ABSTRACT
The two main methods used are to either use a unique algorithm that both Bob and Alice know and not tell Eve or use a well-known algorithm that Eve also knows, and use some special electronic key to uniquely define how the message is converted into cipertext, and back again. A particular problem in any type of encryption is the passing of the secret algorithm or the key in a secure way, as Bob or Alice does not know if Eve is listening to their communications. If Eve finds out the algorithm or the key, neither Bob nor Alice is able to detect this. This chapter looks at some of the basic principles of encryption, including the usage of private-key and public-key methods. As we will find public-and private-key methods work together in perfect harmony, with, typically, privatekey methods providing the actual core encryption and public-key methods providing ways to authenticate and pass keys.
