Replace Zend\Math\Rand usage of mt_rand() with RandomLib generator an…

…d SHA1 hash timing source for CPU drift entropy mining
vicular · Mar 13, 2013 · 97b98e7 · 97b98e7
1 parent 977f491
commit 97b98e7
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Showing 5 changed files with 195 additions and 23 deletions.
diff --git a/composer.json b/composer.json
@@ -8,12 +8,14 @@
     ],
     "homepage": "http://framework.zend.com/",
     "license": "BSD-3-Clause",
+    "minimum-stability": "dev",
     "require": {
         "php": ">=5.3.3"
     },
     "require-dev": {
         "doctrine/common": ">=2.1",
-        "phpunit/PHPUnit": "3.7.*"
+        "phpunit/PHPUnit": "3.7.*",
+        "ircmaxell/random-lib": "dev-master"
     },
     "suggest": {
         "doctrine/common": "Doctrine\\Common >=2.1 for annotation features",

diff --git a/library/Zend/Math/Rand.php b/library/Zend/Math/Rand.php
@@ -14,6 +14,14 @@
  */
 abstract class Rand
 {
+
+    /**
+     * Alternative random byte generator using RandomLib
+     *
+     * @var \RandomLib\Generator
+     */
+    protected static $generator = null;
+
     /**
      * Generate random bytes using OpenSSL or Mcrypt and mt_rand() as fallback
      *
@@ -27,34 +35,52 @@ public static function getBytes($length, $strong = false)
         if ($length <= 0) {
             return false;
         }
-        if (extension_loaded('openssl')) {
-            $rand = openssl_random_pseudo_bytes($length, $secure);
-            if ($secure === true) {
-                return $rand;
+        $bytes = '';
+        if (function_exists('openssl_random_pseudo_bytes')
+        && (version_compare(PHP_VERSION, '5.3.4') >= 0
+        || strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN')) {
+            $bytes = openssl_random_pseudo_bytes($length, $usable);
+            if (true === $usable) {
+                return $bytes;
             }
-        }
-        if (extension_loaded('mcrypt')) {
-            // PHP bug #55169
-            // @see https://bugs.php.net/bug.php?id=55169
-            if (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN' ||
-                version_compare(PHP_VERSION, '5.3.7') >= 0) {
-                $rand = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
-                if ($rand !== false && strlen($rand) === $length) {
-                    return $rand;
-                }
+        } elseif (function_exists('mcrypt_create_iv')
+        && (version_compare(PHP_VERSION, '5.3.7') >= 0
+        || strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN')) {
+            $bytes = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
+            if ($bytes !== false && strlen($bytes) === $length) {
+                return $bytes;
             }
         }
-        if ($strong) {
-            throw new Exception\RuntimeException(
-                'This PHP environment doesn\'t support secure random number generation. ' .
-                'Please consider to install the OpenSSL and/or Mcrypt extensions'
+        $checkAlternatives = (file_exists('/dev/urandom') && is_readable('/dev/urandom'))
+            || class_exists('\\COM', false);
+        if (true === $strong && false === $checkAlternatives) {
+            throw new Exception\RuntimeException (
+                'Unable to generate sufficiently strong random bytes'
             );
         }
-        $rand = '';
-        for ($i = 0; $i < $length; $i++) {
-            $rand .= chr(mt_rand(0, 255));
+        $generator = self::getAlternativeGenerator();
+        return $generator->generate($length);
+    }
+
+    public static function getAlternativeGenerator()
+    {
+        if (!is_null(self::$generator)) {
+            return self::$generator;
+        }
+        if (!class_exists('\\RandomLib\\Factory')) {
+            throw new Exception\RuntimeException(
+                'The RandomLib fallback pseudorandom number generator (PRNG) '
+                . ' must be installed in the absence of the OpenSSL and '
+                . 'Mcrypt extensions'
+            );
         }
-        return $rand;
+        $factory = new \RandomLib\Factory;
+        $factory->registerSource(
+            'HashTiming',
+            '\Zend\Math\Source\HashTiming'
+        );
+        self::$generator = $factory->getMediumStrengthGenerator();
+        return self::$generator;
     }
 
