Recap of Basic Principles

Summary

In this chapter, we talked about why we need cryptography and discussed issues concerning its use. In particular, we introduced the basic model of a cryptosystem as well as important terminology related to it. These are some of the lessons that have emerged:

• The need to secure information isn’t a new concept, but the environment within which information must be protected has changed significantly.

• Cryptography provides the technical means to replicate some of the fundamental security requirements of the physical world in an electronic environment.

• Cryptography can offer strong protection, but only against certain specific threats. It’s just as important to be aware of the security threats cryptography does not protect against as to be mindful of the threats that it does address.

• There are two different types of cryptosystems—symmetric and public keys. These have significantly different properties, and every kind of cryptosystem has its inherent advantages and disadvantages, which we’ll discuss in later chapters. Symmetric and public-key cryptosystems are often combined in natural systems.

• To assess the security offered by a cryptosystem, it’s essential to establish explicit assumptions about what an attacker can do and what resources they might utilize to attack the cryptosystem.