Cryptanalysis is the exact opposite of cryptography. Specifically, it is the science of code breaking, decoding secrets, cracking authentication schemes, and destroying
cryptographic protocols. You might be tempted into thinking that cryptanalysis is practiced exclusively by criminals and government code breakers. The truth is that cryptography has a tremendous need for cryptanalysis.
Cryptanalysis is a tool that all cryptographers use to test and prove their latest and greatest encryption schemes. The only way to determine the strength of a particular method of encryption is to try to break the key and decode the message.
Companies that sell encryption systems, such as RSA, actively challenge cryptanalysts to crack their algorithms. The results can either help them fix a broken system, or prove the effectiveness of a good system.
The techniques that are used in cryptanalysis are called attacks. There are many different types of attacks; some specific in nature and others aimed at more general
methods of code breaking.
The above information is the start of a chapter in "Network Security Illustrated," published by McGraw-Hill and available from amazon.com, as well as your local bookstore. The book goes into much greater depth on this topic. To learn more about the book and what it covers, click here.
Below, you'll find links to online resources that supplement this portion of the book.