reversible sneaky algorithm#0 - NACTF 2019

Tue, 17 Sept. 2019, 22:00 UTC - Sun, 22 Sept. 2019, 22:00 UTC

Summary: A simple crypto challenge requiring basic scripting skills and some knowledge of RSA encryption.

Starting this challenge off we are given a text file with the following large numbers in it.



Looking through RSA's wikipedia page specifically the decryption section, the following formula tells us how to use these numbers to decrypt the message!



So all we need to do is power d to c and then modulus the result with n, this can be achieved with a simple python script! Let's run the script and see what output we get!



And looks like it decoded to hex, all we have to do is use this hex converter to get the flag!