Abstract: A system, method, business method, and computer program product for conducting electronic transactions with a potentially untrusted server while maintaining user anonymity and transaction privacy, yet allowing the server to verify the user is a valid subscriber entitled to participate in the transaction. Anonymous service requests are sent to the server. The server transmits responses that have been encrypted such that only valid subscribers can decrypt them. Broadcast encryption schemes that enable selective revocation of misbehaving subscribers will tip off requestors that the server is trying to identify them. Transaction and content quantity can be monitored for usage-based billing while maintaining anonymity. Each content item may be uniquely encrypted with a content key that is then encrypted by a session key and included in encrypted form with a response, to reduce the computational workload.

Abstract: Packet messages transmitted on a packet communications network include origin and destination addresses in the form of stacked address elements which can be pushed or popped off of the stack. A plurality of interconnected packet communications network include routing nodes which utilize the top address element on the destination stack to route the message. Such routing nodes also include stack element editing facilities for popping elements from the stocks, constructing new elements to be pushed onto the stacks, and amending the contents of elements on the stack. This arrangement allows messages to be launched on the networks where the originating station does not have full knowledge of the destination station, and the routing nodes add the necessary destination information as it becomes necessary for routing.