Merge pull request #248 from dcousens/hdnode

HDNode / BIP32 Neutering

Author: weilu

src/hdnode.js

@@ -31,6 +31,7 @@ function HDNode(K, chainCode, network) {
   network = network || networks.bitcoin
 
   assert(Buffer.isBuffer(chainCode), 'Expected Buffer, got ' + chainCode)
+  assert.equal(chainCode.length, 32, 'Expected chainCode length of 32, got ' + chainCode.length)
   assert(network.bip32, 'Unknown BIP32 constants for network')
 
   this.chainCode = chainCode
@@ -142,12 +143,27 @@ HDNode.prototype.getAddress = function() {
   return this.pubKey.getAddress(this.network)
 }
 
+HDNode.prototype.neutered = function() {
+  var neutered = new HDNode(this.pubKey.Q, this.chainCode, this.network)
+  neutered.depth = this.depth
+  neutered.index = this.index
+  neutered.parentFingerprint = this.parentFingerprint
+
+  return neutered
+}
+
 HDNode.prototype.toBase58 = function(isPrivate) {
   return base58check.encode(this.toBuffer(isPrivate))
 }
 
 HDNode.prototype.toBuffer = function(isPrivate) {
-  if (isPrivate == undefined) isPrivate = !!this.privKey
+  if (isPrivate == undefined) {
+    isPrivate = !!this.privKey
+
+  // FIXME: remove in 2.x.y
+  } else {
+    console.warn('isPrivate flag is deprecated, please use the .neutered() method instead')
+  }
 
   // Version
   var version = isPrivate ? this.network.bip32.private : this.network.bip32.public
@@ -173,6 +189,7 @@ HDNode.prototype.toBuffer = function(isPrivate) {
 
   // 33 bytes: the public key or private key data
   if (isPrivate) {
+    // FIXME: remove in 2.x.y
     assert(this.privKey, 'Missing private key')
 
     // 0x00 + k for private keys

test/hdnode.js

@@ -49,7 +49,13 @@ describe('HDNode', function() {
       assert.equal(hd.network, networks.testnet)
     })
 
-    it('throws an exception when an unknown network is given', function() {
+    it('throws when an invalid length chain code is given', function() {
+      assert.throws(function() {
+        new HDNode(d, chainCode.slice(0, 20), networks.testnet)
+      }, /Expected chainCode length of 32, got 20/)
+    })
+
+    it('throws when an unknown network is given', function() {
       assert.throws(function() {
         new HDNode(d, chainCode, {})
       }, /Unknown BIP32 constants for network/)
@@ -82,20 +88,21 @@ describe('HDNode', function() {
   describe('toBase58', function() {
     fixtures.valid.forEach(function(f) {
       it('exports ' + f.master.base58 + ' (public) correctly', function() {
-        var hd = HDNode.fromSeedHex(f.master.seed)
+        var hd = HDNode.fromSeedHex(f.master.seed).neutered()
 
-        assert.equal(hd.toBase58(false), f.master.base58)
+        assert.equal(hd.toBase58(), f.master.base58)
       })
     })
 
     fixtures.valid.forEach(function(f) {
       it('exports ' + f.master.base58Priv + ' (private) correctly', function() {
         var hd = HDNode.fromSeedHex(f.master.seed)
 
-        assert.equal(hd.toBase58(true), f.master.base58Priv)
+        assert.equal(hd.toBase58(), f.master.base58Priv)
       })
     })
 
+    // FIXME: remove in 2.x.y
     it('fails when there is no private key', function() {
       var hd = HDNode.fromBase58(fixtures.valid[0].master.base58)
 
@@ -160,20 +167,21 @@ describe('HDNode', function() {
   describe('toBuffer/toHex', function() {
     fixtures.valid.forEach(function(f) {
       it('exports ' + f.master.hex + ' (public) correctly', function() {
-        var hd = HDNode.fromSeedHex(f.master.seed)
+        var hd = HDNode.fromSeedHex(f.master.seed).neutered()
 
-        assert.equal(hd.toHex(false), f.master.hex)
+        assert.equal(hd.toHex(), f.master.hex)
       })
     })
 
     fixtures.valid.forEach(function(f) {
       it('exports ' + f.master.hexPriv + ' (private) correctly', function() {
         var hd = HDNode.fromSeedHex(f.master.seed)
 
-        assert.equal(hd.toHex(true), f.master.hexPriv)
+        assert.equal(hd.toHex(), f.master.hexPriv)
       })
     })
 
+    // FIXME: remove in 2.x.y
     it('fails when there is no private key', function() {
       var hd = HDNode.fromHex(fixtures.valid[0].master.hex)
 
@@ -220,6 +228,21 @@ describe('HDNode', function() {
     })
   })
 
+  describe('neutered', function() {
+    var f = fixtures.valid[0]
+
+    it('strips all private information', function() {
+      var hd = HDNode.fromBase58(f.master.base58)
+      var hdn = hd.neutered()
+
+      assert.equal(hdn.privKey, undefined)
+      assert.equal(hdn.pubKey.toHex(), hd.pubKey.toHex())
+      assert.equal(hdn.chainCode, hd.chainCode)
+      assert.equal(hdn.depth, hd.depth)
+      assert.equal(hdn.index, hd.index)
+    })
+  })
+
   describe('derive', function() {
     function verifyVector(hd, v, depth) {
       assert.equal(hd.privKey.toWIF(), v.wif)
@@ -256,32 +279,28 @@ describe('HDNode', function() {
       var f = fixtures.valid[1]
       var c = f.children[0]
 
-      var parentNode = HDNode.fromBase58(f.master.base58Priv)
-      var child = parentNode.derive(c.m)
+      var master = HDNode.fromBase58(f.master.base58Priv)
+      var child = master.derive(c.m).neutered()
 
-      // FIXME: N(CKDpriv((kpar, cpar), i)), could be done better...
-      var childNeutered = HDNode.fromBase58(child.toBase58(false)) // neuter
-      assert.equal(childNeutered.toBase58(), c.base58)
+      assert.equal(child.toBase58(), c.base58)
     })
 
     it('works for Private -> public (neutered, hardened)', function() {
       var f = fixtures.valid[0]
       var c = f.children[0]
 
-      var parentNode = HDNode.fromBase58(f.master.base58Priv)
-      var child = parentNode.deriveHardened(c.m)
+      var master = HDNode.fromBase58(f.master.base58Priv)
+      var child = master.deriveHardened(c.m).neutered()
 
-      // FIXME: N(CKDpriv((kpar, cpar), i)), could be done better...
-      var childNeutered = HDNode.fromBase58(child.toBase58(false)) // neuter
-      assert.equal(childNeutered.toBase58(), c.base58)
+      assert.equal(child.toBase58(), c.base58)
     })
 
     it('works for Public -> public', function() {
       var f = fixtures.valid[1]
       var c = f.children[0]
 
-      var parentNode = HDNode.fromBase58(f.master.base58)
-      var child = parentNode.derive(c.m)
+      var master = HDNode.fromBase58(f.master.base58)
+      var child = master.derive(c.m)
 
       assert.equal(child.toBase58(), c.base58)
     })
@@ -290,10 +309,10 @@ describe('HDNode', function() {
       var f = fixtures.valid[0]
       var c = f.children[0]
 
-      var parentNode = HDNode.fromBase58(f.master.base58)
+      var master = HDNode.fromBase58(f.master.base58)
 
       assert.throws(function() {
-        parentNode.deriveHardened(c.m)
+        master.deriveHardened(c.m)
       }, /Could not derive hardened child key/)
     })
   })