准备在 PHP 7.2 中删除 Mcrypt

问题描述

因此，随着时间的推移，mcrypt 将在 PHP 7.2 中出现.当然还有一个选择:openssl.

So as time moves on mcrypt will go in PHP 7.2. Of course there is an alternative: openssl.

我发现很难从 mcrypt 切换到 openssl，使用 AES 256 CBC 并保留 IV.我对密码学有点陌生，所以我并不是什么都知道，但我了解基础知识.

I find it difficult to switch from mcrypt to openssl, using AES 256 CBC and preserving IVs. I am sort of new to cryptography, so I don't really know everything, but I understand the basics.

假设我有以下代码

function encrypt($masterPassword, $data) 
{
    $keySize = mcrypt_get_key_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
    $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
    $key = mb_substr(hash('SHA256', $masterPassword), 0, $keySize);
    $encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $data, MCRYPT_MODE_CBC, $iv);
    return base64_encode($iv . $encrypted);
}

function decrypt($masterPassword, $base64) 
{
    $keySize = mcrypt_get_key_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
    $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
    $key = mb_substr(hash('SHA256', $masterPassword), 0, $keySize);
    $data = base64_decode($base64);
    $iv = substr($data, 0, $ivSize);
    $encrypted = substr($data, $ivSize, strlen($data));
    $decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encrypted, MCRYPT_MODE_CBC, $iv);
    return trim($decrypted);
}

如何转换"此代码以使用由 mcrypt 插入的 openssl?

How can I "convert" this code to use openssl insted of mcrypt?

推荐答案

您无法转换它，因为 Rijndael-256 不是 AES-256，并且 OpenSSL 扩展不附带 Rijndael-256 支持.
AES-256 是具有 256 位(32 字节)密钥的 Rijndael-128.

You can't convert it, because Rijndael-256 is not AES-256, and the OpenSSL extension doesn't ship with Rijndael-256 support.
AES-256 is Rijndael-128 with a 256-bit (32-byte) key.

很遗憾，您必须重新加密所有数据.

Unfortunately, you'll have to re-encrypt all of your data.

此外，您当前使用的方案存在一些问题:

Also, the scheme you're currently using has some problems:

• 它缺乏身份验证(HMAC 是在 PHP 中最简单的方法)
• 它缺少适当的填充(mcrypt 填充零字节；您需要类似 PKCS#5 的填充)，这是块模式加密安全所必需的.
• 它不是字节安全的(您使用的是 mb_substr())

好消息是 OpenSSL 会自动为你做 PKCS#5 填充，但你应该更进一步，使用像 defuse/php-encryption.

The good news is that OpenSSL will do PKCS#5 padding for you automatically, but you should go even further and use a solid encryption library like defuse/php-encryption.

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