Simple reverse engineering - dora

The binary, script for exploitation, and a PDF of the solution can be found in this repository:

Binary, script for exploitation, and PDF of solution

I completed this challenge using brute force. If we look at the decompiler, we can see that the entered key needs to be between 0 and 255 (inclusive). So, we could just brute force all numbers from 0 to 255 to get the key. Please see the python solver script.