In order to transmit the secure message, a deterministic secure quantum direct communication protocol which was called ＂Ping-pong＂ protocol was proposed by Bostrrm and Felbinger [Bostrom K, et al. Phys Rev Lett, 200...In order to transmit the secure message, a deterministic secure quantum direct communication protocol which was called ＂Ping-pong＂ protocol was proposed by Bostrrm and Felbinger [Bostrom K, et al. Phys Rev Lett, 2002, 89： 187902]. But the protocol was proved very vulnerable, and can be attacked by an eavesdropper. An improved ＂Ping-pong＂ protocol is presented to overcome the problem. The GHZ state particles are used to detect eavesdroppers, and the classical XOR operation which serves as a one-time-pad is used to ensure the security of the protocol. During the security analysis, the method of the entropy theory is introduced, and three detection strategies are compared quantitatively by using the constraint between the information which an eavesdropper can obtain and the interference introduced. If the eavesdropper gets the full information, the detection rate of the original ＂Ping-pong＂ protocol is 50%; the detection rate of the second protocol which used two particles of EPR pair as detection particles is also 50%; and the detection rate of the presented protocol is 75%. In the end, the security of the pro-posed protocol is discussed. The analysis results show that the improved ＂Ping-pong＂ protocol in this paper is more secure than the other two.展开更多
Collaborative filtering （CF） has been widely applied to recommender systems, since it can assist users to discover their favorite items. Similarity measurement that measures the similarity between two users or items...Collaborative filtering （CF） has been widely applied to recommender systems, since it can assist users to discover their favorite items. Similarity measurement that measures the similarity between two users or items is critical to CF. However, traditional similarity measurement approaches for memory-based CF can be strongly improved. In this paper, we propose a novel similarity measurement, named Jaccard Uniform Operator Distance （JacUOD）, to effectively measure the similarity. Our JacUOD approach aims at unifying similarity comparison for vectors in different multidimensional vector spaces. Compared with traditional similarity measurement approaches, JacUOD properly handles dimension-number difference for different vector spaces. We conduct experiments based on the well-known MovieLens datasets, and take user-based CF as an example to show the effectiveness of our approach. The experimental results show that our JacUOD approach achieves better prediction accuracy than traditional similarity measurement approaches.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20060013007)the Natural Science Foundation of Beijing (Grant No. 4092029)the National Natural Science Foundation of China (Grant No. 60873001)
文摘In order to transmit the secure message, a deterministic secure quantum direct communication protocol which was called ＂Ping-pong＂ protocol was proposed by Bostrrm and Felbinger [Bostrom K, et al. Phys Rev Lett, 2002, 89： 187902]. But the protocol was proved very vulnerable, and can be attacked by an eavesdropper. An improved ＂Ping-pong＂ protocol is presented to overcome the problem. The GHZ state particles are used to detect eavesdroppers, and the classical XOR operation which serves as a one-time-pad is used to ensure the security of the protocol. During the security analysis, the method of the entropy theory is introduced, and three detection strategies are compared quantitatively by using the constraint between the information which an eavesdropper can obtain and the interference introduced. If the eavesdropper gets the full information, the detection rate of the original ＂Ping-pong＂ protocol is 50%; the detection rate of the second protocol which used two particles of EPR pair as detection particles is also 50%; and the detection rate of the presented protocol is 75%. In the end, the security of the pro-posed protocol is discussed. The analysis results show that the improved ＂Ping-pong＂ protocol in this paper is more secure than the other two.
基金supported by the National Basic Research 973 Program of China under Grant No.2011CB302506the National Natural Science Foundation of China under Grant Nos.61001118,61132001,61003067+1 种基金the National Major Science and Technology Project of New Generation Broadband Wireless Network of China under Grant No.2010ZX03004-001the Fundamental Research Funds for the Central Universities of Beijing University of Posts and Telecommunications of China under Grant No.2011RC0502
文摘Collaborative filtering （CF） has been widely applied to recommender systems, since it can assist users to discover their favorite items. Similarity measurement that measures the similarity between two users or items is critical to CF. However, traditional similarity measurement approaches for memory-based CF can be strongly improved. In this paper, we propose a novel similarity measurement, named Jaccard Uniform Operator Distance （JacUOD）, to effectively measure the similarity. Our JacUOD approach aims at unifying similarity comparison for vectors in different multidimensional vector spaces. Compared with traditional similarity measurement approaches, JacUOD properly handles dimension-number difference for different vector spaces. We conduct experiments based on the well-known MovieLens datasets, and take user-based CF as an example to show the effectiveness of our approach. The experimental results show that our JacUOD approach achieves better prediction accuracy than traditional similarity measurement approaches.
