An Example Check out the new USENIX Web site.



next up previous
Next: Revocation Up: Delegation Protocols Previous: Chained Invocations

An Example

Consider an example of an user, A, using the services of a TravelAgent object, B. Let object B provide services related to travel reservations and travel arrangments. It might in turn need to make use of the services of AirlinesServices provided by an object, C. A obtains the reference of B and invokes the makeReservation method on B. Object B might specify, attached with its object reference, a set of security requirements. Let the security requirements specify that Delegation is required. In SDM, our system will analyse this security requirement attached to an intermediate object (in this case, object B) and whether A is willing to delegate (known from A's security specification attached to its object reference). Mapping this example to the delegation protocol described in Figure gif, the underlying system generates a delegation certificate and passes it on to B.

Let the travel agent B contact the airline object, C, to make an airline reservation by invoking the purchaseTicket method. At this point, B provides its certificates (preferred travel agent certificate, certified travel agent, etc) along with the delegation certificate issued by A. B acts as a delegate, acting on behalf of A, and makes a request to C. For this request B combines its own privileges (of being a preferred travel agent, authorizzation to make reservations, etc) along with the privileges of the intiator A (as the service might make use of A's credit card, or a travel coupon issued explicitly to A). Thus B makes use of CascadedDelegation facility provided by SDM while invoking the purchaseTicket method on the object C.



Nataraj Nagaratnam
Mon Mar 16 18:02:57 EST 1998