Hardware-Rooted Attestation for Precision Time Protocol: Scalable Workload Identity and Phased PQC Readiness

This document defines a scalable framework for hardware-rooted cryptographic attestation in the Precision Time Protocol (PTP). Standard PTP security mechanisms rely on symmetric keys, which suffer from identity ambiguity and source non-repudiation failures—vulnerabilities that allow any node possessing the shared secret to impersonate a Grandmaster. To resolve these issues while overcoming the silicon throughput limits of traditional TPMs and the overhead of Post-Quantum Cryptography (PQC), this draft specifies a tiered trust model. A Hardware Root (e.g., TPM) establishes a long- term PQC identity, while a workload identity management plane (e.g., SPIFFE/SPIRE) manages the frequent rotation of short-lived operational keys. These keys perform amortized signing of PTP message batches via Merkle Trees, ensuring wire-speed synchronization and irrefutable provenance for regulated environments.