Encryption usage in iOS

I'd like to learn how to store different encrypted sensitive information of any kind, but unfortunately don't know how and where to start learning from. I can write whole of things in application except password encryption/protection. Can someone show me the right direct开发者_如何转开发ion to look at? Any help will be appreciated. Thanks.

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Can't you use the keychain to store the user/password?

Some tutorial and examples can be found here.