In the past I mentioned an excellent framework for easily using the keychain to store usernames and passwords within your apps, and a keychain tutorial for those looking to use the keychain from scratch.
Developer Chris Lowe has written an in-depth tutorial covering several different aspects for those looking to secure app data going beyond the basics of using the keychain.
In the tutorial you’ll build a secured app and a keychain wrapper class. Some of the topics covered include secure text entry with the iOS 5 alert views, using hashing algorithms, protecting files with the Data Protection API and more.
A great tutorial for anyone looking to secure data within their apps.