Defense in depth.
The Mac worker app runs in a restricted sandbox, audio is sharded so no single worker sees a full recording, and the coordinator enforces trust tiers before accepting shard results.
Mac app sandbox entitlements
The Acorn worker app (Acorn.app) is a macOS menu-bar application built with SwiftUI. It runs with these entitlements only:
- Outbound network — reach the coordinator API and download audio fragments.
- File access (user-selected) — only when the user explicitly chooses a local audio file.
- Keychain access — stores the worker credential securely.
- GPU / Metal compute — used by the Whisper and Parakeet backends. No data leaves the Mac during inference.
The app does NOT request camera, microphone, contacts, location, screen recording, or full disk access. App Sandbox is enforced by macOS.
Threat model
Acorn distributed design limits the damage any single worker or coordinator compromise can cause:
- Audio sharding — 60-second segments with overlap. A compromised worker sees at most one fragment.
- Trust tiers — new workers are untrusted by default, validated against canary audio.
- Coordinator auth — WebAuthn passkeys. No password to phish.
- API key hashing — keys stored as SHA-256 hashes. Coordinator cannot leak plaintext.
- HMAC-signed webhooks — outbound deliveries signed so receivers can verify the payload.
Data in transit
All coordinator traffic uses HTTPS. No plaintext connections accepted in production.
Reporting a vulnerability.
Email security@acorncompute.com with reproduction steps and your contact details. We respond within two business days. Give us reasonable time to fix confirmed issues before publishing. Valid reports get a public credit (unless you prefer anonymity).