3 simple encryption algorithms:
- RailFence
- Vigenere Cipher
- A special case of the Cardano Crille (rotating square)
BSUIR, Laboratory work on the Theory of Information (1)
The essence of the permutation methods is that the original message is M divided into data blocks consisting of d characters M = m1, ..., md, md + 1, ..., m2d, ..., after which the resulting blocks of source text are converted in accordance with some vector, function or figure.
Cryptographic systems based on the substitution method can divided into four main classes:
1. Single-alphabetic substitution cipher (simple substitution cipher) - cipher where each plaintext character is replaced by some fixed for this key with the symbol of the same alphabet. Example Caesar's cipher can serve.
2. A monotone substitution cipher (homophonic) is similar to single alphabetic except that the plaintext character can be replaced by one of several possible characters. To these ciphers carry the cipher bill.
3. The polygram substitution cipher replaces not one character, but a whole group of characters. Examples of such ciphers are the Playfeira cipher, the cipher Hill's
4. The multi-alphabet substitution cipher consists of several ciphers. easy replacement. For example, cipher Vizhenera, disposable notebook.