Tags: gate logic 

Rating:

Lost Assignment involved an XML file that included a circuit scheme. I googled the "include" statements at the top of the file, which lead me to a free tool called LogiSim. This is a program that allows you to create, edit, visualize, and interact with circuit diagrams. The goal was to get the numeric display to show the number "4" in a premade circuit. At first I flipped a few inputs to get a better understanding of which input to the component was responsible for which line on the display. It quickly became apparent which lines I needed to flip and from there I could work back the lines to each input through their respective logic. Granted it's important to know what the different logic gate operators look like. After this I took the bits at the top, and tried submitting these directly: vsctf{0110001011000010001111101001}. This wasn't correct and after conferring with the crew, I used cyberchef to convert them from 7bit binary to ASCII, which got the correct flag: vsctf{10Gi}

Original writeup (https://lockboxx.blogspot.com/2022/07/vsctf-2022-writeup-lost-assignment.html).