- Published: 02/08/2024 (#5/11 in round)
- Category: Cryptography
- Points: 80
- Author: Vipin
My friend Viggy sent me a cipher. he told me that to decode it you need... and then he started yapping and then said something about "you rock" and "keys" and gave me a piece of paper. Can you decode it for me?
This hint costed 35 points.
Reveal hint
Vignere [sic] & Rockyou.txt, Password has something to do with Linux & Penguins?!
Reveal write-up
After downloading the file, it appears that the text is an encoded text or cipher of some sort. The title and challenge description suggests that the specific cipher being used is the Vigenère cipher.
You rock refers to the common password list rockyou.txt. The list is commonly used for
dictionary attacks, which we can use to decode this cipher.
We can write a script to decode the Vigenère cipher using the rockyou.txt wordlist. The script will iterate through
the wordlist and attempt to decode the cipher using each word as the key. Because we know that the flag starts with
csd, we can use this to filter the results. Additionally, the flag will likely be in 1337 code (leet speak).
Therefore, the key is tuxtla.
Flag: csd{V16N3r3_5UCK5_N0_M0r3}
Write-up by GodderE2D