Basics of Cryptology – Part 21 (Cryptanalysis – The Index of Coincidence (IoC))

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RockSinCity
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In this video, we show the basics of cryptology (cryptology = cryptography and cryptanalysis).

This video here gives an introduction to William Friedman's Index of Coincedence (IoC). Friedman used it for determing the keylength of polyalphabetic ciphers, e.g. the Vigenère cipher. Today, we use the IoC as cost or fitness function in modern heuristics to create powerful divide-and-conquer attacks on e.g. the ADFGVX cipher or the Enigma machine.

Here, we also show how to compute the IoC and how it was used and is currently used in cryptanalysis of classical ciphers. In the second part of the video, we show how to compute the IoC using CrypTool 2.

To see all videos in the "Basics of Cryptology" series, use this playlist: https://www.youtube.com/playlist?list=PLMuvAbyIl0PT6zaRVpK0FCSNMgwAOckTt

If you are interested in details about CrypTool 2, you may have a look at this video here, which gives a short introduction: https://www.youtube.com/watch?v=dELT2-Vgsr8

Finally, you may download the latest version of CrypTool 2 here: https://www.cryptool.org/en/ct2/downloads
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