The Quantum State Continuity Problem and Temporal Enforcement Against Fork Attacks

TL;DR

This paper introduces the Quantum State Continuity Problem (QSCP) as a new security goal to prevent fork attacks in quantum systems, proposing a quantum-assisted primitive called QSCW that enforces temporal linkage and demonstrates exponential security gains.

Contribution

It defines the QSCP, shows classical and quantum stateless methods fail to enforce it, and proposes QSCW as a novel quantum-assisted primitive to ensure execution continuity.

Findings

QSCW effectively suppresses fork attacks with exponential decay in success probability.

Classical and stateless quantum authentication mechanisms are vulnerable to fork attacks.

Simulation results confirm robustness of QSCW against noise and system variations.

Abstract

We introduce the Quantum State Continuity Problem (QSCP), a security objective orthogonal to identity authentication that captures whether a systems current execution is a legitimate continuation of a unique past execution. We show that classical and stateless quantum authentication mechanisms fail to enforce continuity and remain vulnerable to fork attacks. To address this gap, we propose the Quantum State Continuity Witness (QSCW), a minimal quantum-assisted primitive that enforces temporal linkage of execution through stateful quantum evolution and cumulative auditing. Using a GHZ-based toy instantiation and extensive simulation, we demonstrate that temporal enforcement suppresses fork attacks with exponential decay in success probability, while remaining robust to noise and system parameters. Our results highlight execution continuity as a distinct and underexplored dimension of system security.