Sensor Attestation and Trust Anchoring (SATA): A Hardware-Anchored τ-Chain Protocol for Autonomous Mission Authority — Technical Assurance Report v3.8.9

Sensor Attestation and Trust Anchoring (SATA) is a hardware-anchored trust architecture that produces a continuous trust scalar τ ∈ [0,1] from a TPM-anchored τ-Chain of cryptographically committed sensor attestation records. Unlike traditional remote attestation systems that treat trust as binary, SATA models trust as a continuously updated scalar derived from a sliding window of recent attestations, enabling graded operational authority decisions rather than single point-in-time authentication.

SATA forms the hardware-anchored trust layer of a three-component authority stack together with the Hierarchical Mission Authority Architecture (HMAA) and the Cognitive Authority Recovery Architecture (CARA). In this architecture, SATA provides the trust signal τ, HMAA translates τ into graded operational authority A and mission tiers Tier(A) ∈ {T0–T4}, and CARA performs structured recovery through GREP phases I–IV when authority collapses.

This technical assurance report presents the formal and empirical foundation of the SATA protocol, including:

• Mathematical specification of the τ-Chain trust computation
• Six-barrier replay-resistance architecture (nonce, signature, PCR, sequence, counter, freshness)
• Deterministic boundary test vectors and CI verification (45 tests)
• Monte Carlo evaluation (N = 10,000 runs) with explicitly defined generative models
• Bounded TLA+ model checking (18,892 reachable states) validating safety invariants
• A Goal Structuring Notation (GSN) safety argument covering ten hazard scenarios aligned with MIL-STD-882E system safety methodology
• A reproducibility artifact set including simulation dashboard, CI harness, and TLA+ specification

SATA is designed for adversary classes A1 (network attacker) and A2 (OS-level attacker) with an intact TPM root of trust. Under these conditions the six-barrier replay-resistance architecture yields a conservative composite bound P(T5) < 2⁻¹²⁸. Physical adversary scenarios (A3) and hardware dependency modeling remain open assurance gaps.

This record is part of a three-report technical assurance series describing a complete authority stack for autonomous systems:

• HMAA — Hierarchical Mission Authority Architecture
• CARA — Cognitive Authority Recovery Architecture
• SATA — Sensor Attestation and Trust Anchoring (this report)

Supplementary files include the primary simulation artifact (sata_dashboard.html), CI test harness (sata_ci_test.js), and TLA+ specification (CSTP_SATA_v3.2.tla) to enable independent verification of the results.

Scope: research simulation artifact. Hardware-in-the-loop validation and formal refinement remain open assurance gaps prior to operational deployment.