}
function bigint_powmod($x, $y, $m)
{
return gmp_powm($x, $y, $m);
}
} else {
if (extension_loaded('big_int')) {
function bigint_dec2num($dec)
/**
* 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 $rnd_generator
* @return big_int resource
* @access public
*/
function getRand($bits_cnt, $random_generator, $is_set_higher_bit = false)
{
$tmp = bi_rand($bits_cnt, $random_generator);
return $is_set_higher_bit ? bi_set_bit($tmp, $bits_cnt - 1) : $tmp;
}
/**
* Constructor
*
* @param String Private key, if not included one shall be generated
*/
function Diffie_Hellman_BI($privkey = "")
{
if (empty($privkey)) {
$privkey = bi_rand(160);
}
$this->privatekey = $privkey;
}
public static function random($n, $s)
{
switch (BigInt::support()) {
case 'gmp':
$result = gmp_init(0);
for ($i = 0; $i < $n; $i++) {
if (mt_rand(0, 1)) {
gmp_setbit($result, $i);
}
}
if ($s) {
gmp_setbit($result, $n - 1);
}
return $result;
case 'big_int':
$result = bi_rand($n);
if ($s) {
$result = bi_set_bit($result, $n - 1);
}
return $result;
case 'bcmath':
bcscale(0);
$t = BigInt::bcpow(2, $n);
if ($s == 1) {
$m = bcdiv($t, 2);
$t = bcsub($m, 1);
} else {
$m = 0;
$t = bcsub($t, 1);
}
$l = strlen($t);
$n = (int) ($l / 9) + 1;
$r = '';
while ($n) {
$r .= substr('000000000' . mt_rand(0, 999999999), -9);
--$n;
}
$r = substr($r, 0, $l);
while (bccomp($r, $t) == 1) {
$r = substr($r, 1, $l) . mt_rand(0, 9);
}
return bcadd($r, $m);
case '':
default:
return BigInt::_random($n, $s);
}
}
echo 'bit_len($a) = ', bi_bit_len($a), "<br/>\n";
echo 'bit1_cnt($a) = ', bi_bit1_cnt($a), "<br/>\n";
echo 'test_bit($a, 0) = ', bi_test_bit($a, 0), "<br/>\n";
echo 'scan0_bit($a, 0) = ', bi_scan0_bit($a, 0), "<br/>\n";
echo 'scan1_bit($a, 0) = ', bi_scan1_bit($a, 0), "<br/>\n";
echo '<h3>pseudorandom functions</h3>' . "\n";
/*
resource bi_rand(int $bit_len[, string $rand_func_name])
Returns pseudorandom number with $bit_len bit length.
Attention: do not use this function in cryptographic
or security applications! The function can be used only
for educational purposes :)
*/
$c = bi_rand(100);
echo 'rand(100) = ', bi_to_str($c), "<br/>\n";
$c = bi_rand(100, 'mt_rand');
// use mt_rand() as random generator
echo 'rand(100, "mt_rand") = ', bi_to_str($c), "<br/>\n";
/*
functions for modular arithmetic calculations
*/
echo '<h3>modular arithmetic functions</h3>' . "\n";
// find next pseudoprime number after $c
$modulus = bi_next_prime($c);
echo '$modulus = next_prime($c) = [', bi_to_str($modulus), "]<br/>\n";
$c = bi_addmod($a, $b, $modulus);
echo '$a + $b (mod $modulus) = [', bi_to_str($c), "]<br/>\n";
$c = bi_submod($a, $b, $modulus);
echo '$a - $b (mod $modulus) = [', bi_to_str($c), "]<br/>\n";
$c = bi_mulmod($a, $b, $modulus);
echo '$a * $b (mod $modulus) = [', bi_to_str($c), "]<br/>\n";
/**
returns a "good" prime $a with length $bit_len with
resrtiction:
$a - 1 != 0 (mod $e)
*/
function get_prime($bit_len)
{
return bi_next_prime(bi_set_bit(bi_rand($bit_len, 'microtime_generator'), $bit_len - 1));
}
/**
example:
usage of user function as random number generator
for bi_rand() function.
bi_rand() uses only lower byte of value, returned by
user function.
*/
require_once dirname(__FILE__) . '/std_header.php';
echo "const generator:<br>\n";
echo bi_to_str(bi_rand(100, 'const_generator'), 16), "<br>\n\n";
echo "time generator:<br>\n";
echo bi_to_str(bi_rand(100, 'time_generator'), 16), "<br>\n\n";
echo "microtime generator:<br>\n";
echo bi_to_str(bi_rand(100, 'microtime_generator'), 16), "<br>\n\n";
echo "static generator:<br>\n";
echo bi_to_str(bi_rand(100, 'static_generator'), 16), "<br>\n\n";
exit;
/***************************************************************************/
/**
'constant' number generator
*/
function const_generator()
{
return 0xff;
}
/**
time() number generator
*/
function time_generator()
{
//sleep(1);
