The Indecipherable Cipher

Description

CTF: Whitehacks 2022

Author: WickedEye (Ying Keat)

Difficulty: Easy

Some say this cipher cannot be deciphered. Well, do you believe them?

Even worse, some say this cipher is misattributed!

I would say that the key to solving this challenge is to remember who the true inventor was.

Solution

Pwned by @skytect

CP2022{j1b3n3e3_15_Pcn_Xa3f@x_K1dC3R_0A_yB3F01Ys}

Looking at the ciphertext, one can see that it’s some form of cipher that substitutes letters. Immediately, one thinks of ROT13 and the Vignère cipher.

some say this cipher is misattributed!

The Vignère cipher just happens to be misattributed! However, the cipher requires a key which is hard to guess with just the cryptic ciphertext.

I would say that the key to solving this challenge is to remember who the true inventor was.

From the Wikipedia site, we can find that the first guy who came up with the cipher is Giovan Battista Bellaso.

If we try to decrypt it on CyberChef with the key GIOVAN, it works!

WH2022{v1g3n3r3_15_Juz_Ca3s@r_C1pH3R_0N_sT3R01Ds}