function rsa_sign($message, $private_key, $modulus, $keylength)
{
$padded = add_PKCS1_padding($message, false, $keylength / 8);
$number = binary_to_number($padded);
$signed = pow_mod($number, $private_key, $modulus);
$result = number_to_binary($signed, $keylength / 8);
return $result;
}
/**
*
* @param $message // $message is expected to be binary data
* @param $private_key // $modulus should be numbers in (decimal) string format
* @param $modulus // $modulus should be numbers in (decimal) string format
* @param $keylength // int
* @param $hash_func // name of hash function, which will be used during signing
* @return $result // signature String in Base64 format
*/
function rsa_sign($message, $private_key, $modulus, $keylength, $hash_func)
{
//only suport sha1 or md5 digest now
if (!function_exists($hash_func) && (strcmp($hash_func, 'sha1') == 0 || strcmp($hash_func, 'md5') == 0)) {
return false;
}
$mssage_digest_info_hex = $hash_func($message);
$mssage_digest_info_bin = hex2bin($mssage_digest_info_hex);
$padded = add_PKCS1_padding($mssage_digest_info_bin, false, $keylength / 8);
$number = binary_to_number($padded);
$signed = pow_mod($number, $private_key, $modulus);
$result = base64_encode($signed);
return $result;
}