Core PHP Programming, Third Edition

12.5. Encryption

Encryption is the process of transforming information to and from an unreadable format. Some algorithms simply scramble text; others allow for reversing the process. PHP offers a wrapper to C's crypt function plus an extension that wraps the mcrypt library.

The mcrypt functions rely on a library of the same name written by Nikos Mavroyanopoulos, which provides an advanced system for encrypting data. The URI for the project is <http://mcrypt.hellug.gr/>. Sascha Schumann added mycrypt functionality to PHP. Derick Rethans added support for the new API introduced in mcrypt 2.4.4.

Cryptography is a topic beyond the scope of this text. Some concepts discussed in this section require familiarity with advanced cryptographic theories. ...