The short version
Every file is encrypted on the device with its own key. Those keys are locked by a master key, and the master key only opens with something you know or are: your password, pattern, Face ID or 12 recovery words. There’s no PocketVault account or server to hack, subpoena or leak.
- Files, thumbnails, the index and vault state are all encrypted with AES-256-GCM.
- Your password is stretched with PBKDF2-HMAC-SHA256, 600,000 rounds.
- Knowing your iPhone passcode never opens a vault.
- iCloud backups and sync carry only ciphertext, padded so sizes are blurred.
- No analytics, crash reporters or third-party SDKs in the app.
Encryption on the device
When you add something, PocketVault generates a fresh random data key for that item and seals it with AES-256-GCM, an authenticated cipher that also detects tampering. Large files are sealed in 1 MB chunks, each with its own nonce, plus an encrypted manifest so chunks can’t be reordered, dropped or swapped.
| Cipher | AES-256-GCM (Apple CryptoKit), random 12-byte nonce per seal, 16-byte tag |
|---|---|
| Per-file keys | Fresh 256-bit data key per file and per revision, wrapped by the vault master key |
| Large files | 1 MB chunks, authenticated manifest of chunk hashes, up to 10 GB per file |
| Key derivation | HKDF-SHA256 with distinct labels per purpose, bound to the vault ID |
| Metadata | File names, dates, thumbnails and the index are encrypted too |
How you unlock
The master key is stored only in wrapped form, inside “access slots”. Each slot is a different way to unwrap the same master key. Changing one doesn’t expose the others.
| Password | PBKDF2-HMAC-SHA256, 600,000 rounds, 32-byte random salt |
|---|---|
| Pattern | 5×5 grid, at least 8 dots, at least 2 changes of direction, each dot once, no dots added automatically. Your drawn sequence feeds the key derivation. |
| Face ID | A device-only secret in the Keychain, gated by your current Face ID enrolment. No passcode fallback. If Face ID enrolment changes, it stops working until you unlock another way. |
| Recovery words | 12 words from the standard BIP-39 English list, generated on your iPhone and shown once |
Wrong guesses
Repeated wrong attempts trigger a cooldown that grows with each miss. It slows guessing down and never erases your data. Private-vault pattern misses share one device-wide counter, so the lock screen behaves the same whether or not a private vault exists.
Private vaults & a neutral lock screen
A private vault only opens from its own pattern and is never listed anywhere in the app. When you draw a pattern, PocketVault tries it against every vault that has one and counts at most one miss. The lock screen looks the same for everyone, so it never reveals whether a pattern, Face ID or private vault exists.
Be realistic about this: someone with forensic access to the raw files can still estimate how much encrypted data is stored. Private vaults hide things from the interface, not from physics.
iCloud backup, sync & sharing
All three are optional and all three use Apple CloudKit with data that’s already encrypted on your iPhone.
- Backup uploads an encrypted snapshot to your private iCloud database. Opening it needs your password or recovery words.
- Sync (Plus) exchanges encrypted changes between your iPhones on the same Apple Account. Turning it off disconnects only that iPhone.
- Sharing publishes an encrypted package that only opens with a one-time phrase you send separately. You set expiry and how many times it can open, and you can revoke it.
Before upload, ciphertext is padded up to the next 1 MB plus a random 0–255 KB, so Apple can’t read exact file sizes. Apple can see that records exist, roughly how big they are, and when they change. It can’t see what’s inside.
Crash safety
Every change is written in a fixed order: the encrypted file first, then its index entry, then the vault state. If your iPhone dies mid-write, the vault opens at the last consistent point instead of a half-written mess. When you add from Photos, the encrypted copy is read back and checked before PocketVault offers to delete the original.
What PocketVault can’t protect against
We’d rather you heard this from us:
- An unlocked vault in someone else’s hands. If it’s open, it’s open. PocketVault locks as soon as you leave the app.
- A compromised iPhone. Malware or a jailbroken device can watch what you see on screen.
- Losing every key. Forget your password and pattern, lose Face ID and your recovery words, and the vault can’t be opened by anyone, us included.
- Deleting the app. That deletes the vault on that iPhone. Keep a backup.
- A weak password. PBKDF2 slows guessing down; it can’t make “password1” strong.
PocketVault hasn’t had an independent security audit yet. When it does, the report will be linked here.