Security-Performance Analysis of Post-Quantum Blockchain for Smart Cities: An Adaptive Edge-Batched ML-DSA Framework

Abstract

Blockchain technologies are widely used to ensure the integrity and traceability of data in smart city services for the Internet of Things (IoT). To address this issue, switching to post-quantum cryptography increases network costs, a factor that is frequently ignored when assessing the strength of cryptographic methods. NIST-standardized ML-DSA signatures can range from 2,420 to 4,627 bytes, depending on the specific signature, which may seem large given the need to protect sensor records. In this study, the costs across the various layers are investigated, and an Adaptive Edge-batched ML-DSA platform-independent Quantum-Resistant Smart City Blockchain Traffic (QRSCTV) system is proposed. Supervised device-to-edge trust-domain routine telemetry is divided into Merkle batches and then committed to the blockchain with a single ML-DSA signature. Public device-level non-repudiation is not included in the batching process; it is performed only when necessary. A closed-form solution is developed for transaction expansion, normalized block capacity, constrained-link fragmentation, batching delay, and batch selection, accounting for the service-level agreement (SLA). A discrete-event simulation is offered for the model, with Poisson arrival rates varying from 10 to 1000 transactions per second and latency budgets ranging from 50 to 500 milliseconds, and the simulation is easy to reproduce. When the application transaction size is 256 bytes, direct ML-DSA-44 produces a 2,676-byte normalized transaction, allowing for 391 transactions within a 1-MiB budget. AEB-MLDSA uses 70.56 bytes per record and has a normalized capacity of 3210 transactions (that is, 97.1% fewer bytes of authentication per record than direct ML-DSA-44). Moreover, the usefulness of the simulation depends on the workload: if the traffic is light, then small batches or direct signing should be used; if it is telemetry, then a high-rate signature can be efficiently distributed within a bounded delay. The results show that the move from quantum to post-quantum blockchain in smart cities must be handled at both the network architecture and cryptographic levels.