From c7b33eca9ab40ddb2afa629e0c6b8c6f0cba2518 Mon Sep 17 00:00:00 2001
From: "Ryan X. Charles" <ryan@bitpay.com>
Date: Fri, 25 Apr 2014 15:00:51 -0300
Subject: [PATCH] update key signing to use new SecureRandom

...and throw an error if you try to use the old, non-secure random number
generator.
---
 browser/vendor/eckey.js |  2 +-
 browser/vendor/rng.js   |  4 ++-
 lib/browser/Key.js      | 64 ++++++++++++++++++++++++++++++++++++++---
 lib/browser/Point.js    |  1 -
 4 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/browser/vendor/eckey.js b/browser/vendor/eckey.js
index 74e3e4562..62b6cd067 100644
--- a/browser/vendor/eckey.js
+++ b/browser/vendor/eckey.js
@@ -7,7 +7,7 @@ Bitcoin.ECKey = (function () {
     if (!input) {
       // Generate new key
       var n = ecparams.getN();
-      this.priv = ECDSA.getBigRandom(n);
+      //this.priv = ECDSA.getBigRandom(n);
     } else if (input instanceof BigInteger) {
       // Input is a private key value
       this.priv = input;
diff --git a/browser/vendor/rng.js b/browser/vendor/rng.js
index 03afc3a9f..77918e59a 100644
--- a/browser/vendor/rng.js
+++ b/browser/vendor/rng.js
@@ -65,4 +65,6 @@ function rng_get_bytes(ba) {
 
 function SecureRandom() {}
 
-SecureRandom.prototype.nextBytes = rng_get_bytes;
+SecureRandom.prototype.nextBytes = function() {
+  throw new Error('Should not use old RNG');
+};
diff --git a/lib/browser/Key.js b/lib/browser/Key.js
index 259e9a7b9..e5df2644a 100644
--- a/lib/browser/Key.js
+++ b/lib/browser/Key.js
@@ -90,6 +90,62 @@ 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 rng = {};
+  rng.nextBytes = function(array) {
+    var buf = SecureRandom.getRandomBuffer(array.length);
+    var a = bufferToArray(SecureRandom.getRandomBuffer(array.length));
+    for (var i in array) {
+      array[i] = a[i];
+    }
+  };
+
+  var getBigRandom = function (limit) {
+    return new BigInteger(limit.bitLength(), rng)
+      .mod(limit.subtract(BigInteger.ONE))
+      .add(BigInteger.ONE);
+  };
+  
+  var sign = function (hash, priv) {
+    var d = priv;
+    var n = ecparams.getN();
+    var e = BigInteger.fromByteArrayUnsigned(hash);
+
+    do {
+      var k = getBigRandom(n);
+      var G = ecparams.getG();
+      var Q = G.multiply(k);
+      var r = Q.getX().toBigInteger().mod(n);
+    } while (r.compareTo(BigInteger.ZERO) <= 0);
+
+    var s = k.modInverse(n).multiply(e.add(d.multiply(r))).mod(n);
+
+    return serializeSig(r, s);
+  };
+
+  var serializeSig = function (r, s) {
+    var rBa = r.toByteArraySigned();
+    var sBa = s.toByteArraySigned();
+
+    var sequence = [];
+    sequence.push(0x02); // INTEGER
+    sequence.push(rBa.length);
+    sequence = sequence.concat(rBa);
+
+    sequence.push(0x02); // INTEGER
+    sequence.push(sBa.length);
+    sequence = sequence.concat(sBa);
+
+    sequence.unshift(sequence.length);
+    sequence.unshift(0x30); // SEQUENCE
+
+    return sequence;
+  };
+
   if (!this.private) {
     throw new Error('Key does not have a private key set');
   }
@@ -97,10 +153,10 @@ Key.prototype.signSync = function(hash) {
   if (!Buffer.isBuffer(hash) || hash.length !== 32) {
     throw new Error('Arg should be a 32 bytes hash buffer');
   }
-  var eck = new ECKey(this.private.toString('hex'));
-  eck.setCompressed(this._compressed);
-  var signature = eck.sign(bufferToArray(hash));
-  // return it as a buffer to keep c++ compatibility
+  var privhex = this.private.toString('hex');
+  var privnum = new BigInteger(privhex, 16);
+  var signature = sign(bufferToArray(hash), privnum);
+
   return new Buffer(signature);
 };
 
diff --git a/lib/browser/Point.js b/lib/browser/Point.js
index fba0b3d45..8c6c085f8 100644
--- a/lib/browser/Point.js
+++ b/lib/browser/Point.js
@@ -4,7 +4,6 @@ var imports = require('soop').imports();
 var Key = imports.Key || require('./Key'); 
 var bignum = imports.bignum || require('bignum');
 var assert = require('assert');
-var ECKey = require('../../browser/vendor-bundle.js').ECKey;
 var ECPointFp = require('../../browser/vendor-bundle.js').ECPointFp;
 var ECFieldElementFp = require('../../browser/vendor-bundle.js').ECFieldElementFp;
 var getSECCurveByName = require('../../browser/vendor-bundle.js').getSECCurveByName;