From a5f79c7651fcb7511c2034d51fecd45d0d6b52c6 Mon Sep 17 00:00:00 2001
From: "Ryan X. Charles" <ryan@bitpay.com>
Date: Thu, 28 Aug 2014 16:38:21 -0700
Subject: [PATCH] Signature.prototype.set

---
 lib/ecdsa.js           |  2 +-
 lib/signature.js       | 17 +++++++++++------
 test/test.ecdsa.js     |  2 +-
 test/test.signature.js | 12 ++++++++++--
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/lib/ecdsa.js b/lib/ecdsa.js
index c5fe908..ec57b23 100644
--- a/lib/ecdsa.js
+++ b/lib/ecdsa.js
@@ -166,7 +166,7 @@ ECDSA.prototype.sign = function() {
     var s = k.invm(N).mul(e.add(d.mul(r))).mod(N);
   } while (r.cmp(0) <= 0 || s.cmp(0) <= 0);
 
-  this.sig = new Signature(r, s, undefined, this.key.pubkey.compressed);
+  this.sig = new Signature({r: r, s: s, compressed: this.key.pubkey.compressed});
   return this.sig;
 };
 
diff --git a/lib/signature.js b/lib/signature.js
index 775d9b4..d6d3739 100644
--- a/lib/signature.js
+++ b/lib/signature.js
@@ -2,14 +2,19 @@ var BN = require('./bn');
 var Point = require('./point');
 var Pubkey = require('./pubkey');
 
-var Signature = function Signature(r, s, i, compressed) {
+var Signature = function Signature(obj) {
   if (!(this instanceof Signature))
-    return new Signature(r, s, i, compressed);
+    return new Signature(obj);
+  if (obj)
+    this.set(obj);
+};
 
-  this.r = r;
-  this.s = s;
-  this.i = i; //public key recovery parameter in range [0, 3]
-  this.compressed = compressed;
+Signature.prototype.set = function(obj) {
+  this.r = obj.r || this.r || undefined;
+  this.s = obj.s || this.s || undefined;
+  this.i = typeof obj.i !== 'undefined' ? obj.i : this.i; //public key recovery parameter in range [0, 3]
+  this.compressed = typeof obj.compressed !== 'undefined' ? obj.compressed : this.compressed; //whether the recovered pubkey is compressed
+  return this;
 };
 
 Signature.prototype.fromCompact = function(buf) {
diff --git a/test/test.ecdsa.js b/test/test.ecdsa.js
index f17a8a4..b8ff3bc 100644
--- a/test/test.ecdsa.js
+++ b/test/test.ecdsa.js
@@ -48,7 +48,7 @@ describe("ECDSA", function() {
       ecdsa.key.privkey.bn = BN().fromBuffer(Hash.sha256(new Buffer('test')));
       ecdsa.key.privkey2pubkey();
       ecdsa.hashbuf = hashbuf;
-      ecdsa.sig = new Signature(r, s);
+      ecdsa.sig = new Signature({r: r, s: s});
 
       ecdsa.calci();
       ecdsa.sig.i.should.equal(1);
diff --git a/test/test.signature.js b/test/test.signature.js
index d52bcd5..1d6972b 100644
--- a/test/test.signature.js
+++ b/test/test.signature.js
@@ -9,6 +9,14 @@ describe('Signature', function() {
     should.exist(sig);
   });
 
+  describe('#set', function() {
+    
+    it('should set compressed', function() {
+      should.exist(Signature().set({compressed: true}));
+    });
+
+  });
+
   describe('#fromCompact', function() {
     
     it('should create a signature from a compressed signature', function() {
@@ -110,7 +118,7 @@ describe('Signature', function() {
     it('should convert these known r and s values into a known signature', function() {
       var r = bn('63173831029936981022572627018246571655303050627048489594159321588908385378810');
       var s = bn('4331694221846364448463828256391194279133231453999942381442030409253074198130');
-      var sig = new Signature(r, s);
+      var sig = new Signature({r: r, s: s});
       var der = sig.toDER(r, s);
       der.toString('hex').should.equal('30450221008bab1f0a2ff2f9cb8992173d8ad73c229d31ea8e10b0f4d4ae1a0d8ed76021fa02200993a6ec81755b9111762fc2cf8e3ede73047515622792110867d12654275e72');
     });
@@ -122,7 +130,7 @@ describe('Signature', function() {
     it('should convert this signature in to hex DER', function() {
       var r = bn('63173831029936981022572627018246571655303050627048489594159321588908385378810');
       var s = bn('4331694221846364448463828256391194279133231453999942381442030409253074198130');
-      var sig = new Signature(r, s);
+      var sig = new Signature({r: r, s: s});
       var hex = sig.toString();
       hex.should.equal('30450221008bab1f0a2ff2f9cb8992173d8ad73c229d31ea8e10b0f4d4ae1a0d8ed76021fa02200993a6ec81755b9111762fc2cf8e3ede73047515622792110867d12654275e72');
     });