If anyone is starting out with crypto security puzzles on sites like hack the box or diving into the world of encryption there’s a site worth taking a look at before you ever need it:
Don’t be put off that it’s a french site, the link above takes you to the English translated version.
The site holds tools for decoding/encoding practically every type of encryption you will come across in all but the more advanced challenges. Instead of having to write your own tools for a variety of possible ciphers you think the puzzle uses you can stick your text in a bunch of possible decoders on this site and see what comes back with something sensible looking. It’s many times quicker than doing it manually or trying to search for a reliable tool.
All the encoding/decoding happens in the browser so you don’t need to wait for downloads. It’s quick and free. The list of tools it has is massive but some of the ones I’ve used to solve puzzles online are:
- https://www.dcode.fr/md5-hash
- https://www.dcode.fr/sha256-hash
- https://www.dcode.fr/differences-2-texts
- https://www.dcode.fr/caesar-cipher
- https://www.dcode.fr/rot-cipher
Even if you don’t know which Cipher you need for a challenge you can have a browse around this site and get some inspiration for possible cipher methods in a specific category.
As an example of how useful the site is here’s a basic rot cipher code where the letters have been shifted forward in the alphabet, the problem is you don’t know by how many places. Instead of running a rot decoder 26x the site has a brute force feature which will do it all at once for you:
Aopz dlizpal pz clyf bzlmbs
From that list we can clearly see that the code is shifted 7x and the decoded text is given to us.
Urban Security Research 