Provable Security Analysis of Butterfly Key Mechanism Protocol in IEEE 1609.2.1 Standard

The paper provides the first provable security analysis of the Butterfly Key Mechanism (BKM) protocol from IEEE 1609.2.1 standard. The BKM protocol specifies a novel approach for efficiently requesting multiple certificates for use in vehicle-to-everything (V2X) communication. We define the main security goals of BKM, such as vehicle privacy and communication authenticity. We prove that the BKM protocol, with small modifications, meets those security goals. We also propose a way to significantly improve the protocol's efficiency without sacrificing security.