What is a significant disadvantage of using X.509 certificates?

When considering the use of X.509 certificates, one significant disadvantage is that they require a public-key infrastructure (PKI). A PKI is essential for managing the issuance, renewal, and revocation of certificates, which adds complexity and overhead to the system. Implementing a PKI requires a structured approach to set up certificate authorities, validate identities, and maintain security policies, which can involve significant resources and administrative effort.

This requirement can be a barrier for smaller organizations or projects that may not have the necessary infrastructure or expertise. Without a proper PKI in place, the benefits of using X.509 certificates—such as establishing secure, encrypted connections and verifying identities—may not be fully realized. Consequently, the reliance on a comprehensive PKI illustrates a key drawback of adopting X.509 certificates in various applications.