High strength mixer using mcrypt

lib/RandomLib/AbstractMcryptMixer.php

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+<?php
+/**
+ * The Mcrypt abstract mixer class
+ *
+ * PHP version 5.3
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Mixer
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @copyright  2013 The Authors
+ * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
+ * @version    Build @@version@@
+ */
+
+namespace RandomLib;
+
+/**
+ * The mcrypt abstract mixer class
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Mixer
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @author     Chris Smith <chris@cs278.org>
+ */
+abstract class AbstractMcryptMixer extends AbstractMixer {
+    /**
+     * mcrypt module resource
+     *
+     * @var resource
+     */
+    private $mcrypt;
+
+    /**
+     * Block size of cipher
+     *
+     * @var int
+     */
+    private $blockSize;
+
+    /**
+     * Cipher initialization vector
+     *
+     * @var string
+     */
+    private $initv;
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function test() {
+        return extension_loaded('mcrypt');
+    }
+
+    /**
+     * Construct mcrypt mixer
+     */
+    public function __construct() {
+        $this->mcrypt    = mcrypt_module_open($this->getCipher(), '', MCRYPT_MODE_ECB, '');
+        $this->blockSize = mcrypt_enc_get_block_size($this->mcrypt);
+        $this->initv     = str_repeat(chr(0), mcrypt_enc_get_iv_size($this->mcrypt));
+    }
+
+    /**
+     * Performs cleanup
+     */
+    public function __destruct() {
+        if ($this->mcrypt) {
+            mcrypt_module_close($this->mcrypt);
+        }
+    }
+
+    /**
+     * Fetch the cipher for mcrypt.
+     *
+     * @return string
+     */
+    abstract protected function getCipher();
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function getPartSize() {
+        return $this->blockSize;
+    }
+
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function mixParts1($part1, $part2) {
+        return $this->encryptBlock($part1, $part2);
+    }
+
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function mixParts2($part1, $part2) {
+        return $this->decryptBlock($part2, $part1);
+    }
+
+    /**
+     * Encrypts a block using the suppied key
+     *
+     * @param  string $input Plaintext to encrypt
+     * @param  string $key   Encryption key
+     * @return string Resulting ciphertext
+     */
+    private function encryptBlock($input, $key) {
+        if (!$input && !$key) {
+            return '';
+        }
+
+        $this->prepareCipher($key);
+        $result = mcrypt_generic($this->mcrypt, $input);
+        mcrypt_generic_deinit($this->mcrypt);
+
+        return $result;
+    }
+
+    /**
+     * Derypts a block using the suppied key
+     *
+     * @param  string $input Ciphertext to decrypt
+     * @param  string $key   Encryption key
+     * @return string Resulting plaintext
+     */
+    private function decryptBlock($input, $key) {
+        if (!$input && !$key) {
+            return '';
+        }
+
+        $this->prepareCipher($key);
+        $result = mdecrypt_generic($this->mcrypt, $input);
+        mcrypt_generic_deinit($this->mcrypt);
+
+        return $result;
+    }
+
+    /**
+     * Sets up the mcrypt module
+     *
+     * @param  string $key
+     * @return void
+     */
+    private function prepareCipher($key) {
+        if (0 !== mcrypt_generic_init($this->mcrypt, $key, $this->initv)) {
+            throw new \RuntimeException('Failed to prepare mcrypt module');
+        }
+    }
+}

lib/RandomLib/Mixer/McryptRijndael128.php

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+<?php
+/**
+ * mcrypt mixer using the Rijndael cipher with 128 bit block size
+ *
+ * PHP version 5.3
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Mixer
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @copyright  2013 The Authors
+ * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
+ * @version    Build @@version@@
+ */
+
+namespace RandomLib\Mixer;
+
+use RandomLib\AbstractMcryptMixer;
+use SecurityLib\Strength;
+
+/**
+ * mcrypt mixer using the Rijndael cipher with 128 bit block size
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Mixer
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @author     Chris Smith <chris@cs278.org>
+ */
+class McryptRijndael128 extends AbstractMcryptMixer {
+    /**
+     * {@inheritdoc}
+     */
+    public static function getStrength() {
+        return new Strength(Strength::HIGH);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function getCipher() {
+        return 'rijndael-128';
+    }
+}

test/Unit/RandomLib/Mixer/McryptRijndael128Test.php

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+<?php
+
+namespace RandomLib\Mixer;
+
+use SecurityLib\Strength;
+
+class McryptRijndael128Test extends \PHPUnit_Framework_TestCase {
+
+    public static function provideMix() {
+        $data = array(
+            array(array(), ''),
+            array(array('', ''), ''),
+            array(array('a'), '61'),
+            array(array('a', 'b'), '6a'),
+            array(array('aa', 'ba'), '688d'),
+            array(array('ab', 'bb'), 'f8bc'),
+            array(array('aa', 'bb'), 'a0f3'),
+            array(array('aa', 'bb', 'cc'), '87c3'),
+            array(array('aabbcc', 'bbccdd', 'ccddee'), '7cf2273e46c7'),
+        );
+        return $data;
+    }
+
+    protected function setUp() {
+        if (!extension_loaded('mcrypt')) {
+            $this->markTestSkipped('mcrypt extension is not available');
+        }
+    }
+
+    public function testConstructWithoutArgument() {
+        $hash = new McryptRijndael128;
+        $this->assertTrue($hash instanceof \RandomLib\Mixer);
+    }
+
+    public function testGetStrength() {
+        $strength = new Strength(Strength::HIGH);
+        $actual = McryptRijndael128::getStrength();
+        $this->assertEquals($actual, $strength);
+    }
+
+    public function testTest() {
+        $actual = McryptRijndael128::test();
+        $this->assertTrue($actual);
+    }
+
+    /**
+     * @dataProvider provideMix
+     */
+    public function testMix($parts, $result) {
+        $mixer = new McryptRijndael128;
+        $actual = $mixer->mix($parts);
+        $this->assertEquals($result, bin2hex($actual));
+    }
+}