Question

我编写了一个加密和解密字符串的类，但我不能使用除MCRYPT_RIJNDAEL_256之外的任何密码。程序始终报告邮件已损坏。我该如何解决？

我测试过的失败的密码是MCRYPT_RIJNDAEL_128 MCRYPT_RIJNDAEL_192 MCRYPT_BLOWFISH MCRYPT_SERPENT和MCRYPT_TWOFISH。

这是我的代码：

class Crypt {
    private $masterKey;
    private $subKey;
    private $cipher = MCRYPT_RIJNDAEL_256 ;
    private $cipherMode = MCRYPT_MODE_CFB;
    //private $hashAlog = 'sha256';

    public function __construct($masterKey) {
        $this->masterKey = $masterKey;
    }

    public function setKey($masterKey) {
        $this->__construct($masterKey);
    }

    public function encrypt($message) {
        $iv = mcrypt_create_iv($this->getIVSize());
        $hmac = $this->signMsg($message);
        $this->genSubKey($iv);
        $cipherText = mcrypt_encrypt($this->cipher, $this->subKey, $message, $this->cipherMode, $iv);
        $cipherText = $iv . $hmac . $cipherText;
        return base64_encode($cipherText);
    }

    public function decrypt($enc_message) {
        $mixedMsg = base64_decode($enc_message);
        $iv = substr($mixedMsg, 0, $this->getIVSize());
        $this->genSubKey($iv);
        $hmac = substr($mixedMsg, $this->getIVSize(), strlen($this->signMsg(null)));
        $cipherText = substr($mixedMsg, $this->getIVSize() + strlen($this->signMsg(null)));
        $message = mcrypt_decrypt($this->cipher, $this->subKey, $cipherText, $this->cipherMode, $iv);
        if(!$message)
            die("Decrypt Error!");
        if($hmac != $this->signMsg($message))
            die("Message Corrupted");
        return $message;
    }

    private function genSubKey($iv) {
        $this->subKey = hash_pbkdf2("sha256", $this->masterKey, $iv, 50000, $this->getKeySize());
    }

    private function getKeySize() {
        return mcrypt_get_key_size($this->cipher, $this->cipherMode);
    }

    private function getIVSize() {
        return mcrypt_get_iv_size($this->cipher, $this->cipherMode);
    }

    private function signMsg($message) {
        return hash_hmac("sha512", $message, $this->masterKey, true);
    }
}

Answer 1

问题是由hash_pbkdf2函数中的genSubKey函数引起的。由于hash_pbkdf2将输出十六进制编码的字符串，因此它将是密钥大小的两倍。要解决这个问题，我们需要将true作为附加参数传递给它，让它输出原始字节并适合密钥大小。

以下是更正后的代码：

private function genSubKey($iv) {
    $this->subKey = hash_pbkdf2("sha256", $this->masterKey, $iv, 50000, $this->getKeySize(), true);
}

除非使用AES-256，否则PHP MCrypt解密将失败

1 个答案: