Looks like I cannot send and/or receive PMs :/

In latest WhatsApp versions I found a class that implements the RC4 cipher and I was able to extract from it the key used to encrypt data (if i'm not wrong, rc4 is symmetric so it's valid for encryption and decryption). I don't know exactly where it's used, but I know it's called during the login process (or something that's done before or after the login).