No need for Brutus (Huntress CTF 2024)

Author: @aenygma

A simple message for you to decipher:

squiqhyiiycfbudeduutvehrhkjki

Submit the original plaintext hashed with MD5, wrapped between the usual flag format: flag{}

In hindsight, Brutus is a big flag HAHAHAH but when I looked at this string, I saw some interesting clues:

• repeated letters like ii and uu
• the letters that appear like y and k at one part but not throughout
• all alphabets, no numbers or symbols

This has to be a shift-cipher. I had a tummy ache, so while on Neptune’s throne I copied the text and searched for an online cipher app, this one in particular. I pasted, and then I slowly incremented the shift count one by one. At 16 (a -> q), I suddenly saw a caesar in the plaintext output. I had accidentally incremented so i went back and yup!

caesarissimplenoneedforbrutus

I piped this into the md5sum to get the hash and inputted the flag, according to the instructions.