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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Crypt_RSA allows to do following operations:
* - key pair generation
* - encryption and decryption
* - signing and sign validation
*
* PHP versions 4 and 5
*
* LICENSE: This source file is subject to version 3.0 of the PHP license
* that is available through the world-wide-web at the following URI:
* http://www.php.net/license/3_0.txt. If you did not receive a copy of
* the PHP License and are unable to obtain it through the web, please
* send a note to license@php.net so we can mail you a copy immediately.
*
* @category Encryption
* @package Crypt_RSA
* @author Alexander Valyalkin <valyala@gmail.com>
* @copyright 2005 Alexander Valyalkin
* @license http://www.php.net/license/3_0.txt PHP License 3.0
* @version 1.0.0
* @link http://pear.php.net/package/Crypt_RSA
*/
/**
* Crypt_RSA_Math_BCMath class.
*
* Provides set of math functions, which are used by Crypt_RSA package
* This class is a wrapper for PHP BCMath extension.
* See http://php.net/manual/en/ref.bc.php for details.
*
* @category Encryption
* @package Crypt_RSA
* @author Alexander Valyalkin <valyala@gmail.com>
* @copyright 2005 Alexander Valyalkin
* @license http://www.php.net/license/3_0.txt PHP License 3.0
* @link http://pear.php.net/package/Crypt_RSA
* @version @package_version@
* @access public
*/
class Crypt_RSA_Math_BCMath
{
/**
* error description
*
* @var string
* @access public
*/
var $errstr = '';
/**
* Tests $num on primality. Returns true, if $num is strong pseudoprime.
* Else returns false.
*
* @param string $num
* @return bool
* @access private
*/
function _isPrime($num)
{
static $primes = null;
static $primes_cnt = 0;
if (is_null($primes)) {
// generate all primes up to 10000
$primes = array();
for ($i = 0; $i < 10000; $i++) {
$primes[] = $i;
}
$primes[0] = $primes[1] = 0;
for ($i = 2; $i < 100; $i++) {
while (!$primes[$i]) {
$i++;
}
$j = $i;
for ($j += $i; $j < 10000; $j += $i) {
$primes[$j] = 0;
}
}
$j = 0;
for ($i = 0; $i < 10000; $i++) {
if ($primes[$i]) {
$primes[$j++] = $primes[$i];
}
}
$primes_cnt = $j;
}
// try to divide number by small primes
for ($i = 0; $i < $primes_cnt; $i++) {
if (bccomp($num, $primes[$i]) <= 0) {
// number is prime
return true;
}
if (!bccomp(bcmod($num, $primes[$i]), '0')) {
// number divides by $primes[$i]
return false;
}
}
/*
try Miller-Rabin's probable-primality test for first
7 primes as bases
*/
for ($i = 0; $i < 7; $i++) {
if (!$this->_millerTest($num, $primes[$i])) {
// $num is composite
return false;
}
}
// $num is strong pseudoprime
return true;
}
/**
* Performs Miller-Rabin primality test for number $num
* with base $base. Returns true, if $num is strong pseudoprime
* by base $base. Else returns false.
*
* @param string $num
* @param string $base
* @return bool
* @access private
*/
function _millerTest($num, $base)
{
if (!bccomp($num, '1')) {
// 1 is not prime ;)
return false;
}
$tmp = bcsub($num, '1');
$zero_bits = 0;
while (!bccomp(bcmod($tmp, '2'), '0')) {
$zero_bits++;
$tmp = bcdiv($tmp, '2');
}
$tmp = $this->powmod($base, $tmp, $num);
if (!bccomp($tmp, '1')) {
// $num is probably prime
return true;
}
while ($zero_bits--) {
if (!bccomp(bcadd($tmp, '1'), $num)) {
// $num is probably prime
return true;
}
$tmp = $this->powmod($tmp, '2', $num);
}
// $num is composite
return false;
}
/**
* Crypt_RSA_Math_BCMath constructor.
* Checks an existance of PHP BCMath extension.
* On failure saves error description in $this->errstr
*
* @access public
*/
function Crypt_RSA_Math_BCMath()
{
if (!extension_loaded('bcmath')) {
if (!@dl('bcmath.' . PHP_SHLIB_SUFFIX) && !@dl('php_bcmath.' . PHP_SHLIB_SUFFIX)) {
// cannot load BCMath extension. Set error string
$this->errstr = 'Crypt_RSA package requires the BCMath extension. See http://php.net/manual/en/ref.bc.php for details';
return;
}
}
}
/**
* Transforms binary representation of large integer into its native form.
*
* Example of transformation:
* $str = "\x12\x34\x56\x78\x90";
* $num = 0x9078563412;
*
* @param string $str
* @return string
* @access public
*/
function bin2int($str)
{
$result = '0';
$n = strlen($str);
do {
$result = bcadd(bcmul($result, '256'), ord($str{--$n}));
} while ($n > 0);
return $result;
}
/**
* Transforms large integer into binary representation.
*
* Example of transformation:
* $num = 0x9078563412;
* $str = "\x12\x34\x56\x78\x90";
*
* @param string $num
* @return string
* @access public
*/
function int2bin($num)
{
$result = '';
do {
$result .= chr(bcmod($num, '256'));
$num = bcdiv($num, '256');
} while (bccomp($num, '0'));
return $result;
}
/**
* Calculates pow($num, $pow) (mod $mod)
*
* @param string $num
* @param string $pow
* @param string $mod
* @return string
* @access public
*/
function powmod($num, $pow, $mod)
{
if (function_exists('bcpowmod')) {
// bcpowmod is only available under PHP5
return bcpowmod($num, $pow, $mod);
}
// emulate bcpowmod
$result = '1';
do {
if (!bccomp(bcmod($pow, '2'), '1')) {
$result = bcmod(bcmul($result, $num), $mod);
}
$num = bcmod(bcpow($num, '2'), $mod);
$pow = bcdiv($pow, '2');
} while (bccomp($pow, '0'));
return $result;
}
/**
* Calculates $num1 * $num2
*
* @param string $num1
* @param string $num2
* @return string
* @access public
*/
function mul($num1, $num2)
{
return bcmul($num1, $num2);
}
/**
* Compares abs($num1) to abs($num2).
