Fix XORMixer double XOR issue

lib/RandomLib/Mixer/XorMixer.php

@@ -10,15 +10,10 @@
  */
 
 /**
- * The Hash medium strength mixer class
- *
- * This class implements a mixer based upon the recommendations in RFC 4086
- * section 5.2
+ * XOR mixer
  *
  * PHP version 5.3
  *
- * @see http:https://tools.ietf.org/html/rfc4086#section-5.2
- *
  * @category PHPCryptLib
  * @package Random
  * @subpackage Mixer
@@ -34,12 +29,7 @@
 use SecurityLib\Strength;
 
 /**
- * The Hash medium strength mixer class
- *
- * This class implements a mixer based upon the recommendations in RFC 4086
- * section 5.2
- *
- * @see http:https://tools.ietf.org/html/rfc4086#section-5.2
+ * XOR mixer
  *
  * @category PHPCryptLib
  * @package Random
@@ -51,7 +41,7 @@ class XorMixer extends \RandomLib\AbstractMixer
 {
 
  /**
- * Return an instance of Strength indicating the strength of the source
+ * Return an instance of Strength indicating the strength of the mixer
  *
  * @return \SecurityLib\Strength An instance of one of the strength classes
  */
@@ -90,7 +80,10 @@ protected function getPartSize()
  */
  protected function mixParts1($part1, $part2)
  {
- return $part1 ^ $part2;
+ // The XOR operation is done in AbstractMixer; repeating it here will
+ // cause the previous source to get XORed with itself, setting it to
+ // zero
+ return $part2;
  }
 
  /**
@@ -104,6 +97,6 @@ protected function mixParts1($part1, $part2)
  protected function mixParts2($part1, $part2)
  {
  // Both mixers are identical, this is for speed, not security
- return $part1 ^ $part2;
+ return $part2;
  }
 }

test/Unit/RandomLib/Mixer/XorMixerTest.php

@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * The RandomLib library for securely generating random numbers and strings in PHP
+ *
+ * @author Anthony Ferrara <[email protected]>
+ * @copyright 2011 The Authors
+ * @license http:https://www.opensource.org/licenses/mit-license.html MIT License
+ * @version Build @@version@@
+ */
+namespace RandomLib\Mixer;
+
+use SecurityLib\Strength;
+
+class XorMixerTest extends \PHPUnit_Framework_TestCase
+{
+ public static function provideMix()
+ {
+ $data = array(
+ array(array(), ''),
+ array(array('1', '1'), '00'),
+ array(array('a'), '61'),
+ array(array('a', 'b'), '03'),
+ array(array('aa', 'ba'), '0300'),
+ array(array('ab', 'bb'), '0300'),
+ array(array('aa', 'bb'), '0303'),
+ array(array('aa', 'bb', 'cc'), '6060'),
+ array(array('aabbcc', 'bbccdd', 'ccddee'), '606065656262'),
+ );
+
+ return $data;
+ }
+
+ public function testConstructWithoutArgument()
+ {
+ $xorMixer = new XorMixer();
+ $this->assertTrue($xorMixer instanceof \RandomLib\Mixer);
+ }
+
+ public function testGetStrength()
+ {
+ $strength = new Strength(Strength::VERYLOW);
+ $actual = XorMixer::getStrength();
+ $this->assertEquals($actual, $strength);
+ }
+
+ public function testTest()
+ {
+ $actual = XorMixer::test();
+ $this->assertTrue($actual);
+ }
+
+ /**
+ * @dataProvider provideMix
+ */
+ public function testMix($parts, $result)
+ {
+ $mixer = new XorMixer();
+ $actual = $mixer->mix($parts);
+ $this->assertSame($result, bin2hex($actual));
+ }
+}