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- improved random number generator

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git-svn-id: http://phpseclib.svn.sourceforge.net/svnroot/phpseclib/trunk@89 21d32557-59b3-4da0-833f-c5933fad653e
This commit is contained in:
Jim Wigginton 2010-02-19 22:39:44 +00:00
parent 21184a90e4
commit f2ccfdb0ac
1 changed files with 84 additions and 16 deletions
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phpseclib/Crypt/Random.php
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@ -35,36 +35,104 @@
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVII Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: Random.php,v 1.4 2008-05-21 05:15:32 terrafrost Exp $
* @version $Id: Random.php,v 1.5 2010-02-19 22:39:44 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**
* Generate a random value. Feel free to replace this function with a cryptographically secure PRNG.
* Generate a random value.
*
* On 32-bit machines, the largest distance that can exist between $min and $max is 2**31.
* If $min and $max are farther apart than that then the last ($max - range) numbers.
*
* Depending on how this is being used, it may be worth while to write a replacement. For example,
* a PHP-based web app that stores its data in an SQL database can collect more entropy than this function
* can.
*
* @param optional Integer $min
* @param optional Integer $max
* @param optional String $randomness_path
* @return Integer
* @access public
*/
function crypt_random($min = 0, $max = 0x7FFFFFFF, $randomness_path = '/dev/urandom')
function crypt_random($min = 0, $max = 0x7FFFFFFF)
{
static $seeded = false;
// see http://en.wikipedia.org/wiki//dev/random
if (file_exists('/dev/urandom')) {
$fp = fopen('/dev/urandom', 'rb');
extract(unpack('Nrandom', fread($fp, 4)));
fclose($fp);
if (!$seeded) {
$seeded = true;
if (file_exists($randomness_path)) {
$fp = fopen($randomness_path, 'r');
$temp = unpack('Nint', fread($fp, 4));
mt_srand($temp['int']);
fclose($fp);
} else {
list($sec, $usec) = explode(' ', microtime());
mt_srand((float) $sec + ((float) $usec * 100000));
// say $min = 0 and $max = 3. if we didn't do abs() then we could have stuff like this:
// -4 % 3 + 0 = -1, even though -1 < $min
return abs($random) % ($max - $min) + $min;
}
/* Prior to PHP 4.2.0, mt_srand() had to be called before mt_rand() could be called.
Prior to PHP 5.2.6, mt_rand()'s automatic seeding was subpar, as elaborated here:
http://www.suspekt.org/2008/08/17/mt_srand-and-not-so-random-numbers/
The seeding routine is pretty much ripped from PHP's own internal GENERATE_SEED() macro:
http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3_2/ext/standard/php_rand.h?view=markup */
if (version_compare(PHP_VERSION, '5.2.5', '<=')) {
static $seeded;
if (!isset($seeded)) {
$seeded = true;
mt_srand(fmod(time() * getmypid(), 0x7FFFFFFF) ^ fmod(1000000 * lcg_value(), 0x7FFFFFFF));
}
}
return mt_rand($min, $max);
static $crypto;
// The CSPRNG's Yarrow and Fortuna periodically reseed. This function can be reseeded by hitting F5
// in the browser and reloading the page.
if (!isset($crypto)) {
switch (true) {
case class_exists('Crypt_AES'):
$key = $iv = '';
for ($i = 0; $i < 8; $i++) {
$key.= pack('n', mt_rand(0, 0xFFFF));
$iv .= pack('n', mt_rand(0, 0xFFFF));
}
$crypto = new Crypt_AES(CRYPT_AES_MODE_CTR);
$crypto->setKey($key);
$crypto->setIV($iv);
break;
case class_exists('Crypt_TripleDES'):
case class_exists('Crypt_DES'):
$key = $iv = '';
for ($i = 0; $i < 4; $i++) {
$key.= pack('n', mt_rand(0, 0xFFFF));
$iv .= pack('n', mt_rand(0, 0xFFFF));
}
if (class_exists('Crypt_TripleDES')) {
for ($i = 0; $i < 4; $i++) {
$key.= pack('n', mt_rand(0, 0xFFFF));
}
$crypto = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
} else {
$crypto = new Crypt_DES(CRYPT_DES_MODE_CTR);
}
$crypto->setKey($key);
$crypto->setIV($iv);
break;
case class_exists('Crypt_RC4'):
$key = '';
for ($i = 0; $i < 8; $i++) {
$key.= pack('n', mt_rand(0, 0xFFFF));
}
$crypto = new Crypt_RC4();
$crypto->setKey($key);
break;
default:
extract(unpack('Nrandom', pack('H*', sha1(mt_rand(0, 0x7FFFFFFF)))));
return abs($random) % ($max - $min) + $min;
}
}
extract(unpack('Nrandom', $crypto->encrypt("\0\0\0\0")));
return abs($random) % ($max - $min) + $min;
}
?>