From ac4d3186bfbb4df2aee4389d1a51e488df08b52a Mon Sep 17 00:00:00 2001
From: "Ryan X. Charles" <ryan@bitpay.com>
Date: Sat, 5 Jul 2014 16:05:38 -0700
Subject: [PATCH] update sign function to use elliptic

---
 lib/browser/Key.js          | 49 +++++++++++++++++--------------------
 test/test.Bignum.browser.js | 11 +++++++++
 2 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/lib/browser/Key.js b/lib/browser/Key.js
index f824939..73d8716 100644
--- a/lib/browser/Key.js
+++ b/lib/browser/Key.js
@@ -101,45 +101,40 @@ Key.prototype.regenerateSync = function() {
 };
 
 Key.prototype.signSync = function(hash) {
+  /*
   var getSECCurveByName = require('../../browser/vendor-bundle.js').getSECCurveByName;
   var BigInteger = require('../../browser/vendor-bundle.js').BigInteger;
   var rng = new SecureRandom();
   var ecparams = getSECCurveByName('secp256k1');
+  */
+  var ec = elliptic.curves.secp256k1;
 
-  var rng = {};
-  rng.nextBytes = function(array) {
-    var buf = SecureRandom.getRandomBuffer(array.length);
-    var a = bufferToArray(SecureRandom.getRandomBuffer(array.length));
-    for (var i in a) {
-      array[i] = a[i];
-    }
-  };
-
-  var getBigRandom = function(limit) {
-    return new BigInteger(limit.bitLength(), rng)
-      .mod(limit.subtract(BigInteger.ONE))
-      .add(BigInteger.ONE);
+  var genk = function() {
+    //TODO: account for when >= n
+    return new bignum(SecureRandom.getRandomBuffer(8));
   };
 
   var sign = function(hash, priv) {
     var d = priv;
-    var n = ecparams.getN();
-    var e = BigInteger.fromByteArrayUnsigned(hash);
+    //var n = ecparams.getN();
+    var n = ec.n;
+    //var e = BigInteger.fromByteArrayUnsigned(hash);
+    var e = new bignum(hash);
 
     do {
-      var k = getBigRandom(n);
-      var G = ecparams.getG();
-      var Q = G.multiply(k);
-      var r = Q.getX().toBigInteger().mod(n);
-      var s = k.modInverse(n).multiply(e.add(d.multiply(r))).mod(n);
-    } while (r.compareTo(BigInteger.ZERO) <= 0 || s.compareTo(BigInteger.ZERO) <= 0);
+      var k = genk();
+      var G = ec.g;
+      var Q = G.mul(k);
+      var r = Q.getX().mod(n);
+      var s = k.invm(n).mul(e.add(d.mul(r))).mod(n);
+    } while (r.cmp(new bignum(0)) <= 0 || s.cmp(new bignum(0)) <= 0);
 
     return serializeSig(r, s);
   };
 
   var serializeSig = function(r, s) {
-    var rBa = r.toByteArraySigned();
-    var sBa = s.toByteArraySigned();
+    var rBa = r.toArray();
+    var sBa = s.toArray();
 
     var sequence = [];
     sequence.push(0x02); // INTEGER
@@ -163,9 +158,11 @@ Key.prototype.signSync = function(hash) {
   if (!Buffer.isBuffer(hash) || hash.length !== 32) {
     throw new Error('Arg should be a 32 bytes hash buffer');
   }
-  var privhex = this.private.toString('hex');
-  var privnum = new BigInteger(privhex, 16);
-  var signature = sign(bufferToArray(hash), privnum);
+  //var privhex = this.private.toString('hex');
+  //var privnum = new BigInteger(privhex, 16);
+  var privnum = new bignum(this.private);
+  //var signature = sign(bufferToArray(hash), privnum);
+  var signature = sign(hash, privnum);
 
   return new Buffer(signature);
 };
diff --git a/test/test.Bignum.browser.js b/test/test.Bignum.browser.js
index 598683e..40dff34 100644
--- a/test/test.Bignum.browser.js
+++ b/test/test.Bignum.browser.js
@@ -31,6 +31,17 @@ if (typeof process == 'undefined' || typeof process.versions == 'undefined') {
 
     });
 
+    describe('#sub', function() {
+
+      it('should subtract a small number', function() {
+        var bn1 = new Bignum(50);
+        var bn2 = new Bignum(25);
+        var bn3 = bn1.sub(bn2);
+        bn3.toString().should.equal('25');
+      });
+
+    });
+
     describe('#gt', function() {
 
       it('should say 1 is greater than 0', function() {