Classical Cryptanalysis

This page documents the ways in which many classical cryptographic algorithms can be cryptanalysed. For a list of many classical cryptographic algorithms and specific cryptanalysis methods, see Classical Cryptography.

This page is a very general introduction to the techniques used to automatically cryptanalyse just about any algorithm that enciphers text. Much of this will be slightly mathematical, but programs will be provided for everything so even if you don't understand something, you should still be able to use it.

Most of the techniques described here will not work on modern cryptographic algorithms, if this is what you are looking for you should look for some different methods will be needed.

Text Characterisation

Monogram, Bigram and Trigram frequency counts

Markov Models for text recognition

Statistics for Cryptanalysis - common statistical tools

Stochastic Searching

Genetic Algorithms

Simulated Annealing

Putting it all together

A cipher cryptanalysis tool

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