picoCTF Cryptography Guide

Mod 26

Name: Mod 26
Description: Cryptography can be easy, do you know what ROT13 is? cvpbPGS{arkg_gvzr_V'yy_gel_2_ebhaqf_bs_ebg13_MAZyqFQj}
Author: Pandu
Tags: Easy, Cryptography, picoCTF 2021
Challenge from: picoCTF 2021
Hints:
1. This can be solved online if you don't want to do it by hand!

Theory

According to the description, to get the flag, it's just a rotation 13 cypher, or well, Caesar Cypher with a shift of 13, which is exactly halfway through the alphabet, that's why it's used so much. So yeah, let's just use the online decipherer for Caesar Cypher.

Solution

Now let's just put it in the Caesar Cypher with a shift of 13 and let's see what we get:

Caesar Cypher (online tool i think)

INPUT: cvpbPGS{arkg_gvzr_V'yy_gel_2_ebhaqf_bs_ebg13_MAZyqFQj}

SHIFT: 13

OUTPUT:
<13 (>13) - picoCTF{next_time_I'll_try_2_rounds_of_rot13_ZNMldSDw}

There we go! That's the flag.

I rated this level as "good"! :3