PHP encryption for the common man (read as newbie)
FTA, "...In this increasingly virtual online world, you have to be careful to protect your data. Learn the basics of encoding and encrypting important bits of information, such as passwords, credit card numbers, and even entire messages. Get an overview of what it means to encrypt and decrypt information, as well as some practical examples involving passwords and other data, using PHP's built-in functionality.
Fast-forward to today and encryption is everywhere. Passwords are stored encrypted in databases. Encrypted tunnels through cyberspace are possible via SSL, SSH, and other technologies -- not to mention virtual private networks. Everyday people can and do use Pretty Good Privacy (PGP) to armor their sensitive files and e-mail.
As a PHP developer, you should be aware that strong security practices aren't just for exotic applications -- they're for the project you're working on now. This awareness runs from the pedestrian (such as not showing plaintext in a password field on a login page) to dizzying heights of cryptographic methods (such as DES, MD5, SHA1, Blowfish)...."
Read more at IBM developerworks