Encryption that happens on your iPhone

VaultCube never keeps a readable copy. What sits in the vault is ciphertext under random file names. While a video is recorded, or an item is imported or shared, it can pass briefly through a temporary file that iOS keeps unreadable while your iPhone is locked. It is deleted as soon as the item is encrypted, and any leftover is cleared when the app starts or locks.

1. You draw a pattern on a 5×5 grid (at least 6 dots and one turn).
2. The pattern is stretched into a key with PBKDF2-HMAC-SHA256 and 600,000 rounds. That takes about half a second, which you barely notice. Someone guessing patterns has to pay that half-second on every try.
3. That key opens your vault key. Each vault has its own random 256-bit key. It is stored only in sealed form, never in the clear.
4. Every file gets its own key, derived from the vault key. Large videos are encrypted in 256 KB chunks. Changing, reordering or cutting a chunk makes the file refuse to open.
5. The details are encrypted too: the vault's name, folder names, titles, notes, dates and thumbnails.

• Someone copying the app's files, from a computer backup or other tools. They get ciphertext.
• Someone opening the app on your unlocked phone. They see a pattern grid that gives no hint. After 5 wrong tries they wait 30 seconds, after 10 five minutes, after 15 an hour.
• Someone in your iCloud account. The backup is ciphertext too. How the backup works

• Patterns are shorter than long passwords. If someone steals a copy of the vault's key file, they can try every pattern on powerful computers. That could take hours to a day. The 600,000 rounds slow it down; they don't make it impossible. The key file can only be read while your iPhone is unlocked.
• An open vault is decrypted in memory. Spyware on a compromised phone can see what you see.
• Photos you leave in the Photos app aren't protected. VaultCube offers to delete the originals after import; iOS keeps them in Recently Deleted for 30 days until you empty it.