
When a user secures a note, a 16-byte key is derived from the user’s passphrase using PBKDF2 and SHA256. Each iCloud account (including “On my” device accounts) can have a separate passphrase. Secure notes are end-to-end encrypted using a user-provided passphrase that is required to view the notes on iOS, iPadOS, macOS devices, and the iCloud website.


