This site makes a transition from the modular arithmetic (of the last section) to writing secret codes (of this section). A Caesar cipher is a secret code in which each letter in the plain text is replaced by a letter … See the whole entry
Problems 1-12
This is a simple code. Write down the alphabet, a comma, and a period, as requested in the directions. Number each of these symbols, and use this “coding key” to answer these questions.
Problems 13-24
This is a … See the whole entry
Cryptography is the art of writing or deciphering messages in code. This is an applied section which uses essential ideas … See the whole entry