bugfix: private key less than 32 bytes in derive(), pad out with zeros

CHANGELOG.md

@@ -1,3 +1,8 @@
+0.3.0 / 2014-06-29
+------------------
+- bugfix: if private key was less than 32 bytes, pad out to 32 bytes with leading zeros (this happens in derive)
+
+
 0.2.0 / 2014-06-25
 ------------------
 - upgraded `"ecurve": "^0.8.0"` to `"ecurve": "^1.0.0"`

lib/hdkey.js

@@ -136,7 +136,8 @@ HDKey.prototype.deriveChild = function(index) {
       return this.derive(index + 1)
     }
 
-    hd.privateKey = ki.toBuffer()
+    //if less than 32 bytes, pad with 0's
+    hd.privateKey = ki.toBuffer(32)
 
   // Public parent key -> public child key
   } else {
@@ -149,8 +150,6 @@ HDKey.prototype.deriveChild = function(index) {
       return this.derive(index + 1)
     }
 
-    //hd.pub = new ECPubKey(Ki, true)
-    //this._publicPoint = Ki
     hd.publicKey = Ki.getEncoded(true)
   }
 

test/hdkey.test.js

@@ -113,4 +113,15 @@ describe('hdkey', function() {
 
     })
   })
+
+  describe('> when private key integer is less than 32 bytes', function() {
+    it('should work', function() {
+      var seed = "000102030405060708090a0b0c0d0e0f"
+      var masterKey = HDKey.fromMasterSeed(new Buffer(seed, 'hex'))
+      
+      var newKey = masterKey.derive("m/44'/6'/4'")
+      var expected = 'xprv9ymoag6W7cR6KBcJzhCM6qqTrb3rRVVwXKzwNqp1tDWcwierEv3BA9if3ARHMhMPh9u2jNoutcgpUBLMfq3kADDo7LzfoCnhhXMRGX3PXDx'
+      assert.equal(cs.encode(newKey.privateExtendedKey), expected)
+    })
+  })
 })