingWritingState(hs, direction)
+
+  # We decrypt the transportMessage, if any
+  if reading:
+    payload = hs.ss.decryptAndHash(transportMessage)
+  elif writing:
+    payload = hs.ss.encryptAndHash(transportMessage)
+
+  return payload
+
+# We process an input handshake message according to current handshake state and we return the next handshake step's handshake message
+proc processMessagePatternTokens*(rng: var BrHmacDrbgContext, hs: var HandshakeState, inputHandshakeMessage: seq[NoisePublicKey] = @[]): Result[seq[NoisePublicKey], cstring]
+  {.raises: [Defect, NoiseHandshakeError, NoiseMalformedHandshake, NoisePublicKeyError, NoiseDecryptTagError, NoiseNonceMaxError].} =
+
+  # We retrieve current message pattern (direction + tokens) to process
+  let
+    messagePattern = hs.handshakePattern.messagePatterns[hs.msgPatternIdx]
+    direction = messagePattern.direction
+    tokens = messagePattern.tokens
+    
+  # We get if the user is reading or writing the input handshake message
+  var (reading, writing) = getReadingWritingState(hs , direction)
+
+  # I make a copy of the handshake message so that I can easily delete processed PKs without using iterators/counters
+  # (Possibly) non-empty if reading
+  var inHandshakeMessage = inputHandshakeMessage
+
+  # The party's output public keys
+  # (Possibly) non-empty if writing
+  var outHandshakeMessage: seq[NoisePublicKey] = @[]
+
+  # In currPK we store the currently processed public key from the handshake message
+  var currPK: NoisePublicKey
+
+  # We process each message pattern token
+  for token in tokens:
+    
+    case token
+    of T_e:
+
+      # If user is reading the "s" token
+      if reading:
+        trace "noise read e"
+
+        # We expect an ephemeral key, so we attempt to read it (next PK to process will always be at index 0 of preMessagePKs)
+        if inHandshakeMessage.len > 0:
+          currPK = inHandshakeMessage[0]
+        else:
+          raise newException(NoiseHandshakeError, "Noise read e, expected a public key")
+
+        # We check if current key is encrypted or not
+        # Note: by specification, ephemeral keys should always be unencrypted. But we support encrypted ones.
+        if currPK.flag == 0.uint8:
+
+          # Unencrypted Public Key 
+          # Sets re and calls MixHash(re.public_key).
+          hs.re = intoCurve25519Key(currPK.pk)
+          hs.ss.mixHash(hs.re)
+
+        # The following is out of specification: we call decryptAndHash for encrypted ephemeral keys, similarly as happens for (encrypted) static keys
+        elif currPK.flag == 1.uint8:
+
+          # Encrypted public key
+          # Decrypts re, sets re and calls MixHash(re.public_key).
+          hs.re = intoCurve25519Key(hs.ss.decryptAndHash(currPK.pk))
+
+        else:
+          raise newException(NoisePublicKeyError, "Noise read e, incorrect encryption flag for public key")
+ 
+        # Noise specification: section 9.2
+        # In non-PSK handshakes, the "e" token in a pre-message pattern or message pattern always results 
+        # in a call to MixHash(e.public_key). 
+        # In a PSK handshake, all of these calls are followed by MixKey(e.public_key).
+        if "psk" in hs.handshakePattern.name:
+          hs.ss.mixKey(hs.re)
+
+        # We delete processed public key
+        inHandshakeMessage.delete(0)
+
+      # If user is writing the "e" token
+      elif writing:
+        trace "noise write e"
+
+        # We generate a new ephemeral keypair
+        hs.e = genKeyPair(rng)
+
+        # We update the state
+        hs.ss.mixHash(hs.e.publicKey)
+
+        # Noise specification: section 9.2
+        # In non-PSK handshakes, the "e" token in a pre-message pattern or message pattern always results 
+        # in a call to MixHash(e.public_key). 
+        # In a PSK handshake, all of these calls are followed by MixKey(e.public_key).
