PIN-unlock used to freeze the renderer for ~1-2 s on mid-hardware while
the moderate-preset Argon2id KDF + sealed-key secretbox open ran on the
main thread. Push that work into a Vite-bundled ESM Web Worker so the
unlock screen stays responsive.
The worker (apps/desktop/src/workers/crypto.worker.ts) bundles its own
libsodium-wrappers-sumo instance and registers a fresh CryptoBackend
inside the worker realm. Client wrapper (apps/desktop/src/lib/cryptoWorker.ts)
spawns a one-shot worker per unlock — workers are cheap, PIN-unlock is
once-per-session, and one-shot avoids the request-id bookkeeping that the
existing decrypt.worker needs for high-volume per-message decrypts.
Falls back to inline main-thread openUserKey when the Worker constructor
is unavailable (vitest's jsdom) or when worker spawn / round-trip fails
(strict CSP). All 14 desktop + 71 shared tests still pass — the existing
loadOrUnlockUserKey test exercises the inline-fallback branch.
Private key bytes are transferred (zero-copy) back to the main thread,
detaching the worker-side ArrayBuffer view on transfer.
Build emits crypto.worker-<hash>.js (~2.5 MB, mostly libsodium WASM glue
duplicated from the main bundle). Acceptable trade-off for the unblocked
UI; a future change could lazy-load libsodium on the main thread to drop
the duplication.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
byGalax
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