[Pkg-javascript-commits] [node-browserify-aes] 28/43: ghash: inline xor

[Bastien Roucariès]

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rouca pushed a commit to branch master
in repository node-browserify-aes.

commit 1fe283662f8aa34e02e9a01576d8c6d9db221caa
Author: Daniel Cousens <github at dcousens.com>
Date:   Fri May 19 14:56:40 2017 +1000

    ghash: inline xor
---
 ghash.js | 60 ++++++++++++++++++++++++++----------------------------------
 1 file changed, 26 insertions(+), 34 deletions(-)

diff --git a/ghash.js b/ghash.js
index 8763d31..26bfedd 100644
--- a/ghash.js
+++ b/ghash.js
@@ -1,5 +1,23 @@
 var Buffer = require('safe-buffer').Buffer
-var zeros = Buffer.alloc(16, 0)
+var ZEROES = Buffer.alloc(16, 0)
+
+function toArray (buf) {
+  return [
+    buf.readUInt32BE(0),
+    buf.readUInt32BE(4),
+    buf.readUInt32BE(8),
+    buf.readUInt32BE(12)
+  ]
+}
+
+function fromArray (out) {
+  var buf = Buffer.allocUnsafe(16)
+  buf.writeUInt32BE(out[0] >>> 0, 0)
+  buf.writeUInt32BE(out[1] >>> 0, 4)
+  buf.writeUInt32BE(out[2] >>> 0, 8)
+  buf.writeUInt32BE(out[3] >>> 0, 12)
+  return buf
+}
 
 function GHASH (key) {
   this.h = key
@@ -26,7 +44,10 @@ GHASH.prototype._multiply = function () {
     xi = (this.state[~~(i / 8)] & (1 << (7 - (i % 8)))) !== 0
     if (xi) {
       // Z_i+1 = Z_i ^ V_i
-      Zi = xor(Zi, Vi)
+      Zi[0] ^= Vi[0]
+      Zi[1] ^= Vi[1]
+      Zi[2] ^= Vi[2]
+      Zi[3] ^= Vi[3]
     }
 
     // Store the value of LSB(V_i)
@@ -58,40 +79,11 @@ GHASH.prototype.update = function (buf) {
 
 GHASH.prototype.final = function (abl, bl) {
   if (this.cache.length) {
-    this.ghash(Buffer.concat([this.cache, zeros], 16))
+    this.ghash(Buffer.concat([this.cache, ZEROES], 16))
   }
-  this.ghash(fromArray([
-    0, abl,
-    0, bl
-  ]))
-  return this.state
-}
 
-function toArray (buf) {
-  return [
-    buf.readUInt32BE(0),
-    buf.readUInt32BE(4),
-    buf.readUInt32BE(8),
-    buf.readUInt32BE(12)
-  ]
-}
-
-function fromArray (out) {
-  var buf = Buffer.allocUnsafe(16)
-  buf.writeUInt32BE(out[0] >>> 0, 0)
-  buf.writeUInt32BE(out[1] >>> 0, 4)
-  buf.writeUInt32BE(out[2] >>> 0, 8)
-  buf.writeUInt32BE(out[3] >>> 0, 12)
-  return buf
-}
-
-function xor (a, b) {
-  return [
-    a[0] ^ b[0],
-    a[1] ^ b[1],
-    a[2] ^ b[2],
-    a[3] ^ b[3]
-  ]
+  this.ghash(fromArray([0, abl, 0, bl]))
+  return this.state
 }
 
 module.exports = GHASH

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