A Photo Vault Is Not a Lock Screen

A private-file app can look convincing before it has explained the one thing that matters most: what happens to a file after import. A passcode, pattern, or biometric prompt can control whether someone can open an app. That is useful. It does not, on its own, explain whether the photo, video, recording, or document stored by the app is unreadable without a cryptographic key. For an iPhone privacy app, those are separate questions. A screen lock is an interface decision. Encryption is a storage decision. At ArkWarden, that distinction is the starting point for the product. We build a private vault for photos, videos, audio, and documents, but the more general point applies to any app that asks users to trust it with sensitive material. The stored file needs its own protection An app can require Face ID or a PIN and still leave the stored file in its original form. If another process can reach that file through an export, backup, device connection, or an implementation mistake, the app-level prompt was never the protection boundary. The useful question is concrete: does the app turn the stored file into ciphertext that cannot be opened without the correct key? ArkWarden encrypts each file on the device with AES-256-GCM through Apple CryptoKit. Authentication matters as much as confidentiality here. A system should reject changed or substituted encrypted data rather than quietly opening it as though it were valid. Naming an algorithm is not enough by itself. An honest description should explain where the key comes from, what unlock secret protects it, and what recovery path exists when the user forgets that secret. Key custody is a product decision Many privacy products make an account part of the access or recovery path. That can be useful when someone needs password reset, multi-device synchronization, or customer support. It also means the provider and an email address have a role in access to private material. ArkWarden takes a local-first approach. Normal use does not require an ArkWarden account or an ArkWarden server. ArkWarden creates a random 256-bit master key on the iPhone and never sends it elsewhere. For pattern unlock, the pattern goes through PBKDF2 at 600,000 iterations with a vault-specific salt. ArkWarden combines that result with a secret from the iPhone's Secure Enclave. Both are required to unlock the master key, so copied vault data cannot be attacked on another computer. Users can choose Face ID or Touch ID, a PIN, or YubiKey NFC as a second factor. This approach has a cost: there is no email reset. Instead, a user can create a 12- or 24-word recovery phrase and keep it somewhere safe. That is not universally better. It is a deliberate trade: more user control, and more user responsibility. A recovery path should not create a new weak point Privacy apps need a clear answer for two different failures: The user forgets how to unlock the vault. The device, backup, or file list needs recovery. Those are not the same problem. A password-reset email addresses the first one, but it also places the provider in the access path. A recovery phrase held by the user avoids that provider reset path, but it must be treated like a key because it is one. For data recovery, an app should explain what its backup contains, whether it remains encrypted, and what is required to restore it. ArkWarden supports encrypted backup through a user's own iCloud account or an exported encrypted backup file. Both are optional. Restoring requires the recovery phrase. Transparency should be practical Security claims are easier to make than to check. The useful standard is not that every user must read cryptographic code. It is that a technically experienced person has something real to inspect, and that the product does not ask everyone else to rely on unexplained promises. ArkWarden publishes its core encryption source code. That does not make an app automatically secure, and it is not a substitute for independent review. It does make the relevant design choices available for inspection instead of treating them as marketing language. For an example of how these questions apply to actual products, ArkWarden has published a source-led comparison of seven photo vault apps for iPhone. It links to each provider's public documentation and marks technical details as undocumented rather than guessing.