Keychain overview

- [Instructor] The Keychain is a secure database. We can store sensitive data in it like passwords, Cryptographic keys, credit card data, and so on. The Keychain acts like user defaults in that it's meant to persist small chunks of data. But, there is a big difference. Unlike user defaults, the Keychain is secure. The contents of the Keychain are processed and kept securely on the device and can be extracted from the file system or from backups.

The Keychain can be configured to lock automatically when the device is locked. In this state, the stored Keychain items can't be assessed or decrypted. Before we go on, we need to understand how the Keychain works. The Keychain is basically a database and we can run queries on it. The Keychain services functions take a dictionary that contain the attributes of the query. Each entry in the secure database must have a unique identifier associated with it.