S/MIME Certificate Test Suite

Abstract

In today's world, email usage has become a necessity. Emails, with a large user base, serve various functions not only for personal purposes but also for facilitating communication between teams in the business world and acting as a point of contact for organizations with their customers. Emails that have infiltrated our lives are also at the center of data breaches, leaks, and malicious attacks. To ensure email security, it is possible to send digitally signed and encrypted emails using the public key infrastructure-based S/MIME certificates. The existing standards for S/MIME certificates were deemed insufficient, and in 2023, for the first time, the Certificate Authority/Browser (CA/B) Forum, consisting of Certificate Authorities (CA) and application software providers and recognized as an international authority, published the S/MIME Baseline Requirements (BR) document. While compliance with the Baseline Requirements document published by the CA/B Forum ensures reliability through conformity checks for SSL certificates used in web security, this audit was considered insufficient. To monitor and audit SSL certificates, the Certificate Transparency project was introduced, aiming to provide an open structure to safeguard the certificate issuance process. However, in reliable S/MIME certificates, the control mechanism is limited to BR audits. The study establishes a comprehensive S/MIME certificate public key infrastructure that allows analyzing email applications; behaviors in the face of certificates that do not comply with the BR during the certificate validation phase. Additionally, the study aims to develop a user application that enables end-users to test the security and compliance of certificates with the BR.