     /**

diff --git a/library/Zend/Math/Source/HashTiming.php b/library/Zend/Math/Source/HashTiming.php
@@ -0,0 +1,115 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ */
+namespace Zend\Math\Source;
+
+use RandomLib;
+use SecurityLib\Strength;
+
+/*
+* Author:
+* George Argyros <[email protected]>
+*
+* Copyright (c) 2012, George Argyros
+* All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+* * Redistributions of source code must retain the above copyright
+* notice, this list of conditions and the following disclaimer.
+* * Redistributions in binary form must reproduce the above copyright
+* notice, this list of conditions and the following disclaimer in the
+* documentation and/or other materials provided with the distribution.
+* * Neither the name of the <organization> nor the
+* names of its contributors may be used to endorse or promote products
+* derived from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+* DISCLAIMED. IN NO EVENT SHALL GEORGE ARGYROS BE LIABLE FOR ANY
+* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*
+*
+*
+* The function is providing, at least at the systems tested :),
+* $len bytes of entropy under any PHP installation or operating system.
+* The execution time should be at most 10-20 ms in any system.
+*
+* Modified by Padraic Brady as part of Zend Framework to use 25% of the
+* original version's iterations.
+*/
+class HashTiming implements RandomLib\Source
+{
+
+    /**
+    * Return an instance of Strength indicating the strength of the source
+    *
+    * @return Strength An instance of one of the strength classes
+    */
+    public static function getStrength()
+    {
+        return new Strength(Strength::VERYLOW);
+    }
+
+    /**
+    * Generate a random string of the specified size
+    *
+    * @param int $size The size of the requested random string
+    *
+    * @return string A string of the requested size
+    */
+    public function generate($size) {
+        $result = '';
+        $entropy = '';
+        $msec_per_round = 400;
+        $bits_per_round = 2;
+        $total = $size;
+        $bytes = 0;
+        $hash_length = 20;
+        $rounds = 0;
+        while (strlen($result) < $size) {
+            $bytes = ($total > $hash_length)? $hash_length : $total;
+            $total -= $bytes;
+            for ($i=1; $i < 3; $i++) {
+                $t1 = microtime(true);
+                $seed = mt_rand();
+                for ($j=1; $j < 50; $j++) {
+                    $seed = sha1($seed);
+                }
+                $t2 = microtime(true);
+                $entropy .= $t1 . $t2;
+            }
+            $div = (int) (($t2 - $t1) * 1000000);
+            if ($div <= 0) {
+                $div = 400;
+            }
+            $rounds = (int) ($msec_per_round * 50 / $div);
+            $iter = $bytes * (int) (ceil(8 / $bits_per_round));
+            for ($i = 0; $i < $iter; $i ++)
+            {
+                $t1 = microtime();
+                $seed = sha1(mt_rand());
+                for ($j = 0; $j < $rounds; $j++)
+                {
+                   $seed = sha1($seed);
+                }
+                $t2 = microtime();
+                $entropy .= $t1 . $t2;
+            }
+            $result .= sha1($entropy, true);
+        }
+        return substr($result, 0, $size);
+    }
+
+}
diff --git a/library/Zend/Math/composer.json b/library/Zend/Math/composer.json
@@ -2,6 +2,7 @@
     "name": "zendframework/zend-math",
     "description": " ",
     "license": "BSD-3-Clause",
+    "minimum-stability": "dev",
     "keywords": [
         "zf2",
         "math"
@@ -15,6 +16,9 @@
     "require": {
         "php": ">=5.3.3"
     },
+    "suggest": {
+        "ircmaxell/random-lib": "Fallback random byte generator for Zend\\Math\\Rand if OpenSSL/Mcrypt extensions are unavailable"
+    }
     "extra": {
         "branch-alias": {
             "dev-master": "2.1-dev",

diff --git a/tests/ZendTest/Math/RandTest.php b/tests/ZendTest/Math/RandTest.php
@@ -10,7 +10,9 @@
 
 namespace ZendTest\Math;
 
+use Zend\Math;
 use Zend\Math\Rand;
+use RandomLib;
 
 /**
  * @category   Zend
@@ -127,4 +129,27 @@ public function testGetStringBase64()
             $this->assertTrue(preg_match('#^[0-9a-zA-Z+/]+$#', $rand) === 1);
         }
     }
+
+    public function testHashTimingSourceStrengthIsVeryLow()
+    {
+        $this->assertEquals(1, (string) Math\Source\HashTiming::getStrength());
+    }
+
+    public function testHashTimingSourceStrengthIsRandomWithCorrectLength()
+    {
+        $source = new Math\Source\HashTiming;
+        $rand = $source->generate(32);
+        $this->assertTrue(32 === strlen($rand));
+        $rand2 = $source->generate(32);
+        $this->assertNotEquals($rand, $rand2);
+    }
+
+    public function testAltGeneratorIsRandomWithCorrectLength()
+    {
+        $source = Math\Rand::getAlternativeGenerator();
+        $rand = $source->generate(32);
+        $this->assertTrue(32 === strlen($rand));
+        $rand2 = $source->generate(32);
+        $this->assertNotEquals($rand, $rand2);
+    }
 }