The Chaocipher
The Chaocipher is a mechanical encryption algorithm invented in 1918. No one was able to reverse-engineer the algorithm, given sets of plaintexts and ciphertexts—at least, nobody publicly. On the other hand, I don’t know how many people tried, or even knew about the algorithm. I’d never heard of it before now. Anyway, for the first time, the algorithm has been revealed. Of course, it’s not able to stand up to computer cryptanalysis.
Clive Robinson • July 13, 2010 8:56 AM
Hmm,
It uses two fairly simple “card shuffling” algorithms.
You could with a little patience do this with a single deck of cards split into two packs of red cards and black cards.
I’ll have a think to see how difficult it is to do the shuffeling by hand. On the face of it it is quite simple for the left deck and does not need the use of jokers or other cards etc.