Analysis Of Quantum Private Query Protocol Against Joint Measurement Attack

With the society entering the information age,people pay more and more attention to the protection of information,which makes the application of code more and more widely.With the development of traditional cryptography,quantum mechanics and quantum cryptography,quantum private query(QPQ)has become an important branch of quantum cryptography.Since the first QPQ protocol was proposed by Giovannetti et al.in 2008,many QPQ protocols have been proposed.QPQ protocol based on QKD has attracted many scholars' attention because of its practicability,but some of them still have some security problems.For example,by using quantum storage,joint measurement(JM)attacks seriously threaten the security of QPQ protocol.In this thesis,we studied the QPQ protocol which can resist JM attack,analyze the security of two QPQ protocols which can resist JM attack in different ways,and give a new JM attack strategy.Specifically,through analyzing the classical post-processing designed by Yang et al.The conclusion that the classical post-processing not only leaks some database entries under general individual attacks,but also cannot resist JM attacks.Because the row vector T is set to[t1 t2…tk],and the value of t1 is inconsistent,Alice can illegally obtain additional database entry information in individual attack by adjusting the value of row vector T.Alice can also perform the following JM attacks:prepare the initial state |?>,send the first particle to Bob,and save the second particle in her own hands.At the end of the protocol,Alice can know which particles she keeps for joint measurement to successfully implement the attack.By analyzing the two-way communi-cation QPQ protocol designed by Zhou et al,we conclude that the protocol cannot resist JM attack.Although the protocol is Alice sending,Bob measuring and returning the quantum state,because the returned quantum state carries the information of the original key bit,and Alice knows the information of the initial quantum state,Alice knows which particles should be jointly measured when receiving the particles,and then successfully implements the JM attack.In this attack,Alice doesn't even need to use quantum storage.Based on the above analysis,we find that two-way quantum state transmission is not a sufficient condition to resist JM attack.In order to execute JM attack,Alice must satisfy the following two conditions at the same time:(1)Alice must have the carrier particle with the original key information in her hand;(2)Alice needs to know which particles to measure jointly.The real effective way to resist JM attack is to split these two conditions,so that Alice cannot have the carrier state and know which particles to measure jointly.