use elliptic for Point.multiply and key regeneration

lib/browser/Key.js

@@ -2,6 +2,7 @@ var ECKey = require('../../browser/vendor-bundle.js').ECKey;
 var SecureRandom = require('../SecureRandom');
 var Curve = require('../Curve');
 var bignum = require('bignum');
+var elliptic = require('elliptic');
 
 var Key = function() {
   this._pub = null;
@@ -85,9 +86,17 @@ Key.prototype.regenerateSync = function() {
     throw new Error('Key does not have a private key set');
   }
 
-  var eck = new ECKey(this.private.toString('hex'));
+  var ec = elliptic.curves.secp256k1;
-  eck.setCompressed(this._compressed);
+  var g = ec.g;
-  this._pub = new Buffer(eck.getPub());
+  var ecp = ec.g.mul(this.private);
+  var x = new bignum(ecp.x.toArray());
+  var y = new bignum(ecp.y.toArray());
+  var p = new Point(x, y);
+  if (this.compressed)
+    this._pub = p.toCompressedPubKey();
+  else
+    this._pub = p.toUncompressedPubKey();
+
   return this;
 };
 

lib/browser/Point.js

@@ -55,4 +55,16 @@ Point.prototype.toUncompressedPubKey = function() {
   return pub;
 };
 
+Point.prototype.toCompressedPubKey = function() {
+  var xbuf = this.x.toBuffer({size: 32});
+  var ybuf = this.y.toBuffer({size: 32});
+  if (ybuf[ybuf.length-1] % 2) { //odd
+    var pub = Buffer.concat([new Buffer([3]), xbuf]);
+  }
+  else { //even
+    var pub = Buffer.concat([new Buffer([2]), xbuf]);
+  }
+  return pub;
+};
+
 module.exports = (Point);