Secure token passing at application level

Abstract

We introduce an application level implementation of a token passing operation. After an introduction that explains the conceptual principles, we describe exhaustively the state machines that implement our solution. The security requirements are carefully considered, since the token is a sensitive resource, but without introducing scalability limits.We aim at a general purpose token passing primitive: we do not enter the domain of the distributed coordination algorithms that can be implemented using the proposed operation. We discuss its practical utilization, and we indicate as primary application area the coordination of servers in a distributed infrastructure: this matches service oriented Grids as well as other emerging paradigms.Its usage is explained with a simplified use case. A working prototype exists, and we report about experimental results that confirm our claims concerning performance.

The wandering token: Congestion avoidance of a shared resource

“…We injected a token loss event every 10000 seconds (3 hours), while the system supports the nominal number of subscribers. The frequency of token loss events used in our simulation is more than ten times higher than packet loss rate observed in the open Internet: further, a 4-way secure token passing protocol has been developed and described in Ciuffoletti (2007) that reduces the average frequency of loss events to approximately one week, in the scale of our case study, introducing a token latency that is compatible with our use case. Simulation results show that the algorithm promptly recovers from the presence of spurious tokens, indicated by narrow positive spikes; spurious tokens never exceed the number of two.…”

“…The risk of overkilling such problems, introducing algorithms that are more expensive than the resource sharing protocol is real. We have studied such problems, and presented our results in Ciuffoletti (2007).…”

“…A token loss event, which has a probability that is significantly reduced by a 4-way token passing protocol illustrated in the companion paper Ciuffoletti (2007) if (∃i, j, i < j ∧ history(j). id = token.id ∧ history(i).timestamp < token.timestam triggered when the agent does not receive one within a timeout that is obtained incrementing ∆ min of a random quantity (8).…”

“…They turn out to be more expensive, in terms of resource utilization, than the token passing algorithm itself. Therefore, we have studied and presented in Ciuffoletti (2007) a secure group membership protocol whose performance and cost are adequate to the issue presented in this paper. Since its features are relevant for the applicability of our work, we include the reference as a further reading.…”

Scalable Concurrency Control in a Dynamic Membership

“…The former simplification is meant to have a small impact on the significance of our protoytpe: in a separate paper [4] we address experimental results for an authenticated token passing protocol, and the impact of signing/checking is minimal The prototype has been run on a testbed on the development infrastructure Grid5000 [1]. Grid5000 is a research project of the French Government.…”