+        if "psk" in hs.handshakePattern.name:
+          hs.ss.mixKey(hs.e.publicKey)
+
+        # We add the ephemeral public key to the Waku payload
+        outHandshakeMessage.add toNoisePublicKey(getPublicKey(hs.e))
+
+    of T_s:
+
+      # If user is reading the "s" token
+      if reading:
+        trace "noise read s"
+
+        # We expect a static key, so we attempt to read it (next PK to process will always be at index 0 of preMessagePKs)
+        if inHandshakeMessage.len > 0:
+          currPK = inHandshakeMessage[0]
+        else:
+          raise newException(NoiseHandshakeError, "Noise read s, expected a public key")
+
+        # We check if current key is encrypted or not
+        if currPK.flag == 0.uint8:
+
+          # Unencrypted Public Key 
+          # Sets re and calls MixHash(re.public_key).
+          hs.rs = intoCurve25519Key(currPK.pk)
+          hs.ss.mixHash(hs.rs)
+
+        elif currPK.flag == 1.uint8:
+
+          # Encrypted public key
+          # Decrypts rs, sets rs and calls MixHash(rs.public_key).
+          hs.rs = intoCurve25519Key(hs.ss.decryptAndHash(currPK.pk))
+
+        else:
+          raise newException(NoisePublicKeyError, "Noise read s, incorrect encryption flag for public key")
+ 
+        # We delete processed public key
+        inHandshakeMessage.delete(0)
+
+      # If user is writing the "s" token
+      elif writing:
+
+        trace "noise write s"
+
+        # If the local static key is not set (the handshake state was not properly initialized), we raise an error
+        if hs.s == default(KeyPair):
+          raise newException(NoisePublicKeyError, "Static key not set")
+
+        # We encrypt the public part of the static key in case a key is set in the Cipher State
+        # That is, encS may either be an encrypted or unencrypted static key.
+        let encS = hs.ss.encryptAndHash(hs.s.publicKey)
+
+        # We add the (encrypted) static public key to the Waku payload
+        # Note that encS = (Enc(s) || tag) if encryption key is set, otherwise encS = s.
+        # We distinguish these two cases by checking length of encryption and we set the proper encryption flag
+        if encS.len > Curve25519Key.len:
+          outHandshakeMessage.add NoisePublicKey(flag: 1, pk: encS)
+        else:
+          outHandshakeMessage.add NoisePublicKey(flag: 0, pk: encS)
+
+    of T_psk:
+
+      # If user is reading the "psk" token
+
+      trace "noise psk"
+
+      # Calls MixKeyAndHash(psk)
+      hs.ss.mixKeyAndHash(hs.psk)
+
+    of T_ee:
+
+      # If user is reading the "ee" token
+
+      trace "noise dh ee"
+
+      # If local and/or remote ephemeral keys are not set, we raise an error
+      if hs.e == default(KeyPair) or hs.re == default(Curve25519Key):
+        raise newException(NoisePublicKeyError, "Local or remote ephemeral key not set")
+
+      # Calls MixKey(DH(e, re)).
+      hs.ss.mixKey(dh(hs.e.privateKey, hs.re))
+
+    of T_es:
+
+      # If user is reading the "es" token
+
+      trace "noise dh es"
+
+      # We check if keys are correctly set.
+      # If both present, we call MixKey(DH(e, rs)) if initiator, MixKey(DH(s, re)) if responder.
+      if hs.initiator:
+        if hs.e == default(KeyPair) or hs.rs == default(Curve25519Key):
+          raise newException(NoisePublicKeyError, "Local or remote ephemeral/static key not set")
+        hs.ss.mixKey(dh(hs.e.privateKey, hs.rs))
+      else:
+        if hs.re == default(Curve25519Key) or hs.s == default(KeyPair):
+          raise newException(NoisePublicKeyError, "Local or remote ephemeral/static key not set")
+        hs.ss.mixKey(dh(hs.s.privateKey, hs.re))
+
+    of T_se:
+
+      # If user is reading the "se" token
+
+      trace "noise dh se"
+
+      # We check if keys are correctly set.
+      # If both present, call MixKey(DH(s, re)) if initiator, MixKey(DH(e, rs)) if responder.
