/**
returns RSA key pair with length $bit_len
*/
function generate_key_pair($bit_len)
{
// generate two primes p and q
$p_len = (int) ($bit_len / 2) + 1;
$q_len = $bit_len - $p_len;
$p = get_prime($p_len);
$q = get_prime($q_len);
// $n - is shared modulus
$n = bi_mul($p, $q);
// generate public ($e) and private ($d) keys
$pq = bi_mul(bi_dec($p), bi_dec($q));
do {
$e = bi_rand($q_len, 'microtime_generator');
} while (!bi_is_zero(bi_dec(bi_gcd($e, $pq))));
$d = bi_invmod($e, $pq);
return array('n' => bi_serialize($n), 'public_key' => bi_serialize($e), 'private_key' => bi_serialize($d));
}
/**
* Returns true, if $num is equal to zero. Else returns false
*
* @param big_int resource $num
* @return bool
* @access public
*/
function isZero($num)
{
return bi_is_zero($num);
}
echo '$a / $b = [', bi_to_str($c), "]<br/>\n";
$c = bi_mod($a, $b);
echo '$a % $b = [', bi_to_str($c), "]<br/>\n";
$c = bi_abs($a);
echo 'abs($a) = [', bi_to_str($c), "]<br/>\n";
$c = bi_neg($a);
echo 'neg($a) = [', bi_to_str($c), "]<br/>\n";
$c = bi_inc($a);
echo 'inc($a) = [', bi_to_str($c), "]<br/>\n";
$c = bi_dec($a);
echo 'dec($a) = [', bi_to_str($c), "]<br/>\n";
$c = bi_sqr($a);
echo 'sqr($a) = [', bi_to_str($c), "]<br/>\n";
echo 'cmp($a, $b) = ', bi_cmp($a, $b), "<br/>\n";
echo 'cmp_abs($a, $b) = ', bi_cmp_abs($a, $b), "<br/>\n";
echo 'is_zero($a) = ', bi_is_zero($a) ? 'true' : 'false', "<br/>\n";
echo 'is_one($a) = ', bi_is_one($a) ? 'true' : 'false', "<br/>\n";
echo 'sign($a) = ', bi_sign($a), "<br/>\n";
/*
bitset functions
*/
echo '<h3>bitset functions</h3>' . "\n";
echo '<div style="text-align:right">';
echo '$a = [', bi_to_str($a, 2), "]<br/>\n";
echo '$b = [', bi_to_str($b, 2), "]<br/>\n";
$c = bi_or($a, $b);
echo '$a or $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_xor($a, $b);
echo '$a xor $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_and($a, $b);
echo '$a and $b = [', bi_to_str($c, 2), "]<br/>\n";