The Affine Cipher - A Mathematical Substitution Cipher

#cryptology, #cryptography, #cryptanalysis
In this video, you learn how the affine cipher works. First, we introduce additive and multiplicative ciphers. Then we have a look at the affine cipher, its keyspace size and unicity distance. Finally, we build our own affine cipher workspace in CrypTool 2.
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
Join Discord server: / discord

[@jonkirk2118]

Thanks Nils! Another great explanation. That artwork is phenomenal too!
In historical practice, was the key space size expanded by using a larger alphabet? i.e., numbers, maybe letters from other alphabets, etc.?
Or, does the language used in the plaintext limit the key space size? So, would a plaintext message in Icelandic be harder to discover (32 letters in their alphabet) than a plaintext message using the Latin alphabet (26 letters)?
Thanks!

[@CryptographyForEverybody]

Hi @jonkirk2118,
The artworks are made with AI and I like them very much too :D
In history, the key space was increased by these methods:
1) homophones (so many ciphertext symbols for the same plaintext symbol, e.g. A = 01 and A = 10, B = 02 and B = 20, etc).
2) Inclusion of higher order elements of the language (e.g. syllables, double letters, etc.). They did not increase the size of the used basic alphabet, but they increased the possibilities of encrypting language
3) A nomenclature table (basically a small codebook), in which words have their own cipher symbols.
4) Finally, codebooks, which contained a codeword for each and every word of a language
But yes. Still, I would agree that a 32-letter alphabet would make analysis more difficult than a 26-letter alphabet :-)
Many greetings,
Nils

[@jonkirk2118]

@@CryptographyForEverybodyThanks a lot for the explanation Nils.

[@Merryfrankster_]

Can I contact you for professional help with a project?

[@CryptographyForEverybody]

Hiho,
Sorry, I work full-time for the University of Siegen and in the DECRYPT project, So I have no time for any additional project(s).
Greetings,
Nils

[@Merryfrankster_]

@@CryptographyForEverybody thank you for the reply. This is a relatively small project - maybe you know someone else, a graduate student or fellow, who would be willing to assist for a consulting fee?

[@Merryfrankster_]

@@CryptographyForEverybody after seeing this video, I have a feeling what I am dealing with is some variant of the affine cipher but with a much larger "alphabet."

[@Merryfrankster_]

@@CryptographyForEverybody I have succeeded in making a brute force mapping but the formula is still not evident.