Jefferson Disk


Jefferson disk is an amazing cryptographic system. Rather than just plain substitution like in the Caesar cipher Jefferson used a primitive “key” which is a novel idea at that time IMO.

If you think about it a little bit, it’s doesn’t suffer any form of popular cryptanalyst attacks (ciphertext only, known plaintext, and chosen plaintext). It’s immune to ciphertext only attacks because there is no ciphertext to begin with! The message could be anything. Mathematically speaking the value would be factorial of number of characters in a wheel into number of wheels. In short a phenominally large amount of possibilities. It’s immune to known plaintext attack because the mapping mechanism could be changed at will. It’s not static at all. Similarly it’s completely immune from chosen plaintext attacks because the very dynamic nature of used methodology (in other words “algorithm”) used.

The main problem being conveying the method that should be used to arrange the disks in order. Or the key. So parties involved should pre arrange a scheme for the key and then it can be transmitted without having to worry about someone reading it.

Yes we have better methods now, but at that time, it truly would’ve been a great system.


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