Decrypting strings in Python that were encrypted with MCRYPT_RIJNDAEL_256 in PHP

Question

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

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

    return trim(base64_encode(mcrypt_encrypt(MCRYPT_         


        

Answer 1

Although the answer from @101100 was a good one at the time, it's no longer viable. The reference is now a broken link, and the code would only run on older Pythons (<3).

Instead, the pprp project seems to fill the void nicely. On Python 2 or Python 3, just pip install pprp, then:

import pprp
import base64

KEY_SIZE = 16
BLOCK_SIZE = 32


def encrypt(key, plaintext):
    key = key.encode('ascii')
    plaintext = plaintext.encode('utf-8')
    padded_key = key.ljust(KEY_SIZE, b'\0')

    sg = pprp.data_source_gen(plaintext, block_size=BLOCK_SIZE)
    eg = pprp.rjindael_encrypt_gen(padded_key, sg, block_size=BLOCK_SIZE)

    ciphertext = pprp.encrypt_sink(eg)

    encoded = base64.b64encode(ciphertext)

    return encoded.decode('ascii')


def decrypt(key, encoded):
    key = key.encode('ascii')
    padded_key = key.ljust(KEY_SIZE, b'\0')

    ciphertext = base64.b64decode(encoded.encode('ascii'))

    sg = pprp.data_source_gen(ciphertext, block_size=BLOCK_SIZE)
    dg = pprp.rjindael_decrypt_gen(padded_key, sg, block_size=BLOCK_SIZE)

    return pprp.decrypt_sink(dg).decode('utf-8')


key = 'MyKey'
text = 'test'

encoded = encrypt(key, text)
print(repr(encoded))
# prints 'ju0pt5Y63Vj4qiViL4VL83Wjgirq4QsGDkj+tDcNcrw='

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

I'm a little dismayed that the ciphertext comes out different than what you see with 101100's answer. I have, however, used this technique to successfully decrypt data encrypted in PHP as described in the OP.