picoCTF 2022 credstuff (Cryptography 100 points)

The challenge is the following,

We are also given the file leak.tar. I uncompressed this, and gave a text files usernames.txt and passwords.txt.

The challenge told us to look for the user cultiris, which was on line 378 of usernames.txt. I looked at line 378 of passwords.txt.

cultiris's password was cvpbPGS{P7e1S_54I35_71Z3}. I assumed this was a ROT cipher, so I went over to CyberChef and applied the ROT 13 cipher.

Therefore, the flag is,

picoCTF{C7r1F_54V35_71M3}.

Original writeup (https://github.com/LambdaMamba/CTFwriteups/tree/main/picoCTF_2022/Cryptography/credstuff).