Welcome to the crypto vault, where you can learn the fundamental principles behind encryption techniques in use thousands of years ago be Julius Ceasar, those of the Axis and Allies during WWII, a nd even the basics behind digital encryption emerging today.

Each lesson below contains historical background, mathematical principles, instructions for use, examples, popular relevant systems, and at the end of each lesson -- an AgentPoints Challenge! It' s recommended that you begin with classical cryptology and work your way through the entire series so as to build a base of understanding.

Cryptanalysis - A quick introduction to cryptanalysis
Transposition - Encryption in which the order of the letters and/or words rearranged are.
Monalphabetic Substitution - Replaces one letter with another, always using the same substitute. One of the most popular systems, with several well known systems.
Advanced Monoalphabetic Substitutions - More secure mono substitutions (using varients), as well as the Playfair system
Polyalphabetic Substitution - Replaces each letter with a another letter that is different each time

Skytale - An ancient, extremely simple, and unique device
Wheel Cipher - A simple device to create mono or poly alphabetic ciphertext
Jefferson - U.S. President Thomas Jefferson's polyalphabetic cryptographic device
Rotor Systems - Widely used during the second World War, these mechanical machines are nearly unbreakable

Block - Encryption of smaller blocks of data
Stream - Encryption of data one bit at a time
Public Key - The basis for the cryptography behind PGP.

Classic - Secret inks, jargon, and other ways to comminicate without even hinting that a message is present
Modern - Digital ways to hide information within innocolous looking data

Codes - Large, comprehensive, unwieldly code books allow secure communication -- granted no one finds (or figures out) the codebook.