The Craft of System Security

7. Using Cryptography

To a large extent, computers and computation consist of information: bits and bytes, some stored locally and some sent over a network wire or carried on a CD-ROM. Ensuring that the adversary cannot coax such systems into bad behaviors can thus depend on ensuring that the adversary cannot do bad things with this information, such as spy on or alter or forge it. Focusing on how to prevent the adversary from doing such bad things to information, the field of cryptography provides many useful items for the computer security toolkit. In this chapter, we survey these tools.

• Section 7.1 sets the stage and introduces some basic terminology.
• Section 7.2 discusses the importance of randomness to cryptography.
• Section 7.3 explores ...