CISSP Training Kit

Symmetric key algorithms and cryptosystems

As stated previously, a cryptographic cipher is a manipulation process that transforms organized, readable information into unreadable content and can be used later to recover the meaning of the information by making it readable again. Algorithms introduce confusion or diffusion, often by performing substitution, transposition, or mathematical functions on the data.

Cryptographic algorithms fall into two major categories:

• Symmetric key algorithms

• Asymmetric key algorithms

This section and the following sections cover these algorithms in depth, starting here with symmetric key algorithms.

The term symmetric implies that the key used to encrypt the content is the same as the key used to decrypt the content. ...