Certificate revocation and certificate update

A new solution is suggested for the problem of certificate revocation. This solution represents Certificate Revocation Lists by an authenticated search data structure. The process of verifying whether a certificate is in the list or not, as well as updating the list, is made very efficient. The suggested solution gains in scalability, communication costs, robustness to parameter changes and update rate. Comparisons to the following solutions are included: traditional' CRLs (Certificate Revocation Lists), Micali's Certificate Revocation System (CRS) and Kocher's Certificate Revocation Trees (CRT). Finally, a scenario in which certificates are not revoked, but frequently issued for short-term periods is considered. Based on the authenticated search data structure scheme, a certificate update scheme is presented in which all certificates are updated by a common message. The suggested solutions for certificate revocation and certificate update problems is better than current solutions with respect to communication costs, update rate, and robustness to changes in parameters and is compatible e.g. with X.500 certificates.