The Big Programming Thread - Page 783

else {
    ArrayList courseList = new ArrayList<String>();
    courseList.add(course);
    courses.put(student, courseList);
}

    final public static function encrypt($data)
    {
        $serialized = serialize($data);

        $iv = static::getIv();
        $key = static::getKey();
        $mac = static::getMac($serialized, $key);

        $serialized .= $mac;

        $passcrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $serialized, MCRYPT_MODE_CBC, $iv);

        return sprintf('%s|%s', base64_encode($passcrypt), base64_encode($iv));
    }

    final public static function decrypt($data)
    {
        $key = static::getKey();
        $decrypt = explode('|', $data);

        if (count($decrypt) !== 2) {
            return false;
        }

        $decoded = base64_decode($decrypt[0]);
        $iv = base64_decode($decrypt[1]);

        if (!static::validIv($iv)) {
            return false;
        }

        $decrypted = trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $decoded, MCRYPT_MODE_CBC, $iv));

        if (!static::validMac($decrypted, $key)) {
            return false;
        }

        return unserialize(substr($decrypted, 0, -64));
    }

    final public static function getIvSize()
    {
        return mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
    }

    final public static function getIv()
    {
        return mcrypt_create_iv(static::getIvSize(), MCRYPT_DEV_URANDOM);
    }

    final public static function validIv($iv)
    {
        return strlen($iv) === static::getIvSize();
    }

    final public static function getMac($data, $key)
    {
        return hash_hmac('sha256', $data, substr(bin2hex($key), -32));
    }

    final public static function validMac($decrypted, $key)
    {
        return substr($decrypted, -64) === static::getMac(substr($decrypted, 0, -64), $key);
    }

    final public static function getPublicKey()
    {
        return static::generateRandomKey(); // obviously there's something else here (doesn't return random key)
    }

    final public static function getPrivateKey()
    {
        return static::generateRandomKey(); // obviously there's something else here (doesn't return random key)
    }

    final public static function getKey()
    {
        $compositeKey = static::getPublicKey();
        $compositeKey .= static::getPrivateKey();

        return pack('H*', hash('sha256', $compositeKey));
    }

    final public static function generateRandomKey()
    {
        return md5(uniqid(mt_rand(), true)); // to illustrate sample keys
    }