How photo vault encryption works: keys, patterns and recovery
Understand what AES-256-GCM protects, why a pattern is not your file key, and why a recovery phrase cannot replace a backup of your photos.
The short answer
A photo vault encrypts a copy of your file using a secret key. The resulting bytes cannot be viewed as the original photo without the key. The password, pattern or recovery phrase usually protects access to those keys rather than directly serving as the key for every photo. This explanation describes Kofrix’s current implementation, not every app marketed as a vault.
A separate key for each photo
Kofrix generates a random key for each imported file. It stores that key in an encrypted catalogue, alongside information such as the file name and album. A separate random master key protects the catalogue. This means that choosing the same pattern as another person does not give you their master key. The algorithm is shared; the randomly generated keys are not.
What AES-256-GCM actually means
AES is the encryption algorithm and 256 is the number of bits in the key. GCM adds authentication: the application can detect a wrong key or modified encrypted data. Kofrix processes large files in blocks, binding each block to its file, position and final-block status. A standard algorithm is a building block, not proof that an entire application has been independently audited.
Why the pattern depends on the phone
Kofrix combines the pattern with a random value held in the device’s secure storage. PBKDF2-SHA512 performs 600,000 iterations to derive a key that opens the master-key envelope. This slows guessing attempts; it does not make a predictable pattern strong. Repeating the pattern on a different phone is insufficient without the original device value.
How the nine-word phrase helps
During setup, Kofrix offers nine randomly selected words. In the current device-recovery design, PBKDF2 derives a private recovery key from the phrase, while only its public counterpart is retained for preparing recovery envelopes. The same phrase can reopen envelopes created for that recovery identity. Choosing your own familiar sentence does not provide the same unpredictability as randomly generated words.
What you need after losing a phone
Recovery still needs the encrypted files, their catalogue and the corresponding recovery envelopes. The phrase contains no photos and cannot recreate missing files. Backup and cross-platform sync are not yet available in the current version of Kofrix. The portability of recovery keys should not be confused with a finished iPhone-to-Android transfer feature. Keep an independently recoverable copy of important originals.
What encryption does not cover
Encryption inside a vault does not erase copies in Photos, messages, cloud libraries or exports. It also cannot stop someone photographing an unlocked screen. Protect the phone itself, choose a difficult-to-guess pattern and keep the recovery phrase private. Someone with both a complete encrypted copy and its phrase can attempt recovery without proving they are you.
Sources and method
Descriptions of Kofrix are based on its current implementation. Planned features are distinguished from shipped features. This guide is not an independent security audit.