Encryption and signing

When we look at ways of securing data, either at rest or in transport, many of the methods we discuss will be cryptographically securing data.

"Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks (line like the internet) so that it cannot be read by anyone except the intended recipient."

- An Introduction to Cryptography, Network Associates, Inc.

As a basis for the things we will discuss in this chapter, we must first understand how cryptography works; not in so complex a way that we need a mathematics degree, but to the extent of the parts involved. Cryptography is only as good as the security of the keys involved, and we need to know which of these keys can be distributed freely and which ones need to be guarded with our lives.

Symmetric-key encryption

Symmetric-key encryption is also called secret-key or conventional cryptography: one key is used...