openssl_encrypt() 随机失败 - 传递的 IV 仅为 ${x} 字节长，密码预计 IV 恰好为 16 字节

Question

这是我用来 encrypt/decrypt 数据的代码：

// Set the method
$method = 'AES-128-CBC';

// Set the encryption key
$encryption_key = 'myencryptionkey';

// Generet a random initialisation vector
$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length($method));

// Define the date to be encrypted
$data = "Encrypt me, please!";

var_dump("Before encryption: $data");

// Encrypt the data
$encrypted = openssl_encrypt($data, $method, $encryption_key, 0, $iv);

var_dump("Encrypted: ${encrypted}");

// Append the vector at the end of the encrypted string
$encrypted = $encrypted . ':' . $iv;

// Explode the string using the `:` separator.
$parts = explode(':', $encrypted);

// Decrypt the data
$decrypted = openssl_decrypt($parts[0], $method, $encryption_key, 0, $parts[1]);

var_dump("Decrypted: ${decrypted}");

它通常工作正常，但有时（十分之一或更少）它会失败。当它失败时，文本仅被部分加密：

这是发生时的错误信息：

Warning: openssl_decrypt(): IV passed is only 10 bytes long, cipher expects an IV of precisely 16 bytes, padding with [=12=]

当它发生时，加密的文本看起来像：

Encrypt me���L�se!

我认为这可能是由 PHP 中的错误引起的，但我在不同的主机上进行了测试：PHP 7.0.6 和 PHP 5.6。我还尝试了多个在线 PHP 解析器，例如 phpfidle.org 或 3v4l.org.

似乎openssl_random_pseudo_bytes并不总是returns一个适当长度的字符串，但我不知道为什么。

示例如下：https://3v4l.org/RZV8d

继续刷新页面，有时会报错

Answer 1

当您生成随机 IV 时，您会得到 raw binary. There's a nonzero chance that the binary strings will contain a : or [=11=] character, which you're using to separate the IV from the ciphertext. Doing so makes explode() give you a shorter string. Demo: https://3v4l.org/3ObfJ

简单的解决方案是将 base64 encoding/decoding 添加到此过程。

也就是说，please don't roll your own crypto. In particular, unauthenticated encryption is dangerous and there are already secure libraries that solve this problem。

与其自己编写，不如考虑使用 defuse/php-encryption。这是安全的选择。

Answer 2

这是解决方案

我已经更新了第一个 post 的代码并将其封装在 class 中。这是基于 Scott Arciszewski.

提供的解决方案的固定代码

class Encryptor
{

    /**
     * Holds the Encryptor instance
     * @var Encryptor
     */
    private static $instance;

    /**
     * @var string
     */
    private $method;

    /**
     * @var string
     */
    private $key;

    /**
     * @var string
     */
    private $separator;

    /**
     * Encryptor constructor.
     */
    private function __construct()
    {
        $app = App::getInstance();
        $this->method = $app->getConfig('encryption_method');
        $this->key = $app->getConfig('encryption_key');
        $this->separator = ':';
    }

    private function __clone()
    {
    }

    /**
     * Returns an instance of the Encryptor class or creates the new instance if the instance is not created yet.
     * @return Encryptor
     */
    public static function getInstance()
    {
        if (self::$instance === null) {
            self::$instance = new Encryptor();
        }
        return self::$instance;
    }

    /**
     * Generates the initialization vector
     * @return string
     */
    private function getIv()
    {
        return openssl_random_pseudo_bytes(openssl_cipher_iv_length($this->method));
    }

    /**
     * @param string $data
     * @return string
     */
    public function encrypt($data)
    {
        $iv = $this->getIv();
        return base64_encode(openssl_encrypt($data, $this->method, $this->key, 0, $iv) . $this->separator . base64_encode($iv));
    }

    /**
     * @param string $dataAndVector
     * @return string
     */
    public function decrypt($dataAndVector)
    {
        $parts = explode($this->separator, base64_decode($dataAndVector));
        // $parts[0] = encrypted data
        // $parts[1] = initialization vector
        return openssl_decrypt($parts[0], $this->method, $this->key, 0, base64_decode($parts[1]));
    }

}

用法

$encryptor = Encryptor::getInstance();

$encryptedData = $encryptor->encrypt('Encrypt me please!');
var_dump($encryptedData);

$decryptedData = $encryptor->decrypt($encryptedData);
var_dump($decryptedData);

Answer 3

这也发生在我身上。我收到类似

的错误

openssl_decrypt(): IV passed is only 14 bytes long, cipher expects an IV of precisely 16 bytes, padding with [=10=]

我使用的是像 openssl_cipher_iv_length('aes-128-cbc')

这样的小写方法

小写 aes-- 方法给出的结果长度在 12 到 16 之间变化。参考：https://www.php.net/manual/en/function.openssl-cipher-iv-length.php

将方法设为大写 openssl_cipher_iv_length('AES-128-CBC') 将给出一致的值，即 16。

因此在加密和解密时 IV 长度保持与 16 相同。

openssl_encrypt() 随机失败 - 传递的 IV 仅为 ${x} 字节长，密码预计 IV 恰好为 16 字节

openssl_encrypt() randomly fails - IV passed is only ${x} bytes long, cipher expects an IV of precisely 16 bytes

php

encryption

aes

encryption-symmetric

php-openssl

这是解决方案

用法