Monitoring the Validity, Functionality, and Security of Internet SSL Certificates

This research introduces a novel, cross-platform system for comprehensive SSL/TLS certificate monitoring, assessing validity, functionality, and security. Our solution offers automated inspections, robust error detection in certificate chains, expiration warnings, and risk profiling. An empirical study across Slovak, Czech, and Estonian domains revealed widespread misconfigurations, notably hostname mismatches and incorrect values, and low active management (only $0.9 \%$ of faulty certificates corrected within 30 days). We observed that $4 \%$ of certificates were not renewed, and a significant portion of domains (e.g., $27.1 \%$ in Czechia) lacked HTTPS. This system significantly enhances internet service reliability and security by addressing these prevalent certificate management deficiencies.