Jose\Util\RSA::verifyEMSAPSS PHP Method

    private static function verifyEMSAPSS($m, $em, $emBits, Hash $hash)
    {
        $emLen = $emBits + 1 >> 3;
        $sLen = $hash->getLength();
        $mHash = $hash->hash($m);
        Assertion::greaterThan($emLen, $hash->getLength() + $sLen + 2);
        Assertion::eq($em[mb_strlen($em, '8bit') - 1], chr(0xbc));
        $maskedDB = mb_substr($em, 0, -$hash->getLength() - 1, '8bit');
        $h = mb_substr($em, -$hash->getLength() - 1, $hash->getLength(), '8bit');
        $temp = chr(0xff << ($emBits & 7));
        Assertion::eq(~$maskedDB[0] & $temp, $temp);
        $dbMask = self::getMGF1($h, $emLen - $hash->getLength() - 1, $hash);
        $db = $maskedDB ^ $dbMask;
        $db[0] = ~chr(0xff << ($emBits & 7)) & $db[0];
        $temp = $emLen - $hash->getLength() - $sLen - 2;
        Assertion::eq(mb_substr($db, 0, $temp, '8bit'), str_repeat(chr(0), $temp));
        Assertion::eq(ord($db[$temp]), 1);
        $salt = mb_substr($db, $temp + 1, null, '8bit');
        // should be $sLen long
        $m2 = "" . $mHash . $salt;
        $h2 = $hash->hash($m2);
        return hash_equals($h, $h2);
    }