Threat-modeling the LAN sync in my wildlife app (as a beginner)

说明与用途

开发者使用 ECDH、HKDF 和 AES‑256‑GCM 实现了 Wildlife Incident Handoff 的 LAN 同步功能，并加入了手动配对和计数器防重放机制，但仍存在前向保密和人工验证的缺口。

问题

Designing a secure LAN sync feature for a wildlife incident recording app to prevent data leakage, impersonation, and other network threats.

结果

The LAN sync feature now encrypts data, uses per‑install keypairs, and requires manual pairing approval, reducing the risk of data leakage and impersonation. However, gaps remain in forward secrecy, human verification, and comprehensive testing.

工作流

• 1. Generate a unique keypair per install. 2. Exchange a pairing code and manually approve pairing requests. 3. Perform P‑256 ECDH to derive a shared secret. 4. Derive an AES‑256‑GCM encryption key using HKDF. 5. Encrypt incident records with the derived key before transmission. 6. Include a counter in each message to prevent replay. 7. Reject requests from unpaired devices and from devices when sync is disabled. 8. Provide a fingerprint for manual verification to mitigate impersonation.

证据

Data is encrypted (AES-256-GCM) with a key both devices agree on (P-256 ECDH + HKDF)

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Each install has its own keypair and a fingerprint you can compare

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The first device has to manually approve every request

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Each message carries a counter, and old counters are rejected, even after a restart

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The sync endpoint rejects untrusted devices

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Pairing and sync requests are rejected when sync is disabled

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