Abstract

Programmable logic controllers often remain deployed for decades, making post-quantum attestation a long-term requirement. Prior measurements of OpenPLC attestation show that post-quantum signing can consume 8899 % of round-trip latency and that durable state can further limit throughput. We introduce AMORT-V1, a checkpointed attestation protocol that moves public-key signing and durable commitment from individual reports to periodic checkpoints. An ML-KEM epoch establishes per-device evidence keys, devices authenticate reports with MACs, and the controller commits ordered evidence through hash-chained Merkle checkpoints signed with ML-DSA or SLHDSA. Because shared MACs do not provide transferable proof of device origin, AMORT-V1 adds a device-held disclosure chain whose keys are released after checkpoint commitment. We validate the protocol with a 27-case attack matrix, 149 differential-test vectors, and a seven-node Raspberry Pi 5 testbed with five physical OpenPLC provers. Checkpointing reduces controller cost by 90 % relative to per-report ML-DSA without durable logging and by 878 % when durable logging is required. Transferable device-origin verification costs 2.95 s per report, while controller-side scaling to 10 000 identities requires 6.18 s and 155 octets per report. AMORT-V1 also supports rollbackresistant restart through TPM-backed monotonic state without placing durable hardware operations on the per-report path.