Tags: crypto unintended rsa
Rating:
rsa was a crypto challenge in WRECK CTF 2022. The goal was to break 2048 bit RSA signature and get a sign for a specific message.
[rsa.py](https://github.com/mar232320/ctf-writeups/blob/main/wreck2022/rsa/rsa.py)
I found a non-intended easy solution to this challenge. I simply added a null byte in front of the message that I needed to get a signature of. The message was converted to a number with bytes_to_long() function and the null byte was converted to 0s which were stripped. The author of the challenge did not predict someone using two different messages that give exact bytes_to_long() result ;)
[solve script](https://github.com/mar232320/ctf-writeups/blob/main/wreck2022/rsa/solve.py)
> flag{dan_likes_moes}
