The universal composability framework is a new approach for designing and analyzing the security of cryptographic protocols.In this framework,the security of protocols is maintained under a general protocol compositio...The universal composability framework is a new approach for designing and analyzing the security of cryptographic protocols.In this framework,the security of protocols is maintained under a general protocol composition operation.In the paper,we propose the universal composability framework for the analysis of proxy threshold signature and present a universally composable secure proxy threshold signature scheme which is the first one in this area.The proposed scheme is suitable for the mobile agents,which should migrate across different environment through network.Furthermore,we give the concrete analysis of the reduction to prove the security of the proposed scheme.展开更多
Zhang et al. proposed a sequential multisignature scheme based on RSA. The scheme has advantages of low computation and communication costs, and so on. However, we find a problem in their scheme that the verifier can ...Zhang et al. proposed a sequential multisignature scheme based on RSA. The scheme has advantages of low computation and communication costs, and so on. However, we find a problem in their scheme that the verifier can not distinguish whether the multisignature is signed by all the signers of the group or only by the last signer. Thus, any single signature created by the last signer can be used as a multisignaturr created by the whole group members. This paper proposes an improved scheme that can overcome the defect. In the new scheme, the identity messages of all the signers are added in the multisignature and used in verification phase, so that the verifier can know the signature is generated by which signers. Performance analysis shows that the proposed scheme costs less computation than the original scheme in both signature and verification phases. Furthermore, each partial signature is based on the signer＇s identity certificate, which makes the scheme more secure.展开更多
In this paper,we propose a. practical parallel algorithm for computing ab mod c. The algorithm is based on RES representations of integers. In particular, a technique is introduced for avoiding overflow.The algorithm ...In this paper,we propose a. practical parallel algorithm for computing ab mod c. The algorithm is based on RES representations of integers. In particular, a technique is introduced for avoiding overflow.The algorithm is easy to be implemented on hardware and achieves linear speedup.展开更多
In key escrow field it is important to solve the problem thatuser's secret key completely depends on the trusted escrow agency. In 1995, some methods of solving the problem were presented. But these methods are no...In key escrow field it is important to solve the problem thatuser's secret key completely depends on the trusted escrow agency. In 1995, some methods of solving the problem were presented. But these methods are no better than that of directly using threshold cryptography. In this paper, we present a common pattern of threshold key escrow scheme based on public key cryptosystem, and a detailed design based on the improved RSA algorithm is given. The above problem is solved by this scheme.展开更多
Threshold digital signature and blind signature are playing important roles in cryptography as well as in practical applications such as e-cash and e-voting systems. Over the past few years, many cryptographic researc...Threshold digital signature and blind signature are playing important roles in cryptography as well as in practical applications such as e-cash and e-voting systems. Over the past few years, many cryptographic researchers have made considerable headway in this field. However, to our knowledge, most of existing threshold blind signature schemes are based on the discrete logarithm problem. In this paper, we propose a new robust threshold partial blind signature scheme based on improved RSA cryptosystem, This scheme is the first threshold partial blind signature scheme based on factoring, and the robustness of threshold partial blind signature is also introduced. Moreover, in practical application, the proposed scheme will be especially suitable for blind signature-based voting systems with multiple administrators and secure electronic cash systems to prevent their abuse.展开更多
基金the National Natural Science Foundation of China(Nos.60703031,60703004)the National High Technology Research and Development Program(863)of China(No.2006AA01Z4220the National Basic Research Program(973)of China(No.2007CB311201)
文摘The universal composability framework is a new approach for designing and analyzing the security of cryptographic protocols.In this framework,the security of protocols is maintained under a general protocol composition operation.In the paper,we propose the universal composability framework for the analysis of proxy threshold signature and present a universally composable secure proxy threshold signature scheme which is the first one in this area.The proposed scheme is suitable for the mobile agents,which should migrate across different environment through network.Furthermore,we give the concrete analysis of the reduction to prove the security of the proposed scheme.
基金The National Natural Science Foundation of China (No.60403027)
文摘Zhang et al. proposed a sequential multisignature scheme based on RSA. The scheme has advantages of low computation and communication costs, and so on. However, we find a problem in their scheme that the verifier can not distinguish whether the multisignature is signed by all the signers of the group or only by the last signer. Thus, any single signature created by the last signer can be used as a multisignaturr created by the whole group members. This paper proposes an improved scheme that can overcome the defect. In the new scheme, the identity messages of all the signers are added in the multisignature and used in verification phase, so that the verifier can know the signature is generated by which signers. Performance analysis shows that the proposed scheme costs less computation than the original scheme in both signature and verification phases. Furthermore, each partial signature is based on the signer＇s identity certificate, which makes the scheme more secure.
文摘In this paper,we propose a. practical parallel algorithm for computing ab mod c. The algorithm is based on RES representations of integers. In particular, a technique is introduced for avoiding overflow.The algorithm is easy to be implemented on hardware and achieves linear speedup.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 69772037, 60072018).
文摘In key escrow field it is important to solve the problem thatuser's secret key completely depends on the trusted escrow agency. In 1995, some methods of solving the problem were presented. But these methods are no better than that of directly using threshold cryptography. In this paper, we present a common pattern of threshold key escrow scheme based on public key cryptosystem, and a detailed design based on the improved RSA algorithm is given. The above problem is solved by this scheme.
基金supported by the National Natural Science Foundation of China(Grants Nos.60225007 and 60572155)the National Research Fund for the Doctoral Program of Higher Education of China(Grant No.20020248024)the Science and Technology Research Project of Shanghai(Grant Nos.04JC14055 and 04DZ07067).
文摘Threshold digital signature and blind signature are playing important roles in cryptography as well as in practical applications such as e-cash and e-voting systems. Over the past few years, many cryptographic researchers have made considerable headway in this field. However, to our knowledge, most of existing threshold blind signature schemes are based on the discrete logarithm problem. In this paper, we propose a new robust threshold partial blind signature scheme based on improved RSA cryptosystem, This scheme is the first threshold partial blind signature scheme based on factoring, and the robustness of threshold partial blind signature is also introduced. Moreover, in practical application, the proposed scheme will be especially suitable for blind signature-based voting systems with multiple administrators and secure electronic cash systems to prevent their abuse.
