A computer network security system provides generation of a certificate revocation list (CRL) upon each revocation. The entire certificate revocation list may be published on demand, or only the portion that has changed. The computer network security system provides on-demand publishing of data identifying revoked certificates, such as revocation and expiration data, in response to receipt of revocation request data. The computer network security system stores the on-demand published data for analysis by one or more network nodes, such as a client, to determine whether a certificate is valid. The network nodes include certificate revocation list cache memory that may be selectively activated/deactivated, to effect storage/non-storage of the data identifying the revoked certificates.