Title: Theory / Important / CS / Programming / Objective-C / Library / KeyChain

Name: Keychain
Definition: A secure storage of user's secret
Page: https://developer.apple.com/documentation/security/keychain_services
Variables: Apple

Name: A secret
Definition: Some data that only the user should have access to
Page: https://developer.apple.com/documentation/security/keychain_services
Example: password
Example2: certificate
Example3: card number

Name: A keychain item
Definition: some encrypted data
Page: https://developer.apple.com/documentation/security/keychain_services/keychain_items
Definition2: some attributes that can be used to search it
Conjdef: both

Instruction: SecItemAdd
Page: https://developer.apple.com/documentation/security/keychain_services/keychain_items
Effect: add a secret item to the keychain.
Language: Objective-C

Instruction: SecItemCopyMatching
Page: https://developer.apple.com/documentation/security/keychain_services/keychain_items
Language: Objective-C
Returns: The item in the keychain if it is foud

Instruction: SecItemUpdate
Page: https://developer.apple.com/documentation/security/keychain_services/keychain_items
Language: Objective-C
Returns: Update the secret

Instruction: SecItemDelete
Page: https://developer.apple.com/documentation/security/keychain_services/keychain_items
Language: Objective-C
Returns: Delete the secret