Analysis Of The Security Of Quantum Cryptography Based On Vulnerability Mining

Quantum information theory is the creature in a new cross-discipline which combines quantum mechanics with classical information theory. Employing the properties of quantum mechanism, quantum information can open up an information age with faster, better and more secure communication methods. Quantum cryptography, which guarantees unconditionally security of the information by quantum mechanics, is regarded as the most promising application in quantum information. In recent years, since quantum cryptography has been paid more and more attention by the governments, military establishments, research institutions and industrial departments, it has rapidly evolved with impressive results, both in the theoretical foundation and experimental implementations, and is prepared for coming into a practical and engineering phase. However, in this process, quantum cryptography itself, still faces many security challenges, its own security actually slows this process. Therefore, to enhance the security of quantum cryptography, we study the security of quantum cryptography protocols, systems and networks from a view of an attacker. The details are as follows:With respect to the quantum key distribution protocols, we firstly proposed a novel eavesdropping scheme which reveals a critical weakness of this protocol. We show that the eavesdropping can be done even if Eve have not actually access the quantum system of each signal particle, the mere possibility that she can do it is sufficient for her to obtain all the secret information. To fix this weakness, we have made a little modification to the original protocol as a countermeasure against this attack. Then, we analyze the capacity requirements of semi-quantum key distribution to a communication party. By proposing a additional particle attack strategy, we show that a receiver who cannot perform measurements is not able to ensure the security of a quantum key distribution protocol.As for the security of quantum private comparison protocol, we analyze the security of the first single photon quantum private comparison protocol and point out a subtle loophole. It is shown that both Eve and Charlie could obtain Bob’s secret by launching a special dense-coding attack. Two solutions is also demonstrated to improve the protocol, in order to overcome the fatal flaw. Since previous quantum private comparison protocols are inefficient, unpractical and insecure, we present a quantum private comparison protocol based on a differential phase shift scheme. This protocol employs weak coherent pulses instead of single photons, and can be implemented without expensive and impractical quantum devices, such as entangled photon source and quantum memory. Therefore, it is simpler and more flexible than previous ones.Besides, we identified two weaknesses in the practical differential phase shift quantum key distribution system. One is in the post-process phase of software layer, by exploiting this loophole, we prove the feasibility of double-clicks attack on the practical differential phase shift system and showed that if Bob had not deal with these double-clicks events properly, then Eve may obtain all the secret information. The other weakness exists in the synchronization scheme of the detection system. For a pracitical differential phase shift system, if Alice and Bob construct their detection system by employing traditional gated detections, the eavesdropper can spy the key only through the weakness of the synchronization scheme.Finally, we investigate whether or not unconditional security in a trusted relay quantum key distribution network is possible by virtue of multipath transmission. We proposed that an eavesdropping may cause QKD key-buffers to run empty, thus enforcing local re-routing of packets. If the distribution of load capacity of edges in the network is unreasonable, then a cascade failure, which may threaten the security of the network seriously, could unavoidable happen. Moreover, this form of “cascade failure in quantum network” seems to be unconsidered in the literature so far. To remove these hidden dangers, we present a cascade failure model and a methodto avoid the occurrence of cascade failures.