PicoCTF challenges : Easiest way to tackle NetCat : 168 & similar problems

Challenge 168 in picoCTF

This problem looks very easy to solve and most beginners would have a hard time solving it since it needs an intermediate mastery of cryptography skills. I have however found an easier way to solve it using python.

1. First, the command asks as to use nc command to talk to the mercury.picoctf.net 49039. That is what we gonna do. We type that to our terminal but parse it to an empty text file. This is because the ouput will be a list of ASCII Numbers that is why we can see “but it doesn’t speak English”

Parse the output to lets say test.txt

2. We have to code a python script that converts ASCII code to Alphanumeric as below. The code has comments to explain on each occurence as below. We name it ascii.py

SImple ascii.py

3. Calling the function and printing the flag: We note the correct flag is

picoCTF{g00d_k1tty!_n1c3_k1tty!_3d84edc8}

Follow-Up notes:

Practice more on advanced cryptography — sha1, md5 and RSA cypher