Title: Additional Problems Category: cryptography Points: 500 Solves: 2 Description: Version 1.0 of our new encryption service has just launched! It is blazingly fast and uses state-of-the-art encryption. Stay tuned for version 2.0; I hear it will bring tons of improvements and security fixes. Download challenge files Access the server via nc IP_ADDRESS PORT (the server is now down, but you can run it yourself) Introduction This challenge proved to be among the hardest challenges at ...

This is the second article in a series about reverse engineering the ESP32 Wi-Fi networking stack, with the goal of building our own open-source MAC layer. In the previous article in this series, we built static and dynamic analysis tools for reverse engineering. We also started reverse engineering the transmit path of sending packets, and concluded with a rough roadmap and a call for contributors. In this part, we’ll continue reverse engineering, starting with the ‘receiving packets’ functi...

(This is part 1 of this series, part 2 is here) The ESP32 is a popular microcontroller known in the maker community for its low price (~ €5) and useful features: it has a dual-core CPU, built-in Wi-Fi and Bluetooth connectivity and 520 KB of RAM. It is also used commercially, in devices ranging from smart CO₂-meters to industrial automation controllers. Most of the software development kit that is used to program for the ESP32 is open-source, except notably the wireless bits (Wi-Fi, Bluetoo...