K07 · evidence-bundled critical-infrastructure assurance
Trusted time, sequence, and event ordering
Direct answer
Use multiple time sources, bounded drift, authenticated distribution where supported, local monotonic sequence, and explicit degraded-time operation.
Authority and evidence boundary. K07 publishes knowledge architecture, bounded reference records, procurement structures, local validation tools, signed synthetic fixtures, and point-in-time source review. It does not certify a facility, award a contract, authorize an operation, prove truth, establish deployment, or claim current operation.
Context
Protection, forensics, grid control, sensor fusion and evidence receipts depend on accurate event order and trusted clocks.
Proposed reference decision
Use multiple time sources, bounded drift, authenticated distribution where supported, local monotonic sequence, and explicit degraded-time operation.
Alternatives considered
- single GNSS source
- ordinary NTP without criticality analysis
- timestamp trust without sequence evidence
Consequences
- clock disagreement becomes an incident signal
- evidence includes source and uncertainty
- safe behavior is defined under time loss
Defeaters and reversal conditions
- single time root
- unmeasured drift
- no holdover
- event order reconstructed only after failure
Source relationships
- NIST SP 800-82 Revision 3 — K07 Official Review Record — National Institute of Standards and Technology; Revision 3; FINAL; REVISION 4 PRE-DRAFT PROCESS OPENED 2026. Exact claim-support entries: 1. Revalidated 2026-08-15T23:30:00Z.
- DOE Cyber-Informed Engineering — U.S. Department of Energy, CESER; Official program page reviewed 2026-08-15; OFFICIAL PROGRAM GUIDANCE. Exact claim-support entries: 1. Revalidated 2026-08-15T23:30:00Z.
Use boundary
This record is a proposed reference decision. A competent owner must bind it to actual site constraints, authority, hazards, license conditions, interfaces, implementation evidence, and change control.