<p>Quantum key distribution (QKD) enables unconditional secure communication, but its security is fundamentally limited by reliance on classical identity authentication, which introduces vulnerabilities. This work proposes a quantum-fused authentication and QKD protocol incorporating identity verification entirely within the quantum layer. Specifically, we design a bidirectional identity-authenticated QKD protocol using single-photon sequences and unitary transformations, and further generalize it to the multiparty setting by introducing locally indistinguishable orthogonal product states as the encoding platform—a design exemplified with a detailed three-party case. Theoretical analysis and simulation results demonstrate that the protocol achieves reliable quantum authentication, efficient key distribution, and prevents information leakage, fundamentally removing risks associated with classical authentication. Our findings offer a practical and novel framework for strengthening the security of quantum communication systems.</p>