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<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2014-2018 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/
namespace Jose\Component\Signature\Util;
use Jose\Component\Core\Util\BigInteger;
use Jose\Component\Core\Util\Hash;
use Jose\Component\Core\Util\RSAKey;
/**
* @internal
*/
class RSA
{
/**
* Probabilistic Signature Scheme.
*/
public const SIGNATURE_PSS = 1;
/**
* Use the PKCS#1.
*/
public const SIGNATURE_PKCS1 = 2;
private static function convertIntegerToOctetString(BigInteger $x, int $xLen): string
{
$x = $x->toBytes();
if (\mb_strlen($x, '8bit') > $xLen) {
throw new \RuntimeException();
}
return \str_pad($x, $xLen, \chr(0), STR_PAD_LEFT);
}
/**
* MGF1.
*/
private static function getMGF1(string $mgfSeed, int $maskLen, Hash $mgfHash): string
{
$t = '';
$count = \ceil($maskLen / $mgfHash->getLength());
for ($i = 0; $i < $count; ++$i) {
$c = \pack('N', $i);
$t .= $mgfHash->hash($mgfSeed.$c);
}
return \mb_substr($t, 0, $maskLen, '8bit');
}
/**
* EMSA-PSS-ENCODE.
*/
private static function encodeEMSAPSS(string $message, int $modulusLength, Hash $hash): string
{
$emLen = ($modulusLength + 1) >> 3;
$sLen = $hash->getLength();
$mHash = $hash->hash($message);
if ($emLen <= $hash->getLength() + $sLen + 2) {
throw new \RuntimeException();
}
$salt = \random_bytes($sLen);
$m2 = "\0\0\0\0\0\0\0\0".$mHash.$salt;
$h = $hash->hash($m2);
$ps = \str_repeat(\chr(0), $emLen - $sLen - $hash->getLength() - 2);
$db = $ps.\chr(1).$salt;
$dbMask = self::getMGF1($h, $emLen - $hash->getLength() - 1, $hash);
$maskedDB = $db ^ $dbMask;
$maskedDB[0] = ~\chr(0xFF << ($modulusLength & 7)) & $maskedDB[0];
$em = $maskedDB.$h.\chr(0xBC);
return $em;
}
/**
* EMSA-PSS-VERIFY.
*/
private static function verifyEMSAPSS(string $m, string $em, int $emBits, Hash $hash): bool
{
$emLen = ($emBits + 1) >> 3;
$sLen = $hash->getLength();
$mHash = $hash->hash($m);
if ($emLen < $hash->getLength() + $sLen + 2) {
throw new \InvalidArgumentException();
}
if ($em[\mb_strlen($em, '8bit') - 1] !== \chr(0xBC)) {
throw new \InvalidArgumentException();
}
$maskedDB = \mb_substr($em, 0, -$hash->getLength() - 1, '8bit');
$h = \mb_substr($em, -$hash->getLength() - 1, $hash->getLength(), '8bit');
$temp = \chr(0xFF << ($emBits & 7));
if ((~$maskedDB[0] & $temp) !== $temp) {
throw new \InvalidArgumentException();
}
$dbMask = self::getMGF1($h, $emLen - $hash->getLength() - 1, $hash/*MGF*/);
$db = $maskedDB ^ $dbMask;
$db[0] = ~\chr(0xFF << ($emBits & 7)) & $db[0];
$temp = $emLen - $hash->getLength() - $sLen - 2;
if (\mb_substr($db, 0, $temp, '8bit') !== \str_repeat(\chr(0), $temp)) {
throw new \InvalidArgumentException();
}
if (1 !== \ord($db[$temp])) {
throw new \InvalidArgumentException();
}
$salt = \mb_substr($db, $temp + 1, null, '8bit'); // should be $sLen long
$m2 = "\0\0\0\0\0\0\0\0".$mHash.$salt;
$h2 = $hash->hash($m2);
return \hash_equals($h, $h2);
}
private static function encodeEMSA15(string $m, int $emBits, Hash $hash): string
{
$h = $hash->hash($m);
switch ($hash->name()) {
case 'sha256':
$t = "\x30\x31\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01\x05\x00\x04\x20";
break;
case 'sha384':
$t = "\x30\x41\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x02\x05\x00\x04\x30";
break;
case 'sha512':
$t = "\x30\x51\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x03\x05\x00\x04\x40";
break;
default:
throw new \InvalidArgumentException();
}
$t .= $h;
$tLen = \mb_strlen($t, '8bit');
if ($emBits < $tLen + 11) {
throw new \RuntimeException();
}
$ps = \str_repeat(\chr(0xFF), $emBits - $tLen - 3);
$em2 = "\0\1$ps\0$t";
return $em2;
}
public static function sign(RSAKey $key, string $message, string $hash, int $mode): string
{
switch ($mode) {
case self::SIGNATURE_PSS:
return self::signWithPSS($key, $message, $hash);
case self::SIGNATURE_PKCS1:
return self::signWithPKCS15($key, $message, $hash);
default:
throw new \InvalidArgumentException('Unsupported mode.');
}
}
/**
* Create a signature.
*/
public static function signWithPSS(RSAKey $key, string $message, string $hash): string
{
$em = self::encodeEMSAPSS($message, 8 * $key->getModulusLength() - 1, Hash::$hash());
$message = BigInteger::createFromBinaryString($em);
$signature = RSAKey::exponentiate($key, $message);
return self::convertIntegerToOctetString($signature, $key->getModulusLength());
}
/**
* Create a signature.
*/
public static function signWithPKCS15(RSAKey $key, string $message, string $hash): string
{
$em = self::encodeEMSA15($message, $key->getModulusLength(), Hash::$hash());
$message = BigInteger::createFromBinaryString($em);
$signature = RSAKey::exponentiate($key, $message);
return self::convertIntegerToOctetString($signature, $key->getModulusLength());
}
public static function verify(RSAKey $key, string $message, string $signature, string $hash, int $mode): bool
{
switch ($mode) {
case self::SIGNATURE_PSS:
return self::verifyWithPSS($key, $message, $signature, $hash);
case self::SIGNATURE_PKCS1:
return self::verifyWithPKCS15($key, $message, $signature, $hash);
default:
throw new \InvalidArgumentException('Unsupported mode.');
}
}
/**
* Verifies a signature.
*/
public static function verifyWithPSS(RSAKey $key, string $message, string $signature, string $hash): bool
{
if (\mb_strlen($signature, '8bit') !== $key->getModulusLength()) {
throw new \InvalidArgumentException();
}
$s2 = BigInteger::createFromBinaryString($signature);
$m2 = RSAKey::exponentiate($key, $s2);
$em = self::convertIntegerToOctetString($m2, $key->getModulusLength());
$modBits = 8 * $key->getModulusLength();
return self::verifyEMSAPSS($message, $em, $modBits - 1, Hash::$hash());
}
/**
* Verifies a signature.
*/
public static function verifyWithPKCS15(RSAKey $key, string $message, string $signature, string $hash): bool
{
if (\mb_strlen($signature, '8bit') !== $key->getModulusLength()) {
throw new \InvalidArgumentException();
}
$signature = BigInteger::createFromBinaryString($signature);
$m2 = RSAKey::exponentiate($key, $signature);
$em = self::convertIntegerToOctetString($m2, $key->getModulusLength());
return \hash_equals($em, self::encodeEMSA15($message, $key->getModulusLength(), Hash::$hash()));
}
}
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