Algorithms for Cyrillic encryption I am working on a cryptography application which is to be used in my country. I tried looking up to see if there are any algorithms that support the Cyrillic alphabet, but I found none. Do you know of any? Can mainstream algorithms (Like AES) work with Cyrillic letters?
Modern cryptographic algorithms are specified in terms of bytes or even bits, not characters.
Whether the data you encrypt happens to represent latin or cyrillic letters or pictures or audio data or anything else does not matter at all to an encryption algorithm; all it ever sees is a bunch of bytes.

What this means in practice is: You have to fix some encoding (UTF-8 is very common nowadays) to translate your characters to a string of bytes which can then be processed by any cryptographic implementation as usual.