Elementary Information Security, 3rd Edition

▶ 7.1 Protecting the Accessible

In the previous chapters, we rely on physical and logical security measures to protect our information. These measures are not always enough. For further protection, we can use encryption to hide a file’s contents from others. Encryption is one of several techniques classed as cryptography (“secret writing”). We use cryptographic functions to protect data. The only people who can share the data are those who can decrypt it; that is, reverse the encryption. In Chapter 6, we encountered our first cryptographic function: the one-way hash.

Encryption protects information by presenting the reader with a puzzle. Authorized readers know the puzzle’s secret and can easily read the document. Unauthorized readers must ...