How do you communicate and enforce your PKI revocation policy?

The certificates issued for identification of non-person assets are often revoked when those certificates have been compromised or were improperly requested or handled by the system administrator. Additionally, during the lifecycle of a certificate, the system administrator may determine that their certificate implementation strategy may need to change. If this happens prior to the end of the life of the certificate, and the strategy change involves use of a new certificate, the old certificate should be revoked.

Communicating and enforcing a Public Key Infrastructure (PKI) revocation policy is crucial for maintaining security. First, clearly document the policy, detailing the reasons for revocation, such as key compromise or role changes. Distribute this policy to all stakeholders via training sessions, emails, and intranet postings. Enforce it by integrating automated systems that monitor certificate validity, alerting administrators to potential issues. Utilize Certificate Revocation Lists (CRLs) and the Online Certificate Status Protocol (OCSP) for real-time revocation status. Regularly audit the PKI to ensure compliance and update the policy as necessary to address new security threats.

Effective communication and enforcement of a PKI revocation policy involve clear documentation and regular updates to all stakeholders. This includes publishing revocation lists (CRLs) or using Online Certificate Status Protocol (OCSP) for real-time status checks. Ensuring that all parties are aware of the policy and its procedures, and incorporating these into automated systems for prompt action, helps maintain robust security and trust.

PKI revocation is essential for maintaining trust in a certificate-based system. By invalidating certificates that are no longer secure or valid, organizations can prevent unauthorized access and mitigate risks from compromised certificates. It's a key practice to ensure that only trustworthy certificates are used across the network.

To communicate and enforce your PKI revocation policy, start by clearly documenting the policy and ensuring it is accessible to all relevant stakeholders. Conduct regular training and awareness programs to educate users and administrators about the policy and its importance. Implement technical controls to enforce the policy, such as automated revocation mechanisms and regular updates to CRLs. Monitor compliance through audits and reviews, and address any deviations promptly. Additionally, establish a feedback loop for continuous improvement based on real-world experiences and changes in business needs.

Brad S. makes a very important point. Almost nothing checks revocation anymore. Some TLS stacks don't even have the option to turn it on. That must be part of your threat model. This is one reason that certificate lifetimes are getting shorter.

In addition, revocation status is not always checked by all systems, so the strategy for revocation should be aligned with organization risk appetite, compliance requirements, network bandwidth concerns, publishing impacts on admins, and any other factors which would impact the methods, timing, and distribution of a certificate revocation practice.

PKI revocation presents challenges around balancing timeliness and performance. While frequent updates to Certificate Revocation Lists (CRLs) help maintain accurate validity status and reduce risks, they can also increase network traffic, storage needs, and processing times. Additionally, ensuring consistent propagation of CRLs across all network participants can be problematic, potentially leading to delays or inconsistencies in certificate status updates.

Determining your PKI revocation policy requires a careful balance of security needs, network characteristics, and operational constraints. Tailor your policy to the size and complexity of your PKI and the sensitivity of your data. Consider factors like network bandwidth and latency when deciding on CRL update frequency and distribution. Optimizing CRL size, format, and employing caching and replication can enhance performance while ensuring robust security.