Merge pull request #17 from libp2p/feat/signing

feat: add support for message signing

Author: vasco-santos

src/index.js

@@ -10,6 +10,7 @@ const errcode = require('err-code')
 
 const Peer = require('./peer')
 const message = require('./message')
+const { signMessage } = require('./message/sign')
 const utils = require('./utils')
 
 const nextTick = require('async/nextTick')
@@ -22,17 +23,28 @@ class PubsubBaseProtocol extends EventEmitter {
    * @param {String} debugName
    * @param {String} multicodec
    * @param {Object} libp2p libp2p implementation
+   * @param {Object} options
+   * @param {boolean} options.signMessages if messages should be signed, defaults to true
    * @constructor
    */
-  constructor (debugName, multicodec, libp2p) {
+  constructor (debugName, multicodec, libp2p, options) {
     super()
 
+    options = {
+      signMessages: true,
+      ...options
+    }
+
     this.log = debug(debugName)
     this.log.err = debug(`${debugName}:error`)
     this.multicodec = multicodec
     this.libp2p = libp2p
     this.started = false
 
+    if (options.signMessages) {
+      this.peerId = this.libp2p.peerInfo.id
+    }
+
     /**
      * Map of topics to which peers are subscribed to
      *
@@ -225,16 +237,32 @@ class PubsubBaseProtocol extends EventEmitter {
     this._removePeer(peer)
   }
 
+  /**
+   * Normalizes the message and signs it, if signing is enabled
+   *
+   * @param {Message} message
+   * @param {function(Error, Message)} callback
+   */
+  _buildMessage (message, callback) {
+    const msg = utils.normalizeOutRpcMessage(message)
+    if (this.peerId) {
+      signMessage(this.peerId, msg, callback)
+    } else {
+      nextTick(callback, null, msg)
+    }
+  }
+
   /**
    * Overriding the implementation of publish should handle the appropriate algorithms for the publish/subscriber implementation.
    * For example, a Floodsub implementation might simply publish each message to each topic for every peer
    * @abstract
    * @param {Array<string>|string} topics
    * @param {Array<any>|any} messages
+   * @param {function(Error)} callback
    * @returns {undefined}
    *
    */
-  publish (topics, messages) {
+  publish (topics, messages, callback) {
     throw errcode('publish must be implemented by the subclass', 'ERR_NOT_IMPLEMENTED')
   }
 

src/message/index.js

@@ -3,8 +3,12 @@
 const protons = require('protons')
 
 const rpcProto = protons(require('./rpc.proto.js'))
+const RPC = rpcProto.RPC
 const topicDescriptorProto = protons(require('./topic-descriptor.proto.js'))
 
 exports = module.exports
 exports.rpc = rpcProto
 exports.td = topicDescriptorProto
+exports.RPC = RPC
+exports.Message = RPC.Message
+exports.SubOpts = RPC.SubOpts

src/message/rpc.proto.js

@@ -13,6 +13,8 @@ message RPC {
     optional bytes from = 1;
     optional bytes data = 2;
     optional bytes seqno = 3;
-    repeated string topicIDs = 4; 
+    repeated string topicIDs = 4;
+    optional bytes signature = 5;
+    optional bytes key = 6;
   }
 }`

src/message/sign.js

@@ -0,0 +1,33 @@
+'use strict'
+
+const { Message } = require('./index')
+const SignPrefix = Buffer.from('libp2p-pubsub:')
+
+module.exports.SignPrefix = SignPrefix
+
+/**
+ * Signs the provided message with the given `peerId`
+ *
+ * @param {PeerId} peerId
+ * @param {Message} message
+ * @param {function(Error, Message)} callback
+ * @returns {void}
+ */
+module.exports.signMessage = function (peerId, message, callback) {
+  // Get the message in bytes, and prepend with the pubsub prefix
+  const bytes = Buffer.concat([
+    SignPrefix,
+    Message.encode(message)
+  ])
+
+  // Sign the bytes with the private key
+  peerId.privKey.sign(bytes, (err, signature) => {
+    if (err) return callback(err)
+
+    callback(null, {
+      ...message,
+      signature: signature,
+      key: peerId.pubKey.bytes
+    })
+  })
+}

src/peer.js

@@ -6,7 +6,7 @@ const pull = require('pull-stream')
 const setImmediate = require('async/setImmediate')
 const EventEmitter = require('events')
 
-const rpc = require('./message').rpc.RPC
+const { RPC } = require('./message')
 
 /**
  * The known state of a connected peer.
@@ -109,7 +109,7 @@ class Peer extends EventEmitter {
       })
     })
 
