skip outgoing messages for decryption

Author: kaichaosun

examples/pingpong.nim

@@ -31,7 +31,10 @@ proc main() {.async.} =
   let sIdent = Identity(name: "saro", privateKey: sKey)
 
   # Create Clients
+  info "create saro client"
   var saro = newClient(cfg_saro, sIdent)
+
+  info "create raya client"
   var raya = newClient(cfg_raya, Identity(name: "raya", privateKey: rKey))
 
   var ri = 0

src/chat_sdk/conversations/private_v1.nim

@@ -72,8 +72,16 @@ proc calcMsgId(self: PrivateV1, msgBytes: seq[byte]): string =
 
 proc encrypt*(convo: PrivateV1, plaintext: var seq[byte]): EncryptedPayload =
 
+  info "encrypt metadata"
+  info "Doubleratchet DH Self: ", dhSelf = convo.doubleratchet.dhSelf
+  info "dh self public:" , dhSelfPub = convo.doubleratchet.dhSelf.public
+  info "dhRemote: ", dhRemote = convo.doubleratchet.dhRemote
+
   let (header, ciphertext) = convo.doubleratchet.encrypt(plaintext) #TODO: Associated Data
 
+  info "encrypt done"
+  info "header dh public: ", dhPub = header.dhPublic
+
   result = EncryptedPayload(doubleratchet: proto_types.DoubleRatchet(
     dh: toSeq(header.dhPublic),
     msgNum: header.msgNumber,
@@ -93,6 +101,16 @@ proc decrypt*(convo: PrivateV1, enc: EncryptedPayload): Result[seq[byte], ChatEr
     prevChainLen: dr.prevChainLen
   )
   copyMem(addr header.dhPublic[0], unsafeAddr dr.dh[0], dr.dh.len) # TODO: Avoid this copy
+  
+  info "decrypt metadata"
+  info "header dh public: ", dhPub = header.dhPublic
+  info "Doubleratchet DH Remote: ", dhRemote = convo.doubleratchet.dhRemote
+  info "dh self:", dhSelf = convo.doubleratchet.dhSelf
+  info "dh self public:" , dhSelfPub = convo.doubleratchet.dhSelf.public
+
+  if convo.doubleratchet.dhSelf.public == header.dhPublic:
+    info "outgoing message, no need to decrypt"
+    return err(ChatError(code: errDecryptOutgoing, context: "Attempted to decrypt outgoing message"))
 
   convo.doubleratchet.decrypt(header, dr.ciphertext, @[]).mapErr(proc(e: NaxolotlError): ChatError = ChatError(code: errWrapped, context: repr(e) ))
 

src/chat_sdk/errors.nim

@@ -8,6 +8,7 @@ type
   ErrorCode* = enum
     errTypeError
     errWrapped
+    errDecryptOutgoing
 
 
 proc `$`*(x: ChatError): string =

src/naxolotl/naxolotl.nim

@@ -16,8 +16,8 @@ const maxSkip = 10
 
 
 type Doubleratchet* = object
-  dhSelf: PrivateKey
-  dhRemote: PublicKey
+  dhSelf*: PrivateKey
+  dhRemote*: PublicKey
 
   rootKey: RootKey
   chainKeySend: ChainKey
@@ -73,15 +73,18 @@ func kdfChain(self: Doubleratchet, chainKey: ChainKey): (MessageKey, ChainKey) =
 
   return(msgKey, chainKey)
 
-func dhRatchetSend(self: var Doubleratchet) =
+proc dhRatchetSend(self: var Doubleratchet) =
   # Perform DH Ratchet step when receiving a new peer key.
+  info "dhRatchetSend DH Self: ", dhSelf = self.dhSelf
   let dhOutput : DhDerivedKey = dhExchange(self.dhSelf, self.dhRemote).get()
   let (newRootKey, newChainKeySend) = kdfRoot(self, self.rootKey, dhOutput)
   self.rootKey = newRootKey
   self.chainKeySend = newChainKeySend
   self.msgCountSend = 0
 
 proc dhRatchetRecv(self: var Doubleratchet, remotePublickey: PublicKey ) = 
+  info "dh ratchet happens"
+  info "dhRatchetRecv DH Remote: ", dhRemote = remotePublickey
   self.prevChainLen = self.msgCountSend
   self.msgCountSend = 0
   self.msgCountRecv = 0
@@ -96,7 +99,7 @@ proc dhRatchetRecv(self: var Doubleratchet, remotePublickey: PublicKey ) =
   self.dhSelf = generateKeypair().get()[0]
 
   let dhOutputPost = self.dhSelf.dhExchange(self.dhRemote).get()
-  (self.rootKey, self.chainKeyRecv) = kdfRoot(self, self.rootKey, dhOutputPost)
+  (self.rootKey, self.chainKeySend) = kdfRoot(self, self.rootKey, dhOutputPost)
 
 
 proc skipMessageKeys(self: var Doubleratchet, until: MsgCount): Result[(), string] =
@@ -138,9 +141,15 @@ proc encrypt(self: var Doubleratchet, plaintext: var seq[byte], associatedData:
 
 
 proc decrypt*(self: var Doubleratchet, header: DrHeader, ciphertext: CipherText, associatedData: openArray[byte] ) : Result[seq[byte], NaxolotlError] =
+  info "double ratchet decrypt", header = $header
+  info "dhRemote: ", dhRemote = self.dhRemote
+  info "dhSelf: ", dhSelf = self.dhSelf
+  info "dhSelf public: ", dhSelf = self.dhSelf.public
 
   let peerPublic = header.dhPublic
 
+  info "peerPublic: ", peerPublic = peerPublic
+
   var msgKey : MessageKey
 
   # Check Skipped Keys
@@ -176,8 +185,12 @@ proc encrypt*(self: var Doubleratchet, plaintext: var seq[byte]) : (DrHeader, Ci
   encrypt(self, plaintext,@[])
 
 
-func initDoubleratchet*(sharedSecret: array[32, byte], dhSelf: PrivateKey, dhRemote: PublicKey, isSending: bool = true): Doubleratchet =
+proc initDoubleratchet*(sharedSecret: array[32, byte], dhSelf: PrivateKey, dhRemote: PublicKey, isSending: bool = true): Doubleratchet =
 
+  info "Initializing Double Ratchet"
+  info "DH Self: ", dhSelf = dhSelf
+  info "DH Self public: ", dhSelf = dhSelf.public
+  info "DH Remote: ", dhRemote = dhRemote
   result = Doubleratchet(
       dhSelf: dhSelf,
       dhRemote: dhRemote,