本文将就计算理论对于公钥密码体系中应用的有关整数素因数分解问题及离散对数问题等未解决问题的最新研究进行解说。公钥密码发明至今已20多年，现在的两大未解决问题有“RSA译码问题与因数分解的计算论的等价性”以及“Diffie-Hellma...本文将就计算理论对于公钥密码体系中应用的有关整数素因数分解问题及离散对数问题等未解决问题的最新研究进行解说。公钥密码发明至今已20多年，现在的两大未解决问题有“RSA译码问题与因数分解的计算论的等价性”以及“Diffie-Hellman问题与离散对数问题的计算论的等价性”，虽然还没有安全解决，但最近正以各种形式在解决着。我们通过调查最近的结果，尝试介绍密码理论（cryptography)与计算数论（computational number theory）的最前沿。展开更多
Considering the fact that P2P （Peer-to-Peer） systems are self-organized and autonomous, social-control mechanism （like trust and reputation） is essential to evaluate the trustworthiness of participating peers and ...Considering the fact that P2P （Peer-to-Peer） systems are self-organized and autonomous, social-control mechanism （like trust and reputation） is essential to evaluate the trustworthiness of participating peers and to combat the selfish, dishonest and malicious peer behaviors. So, naturally, we advocate that P2P systems that gradually act as an important information infrastructure should be multi-disciplinary research topic, and reflect certain features of our society. So, from economic and social perspective, this paper designs the incentive-compatible reputation feedback scheme based on well-known economic model, and characterizes the social features of trust network in terms of efficiency and cost. Specifically, our framework has two distinctive purposes： first, from high-level perspective, we argue trust system is a special kind of social network, and an accurate characterization of the structural properties of the network can be of fundamental importance to understand the dynamics of the system. Thus, inspired by the concept of weighted small-world, this paper proposes new measurements to characterize the social properties of trust system, that is, high global and local efficiency, and low cost; then, from relative low-level perspective, we argue that reputation feedback is a special kind of information, and it is not free. So, based on economic model, VCG （Vickrey-Clarke-Grove）-like reputation remuneration mechanism is proposed to stimulate rational peers not only to provide reputation feedback, but truthfully offer feedback. Furthermore, considering that trust and reputation is subjective, we classify the trust into functional trust and referral trust, and extend the referral trust to include two factors： similarity and truthfulness, which can efficiently reduce the trust inference error. The preliminary simulation results show the benefits of our proposal and the emergence of certain social properties in trust network.展开更多
文摘本文将就计算理论对于公钥密码体系中应用的有关整数素因数分解问题及离散对数问题等未解决问题的最新研究进行解说。公钥密码发明至今已20多年，现在的两大未解决问题有“RSA译码问题与因数分解的计算论的等价性”以及“Diffie-Hellman问题与离散对数问题的计算论的等价性”，虽然还没有安全解决，但最近正以各种形式在解决着。我们通过调查最近的结果，尝试介绍密码理论（cryptography)与计算数论（computational number theory）的最前沿。
基金This work was partly supported by the 21st Century COE Program"Reconstruction of Social Infrastructure Related to Information Science and Electrical Engineering"in Kyushu University,Japan,and by the National Grand Fundamental Research 973 Program of China under Grant No.2007CB310607the National Natural Science Foundation of China under Grant Nos.60472067,60572131 and JiangSu Education Bureau(Grant No.5KJB510091).
文摘Considering the fact that P2P （Peer-to-Peer） systems are self-organized and autonomous, social-control mechanism （like trust and reputation） is essential to evaluate the trustworthiness of participating peers and to combat the selfish, dishonest and malicious peer behaviors. So, naturally, we advocate that P2P systems that gradually act as an important information infrastructure should be multi-disciplinary research topic, and reflect certain features of our society. So, from economic and social perspective, this paper designs the incentive-compatible reputation feedback scheme based on well-known economic model, and characterizes the social features of trust network in terms of efficiency and cost. Specifically, our framework has two distinctive purposes： first, from high-level perspective, we argue trust system is a special kind of social network, and an accurate characterization of the structural properties of the network can be of fundamental importance to understand the dynamics of the system. Thus, inspired by the concept of weighted small-world, this paper proposes new measurements to characterize the social properties of trust system, that is, high global and local efficiency, and low cost; then, from relative low-level perspective, we argue that reputation feedback is a special kind of information, and it is not free. So, based on economic model, VCG （Vickrey-Clarke-Grove）-like reputation remuneration mechanism is proposed to stimulate rational peers not only to provide reputation feedback, but truthfully offer feedback. Furthermore, considering that trust and reputation is subjective, we classify the trust into functional trust and referral trust, and extend the referral trust to include two factors： similarity and truthfulness, which can efficiently reduce the trust inference error. The preliminary simulation results show the benefits of our proposal and the emergence of certain social properties in trust network.
