Multi-Party Quantum Key Agreement Protocol Based on G-Like States and χ+ States

Quantum Key Agreement (QKA) is an important branch of quantum cryptography, which uses the characteristics of quantum entanglement to ensure security of the key. The multi-party quantum key agreement requires all communicants to exert the same influence on the result of the protocol, and the key cannot be determined individually. Most of the MQKA protocols that have been proposed are based on a single particle or Bell state, where each particle corresponds to only one classical bit. This paper proposes a multi-party QKA protocol based on the GHZ-like state and χ + state, which can realize that each particle corresponds to 1.5 classical bits. The security of the protocol is guaranteed by the uncertainty of the measurement results of entanglement swapping. The results show that the proposed multi-party QKA protocol is secure, fair, and efficient, which can be implemented with existing physical technology. In addition, it is simpler and less computational in the proposed MQKA protocol.