Santos:CCNA Sec 210-260 OCG

Ciphers and Keys

Understanding the terminology is a large part of understanding any technology, so let’s begin with some fundamentals.

Ciphers

A cipher is a set of rules, which can also be called an algorithm, about how to perform encryption or decryption. Literally hundreds of encryption algorithms are available, and there are likely many more that are proprietary and used for special purposes such as government and national security.

Common methods that ciphers use include the following:

Substitution: This type of cipher substitutes one character for another. The example earlier used a simple cipher that substituted each letter from the alphabet ...