This is a cleaned-up version of the tool i used to find the proper key in my implementation of the arm9loaderhax exploit.
In order to build it you need GCC or MinGW, nothing more should be requested.
Just drag and drop a N3DS FIRM of version 9.6 or more, and then wait for random keys to be tested, it will print them in the screen if they are exploitable.
Current speed : ~2200 keys/sec
Also, this includes my C reproduction of the 3DS AES Engine, feel free to take inspiration and improve it for other PC tools, but remember to credit it.