How do you test CRL functionality and compatibility in PKI?

1 Check the CRL distribution point

The CRL distribution point, or CDP, is the location where the CRLs are published and updated. You can find the CDP in the certificate details or in the certificate authority (CA) configuration. To test the CRL functionality, you need to make sure that the CDP is accessible and up to date. You can use tools like certutil, curl, or openssl to download and inspect the CRLs from the CDP. You should check the CRL version, validity period, signature, and revocation entries.

2 Revoke a test certificate

To test the CRL compatibility, you need to revoke a test certificate and see how it affects the applications or services that use it. You can use the CA management console or the certutil command to revoke a test certificate. You should specify a reason for revocation, such as key compromise, certificate hold, or superseded. You should also update the CRLs after revoking the certificate to ensure that the revocation status is propagated to the CDP.

3 Test the certificate validation

To test the certificate validation, you need to use the test certificate in an application or service that relies on PKI. For example, you can use the test certificate to establish a secure connection, sign a document, or access a resource. You should expect the application or service to reject the test certificate and display an error message indicating that the certificate is revoked. You can use tools like certutil, openssl, or browser dev tools to verify the certificate validation process and the CRL checking.

4 Test the CRL caching and expiration

To test the CRL caching and expiration, you need to monitor how the application or service handles the CRL updates and refreshes. Some applications or services may cache the CRLs locally and use them until they expire or are replaced by newer versions. This may cause delays or inconsistencies in the revocation status. You can test the CRL caching and expiration by changing the CRL validity period, revoking or unrevoking certificates, and checking the application or service behavior.

5 Test the CRL fallback and alternative methods

To test the CRL fallback and alternative methods, you need to simulate scenarios where the CRLs are unavailable or inaccessible. For example, you can block the network access to the CDP, corrupt the CRL files, or change the CRL format. You should observe how the application or service reacts to the CRL failure and whether it uses alternative methods to validate the certificates. Some of the alternative methods include online certificate status protocol (OCSP), delta CRLs, or certificate pinning.

6 Test the CRL interoperability and compliance

To test the CRL interoperability and compliance, you need to check whether the CRLs are compatible and compliant with different standards and protocols. For example, you can check whether the CRLs follow the X.509 or RFC 5280 specifications, whether they support extensions or attributes, and whether they work with different PKI vendors or implementations. You can use tools like certlint, zlint, or openssl to validate and analyze the CRLs and identify any errors or warnings.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?