Post-Quantum Impacts on V2X Certificates - Already at The End of The Road

The current certificate definition for vehicle-to-everything (V2X) communication does not support forward compatibility as it does not take migration toward Post Quantum Cryptography (PQC) into account. As a result, introducing PQC-compatible certificates in V2X can result in similar to Distributed Denial-of-Service (DDoS) attack to both legacy and PQC-ready vehicles. This situation will make the deployment of PQC certificates a stalemate situation. In addition, due to the larger public key and signature sizes in PQC algorithms, V2X message size will significantly increase, causing the channel capacity and effective transmission range to decrease. This situation will negatively impact the operation of V2X communication. In this sense, any unnecessary channel usages need to be avoided. We propose to revise the certificate definitions in IEEE 1609 and ETSI Intelligent Transport System (ITS) standards to address and mitigate these issues and pave the way for the migration toward PQC algorithm.