# Evaluating Transport Layer Security 1.3 Optimization Strategies for 5G Cross-Border Roaming: A Comprehensive Security and Performance Analysis

## TL;DR

This paper introduces a new TLS 1.3 optimization for 5G roaming that reduces latency without sacrificing security.

## Contribution

Zero Round Trip Time Forward Secrecy (0-RTT FS) maintains security while minimizing handshake latency in 5G roaming.

## Key findings

- 0-RTT FS achieves 195.0 μs handshake latency with 17% overhead compared to insecure 0-RTT.
- Existing TLS 1.3 optimization modes have critical replay vulnerabilities.
- The proposed method provides full security guarantees including PFS and replay protection.

## Abstract

Cross-border Fifth Generation Mobile Communication (5G) roaming requires secure N32 connections between network operators via Security Edge Protection Proxy (SEPP) interfaces, but current Transport Layer Security (TLS) 1.3 implementations face a critical trade-off between connection latency and security guarantees. Standard TLS 1.3 optimization modes either compromise Perfect Forward Secrecy (PFS) or suffer from replay vulnerabilities, while full handshakes impose excessive latency penalties for time-sensitive roaming services. This research introduces Zero Round Trip Time Forward Secrecy (0-RTT FS), a novel protocol extension that achieves zero round-trip performance while maintaining comprehensive security properties, including PFS and replay protection. Our solution addresses the fundamental limitation where existing TLS 1.3 optimizations sacrifice security for performance in international roaming scenarios. Through formal verification using ProVerif and comprehensive performance evaluation, we demonstrate that 0-RTT FS delivers 195.0 μs handshake latency (only 17% overhead compared to insecure 0-RTT) while providing full security guarantees that standard modes cannot achieve. Security analysis reveals critical replay vulnerabilities in all existing standard TLS 1.3 optimization modes, which our proposed approach successfully mitigates. The research provides operators with a decision framework for configuring sub-millisecond secure handshakes in next-generation roaming services, enabling both optimal performance and robust security for global 5G connectivity.