feat: Add compact protobuf format

package.json

@@ -42,7 +42,8 @@
     "async": "^2.6.0",
     "libp2p-crypto": "~0.12.1",
     "lodash": "^4.17.5",
-    "multihashes": "~0.4.13"
+    "multihashes": "~0.4.13",
+    "protons": "^1.0.1"
   },
   "repository": {
     "type": "git",

src/index.js

@@ -9,6 +9,9 @@ const crypto = require('libp2p-crypto')
 const assert = require('assert')
 const waterfall = require('async/waterfall')
 
+const protons = require('protons')
+const {PeerIdProto} = protons('message PeerIdProto { required bytes id = 1; bytes pubKey = 2; bytes privKey = 3; }')
+
 class PeerId {
   constructor (id, privKey, pubKey) {
     assert(Buffer.isBuffer(id), 'invalid id provided')
@@ -67,6 +70,15 @@ class PeerId {
     }
   }
 
+  // Return the protobuf version of the peer-id
+  marshal (excludePriv) {
+    return PeerIdProto.encode({
+      id: this.toBytes(),
+      pubKey: this.marshalPubKey(),
+      privKey: excludePriv ? null : this.marshalPrivKey()
+    })
+  }
+
   // pretty print
   toPrint () {
     return this.toJSON()
@@ -221,6 +233,62 @@ exports.createFromPrivKey = function (key, callback) {
   })
 }
 
+exports.createFromProtobuf = function (buf, callback) {
+  if (typeof callback !== 'function') {
+    throw new Error('callback is required')
+  }
+
+  let obj
+  let id
+  let rawPrivKey
+  let rawPubKey
+  let pub
+
+  try {
+    obj = PeerIdProto.decode(buf)
+    id = obj.id
+    rawPrivKey = obj.privKey
+    rawPubKey = obj.pubKey
+    pub = rawPubKey && crypto.keys.unmarshalPublicKey(rawPubKey)
+  } catch (err) {
+    return callback(err)
+  }
+
+  if (rawPrivKey) {
+    waterfall([
+      (cb) => crypto.keys.unmarshalPrivateKey(rawPrivKey, cb),
+      (priv, cb) => priv.public.hash((err, digest) => {
+        cb(err, digest, priv)
+      }),
+      (privDigest, priv, cb) => {
+        if (pub) {
+          pub.hash((err, pubDigest) => {
+            cb(err, privDigest, priv, pubDigest)
+          })
+        } else {
+          cb(null, privDigest, priv)
+        }
+      }
+    ], (err, privDigest, priv, pubDigest) => {
+      if (err) {
+        return callback(err)
+      }
+
+      if (pub && !privDigest.equals(pubDigest)) {
+        return callback(new Error('Public and private key do not match'))
+      }
+
+      if (id && !privDigest.equals(id)) {
+        return callback(new Error('Id and private key do not match'))
+      }
+
+      callback(null, new PeerId(id, priv, pub))
+    })
+  } else {
+    callback(null, new PeerId(id, null, pub))
+  }
+}
+
 exports.createFromJSON = function (obj, callback) {
   if (typeof callback !== 'function') {
     throw new Error('callback is required')