+      if hs.initiator:
+        if hs.s == default(KeyPair) or hs.re == default(Curve25519Key):
+          raise newException(NoiseMalformedHandshake, "Local or remote ephemeral/static key not set")
+        hs.ss.mixKey(dh(hs.s.privateKey, hs.re))
+      else:
+        if hs.rs == default(Curve25519Key) or hs.e == default(KeyPair):
+          raise newException(NoiseMalformedHandshake, "Local or remote ephemeral/static key not set")
+        hs.ss.mixKey(dh(hs.e.privateKey, hs.rs))
+
+    of T_ss:
+
+      # If user is reading the "ss" token
+
+      trace "noise dh ss"
+
+      # If local and/or remote static keys are not set, we raise an error
+      if hs.s == default(KeyPair) or hs.rs == default(Curve25519Key):
+        raise newException(NoiseMalformedHandshake, "Local or remote static key not set")
+
+      # Calls MixKey(DH(s, rs)).
+      hs.ss.mixKey(dh(hs.s.privateKey, hs.rs))
+
+  return ok(outHandshakeMessage)
+
+#################################
+## Procedures to progress handshakes between users
+#################################
+
+# Initializes a Handshake State
+proc initialize*(hsPattern: HandshakePattern, ephemeralKey: KeyPair = default(KeyPair), staticKey: KeyPair = default(KeyPair), prologue: seq[byte] = @[], psk: seq[byte] = @[], preMessagePKs: seq[NoisePublicKey] = @[], initiator: bool = false): HandshakeState 
+  {.raises: [Defect, NoiseMalformedHandshake, NoiseHandshakeError, NoisePublicKeyError].} =
+  var hs = HandshakeState.init(hsPattern)
+  hs.ss.mixHash(prologue)
+  hs.e = ephemeralKey
+  hs.s = staticKey
+  hs.psk = psk
+  hs.msgPatternIdx = 0
+  hs.initiator = initiator
+  # We process any eventual handshake pre-message pattern by processing pre-message public keys
+  processPreMessagePatternTokens(hs, preMessagePKs)
+  return hs
+
+# Advances 1 step in handshake
+# Each user in a handshake alternates writing and reading of handshake messages.
+# If the user is writing the handshake message, the transport message (if not empty) has to be passed to transportMessage and readPayloadV2 can be left to its default value
+# It the user is reading the handshake message, the read payload v2 has to be passed to readPayloadV2 and the transportMessage can be left to its default values. 
+proc stepHandshake*(rng: var BrHmacDrbgContext, hs: var HandshakeState, readPayloadV2: PayloadV2 = default(PayloadV2), transportMessage: seq[byte] = @[]): Result[HandshakeStepResult, cstring]
+  {.raises: [Defect, NoiseHandshakeError, NoiseMalformedHandshake, NoisePublicKeyError, NoiseDecryptTagError, NoiseNonceMaxError].} =
+
+  var hsStepResult: HandshakeStepResult
+
+  # If there are no more message patterns left for processing 
+  # we return an empty HandshakeStepResult
+  if hs.msgPatternIdx > uint8(hs.handshakePattern.messagePatterns.len - 1):
+    debug "stepHandshake called more times than the number of message patterns present in handshake"
+    return ok(hsStepResult)
+
+  # We process the next handshake message pattern
+
+  # We get if the user is reading or writing the input handshake message
+  let direction = hs.handshakePattern.messagePatterns[hs.msgPatternIdx].direction
+  var (reading, writing) = getReadingWritingState(hs, direction)
+
+  # If we write an answer at this handshake step 
+  if writing:
+    # We initialize a payload v2 and we set proper protocol ID (if supported)
+    try:
+      hsStepResult.payload2.protocolId = PayloadV2ProtocolIDs[hs.handshakePattern.name]
+    except:
+      raise newException(NoiseMalformedHandshake, "Handshake Pattern not supported")
+
+    # We set the handshake and transport message
+    hsStepResult.payload2.handshakeMessage = processMessagePatternTokens(rng, hs).get()
+    hsStepResult.payload2.transportMessage = processMessagePatternPayload(hs, transportMessage)
+
+  # If we read an answer during this handshake step
+  elif reading:
+    # We process the read public keys and (eventually decrypt) the read transport message
