Complex things through simple games
Classical ciphers that started the science of protecting information
The Polybius square: encryption using a 5×5 coordinate grid
How a letter shift in Ancient Rome laid the foundations of cryptography
The Vigenère cipher: le chiffre indéchiffrable of the Renaissance
The Vernam cipher: it beat cryptanalysis but lost to reality
The algorithms that protect us today
The future of data protection: the laws of physics instead of math
Ludus Lab is a set of small browser games about cryptography and quantum key distribution. Each game comes with a short article on the history and the idea, and in the game itself you can go through a cipher or a protocol step by step. Everything is free, needs no sign-up and works on a computer or a phone.
It is a niche site, made for people who want to understand how ciphers work and why a quantum key cannot be intercepted unnoticed. If that is you, I hope the games help.
Why “Ludus”: in Latin the word means both “game” and “school”. In ancient Rome it was also the name of the elementary school where children learned to read and count.
I work in telecom, and since 2021 in quantum communications, specifically quantum key distribution.
The project started with a bad talk. At one of the first presentations of the technology the main speaker fell ill, and I had to step in. There was no time to prepare: I read someone else’s slides and somehow stumbled through to the last one. The questions turned out to be easier, since I dealt with those problems every day. But after the talk I realised I could not explain, even to myself, BB84, the first and best-known quantum key distribution protocol.
That is how the first game appeared. That version of BB84 was simplified to an indecent degree: Alice, Bob, a quantum channel with photons flying through it, and Eve, who sometimes interfered at random. There was no basis comparison, no error check and no key processing, only the principle of producing a raw bit sequence. Since then the game has been rewritten several times, and now it covers all four stages of the protocol.
After that, one question led to another. Quantum technologies strengthen cryptography. But what is cryptography, and where did it even start? I got curious myself and began digging, from the Caesar cipher to DES. I put the results here as games. There is nothing fundamentally new in them: this is my way of figuring things out and sharing how I understood them.
I make the project mostly for myself. But quantum communications is a young industry that few people know about, and if the games help someone find their way into it, I will be glad.
Most of my nerves at the start went on things that have nothing to do with games. I had no experience and no money for a hobby, so I had to figure out free hosting and DNS settings in a registrar’s panel that is hard to call user-friendly.
Moved from classical telecom to quantum key distribution.
BB84, simplified down to a single principle.
Ludus Lab went online.
A series of breakdowns on Pikabu. The site translated into English, Spanish and Chinese. BB84 and E91 rebuilt closer to real physics.
Added as I work through them myself.