From d86c4390175a70c96a7d02226ba3d30de3e8cd8a Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Mon, 1 Aug 2016 01:19:09 -0700
Subject: [PATCH] chachapoly: optimize for little-endian.

---
 bench/chacha.js         | 15 +++++++++++++++
 lib/bcoin/chachapoly.js | 11 +++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 bench/chacha.js

diff --git a/bench/chacha.js b/bench/chacha.js
new file mode 100644
index 00000000..32d62530
--- /dev/null
+++ b/bench/chacha.js
@@ -0,0 +1,15 @@
+'use strict';
+
+var chachapoly = require('../lib/bcoin/chachapoly');
+var bench = require('./bench');
+
+var chacha = new chachapoly.ChaCha20();
+var iv = new Buffer('0102030405060708', 'hex');
+chacha.init(iv, 0);
+var data = new Buffer(32);
+for (var i = 0; i < 32; i++)
+  data[i] = i;
+var end = bench('encrypt');
+for (var i = 0; i < 1000000; i++)
+  chacha.encrypt(data);
+end(i);
diff --git a/lib/bcoin/chachapoly.js b/lib/bcoin/chachapoly.js
index 2f7c8ebb..342fa8e1 100644
--- a/lib/bcoin/chachapoly.js
+++ b/lib/bcoin/chachapoly.js
@@ -8,6 +8,8 @@
 
 var assert = require('assert');
 
+var BIG_ENDIAN = new Int8Array(Int16Array.of(1).buffer)[0] === 0;
+
 /**
  * ChaCha20 (used for bip151)
  * @see https://tools.ietf.org/html/rfc7539#section-2
@@ -21,7 +23,11 @@ function ChaCha20() {
 
   this.state = new Uint32Array(16);
   this.stream = new Uint32Array(16);
-  this.bytes = new Buffer(64);
+  this.bytes = new Uint8Array(this.stream.buffer);
+
+  if (BIG_ENDIAN)
+    this.bytes = new Buffer(64);
+
   this.pos = 0;
   this.ivSize = 0;
 }
@@ -116,7 +122,8 @@ ChaCha20.prototype.encrypt = function encrypt(data) {
 
       for (j = 0; j < 16; j++) {
         this.stream[j] += this.state[j];
-        this.bytes.writeUInt32LE(this.stream[j], j * 4, true);
+        if (BIG_ENDIAN)
+          this.bytes.writeUInt32LE(this.stream[j], j * 4, true);
       }
 
       this.state[12]++;