What is MTC3?

MysteryTwister C3 (MTC3), successor of the famous MysteryTwister site, is an international cryptography competition. A variety of tasks and challenges are offered at four levels of difficulty. These challenges can be as easy as deciphering a Caesar cipher (Level I) and as hard as breaking a modern encryption algorithm like AES (Level III). Some of the challenges are still today unsolved (Level X). The various topics covered by the MTC3 challenges are intended to offer a survey of cryptology for everyone. The four levels of difficulty in MTC3 offer cryptographic challenges for a student just starting to learn about cryptography as well as for experts with many years of experience and plenty of resources at their disposal.

How does it work?

All MTC3 challenges in the levels I to III have a secret codeword hidden inside the challenge. By breaking the cipher you will obtain this codeword. If you think that you have found the correct codeword, you can login to this website and submit the codeword. Be aware that the codewords are case-sensitive! If your answer is correct you will automatically be added to the list of successful solvers. The first 4 solvers will appear on the "Hall of Fame" page.

Take note, however, that you only have a limited number of attempts at each challenge. Therefore, you should be certain  that your answer is correct before submitting a codeword. Once you have used all of your attempts, you will not be able to submit additional answers for that particular challenge.

Challenges categorized as level X are unsolved ciphers and therefore do not contain a codeword. If you solve one of the level X challenges, you should contact the author of the challenge or the MTC3 team via email. If your solution is sound, you will be added specially to the Hall of Fame. We will publish your results only with your explicit permission.