[Django]-Encrypt and Decrypt information in a cookie

It’s generally a bad idea: an attacker can do chosen-text dictionary attacks if they can guess what you might be putting in the cookie, which is quite likely, and securing a universal key is harder than looking after a database containing confidential information, because there is not much in the way of an audit trail for these kind of client-side web-based attacks.

If the cost of a security breach is low, then maybe you want to do this anyway. Just use a symmetric-key encryption algorithm.

Take a look here: http://www.example-code.com/python/encryption.asp
I would suggest DES or Blowfish