NullVault security

NullVault is designed to encrypt private photos, videos, files, notes, and their app-managed metadata while a vault is locked. A pattern addresses one vault at a time, and NullVault does not show a master list of vaults in normal use. Those protections reduce exposure on a lost, borrowed, or casually inspected device, but they do not make a compromised phone safe or make encrypted data impossible to detect.

Release status: NullVault is available on iPhone and Android.

The security model in plain language

NullVault starts with a boundary: private content should remain encrypted when the vault is locked. Unlocking derives access from the pattern you draw and platform-protected key material. A successful pattern opens its matching vault; the interface does not provide a browsable inventory of every vault.

The apps are designed around four principles:

1. Encrypt content and metadata at rest. NullVault-managed files are stored as authenticated ciphertext, so modification is detected before content is displayed.
2. Keep local vault use account-free. Opening and using a local vault does not require a NullVault account or a NullVault server.
3. Separate vault access. Different patterns address different vaults instead of selecting from a visible vault list.
4. Fail closed. If required key material or authenticated state is unavailable or invalid, the app should refuse access instead of guessing or falling back to plaintext.

Read the security architecture for a more technical explanation.

Protection on Android

NullVault uses AES-256-GCM authenticated encryption, memory-hard Argon2id key derivation, and Android Keystore key material alongside encrypted private app storage. The active vault locks when NullVault moves to the background, the screen turns off, or the configured timeout is reached.

Portable encrypted backups are deliberate exported copies with their own recovery phrase. Duress and panic wipe invalidate future local access but do not erase those exported backups or guarantee physical erasure.

Protection on iPhone

NullVault for iOS uses AES-256-GCM authenticated encryption, Argon2id pattern processing, Apple CryptoKit, and libsodium to protect local vault data. NullVault detaches the active session and requires the intended vault to be opened again after the app leaves the foreground.

Each iOS vault has a 24-word recovery phrase. Encrypted iCloud backup, controlled read-only sharing with a separate sharing phrase, and local duress configuration have distinct security boundaries. CloudKit still exposes the account, device, network, timing, size, and service metadata Apple needs to operate iCloud.

What NullVault is designed to help against

• A finder or thief who has the locked device but not the vault pattern.
• Casual inspection by someone who can use the phone but should not see private vault content.
• Offline modification of NullVault-managed ciphertext.
• Accidental exposure through ordinary app navigation or a visible master vault list.

What NullVault cannot promise

NullVault does not promise absolute protection or immunity from forensic analysis. Its protection has important boundaries:

• A rooted, jailbroken, maliciously instrumented, or otherwise compromised device may capture patterns, keys, screens, or plaintext during use.
• Human-chosen patterns can be predictable. A longer, less obvious pattern is safer than a familiar shape.
• Hidden-vault design removes the ordinary in-app vault list; it does not remove suspicion that the app can contain other vaults.
• File sizes, storage growth, encrypted object counts, cloud activity, filesystem history, or repeated snapshots can reveal that protected activity occurred.
• A person can photograph a screen or keep content that was previously exported or shared.
• Flash storage does not provide a reliable guarantee that overwritten data is physically erased. Ordinary deletion is logical deletion, and encrypted historical copies may remain in snapshots or backups.
• Duress protection is a local-device response. It cannot revoke keys or plaintext already captured, and it does not promise deletion of previously exported or remote backup copies.

The full list is maintained on security limitations.

Your part of the security boundary

• Use an uncommon pattern that is difficult to observe or guess.
• Keep recovery and sharing phrases offline and separate from the device when possible.
• Do not send a pattern, recovery phrase, sharing phrase, or private file to support.
• Keep the operating system updated and avoid devices you believe are compromised.
• Lock NullVault before handing the device to another person.
• Treat every deliberate export as a new plaintext copy that NullVault can no longer control.

Questions people ask

Can NullVault open my local vault?

NullVault local use has no NullVault account, server-side key escrow, or master recovery service. NullVault cannot retrieve a forgotten pattern or phrase for you. That is why recovery planning matters before data is lost.

Does a hidden vault leave no trace?

No. NullVault avoids displaying a master vault list and is designed to limit what a copied encrypted store proves within a defined model. The presence of the app, encrypted storage, storage growth, device history, or cloud activity may still be observable.

What external security review has NullVault received?

The native projects contain scoped design and implementation reviews, but those do not amount to one blanket approval of the final applications. Release requires review and testing of the exact builds and connected-service configuration.

How do I report a security concern?

Email support@nullvault.app with a concise description, affected platform, app version, and reproduction steps. Do not include real vault content, patterns, recovery phrases, or sharing phrases.

Security content reviewed: 1 September 2026.