This year will mark the 21st anniversary of our Enigma simulator and entering the 20th year of cryptologic challenges. It all started in early 2006 with the Enigma Challenge to decrypt ten messages. Although the challenge was a one-time event, the feedback encouraged us to continue the challenge. The original 2006 results are preserved at the currently running challenge.
![]() |
The Enigma machine, Crypto Box and TSEC/KL-7 ADONIS |
In the following years, we introduced four more challenges, each with its own Table of Honor that lists all participants. The crypto machine simulations in the Enigma Challenge and Operation Tinker Bell work exactly like the real machines, making for authentic experience. Some updated challenge statistics:
Enigma Challenge (est. 2006)
Currently, 356 participants from 46 countries solved 2398 messages. This challenge is quite accessible and no expert knowledge on cryptologic techniques is required. This challenge serves as an introduction to codebreaking. Most participants get quite far with logical thinking, patience and some perseverance, with 55% of them solving eight to ten messages. Visit in English or Nederlands.
Crypto Box Challenge (est. 2007)
This transposition cipher is more difficult and 84 participants from 26 countries submitted 160 solutions. The first Crypto Box is not that difficult, but complexity increases rapidly. To this day, only 13% solved all boxes and 87% solved one or two boxes, which is quite meritorious, given the difficulty level. Some cryptanalytic knowledge is useful but hard work also pays off. Visit in English or Nederlands.
Operation Tinker Bell (est. 2013)
This is a very accessible cryptologic spy adventure in a true Cold War atmosphere, focusing on secure communications between intelligence agencies, their agents and operatives in the field. You don't need any cryptologic skills. All authentic crypto tools, keys and clear instructions are provided to solve this spy case. The participants who complete the operation get their name engraved in the Wall of Honor. Fun and excitement guaranteed. Visit only in English.
Elite Box Challenge (est. 2022)
The Elite Box is a Crypto Box on steroids. To this day, only one person managed to solve two out of the three boxes, and three persons only solved one box. The first box already starts with a higher number of steps, there's one box with an unknown number of steps, and one box has an unknown type of fractionated characters, requiring more than simply shifting rows and columns. Cryptanalytic techniques are required to solve this one. Visit in English or Nederlands.
The Crow's Cryptogram (est. 2010)
Although published in 2010, there's a good reason why the Crow"s Cryptogram is the last one on our statistics list. Only encrypted with a pencil-and-paper system, this one comes with a single hint, and has 600 digits in 120 five-digit groups. The bleak statistics: only one person ever solved this cryptogram. Expertise in cryptanalytic techniques is required. Visit in English or Nederlands.
If you're in for a cryptologic adventure, enjoy the challenges!