A method of managing exchange of secure online instant messages between subscriber devices (102, 104), where the secure messages are signed and encrypted using subscribers' digital certificates, the method comprising steps of: receiving, at a messaging server a certificate request from a local instant messaging module (102a, 104a) of a subscriber device (102, 104); routing the certificate request by the messaging server to a registration authority and sending a digital security certificate to the subscriber device (102, 104) from the registration authority; responsive to a log in request from at least one subscriber to begin a session of exchanging synchronous online messages, the messaging server temporarily storing the certificate of the subscriber device in a publication record in association with the subscriber device (102, 104) as long as the instant messaging module (102a, 104a) remains logged-in to the messaging server; responsive to prescribed events, the messaging server providing logged-in subscriber devices (102, 104) with selected information concerning certificates of other subscriber devices (102, 104); responsive to the subscriber device (102, 104) ending the session, the messaging server automatically removing the certificate from the publication record for the subscriber device (102, 104); receiving, at the messaging server, a request to un-publish the certificate from the local instant messaging module (102a, 104a) of the subscriber device (102, 204); responsive to receiving the request to un-publish the certificate, the messaging server removing the certificate from the publication record for the subscriber device (102, 104); identifying, by the messaging server, other logged-in subscriber devices (102, 104) that previously designated the subscriber device (102, 104) for potential future secured instant messaging; and notifying the identified other logged-in subscriber devices (102, 104) that the certificate for the subscriber device (102, 104) is withdrawn from use. receiving, at a messaging server a certificate request from a local instant messaging module (102a, 104a) of a subscriber device (102, 104); routing the certificate request by the messaging server to a registration authority and sending a digital security certificate to the subscriber device (102, 104) from the registration authority; responsive to a log in request from at least one subscriber to begin a session of exchanging synchronous online messages, the messaging server temporarily storing the certificate of the subscriber device in a publication record in association with the subscriber device (102, 104) as long as the instant messaging module (102a, 104a) remains logged-in to the messaging server; responsive to prescribed events, the messaging server providing logged-in subscriber devices (102, 104) with selected information concerning certificates of other subscriber devices (102, 104); responsive to the subscriber device (102, 104) ending the session, the messaging server automatically removing the certificate from the publication record for the subscriber device (102, 104); receiving, at the messaging server, a request to un-publish the certificate from the local instant messaging module (102a, 104a) of the subscriber device (102, 204); responsive to receiving the request to un-publish the certificate, the messaging server removing the certificate from the publication record for the subscriber device (102, 104); identifying, by the messaging server, other logged-in subscriber devices (102, 104) that previously designated the subscriber device (102, 104) for potential future secured instant messaging; and notifying the identified other logged-in subscriber devices (102, 104) that the certificate for the subscriber device (102, 104) is withdrawn from use.