# Storage encryption (IndexedDB) – Dec 2025

**Scope**
- Encrypt private article content and invoices stored in IndexedDB using Web Crypto (AES-GCM).
- Deterministic per-article secret derived from a persisted master key.
- No fallbacks; fails if IndexedDB or Web Crypto is unavailable.

**Key management**
- Master key generated once in browser (`article_storage_master_key`, random 32 bytes, base64) and kept in localStorage.
- Per-article secret: `<masterKey>:<articleId>` (used only client-side).

**Implementation**
- `lib/storage/cryptoHelpers.ts`: AES-GCM helpers (base64 encode/decode, encrypt/decrypt).
- `lib/storage/indexedDB.ts`: store/get now require a secret; payloads encrypted; unchanged API surface via `storageService`.
- `lib/articleStorage.ts`: derives per-article secret, encrypts content+invoice on write, decrypts on read, same expiration (30 days).

**Behavior**
- If IndexedDB or crypto is unavailable, operations throw (no silent fallback).
- Existing data written before encryption won’t decrypt; new writes are encrypted.

**Next steps (optional)**
- Rotate master key with migration plan.
- Add per-user secrets or hardware-bound keys if required.