Vulnerabilities and Attacks on Quantum Secret Sharing (QSS) Schemes: A Review

Quantum secret sharing (QSS) allows a dealer to split a secret among several players so that only authorized coalitions can recover it, while any eavesdropping is revealed by quantum disturbance. Since the first proposals in 1999 [3–5], a long series of cryptanalyses has shown that many QSS protocols fail not because of outside eavesdroppers but because of their own players. In this paper, we review the flaws in and attacks on QSS from 1999 to 2026. We classify the attacks into three layers: protocol-level attacks (intercept-resend, entangle-measure, Trojan horse and fake-signal); insider attacks by dishonest or colluding participants, which are especially powerful because insiders control part of the security check; and implementation-level (side-channel) attacks, which exploit imperfect sources, detectors and local oscillators. For each class, we describe the attack mechanism, representative protocols that were broken, and the countermeasures that followed, such as decoy states, one-way transmission with wavelength filtering, measurement-device-independent (MDI) and device-independent (DI) QSS, and composable finite-key proofs that treat dishonest players as adversaries. We conclude that the field is converging on a single lesson: a QSS protocol is only as secure as the participant model behind its proof, so security proofs must treat every player as a potential adversary with full access to their own devices. We end with open problems for QSS in quantum networks.