Many people think that computer security begins and ends with encryption. After all, how can data be secure if it is not encrypted?
In fact, cryptography has a lot to do with security?it's one of the most powerful tools for keeping data secure. That's why we have spent so much time on cryptography in this chapter! But there's cryptography and then there's cryptography?as you have seen, cryptography encompasses a range of techniques, algorithms, purposes, and objectives. In this chapter we've tried to present an overview that is good enough for you to understand the basics of encryption as they apply to securing a Unix server.
Now you know enough to be dangerous! Although you should have no problem using an encryption package like OpenSSL or Apache's mod_ssl, before you start designing your own encryption systems, you should read several books that are devoted entirely to the subject.