rail-fence Description A type of transposition cipher is the rail fence cipher, which is described here. Here is one such cipher encrypted using the rail fence with 4 rails. Can you decrypt it? Download the message here. Put the decoded message in the picoCTF flag format, picoCTF{decoded_message}. Solving So – there is everything we need to know in the challenge
diffie-hellman Description Alice and Bob wanted to exchange information secretly. The two of them agreed to use the Diffie-Hellman key exchange algorithm, using p = 13 and g = 5. They both chose numbers secretly where Alice chose 7 and Bob chose 3. Then, Alice sent Bob some encoded text (with both letters and digits) using the generated key as
morse-code Description Morse code is well known. Can you decrypt this? Download the file here. Wrap your answer with picoCTF{}, put underscores in place of pauses, and use all lowercase. Solving The soundfile is a morse code You could either translate it by your self with the morse alphabet or use this link Change all characters to lowercase and replace
credstuff Description We found a leak of a blackmarket website’s login credentials. Can you find the password of the user cultiris and successfully decrypt it? Download the leak here. The first user in usernames.txt corresponds to the first password in passwords.txt. The second user corresponds to the second password, and so on. Solving We got a tar file – extract
basic-mod2 Description A new modular challenge! Download the message here. Take each number mod 41 and find the modular inverse for the result. Then map to the following character set: 1-26 are the alphabet, 27-36 are the decimal digits, and 37 is an underscore. Wrap your decrypted message in the picoCTF flag format (i.e. picoCTF{decrypted_message}) Solving This challenge is similar
basic-mod1 Description We found this weird message being passed around on the servers, we think we have a working decrpytion scheme. Download the message here. Take each number mod 37 and map it to the following character set: 0-25 is the alphabet (uppercase), 26-35 are the decimal digits, and 36 is an underscore. Wrap your decrypted message in the picoCTF
OCEAN What can you do in an ocean of files? nc server.challenge.ctf.thefewchosen.com 1338 Hints There is an official hint: Hint for ocean: The chal file is not relevant. That’s just a shell (basically the entrypoint). Try listing folders and subfolders Todos So we looked around for a while and found this directory (Magic trick was to use ls -R instead
AAAAA AAAAA. That’s all Download AAAAA Okay – first of all, like always I run file on this AAAAA file. This will tell us, that this is a data file. After that, I tried binwalk. BÄM There is an image included. My colleague uses CyberChef for this. There you can import the file and run Extract files on. I just
Lost my Head Oh no! Help! I’ve lost my head! Can you tell me the street name of the trash bin I lost it in? Maybe I can still find it… Flag format: TFCCTF{street_name_and_street_number_as_seen_on_google_maps_separated_by_underscores} Challenge authors: hofill, tomadimitrie Solving Like always we should first check strings, file and so on. Please see the logfiles. In the exif we can find
DISCORD SHENANIGANS We considered giving you a free flag. However, we decided against it. In general, we would never do that! Or would we? That’s the beginning of a good CTF! Discord is the new Twitter. To be able to solve this challenge, you’ll need to join our discord. Link in the Rules page. Todos The flag is hidden in