In December 2019 I participated in PST (Norwegian Police Security Service) advent capture the flag calendar. I ended up in 32nd place, with one unsolved task. I had to read up a lot to be able to solve the tasks, as this is my first CTF, so was quite happy with that result. Here are some useful tools I ended up using during the challenge.
Super easy to use tool to decrypt/encode various ciphers.
Nice tool with lots of possibilities for decrypting and encoding various ciphers.
One of the tasks involved a chess game, this online tool decoded it perfectly.
This Vigenere codebreaker analyzes the encrypted text to determine the most probable key length and then tries to guess the key based on known character frequencies/words in the English language. Helped me a lot in one of the tasks.
Very nice tool to analyze a raw dump of a hard drive.
This quickly became my goto tool in all of the steganography tasks. Very nice and easy to run with the -all mode.
Nice online tool for steganography, also a very handy checklist on what to check.
Also a nice online tool that helped me with the first steganography task in the CTF.