Advancing Zero Trust for SMEs: A Review of Short-Lived Certificates, MFA, and Lightweight Identity Solutions

Small and medium-sized enterprises (SMEs) face growing cybersecurity threats but lack the financial and technical resources to implement complex security architectures. Traditional perimeter-based models fail in today’s cloud-driven and remote work environments, leaving SMEs vulnerable to credential theft, phishing, and ransomware attacks. Zero Trust offers a promising alternative by enforcing continuous verification and least-privilege access; however, most implementations assume enterprise-scale infrastructure, making them impractical for SMEs. This review addresses that gap by focusing on three identity-centric mechanisms that enable Zero Trust adoption without excessive complexity: short-lived certificates, multi-factor authentication (MFA), and lightweight identity solutions. Short-lived certificates minimize credential exposure by limiting validity periods and reducing reliance on revocation processes. MFA improves identity security by reducing phishing risk and limiting damage from reused passwords. Lightweight identity platforms, such as cloud-based identity providers, centralize authentication and enforce policies with minimal administrative work. By synthesizing best practices and empirical findings, this paper presents how these measures can be combined into a practical, identity-centric Zero Trust approach suitable for SMEs. It evaluates security benefits, usability trade-offs, and deployment challenges, highlighting automation as a key enabler for reducing operational burden. The review concludes with adoption considerations and future directions, including decentralized identity and AI-driven risk scoring, offering SMEs a roadmap to achieve robust, identity-driven security within resource constraints.