G-SINC: Global Synchronization Infrastructure for Network Clocks

TL;DR

This paper introduces G-SINC, a Byzantine fault-tolerant global clock synchronization system that enhances security and reliability in distributed networks, maintaining high accuracy even with malicious nodes and outages.

Contribution

It presents a practical, trustless, Byzantine fault-tolerant clock synchronization approach leveraging SCION architecture, improving resilience over existing systems.

Findings

Over 94% of servers maintain accurate time with 20% malicious nodes.

All servers stay synchronized within 2 ms skew after one year of outage.

The system is backward compatible with existing deployments.

Abstract

Many critical computing applications rely on secure and dependable time which is reliably synchronized across large distributed systems. Today's time synchronization architectures are commonly based on global navigation satellite systems at the considerable risk of being exposed to outages, malfunction, or attacks against availability and accuracy. This paper describes a practical instantiation of a new global, Byzantine fault-tolerant clock synchronization approach that does not place trust in any single entity and is able to tolerate a fraction of faulty entities while still maintaining synchronization on a global scale among otherwise sovereign network topologies. Leveraging strong resilience and security properties provided by the path-aware SCION networking architecture, the presented design can be implemented as a backward compatible active standby solution for existing time synchronization deployments. Through extensive evaluation, we demonstrate that over 94% of time servers reliably minimize the offset of their local clocks to real-time in the presence of up to 20% malicious nodes, and all time servers remain synchronized with a skew of only 2 ms even after one year of reference clock outage.