picoCTF - rotation

Posted on Jan 25, 2026
  • URL: https://play.picoctf.org/practice/challenge/373
  • Title: rotation
  • Tags: Medium, Cryptography, picoCTF 2023
  • Author: Loic Shema
  • Started: 21 July 2025
  • Solved: 21 July 2025
  • Description: You will find the flag after decrypting this file Download the encrypted flag here.

File downloaded contains this text

xqkwKBN{z0bib1wv_l3kzgxb3l_7l140864}

The hint and title suggested that I could use ROTX to get the flag. Even so, I didn’t know what is the number for the right rotation. Well, we can always try, right?

alt text

It turned out to be ROT18 and the flag is

picoCTF{r0tat1on_d3crypt3d_7d140864}