Re:What are some innovative encryption methods?
by Someone on Wednesday November 01, 2017 @04:51PM
(#15605371)
Indeed. The two simplest examples are the Caesar cipher (https://learncryptography.com/classical-encryption/caesar-ci..., key length of 1 character) and the Vigenère Cipher (https://learncryptography.com/classical-encryption/vigenere-..., key length as long as you want it to be)
Both extend the key by repeating it. That is not a good idea.
Any way of meaningfully extending the key will be vulnerable to a kind of analysis well understood 70 years ago.
This is basically what almost the entire field of cryptography is about: Figure out how you can effectively and securely encrypt things with a key that's a lot shorter than your cleartext.