From 6a2615d3cc695c29bbd6dbfb85408b8903f096a5 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 27 Jul 2016 04:06:05 -0700
Subject: [PATCH] bip151: 32 bit sequence and 64 bit iv.

---
 lib/bcoin/bip151.js | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/lib/bcoin/bip151.js b/lib/bcoin/bip151.js
index ba150125..8ae277c8 100644
--- a/lib/bcoin/bip151.js
+++ b/lib/bcoin/bip151.js
@@ -70,9 +70,8 @@ function BIP151Stream(cipher, key) {
   this.chacha = new chachapoly.ChaCha20();
   this.aead = new chachapoly.AEAD();
   this.tag = null;
-  this.seqHi = 0;
-  this.seqLo = 0;
-  this.iv = new Buffer(12);
+  this.seq = 0;
+  this.iv = new Buffer(8);
   this.iv.fill(0);
 
   this.highWaterMark = 1024 * (1 << 20);
@@ -106,8 +105,7 @@ BIP151Stream.prototype.init = function init(publicKey) {
   this.k2 = utils.hkdfExpand(this.prk, INFO_KEY2, 32, 'sha256');
   this.sid = utils.hkdfExpand(this.prk, INFO_SID, 32, 'sha256');
 
-  this.seqHi = 0;
-  this.seqLo = 0;
+  this.seq = 0;
 
   this.update();
 
@@ -163,11 +161,8 @@ BIP151Stream.prototype.rekey = function rekey() {
 
 BIP151Stream.prototype.sequence = function sequence() {
   // Wrap sequence number a la openssh.
-  if (++this.seqLo === 0x100000000) {
-    this.seqLo = 0;
-    if (++this.seqHi === 0x100000000)
-      this.seqHi = 0;
-  }
+  if (++this.seq === 0x100000000)
+    this.seq = 0;
 
   this.update();
 
@@ -183,8 +178,7 @@ BIP151Stream.prototype.sequence = function sequence() {
  */
 
 BIP151Stream.prototype.update = function update() {
-  this.iv.writeUInt32LE(this.seqLo, 0, true);
-  this.iv.writeUInt32LE(this.seqHi, 4, true);
+  this.iv.writeUInt32LE(this.seq, 4, true);
   return this.iv;
 };