Slices are encrypted in this browser with a key derived from your passphrase (PBKDF2, 310k rounds → AES-256-GCM). Titles and contents are both encrypted. Prism stores ciphertext, never the key. Each slice carries the highest beam allowed to read it.
Never sent anywhere. Forget it and the vault is gone.
Backups hold encrypted titles and contents, plus sizes and dates. They are useless without your passphrase.
Enter your passphrase. On first use, this creates a new vault in this browser with a couple of example slices.