在 Python 中解密用 PHP 中的 MCRYPT_RIJNDAEL_256 加密的字符串

2021-12-20 00:00:00 python encryption php mcrypt

我在 PHP 中有一个加密文本的函数，如下所示:

I have a function in PHP that encrypts text as follows:

function encrypt($text)
{
    $Key = "MyKey";

    return trim(base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $Key, $text, MCRYPT_MODE_ECB, mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB), MCRYPT_RAND))));
}

如何在 Python 中解密这些值?

How do I decrypt these values in Python?

推荐答案

要解密这种形式的加密，您需要获得 Rijndael 的一个版本.可以在此处找到.然后您需要模拟 PHP Mcrypt 模块中使用的密钥和文本填充.他们添加了 '' 来填充文本和键到正确的大小.他们使用的是 256 位块大小，并且与您提供的密钥一起使用的密钥大小是 128(如果您提供更大的密钥，它可能会增加).不幸的是，我链接到的 Python 实现一次只编码一个块.我创建了 python 函数来模拟 Python 中的加密(用于测试)和解密

To decrypt this form of encryption, you will need to get a version of Rijndael. One can be found here. Then you will need to simulate the key and text padding used in the PHP Mcrypt module. They add '' to pad out the text and key to the correct size. They are using a 256 bit block size and the key size used with the key you give is 128 (it may increase if you give it a bigger key). Unfortunately, the Python implementation I've linked to only encodes a single block at a time. I've created python functions which simulate the encryption (for testing) and decryption in Python

import rijndael
import base64

KEY_SIZE = 16
BLOCK_SIZE = 32

def encrypt(key, plaintext):
    padded_key = key.ljust(KEY_SIZE, '')
    padded_text = plaintext + (BLOCK_SIZE - len(plaintext) % BLOCK_SIZE) * ''

    # could also be one of
    #if len(plaintext) % BLOCK_SIZE != 0:
    #    padded_text = plaintext.ljust((len(plaintext) / BLOCK_SIZE) + 1 * BLOCKSIZE), '')
    # -OR-
    #padded_text = plaintext.ljust((len(plaintext) + (BLOCK_SIZE - len(plaintext) % BLOCK_SIZE)), '')

    r = rijndael.rijndael(padded_key, BLOCK_SIZE)

    ciphertext = ''
    for start in range(0, len(padded_text), BLOCK_SIZE):
        ciphertext += r.encrypt(padded_text[start:start+BLOCK_SIZE])

    encoded = base64.b64encode(ciphertext)

    return encoded


def decrypt(key, encoded):
    padded_key = key.ljust(KEY_SIZE, '')

    ciphertext = base64.b64decode(encoded)

    r = rijndael.rijndael(padded_key, BLOCK_SIZE)

    padded_text = ''
    for start in range(0, len(ciphertext), BLOCK_SIZE):
        padded_text += r.decrypt(ciphertext[start:start+BLOCK_SIZE])

    plaintext = padded_text.split('x00', 1)[0]

    return plaintext

这可以如下使用:

key = 'MyKey'
text = 'test'

encoded = encrypt(key, text)
print repr(encoded)
# prints 'I+KlvwIK2e690lPLDQMMUf5kfZmdZRIexYJp1SLWRJY='

decoded = decrypt(key, encoded)
print repr(decoded)
# prints 'test'

为了比较，这里是 PHP 的输出相同的文本:

For comparison, here is the output from PHP with the same text:

$ php -a
Interactive shell

php > $key = 'MyKey';
php > $text = 'test';
php > $output = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB);
php > $encoded = base64_encode($output);
php > echo $encoded;
I+KlvwIK2e690lPLDQMMUf5kfZmdZRIexYJp1SLWRJY=

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