PHP function conversion to Python - php

Question

I am just wondering is it possible to convert PHP encryption function to Python? I am using PHP function to encrypt USER ID and store it in Database and now I need to decrypt USER ID in Python, I using this PHP function:
function decrypt($id) {
$cryptKey = '123';
$decoded = rtrim( mcrypt_decrypt( MCRYPT_RIJNDAEL_256, md5( $cryptKey ), base64_decode( $id ), MCRYPT_MODE_CBC, md5( md5( $cryptKey ) ) ), "\0");
return( $decoded );
}

Answer 1

Here is your function 'translated' to python
from Crypto.Cipher import AES
from hashlib import md5
def decrypt(id):
cryptKey = '123'
cipher = AES.new(key=md5(cryptKey).hexdigest(), mode=AES.MODE_CBC, IV=md5(md5(cryptKey).hexdigest()).hexdigest()[:16])
decoded = cipher.decrypt(id.decode('base64')).rstrip('\0')
return decoded
A fiew suggestions
1. Use a random iv
2. Use a more complex key
3. Don't hardcode the key
4. Use openssl_decrypt , mcrypt_decrypt is deprecated
Note
This will not work with MCRYPT_RIJNDAEL_256 because it uses 32 byte blocks .
But you could use MCRYPT_RIJNDAEL_128 or openssl
Here is an example with openssl AES CBC in PHP :
function encrypt($data, $key) {
$method = "aes-" . strlen($key) * 8 . "-cbc";
$iv = openssl_random_pseudo_bytes(16);
$encoded = base64_encode($iv . openssl_encrypt($data, $method, $key, TRUE, $iv));
return $encoded;
}
function decrypt($data, $key) {
$method = "aes-" . strlen($key) * 8 . "-cbc";
$iv = substr(base64_decode($data), 0, 16);
$decoded = openssl_decrypt(substr(base64_decode($data), 16), $method, $key, TRUE, $iv);
return $decoded;
}
Python code :
from Crypto.Cipher import AES
from Crypto import Random
import base64
def encrypt(data, key):
pkcs7pad = lambda data: data + chr(16-(len(data)%16)).encode() * (16-(len(data)%16))
iv = Random.new().read(16)
cipher = AES.new(key=key, mode=AES.MODE_CBC, IV=iv)
encoded = base64.b64encode(iv + cipher.encrypt(pkcs7pad(data)))
return encoded
def decrypt(data, key):
pkcs7unpad = lambda data: data[:-ord(data[-1:])]
cipher = AES.new(key=key, mode=AES.MODE_CBC, IV=base64.b64decode(data)[:16])
decoded = cipher.decrypt(base64.b64decode(data)[16:])
return pkcs7unpad(decoded)
With the above functions you can encrypt in PHP - decrypt in python , and vice versa
Assuming that the key has a valid size (16, 24 or 32 bytes)