+    let 
+      readHandshakeMessage = readPayloadV2.handshakeMessage
+      readTransportMessage = readPayloadV2.transportMessage
+
+    # Since we only read, nothing meanigful (i.e. public keys) is returned
+    discard processMessagePatternTokens(rng, hs, readHandshakeMessage)
+    # We retrieve and store the (decrypted) received transport message
+    hsStepResult.transportMessage = processMessagePatternPayload(hs, readTransportMessage)
+
+  else:
+    raise newException(NoiseHandshakeError, "Handshake Error: neither writing or reading user")
+
+  # We increase the handshake state message pattern index to progress to next step
+  hs.msgPatternIdx += 1
+
+  return ok(hsStepResult)
+
+# Finalizes the handshake by calling Split and assigning the proper Cipher States to users
+proc finalizeHandshake*(hs: var HandshakeState): HandshakeResult =
+
+  var hsResult: HandshakeResult
+
+  ## Noise specification, Section 5:
+  ## Processing the final handshake message returns two CipherState objects, 
+  ## the first for encrypting transport messages from initiator to responder, 
+  ## and the second for messages in the other direction.
+
+  # We call Split()
+  let (cs1, cs2) = hs.ss.split()
+
+  # We assign the proper Cipher States
+  if hs.initiator:
+    hsResult.csOutbound = cs1
+    hsResult.csInbound = cs2
+  else:
+    hsResult.csOutbound = cs2
+    hsResult.csInbound = cs1
+
+  # We store the optional fields rs and h
+  hsResult.rs = hs.rs
+  hsResult.h = hs.ss.h
+
+  return hsResult
+
+#################################
+# After-handshake procedures 
+#################################
+
+## Noise specification, Section 5:
+## Transport messages are then encrypted and decrypted by calling EncryptWithAd() 
+## and DecryptWithAd() on the relevant CipherState with zero-length associated data. 
+## If DecryptWithAd() signals an error due to DECRYPT() failure, then the input message is discarded. 
+## The application may choose to delete the CipherState and terminate the session on such an error, 
+## or may continue to attempt communications. If EncryptWithAd() or DecryptWithAd() signal an error 
+## due to nonce exhaustion, then the application must delete the CipherState and terminate the session.
+
+# Writes an encrypted message using the proper Cipher State
+proc writeMessage*(hsr: var HandshakeResult, transportMessage: seq[byte]): PayloadV2
+  {.raises: [Defect, NoiseNonceMaxError].} =
+
+  var payload2: PayloadV2
+
+  # According to 35/WAKU2-NOISE RFC, no Handshake protocol information is sent when exchanging messages
+  # This correspond to setting protocol-id to 0
+  payload2.protocolId = 0.uint8
+  # Encryption is done with zero-length associated data as per specification
+  payload2.transportMessage = encryptWithAd(hsr.csOutbound, @[], transportMessage)
+
+  return payload2
+
+# Reads an encrypted message using the proper Cipher State
+# Associated data ad for encryption is optional, since the latter is out of scope for Noise
+proc readMessage*(hsr: var HandshakeResult, readPayload2: PayloadV2): Result[seq[byte], cstring]
+  {.raises: [Defect, NoiseDecryptTagError, NoiseNonceMaxError].} =
+
+  # The output decrypted message
+  var message: seq[byte]
+
+  # According to 35/WAKU2-NOISE RFC, no Handshake protocol information is sent when exchanging messages
+  if readPayload2.protocolId == 0.uint8:
+    
+    # On application level we decide to discard messages which fail decryption, without raising an error
+    # (this because an attacker may flood the content topic on which messages are exchanged)
+    try:
+      # Decryption is done with zero-length associated data as per specification
+      message = decryptWithAd(hsr.csInbound, @[], readPayload2.transportMessage)
+    except NoiseDecryptTagError:
+      debug "A read message failed decryption. Returning empty message as plaintext."
+      message = @[]
+
+  return ok(message)
\ No newline at end of file