Problems with AES in crypto-js and pycrypto

问题

I try to implement a communication between

crypto-js (a javascript crypto library)
and pycrypto (a python crypto library)

On the python server side I encrypt a string with an iv and a passphrase and send the iv with the encrypted text base64 encoded to the javascript client side. Then I want to decrypt the string with the passphrase the user can enter.

python - server

from Crypto.Cipher import AES
from Crypto import Random

iv = Random.get_random_bytes(16)
key = "1234567812345678"
aes = AES.new(key, AES.MODE_CFB, iv)
encrypted_text = base64.b64encode(aes.encrypt("this is a test.."))
iv = base64.b64encode(iv)
# send iv, encrypted_text to client

javascript - client

// <script type="text/javascript" 
        src="http://crypto-js.googlecode.com/files/2.5.3-crypto-sha1-hmac-pbkdf2-blockmodes-aes.js">
   </script>
// text, and iv is base64encoded from the python script
// key is a string from an <input type='text'>
decrypted = Crypto.AES.decrypt(text, key, {iv: iv, mode: new Crypto.mode.CFB});

With this example I get a javascript error

Uncaught URIError: URI malformed

But this is just one example - I tried every constellation of base64 encodings/decodings I could think of. I also tried to changed the Mode. But these are all random tests and I want to understand what I really have to do.

What encoding does the crypt-js want?
Which mode should I chose?
Is there something I should change on the python server side?
what is about padding? Could there be the fault?
any other javascript libraries you can recommend?

thank you very much and kind reagards, samuirai

回答1:

Before You encode to base64 You must sum iv and encrypted_text:

encrypted_text = base64.b64encode(iv + aes.encrypt("this is a test.."))

From the official documentation (https://www.dlitz.net/software/pycrypto/doc/) :

As an example, encryption can be done as follows:

from Crypto.Cipher import AES
from Crypto import Random

key = b'Sixteen byte key'
iv = Random.new().read(AES.block_size)
cipher = AES.new(key, AES.MODE_CFB, iv)
msg = iv + cipher.encrypt(b'Attack at dawn')

来源：https://stackoverflow.com/questions/9565017/problems-with-aes-in-crypto-js-and-pycrypto

标签

javascript

python

base64

aes

pycrypto