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<?php
/**
* Zend Framework (http://framework.zend.com/)
*
* @link http://github.com/zendframework/zf2 for the canonical source repository
* @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @package Zend_Math
*/
namespace Zend\Math;
/**
* Pseudorandom number generator (PRNG)
*
* @category Zend
* @package Zend_Math
* @subpackage Rand
*/
abstract class Rand
{
/**
* Generate random bytes using OpenSSL or Mcrypt and mt_rand() as fallback
*
* @param integer $length
* @param boolean $strong true if you need a strong random generator (cryptography)
* @return string
* @throws Exception\RuntimeException
*/
public static function getBytes($length, $strong = false)
{
if ($length <= 0) {
return false;
}
if (extension_loaded('openssl')) {
$rand = openssl_random_pseudo_bytes($length, $secure);
if ($secure === true) {
return $rand;
}
}
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 $rand;
}
}
}
if ($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'
);
}
$rand = '';
for ($i = 0; $i < $length; $i++) {
$rand .= chr(mt_rand(0, 255));
}
return $rand;
}
/**
* Generate random boolean
*
* @param boolean $strong true if you need a strong random generator (cryptography)
* @return bool
*/
public static function getBoolean($strong = false)
{
$byte = static::getBytes(1, $strong);
return (boolean) (ord($byte) % 2);
}
/**
* Generate a random integer between $min and $max
*
* @param integer $min
* @param integer $max
* @param boolean $strong true if you need a strong random generator (cryptography)
* @return integer
* @throws Exception\DomainException
*/
public static function getInteger($min, $max, $strong = false)
{
if ($min > $max) {
throw new Exception\DomainException(
'The min parameter must be lower than max parameter'
);
}
$range = $max - $min;
if ($range == 0) {
return $max;
} elseif ($range > PHP_INT_MAX || is_float($range)) {
throw new Exception\DomainException(
'The supplied range is too great to generate'
);
}
$log = log($range, 2);
$bytes = (int) ($log / 8) + 1;
$bits = (int) $log + 1;
$filter = (int) (1 << $bits) - 1;
do {
$rnd = hexdec(bin2hex(self::getBytes($bytes, $strong)));
$rnd = $rnd & $filter;
} while ($rnd > $range);
return ($min + $rnd);
}
/**
* Generate random float (0..1)
* This function generates floats with platform-dependent precision
*
* PHP uses double precision floating-point format (64-bit) which has
* 52-bits of significand precision. We gather 7 bytes of random data,
* and we fix the exponent to the bias (1023). In this way we generate
* a float of 1.mantissa.
*
* @param boolean $strong true if you need a strong random generator (cryptography)
* @return float
*/
public static function getFloat($strong = false)
{
$bytes = static::getBytes(7, $strong);
$bytes[6] = $bytes[6] | chr(0xF0);
$bytes .= chr(63); // exponent bias (1023)
list(, $float) = unpack('d', $bytes);
return ($float - 1);
}
/**
* Generate a random string of specified length.
*
* Uses supplied character list for generating the new string.
* If no character list provided - uses Base 64 character set.
*
* @param integer $length
* @param string|null $charlist
* @param boolean $strong true if you need a strong random generator (cryptography)
* @return string
* @throws Exception\DomainException
*/
public static function getString($length, $charlist = null, $strong = false)
{
if ($length < 1) {
throw new Exception\DomainException('Length should be >= 1');
}
// charlist is empty or not provided
if (empty($charlist)) {
$numBytes = ceil($length * 0.75);
$bytes = static::getBytes($numBytes, $strong);
return substr(rtrim(base64_encode($bytes), '='), 0, $length);
}
$listLen = strlen($charlist);
if ($listLen == 1) {
return str_repeat($charlist, $length);
}
$bytes = static::getBytes($length, $strong);
$pos = 0;
$result = '';
for ($i = 0; $i < $length; $i++) {
$pos = ($pos + ord($bytes[$i])) % $listLen;
$result .= $charlist[$pos];
}
return $result;
}
}
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