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Week 3 — Secure Key Storage & Management

If an attacker gets the key, encryption is irrelevant.

1. Where NOT to Store Keys​

❌ Firmware source
❌ Plain flash
❌ External memory

2. Better Key Storage Options​

  • Secure Element (ATECC, SE050)
  • MCU TrustZone
  • Encrypted flash with device-unique key

3. Device Identity vs Session Keys​

  • Device Identity → long-lived
  • Session Keys → rotated frequently

4. Key Rotation Strategy​

Good systems assume:

  • Keys will leak
  • Rotation must be supported

Week 3 Assignment​

  • Identify all keys in your system
  • Classify them:
    • Static / Rotating
    • Device / Fleet