Analyzing the exhaustiveness of the Synapse protocol

Abstract

The Synapse protocol is a scalable protocol designed for information retrieval over inter-connected heterogeneous overlay networks. In this paper, we give a formal description of Synapse using the Abstract State Machines framework. The formal description pertains to Synapse actions that manipulate distributed keys. Based on this formal description, we present results concerning the expected exhaustiveness for a number of scenarios and systems maintained by the Synapse protocol, and provide comparisons to the results of the corresponding simulations and experiments. We show that the predicted theoretical results match the obtained experimental results, and give recommendations on the design of systems using Synapse.Keywords Peer-to-peer · DHT-based overlay networks · Abstract State Machines · Retrieval probability 1 Introduction

Federating digital contact tracing using structured overlay networks

“…A proposal to solve this issue was given by defining the Synapse protocol in [21]. Its performances were analyzed in [22], whereas one real-life proof of concept was developed in [24].…”

“…On the other hand, the papers [21,22] recognize the fact that the search procedure of the Synapse protocol is not complete nor fully exhaustive. This is due to the fact that the lookup procedure of the Chord network can "skip" in routing some of the Synapse nodes, and thus not to spread the query to all networks that are reachable.…”

“…More precisely, with respect to the specifications that are provided in [22,23], we need to introduce the following changes:…”

“…Using the results from [22,23] we can prove the following statement: Theorem 1 The proposed extension stores and retrieves only consistent information on Covid-19 positive cases (identified by the origin systems) and their contacts and makes it available to all origin systems. Proof.…”

“…Due to the scheduled time intervals for running different tasks, the nodes' leaving from the bubbles will not happen during the unstable states, i.e., there will be only runs compatible with conditions of [23,Theorems 5.3,5.4,and 5.7]. Also, the fact that the algorithm FINDSUCCESSOR is changed guarantees that all nodes will be contacted during the search procedure, and that the retrieving procedure of the Synapse protocol [22] is fully exhaustive.…”