[ Part 1 – Part 2 – Part 3 – Part 4 – Part 5 – Part 6 – Part 7 – Part 8 ]

What’s going on guys?

Welcome to part three of the Python control server series.

In part one we created our simple server and client with about 20 lines of code each (Python 3). Then in part two, we’ve added basic AES encryption to our traffic using pyAesCrypt.

Given the nature of encryption using pyAesCrypt, we we’re unable to receive any data on the server over 1024 bytes with encryption. The main reason for this is that length needs to be passed for the decryption method.

In this part we will be fixing this issue, so let’s get with it.

Traffic Encryption

What exactly is the issue we have here? Why is less than 1024 bytes ok?

Both in our server and client we are sending 1024 bytes at a time. This means that whenever we send a message containing less than 1024 bytes, we won’t run into any issues.

Now considering we have to pass a length argument for decryption, if we send a message that is 1500 bytes, the server will receive the first 1024 bytes and attempt to decrypt it – resulting in an error.

This is where we have a few different options: receive all the encrypted data and then decrypt it all at once; or, receive smaller chunks of data and decrypt on-demand. Both options have their merits, I decided this latter one would be easier to program for a encryption noob like me. 🙂