The Bifid Cipher Explained

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#cryptology, #cryptography, #cryptanalysis
The bifid cipher was invented in 1895 by Félix-Marie Delastelle. It combines substitution, transposition, and fractionation. In this video, we first explain how the cipher works, its keyspace size, and unicity distance. Then, we show how to use the bifid cipher component of CrypTool 2 to encrypt and decrypt texts.
A small article on my blog about the cipher: www.kopaldev.d...
If you are interested in learning the fundaments of cryptology, let me invite you to have a look at our video series about the basics of cryptology, also for beginners: • Basics of Cryptology -...
You can download the latest version of CrypTool 2 from here: www.cryptool.o...
Visit my blog: www.kopaldev.de

Опубликовано:

14 окт 2024

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Комментарии : 7

@ain92ru 9 месяцев назад

The actual number of Bifid cyphers is n^2! divided by n! because there are a lot of cyphers with different tables that are equivalent, see p. 3 in www.dcc.fc.up.pt/Pubs/TR06/dcc-2006-01.pdf

@CryptographyForEverybody 9 месяцев назад

Hiho, interesting. Yeah, seems that there are equivalent keys due to the transposition step. That reduces the keyspace size to ~2^83,68 and the unicity distance to ~25,42 which still is 26 letters :-) But, thanks for pointing to that paper, Greetings, Nils

@kyleeames8229 Год назад

I think there is an improvement I can make to this crypto system to dramatically increase its unicity distance and key space. Is there a way I can send you a python implementation of it when I’m satisfied that it works as intended?

@CryptographyForEverybody 11 месяцев назад

Hiho, No thanks :-) sorry! The Bifid cipher is a "standard" cipher created by the ACA and designed as it is. Clearly, it is not difficult to improve it and a fun project - but I can not review that. I have thousands of subscribers and viewers, so this is not possible. I also work full-time for the University of Siegen and in the DECRYPT project so I am very busy already :-) Greetings, Nils