SALT-V: Lightweight Authentication for 5G V2X Broadcasting

TL;DR

SALT-V is a hybrid authentication framework for 5G V2X that combines ECDSA and lightweight GMAC to enable immediate, efficient, and scalable message authentication suitable for collision avoidance and safety-critical applications.

Contribution

It introduces a novel hybrid protocol with an Ephemeral Session Tag whitelist and Bloom filter revocation, achieving immediate verification and high scalability for V2X communications.

Findings

Achieves 0.035 ms average computation time, 57x faster than pure ECDSA

Provides 1 ms end-to-end latency suitable for safety-critical applications

Scales linearly to 2000 vehicles with minimal overhead

Abstract

Vehicle-to-Everything (V2X) communication faces a critical authentication dilemma: traditional public-key schemes like ECDSA provide strong security but impose 2 ms verification delays unsuitable for collision avoidance, while symmetric approaches like TESLA achieve microsecond-level efficiency at the cost of 20-100 ms key disclosure latency. Neither meets 5G New Radio (NR)-V2X's stringent requirements for both immediate authentication and computational efficiency. This paper presents SALT-V, a novel hybrid authentication framework that reconciles this fundamental trade-off through intelligent protocol stratification. SALT-V employs ECDSA signatures for 10% of traffic (BOOT frames) to establish sender trust, then leverages this trust anchor to authenticate 90% of messages (DATA frames) using lightweight GMAC operations. The core innovation - an Ephemeral Session Tag (EST) whitelist mechanism - enables 95% of messages to achieve immediate verification without waiting for key disclosure, while Bloom filter integration provides O(1) revocation checking in 1 us. Comprehensive evaluation demonstrates that SALT-V achieves 0.035 ms average computation time (57x faster than pure ECDSA), 1 ms end-to-end latency, 41-byte overhead, and linear scalability to 2000 vehicles, making it the first practical solution to satisfy all safety-critical requirements for real-time V2X deployment.