Phase 6 Sprint 6.1 - Tamper-Evident Logging

Threat Model

• Asset: telemetry gateway audit trail for accept/reject outcomes.
• Adversary: operator or attacker attempting to alter or erase prior log history.
• Trust boundary: append path to local audit log storage.

Attack Vectors Considered

• In-place modification of historical audit entries.
• Removal of log records to hide rejected/failed actions.
• Silent truncation and rewrite of recent entries.

Mitigations Implemented

• Added append-only JSONL audit log writer.
• Every record includes previous-hash link and entry hash.
• Hash-chain integrity verification API detects tampering.
• Periodic sealing records inserted automatically every N entries.
• Gateway now records accepted and rejected telemetry outcomes in tamper-evident log.

Residual Risk

• Local file storage can still be deleted by privileged host access.
• Seals are local records; external notarization is not yet implemented.

Future Improvements

• Stream seals to remote immutable store (WORM/S3 Object Lock).
• Add asynchronous off-host replication for log continuity.
• Sign seals with hardware-backed attestation keys.