Abstract: A security mechanism, e.g., a computing system, security server, can effectively serve as a centralized security mechanism, e.g., a computing system, security server, for an ecosystem that can include diverse clients and servers. The security mechanism can obtain redirected requests for services, authenticate credentials of a client and generate a (client-side) token that can be provided by the client to the server for verification of the identity of the client. The security mechanism can also obtain a token from a server that can be similar to a (client-side) token provided to a client and then generate a (server-side) token that can be provided to a server. The server-side token can include authorization information that allows access to one or more services of one or more other servers.

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.