Wicked Cool PHP

#23: Encrypting Data with Mcrypt

MD5 hashes work just fine if you never need to see your data in readable form. Unfortunately, that's not always an option—if you offer to store someone's credit card information in encrypted format, you need to decrypt it at some later point.

One of the easiest solutions is the Mcrypt module, an add-in for PHP that allows high-grade encryption. The Mcrypt library offers more than 30 ciphers to use in encryption and the possibility of a passphrase that ensures that only you (or, optionally, your users) can decrypt data. To use Mcrypt, recompile PHP data with Mcrypt support, as explained in "#18: Adding Extensions to PHP" on #17: Shutting Down Specific Functions.

Let's see some hands-on use. The following script ...