-    this.write(rpc.encode({
+    this.write(RPC.encode({
       subscriptions: subs
     }))
   }
@@ -139,7 +139,7 @@ class Peer extends EventEmitter {
    * @returns {undefined}
    */
   sendMessages (msgs) {
-    this.write(rpc.encode({
+    this.write(RPC.encode({
       msgs: msgs
     }))
   }

src/utils.js

@@ -81,15 +81,17 @@ exports.normalizeInRpcMessages = (messages) => {
   })
 }
 
+exports.normalizeOutRpcMessage = (message) => {
+  const m = Object.assign({}, message)
+  if (typeof message.from === 'string' || message.from instanceof String) {
+    m.from = bs58.decode(message.from)
+  }
+  return m
+}
+
 exports.normalizeOutRpcMessages = (messages) => {
   if (!messages) {
     return messages
   }
-  return messages.map((msg) => {
-    const m = Object.assign({}, msg)
-    if (typeof msg.from === 'string' || msg.from instanceof String) {
-      m.from = bs58.decode(msg.from)
-    }
-    return m
-  })
+  return messages.map(exports.normalizeOutRpcMessage)
 }

test/pubsub.js

@@ -8,7 +8,10 @@ const expect = chai.expect
 const series = require('async/series')
 const parallel = require('async/parallel')
 
+const { Message } = require('../src/message')
+const { SignPrefix } = require('../src/message/sign')
 const PubsubBaseProtocol = require('../src')
+const { randomSeqno, normalizeOutRpcMessage } = require('../src/utils')
 const utils = require('./utils')
 const createNode = utils.createNode
 
@@ -55,14 +58,7 @@ describe('pubsub base protocol', () => {
       })
     })
 
-    after((done) => {
-      parallel([
-        (cb) => nodeA.stop(cb),
-        (cb) => nodeB.stop(cb)
-      ], done)
-    })
-
-    it('mount the pubsub protocol', (done) => {
+    before('mount the pubsub protocol', (done) => {
       psA = new PubsubImplementation(nodeA)
       psB = new PubsubImplementation(nodeB)
 
@@ -73,13 +69,20 @@ describe('pubsub base protocol', () => {
       }, 50)
     })
 
-    it('start both Pubsub', (done) => {
+    before('start both Pubsub', (done) => {
       parallel([
         (cb) => psA.start(cb),
         (cb) => psB.start(cb)
       ], done)
     })
 
+    after((done) => {
+      parallel([
+        (cb) => nodeA.stop(cb),
+        (cb) => nodeB.stop(cb)
+      ], done)
+    })
+
     it('Dial from nodeA to nodeB', (done) => {
       series([
         (cb) => nodeA.dial(nodeB.peerInfo, cb),
@@ -90,6 +93,29 @@ describe('pubsub base protocol', () => {
         }, 1000)
       ], done)
     })
+
+    it('_buildMessage normalizes and signs messages', (done) => {
+      const message = {
+        from: 'QmABC',
+        data: 'hello',
+        seqno: randomSeqno(),
+        topicIDs: ['test-topic']
+      }
+
+      psA._buildMessage(message, (err, signedMessage) => {
+        expect(err).to.not.exist()
+
+        const bytesToSign = Buffer.concat([
+          SignPrefix,
+          Message.encode(normalizeOutRpcMessage(message))
+        ])
+
+        psA.peerId.pubKey.verify(bytesToSign, signedMessage.signature, (err, verified) => {
+          expect(verified).to.eql(true)
+          done(err)
+        })
+      })
+    })
   })
 
   describe('dial the pubsub protocol on mount', () => {

test/sign.spec.js

@@ -0,0 +1,53 @@
+/* eslint-env mocha */
+/* eslint max-nested-callbacks: ["error", 5] */
+'use strict'
+
+const chai = require('chai')
+chai.use(require('dirty-chai'))
+const expect = chai.expect
+
+const { Message } = require('../src/message')
+const { signMessage, SignPrefix } = require('../src/message/sign')
+const PeerId = require('peer-id')
+const { randomSeqno } = require('../src/utils')
+
+describe('message signing', () => {
+  let peerId
+  before((done) => {
+    peerId = PeerId.create({
+      bits: 1024
+    }, (err, id) => {
+      peerId = id
+      done(err)
+    })
+  })
+
+  it('should be able to sign a message', (done) => {
+    const message = {
+      from: 'QmABC',
+      data: 'hello',
+      seqno: randomSeqno(),
+      topicIDs: ['test-topic']
+    }
+
+    const bytesToSign = Buffer.concat([SignPrefix, Message.encode(message)])
+
+    peerId.privKey.sign(bytesToSign, (err, expectedSignature) => {
+      if (err) return done(err)
+
+      signMessage(peerId, message, (err, signedMessage) => {
+        if (err) return done(err)
+
+        // Check the signature and public key
+        expect(signedMessage.signature).to.eql(expectedSignature)
+        expect(signedMessage.key).to.eql(peerId.pubKey.bytes)
+
+        // Verify the signature
+        peerId.pubKey.verify(bytesToSign, signedMessage.signature, (err, verified) => {
+          expect(verified).to.eql(true)
+          done(err)
+        })
+      })
+    })
+  })
+})