KEK/DEK wrapping with an optional Argon2id passphrase

[ngaurav]

Problem or motivation

Currently the security model is exposed to disk theft.

Proposed solution

The current LocalFileCrypto could evolve to:

• Generate a random DEK (as now), store it wrapped under either a fixed KEK or an Argon2id-derived KEK
• Optionally accept a passphrase (or AUTHSOME_MASTER_PASSWORD env var) to derive the KEK
• Wipe the KEK from memory after unwrapping

Alternatives considered

No response

Area

Storage / encryption

Additional context

No response