An Efficient Key Expansion Method Applied to Security Credential Management System

TL;DR

This paper introduces a new, highly efficient key expansion method for security credential management in connected cars, significantly reducing computation time while maintaining security standards.

Contribution

The paper proposes an original key expansion method that enhances efficiency over existing ECC-based approaches in IEEE 1609.2.1-2022, with proven mathematical feasibility.

Findings

Improves key expansion efficiency by thousands of times

Maintains security strength equivalent to existing methods

Proves mathematical feasibility of the new method

Abstract

In recent years, U.S. Department of Transportation has adopts Institute of Electrical and Electronics Engineers (IEEE) 1609 series to build the security credential management system (SCMS) for being the standard of connected cars in U.S. Furthermore, a butterfly key expansion (BKE) method in SCMS has been designed to provide pseudonym certificates for improving the privacy of connected cars. However, the BKE method is designed based on elliptic curve cryptography (ECC) in the standard of IEEE 1609.2.1, but more execution time is required for key expansion. Therefore, this study proposes an original efficient key expansion method, and the mathematical principles have been proposed to prove the encryption/decryption feasibility, car privacy, and method efficiency. In a practical environment, the proposed method improves the efficiency of key expansion method in IEEE 1609.2.1-2022 with the same security strength thousands of times.