remove empty ephemeral key from XX message C

src/encoder.ts

@@ -25,6 +25,10 @@ export function encode1(message: MessageBuffer): bytes {
   return Buffer.concat([message.ne, message.ns, message.ciphertext]);
 }
 
+export function encode2(message: MessageBuffer): bytes {
+  return Buffer.concat([message.ns, message.ciphertext]);
+}
+
 export function decode0(input: bytes): MessageBuffer {
   if (input.length < 32) {
     throw new Error("Cannot decode stage 0 MessageBuffer: length less than 32 bytes.");
@@ -39,7 +43,7 @@ export function decode0(input: bytes): MessageBuffer {
 
 export function decode1(input: bytes): MessageBuffer {
   if (input.length < 80) {
-    throw new Error("Cannot decode stage 0 MessageBuffer: length less than 96 bytes.");
+    throw new Error("Cannot decode stage 1 MessageBuffer: length less than 80 bytes.");
   }
 
   return {
@@ -48,3 +52,15 @@ export function decode1(input: bytes): MessageBuffer {
     ciphertext: input.slice(80, input.length),
   }
 }
+
+export function decode2(input: bytes): MessageBuffer {
+  if (input.length < 48) {
+    throw new Error("Cannot decode stage 2 MessageBuffer: length less than 48 bytes.");
+  }
+
+  return {
+    ne: Buffer.alloc(0),
+    ns: input.slice(0, 48),
+    ciphertext: input.slice(48, input.length),
+  }
+}

src/handshake-xx.ts

@@ -11,7 +11,7 @@ import {
   verifySignedPayload,
 } from "./utils";
 import { logger } from "./logger";
-import { decode0, decode1, encode0, encode1 } from "./encoder";
+import {decode0, decode1, decode2, encode0, encode1, encode2} from "./encoder";
 import { WrappedConnection } from "./noise";
 import PeerId from "peer-id";
 
@@ -99,11 +99,11 @@ export class XXHandshake implements IHandshake {
     if (this.isInitiator) {
       logger('Stage 2 - Initiator sending third handshake message.');
       const messageBuffer = this.xx.sendMessage(this.session, this.payload);
-      this.connection.writeLP(encode1(messageBuffer));
+      this.connection.writeLP(encode2(messageBuffer));
       logger('Stage 2 - Initiator sent message with signed payload.');
     } else {
       logger('Stage 2 - Responder waiting for third handshake message...');
-      const receivedMessageBuffer = decode1((await this.connection.readLP()).slice());
+      const receivedMessageBuffer = decode2((await this.connection.readLP()).slice());
       const {plaintext, valid} = this.xx.recvMessage(this.session, receivedMessageBuffer);
       if(!valid) {
         throw new Error("xx handshake stage 2 validation fail");