I try to implement a communication between
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
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')