randval.php
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<?php
/**
* @package FrameworkOnFramework
* @subpackage utils
* @copyright Copyright (C) 2010-2016 Nicholas K. Dionysopoulos / Akeeba Ltd. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE.txt
*/
// Protect from unauthorized access
defined('FOF_INCLUDED') or die;
/**
* Generates cryptographically-secure random values.
*/
class FOFEncryptRandval implements FOFEncryptRandvalinterface
{
/**
* @var FOFUtilsPhpfunc
*/
protected $phpfunc;
/**
*
* Constructor.
*
* @param FOFUtilsPhpfunc $phpfunc An object to intercept PHP function calls;
* this makes testing easier.
*
*/
public function __construct(FOFUtilsPhpfunc $phpfunc = null)
{
if (!is_object($phpfunc) || !($phpfunc instanceof FOFUtilsPhpfunc))
{
$phpfunc = new FOFUtilsPhpfunc();
}
$this->phpfunc = $phpfunc;
}
/**
*
* Returns a cryptographically secure random value.
*
* @param integer $bytes How many bytes to return
*
* @return string
*/
public function generate($bytes = 32)
{
if ($this->phpfunc->extension_loaded('openssl') && (version_compare(PHP_VERSION, '5.3.4') >= 0 || IS_WIN))
{
$strong = false;
$randBytes = openssl_random_pseudo_bytes($bytes, $strong);
if ($strong)
{
return $randBytes;
}
}
if ($this->phpfunc->extension_loaded('mcrypt'))
{
return $this->phpfunc->mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM);
}
return $this->genRandomBytes($bytes);
}
/**
* Generate random bytes. Adapted from Joomla! 3.2.
*
* @param integer $length Length of the random data to generate
*
* @return string Random binary data
*/
public function genRandomBytes($length = 32)
{
$length = (int) $length;
$sslStr = '';
/*
* Collect any entropy available in the system along with a number
* of time measurements of operating system randomness.
*/
$bitsPerRound = 2;
$maxTimeMicro = 400;
$shaHashLength = 20;
$randomStr = '';
$total = $length;
// Check if we can use /dev/urandom.
$urandom = false;
$handle = null;
// This is PHP 5.3.3 and up
if ($this->phpfunc->function_exists('stream_set_read_buffer') && @is_readable('/dev/urandom'))
{
$handle = @fopen('/dev/urandom', 'rb');
if ($handle)
{
$urandom = true;
}
}
while ($length > strlen($randomStr))
{
$bytes = ($total > $shaHashLength)? $shaHashLength : $total;
$total -= $bytes;
/*
* Collect any entropy available from the PHP system and filesystem.
* If we have ssl data that isn't strong, we use it once.
*/
$entropy = rand() . uniqid(mt_rand(), true) . $sslStr;
$entropy .= implode('', @fstat(fopen(__FILE__, 'r')));
$entropy .= memory_get_usage();
$sslStr = '';
if ($urandom)
{
stream_set_read_buffer($handle, 0);
$entropy .= @fread($handle, $bytes);
}
else
{
/*
* There is no external source of entropy so we repeat calls
* to mt_rand until we are assured there's real randomness in
* the result.
*
* Measure the time that the operations will take on average.
*/
$samples = 3;
$duration = 0;
for ($pass = 0; $pass < $samples; ++$pass)
{
$microStart = microtime(true) * 1000000;
$hash = sha1(mt_rand(), true);
for ($count = 0; $count < 50; ++$count)
{
$hash = sha1($hash, true);
}
$microEnd = microtime(true) * 1000000;
$entropy .= $microStart . $microEnd;
if ($microStart >= $microEnd)
{
$microEnd += 1000000;
}
$duration += $microEnd - $microStart;
}
$duration = $duration / $samples;
/*
* Based on the average time, determine the total rounds so that
* the total running time is bounded to a reasonable number.
*/
$rounds = (int) (($maxTimeMicro / $duration) * 50);
/*
* Take additional measurements. On average we can expect
* at least $bitsPerRound bits of entropy from each measurement.
*/
$iter = $bytes * (int) ceil(8 / $bitsPerRound);
for ($pass = 0; $pass < $iter; ++$pass)
{
$microStart = microtime(true);
$hash = sha1(mt_rand(), true);
for ($count = 0; $count < $rounds; ++$count)
{
$hash = sha1($hash, true);
}
$entropy .= $microStart . microtime(true);
}
}
$randomStr .= sha1($entropy, true);
}
if ($urandom)
{
@fclose($handle);
}
return substr($randomStr, 0, $length);
}
}