Security Analysis Of Quantum Dense Encodings

Quantum information is an interdisciplinary research field combining classical information theory and quantum mechanics.It has been shown a broad prospect of scientific and technological applications.During the past decades,quantum information processes rely on entanglement have been widely studied,and the entanglement is playing more and more important roles in the realization of quantum communication and quantum computation,such as quantum key distribution,quantum teleportation,quantum secret sharing,quantum secure dicret communication.Quantum dense coding attracts much attention as the classical information of two bits can be transmitted by using only one quantum bit,which was first proposed by Bennett in 1992.Besides the designing of the protocol,the security analysis is also of great importance in quantum cryptography.At present,the eavesdropping methods of quantum cryptography are mainly divided into attacks on the protocol itself and attacks on the practical system.The attacks on the protocol including the intercept-resend strategy,false signal attacks,the passive attacks,and so on.The cloning attack includes similar quantum cloning which is an imperfect cloning of unknown quantum states and probability quantum cloning of cloning with a certain probability.Here in this study,we analyze the security of the quantum dense coding protocol in arbitrary d-dimensional space against pauli cloning attacks.Through introducing an auxiliary qubit,we clone the transmitted quantum state by Pauli cloning machine to attack on the scheme.Then the security of the scheme is proved by calculating the fidelity and mutual information of the scheme under this attack.