Security

What Loclavis does technically, and what it does not. Only properties that can be checked in the code are listed here.

Local processing

Encryption and decryption run in your browser, inside a web worker. The files you protect are not uploaded.

Algorithms in use

• AES-256-GCM for contents and metadata, with separate keys.
• Argon2id (64 MiB, 3 passes) to derive keys from your password.
• HKDF-SHA-256 to separate the wrap, metadata and stream keys.
• For ordinary PDFs, optional native AES-256 encryption via qpdf (WebAssembly, bundled locally).

What a container reveals

The public header of a .safe container holds the salt, the algorithm parameters and size information. Filename, folder structure and contents are encrypted inside it.

Which online functions exist

Payment and licence checking. Both are separated from the encryption core and never transmit files, passwords or keys.

Limits

• Security depends on your device and browser. No web application helps on a compromised system.
• A weak password stays a weak password. Argon2id makes guessing expensive, not impossible.
• JavaScript cannot guarantee that memory is overwritten. Key material is wiped on a best-effort basis.
• Loclavis has not been externally certified. There is no security seal and no guarantee.