* Returns:
* -1, if abs($num1) < abs($num2)
* 0, if abs($num1) == abs($num2)
* 1, if abs($num1) > abs($num2)
*
* @param string $num1
* @param string $num2
* @return int
* @access public
*/
function cmpAbs($num1, $num2)
{
return bccomp($num1, $num2);
}
/**
* Finds next strong pseudoprime number, following after $num
*
* @param string $num
* @return string
* @access public
*/
function nextPrime($num)
{
if (!bccomp(bcmod($num, '2'), '0')) {
$num = bcsub($num, '1');
}
do {
$num = bcadd($num, '2');
} while (!$this->_isPrime($num));
return $num;
}
/**
* Generates random number wich bit length $bits_cnt,
* using $random_generator as random generator function.
* If is_set_higher_bit != false, then higer bit of result
* will be set to 1.
*
* @param int $bits_cnt
* @param string $rnd_generator
* @return string
* @access public
*/
function getRand($bits_cnt, $random_generator, $is_set_higher_bit = false)
{
$bytes_cnt = intval($bits_cnt / 8);
$bits_cnt %= 8;
$result = $is_set_higher_bit ? 1 : (call_user_func($random_generator) & 1);
for ($i = 0; $i <= $bytes_cnt; $i++) {
$result = bcadd(bcmul($result, '256'), call_user_func($random_generator) & 0xff);
}
$result = bcdiv($result, 1 << (9 - $bits_cnt));
return $result;
}
/**
* Calculates $num - 1
*
* @param string $num
* @return string
* @access public
*/
function dec($num)
{
return bcsub($num, '1');
}
/**
* Returns true, if $num is equal to zero. Else returns false
*
* @param string $num
* @return bool
* @access public
*/
function isZero($num)
{
return !bccomp($num, '0');
}
/**
* Finds greatest common divider (GCD) of $num1 and $num2
*
* @param string $num1
* @param string $num2
* @return string
* @access public
*/
function gcd($num1, $num2)
{
do {
$tmp = bcmod($num1, $num2);
$num1 = $num2;
$num2 = $tmp;
} while (bccomp($num2, '0'));
return $num1;
}
/**
* Finds inverse number $inv for $num by modulus $mod, such as:
* $inv * $num = 1 (mod $mod)
*
* @param string $num
* @param string $mod
* @return string
* @access public
*/
function invmod($num, $mod)
{
$x = '1';
$y = '0';
$num1 = $mod;
do {
$tmp = bcmod($num, $num1);
$q = bcdiv($num, $num1);
$num = $num1;
$num1 = $tmp;
$tmp = bcsub($x, bcmul($y, $q));
$x = $y;
$y = $tmp;
} while (bccomp($num1, '0'));
if (bccomp($x, '0') < 0) {
$x = bcadd($x, $mod);
}
return $x;
}
/**
* Returns bit length of number $num
*
* @param string $num
* @return int
* @access public
*/
function bitLen($num)
{
$tmp = $this->int2bin($num);
$bit_len = strlen($tmp) * 8;
$tmp = ord($tmp{strlen($tmp) - 1});
if (!$tmp) {
$bit_len -= 8;
} else {
while (!($tmp & 0x80)) {
$bit_len--;
$tmp <<= 1;
}
}
return $bit_len;
}
/**
* Calculates bitwise or of $num1 and $num2,
* starting from bit $start_pos for number $num1
*
* @param string $num1
* @param string $num2
* @param int $start_pos
* @return string
* @access public
*/
function bitOr($num1, $num2, $start_pos)
{
$start_byte = intval($start_pos / 8);
$start_bit = $start_pos % 8;
$tmp1 = $this->int2bin($num1);
$num2 = bcmul($num2, 1 << $start_bit);
$tmp2 = $this->int2bin($num2);
if ($start_byte < strlen($tmp1)) {
$tmp2 |= substr($tmp1, $start_byte);
$tmp1 = substr($tmp1, 0, $start_byte) . $tmp2;
} else {
$tmp1 = str_pad($tmp1, $start_byte, "\0") . $tmp2;
}
return $this->bin2int($tmp1);
}
/**
* Returns part of number $num, starting at bit
* position $start with length $length
*
* @param string $num
* @param int start
* @param int length
* @return string
* @access public
*/
function subint($num, $start, $length)
{
$start_byte = intval($start / 8);
$start_bit = $start % 8;
$byte_length = intval($length / 8);
$bit_length = $length % 8;
if ($bit_length) {
$byte_length++;
}
$num = bcdiv($num, 1 << $start_bit);
$tmp = substr($this->int2bin($num), $start_byte, $byte_length);
$tmp = str_pad($tmp, $byte_length, "\0");
$tmp = substr_replace($tmp, $tmp{$byte_length - 1} & chr(0xff >> (8 - $bit_length)), $byte_length - 1, 1);
return $this->bin2int($tmp);
}
/**
* Returns name of current wrapper
*
* @return string name of current wrapper
* @access public
*/
function getWrapperName()
{
return 'BCMath';
}
}
?>
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