4.4.9. Renewing or Reissuing CA Signing Certificates

When a CA signing certificate expires, all certificates signed with the CA's corresponding signing key become invalid. End entities use information in the CA certificate to verify the certificate's authenticity. If the CA certificate itself has expired, applications cannot chain the certificate to a trusted CA.
There are two ways of resolving CA certificate expiration:
  • Renewing a CA certificate involves issuing a new CA certificate with the same subject name and public and private key material as the old CA certificate, but with an extended validity period. As long as the new CA certificate is distributed to all users before the old CA certificate expires, renewing the certificate allows certificates issued under the old CA certificate to continue working for the full duration of their validity periods.
  • Reissuing a CA certificate involves issuing a new CA certificate with a new name, public and private key material, and validity period. This avoids some problems associated with renewing a CA certificate, but it requires more work for both administrators and users to implement. All certificates issued by the old CA, including those that have not yet expired, must be renewed by the new CA.
There are problems and advantages with either renewing or reissuing a CA certificate. Begin planning the CA certificate renewal or re-issuance before installing any Certificate Managers, and consider the ramifications the planned procedures may have for extensions, policies, and other aspects of the PKI deployment.

NOTE

Correct use of extensions, for example the authorityKeyIdentifier extension, can affect the transition from an old CA certificate to a new one.