In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption an...In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption and decryption operations that depend at least linearly on the number of attributes involved in the access policy. We propose an efficient multi-authority CP-ABE scheme in which the authorities need not interact to generate public information during the system initialization phase. Our scheme has constant ciphertext length and a constant number of pairing computations. Our scheme can be proven CPA-secure in random oracle model under the decision q-BDHE assumption. When user's attributes revocation occurs, the scheme transfers most re-encryption work to the cloud service provider, reducing the data owner's computational cost on the premise of security. Finally the analysis and simulation result show that the schemes proposed in this thesis ensure the privacy and secure access of sensitive data stored in the cloud server, and be able to cope with the dynamic changes of users' access privileges in large-scale systems. Besides, the multi-authority ABE eliminates the key escrow problem, achieves the length of ciphertext optimization and enhances the effi ciency of the encryption and decryption operations.展开更多
An accountable authority attribute-based encryption （A-ABE） scheme is presented in this paper. The notion of accountable authority identity-based encryption （A-IBE） was first introduced by Goyal at Crypto＇07. It ...An accountable authority attribute-based encryption （A-ABE） scheme is presented in this paper. The notion of accountable authority identity-based encryption （A-IBE） was first introduced by Goyal at Crypto＇07. It is a novel approach to mitigate the （inherent） key escrow problem in identity-based cryptosystems. In this work, the concept of accountable authority to attribute-based encryption （ABE） setting is generalized for the first time, and then a construction is given. The scheme non-trivially integrates an A-IBE scheme proposed by Libert et al. with an ABE scheme. In our construction, a user will be identified by a pair （ id, o~）, where id denotes the user＇ s identity and ω denotes the set of attributes associated to the user. In addition, our construction is shown to be secure under some reasonable assumptions.展开更多
China＇s aging society and the family-based model of basic aged care determine that children＇s support for their parents directly affects the standard of living of the majority of the aging population. Existing theor...China＇s aging society and the family-based model of basic aged care determine that children＇s support for their parents directly affects the standard of living of the majority of the aging population. Existing theories indicate that in this era of social transition, the implications of filial piety have shifted from the traditional emphasis on the parent- child generational relationship and children＇s duty to obey their parents to a dual mode in which family love coexists with the authority of the elders. Using data from the Chinese General Social Survey of 2006, we explore the ways in which the two basic dimensions of authoritarian filial piety and reciprocal filial piety connect with various types of filial behavior. The results of our multivariate linear model show that on average, authoritarian filial piety, which emphasizes authority relationships and children＇s duty, increases children＇s financial support for their parents, while reciprocal filial piety, stressing family love and generational equality, significantly increases children＇s emotional support for their parents. A comparison of the basic dimensions of filial piety shows that neither significantly increases children＇s physical support for their parents. Further analysis of the interaction effect indicates that the link between authoritarian filial piety and financial support is more significant among younger groups. In addition, for males, a marginally significant positive relation exists between authoritarian filial piety and physical support for their parents.展开更多
基金supported by National Natural Science Foundation of China under Grant No.60873231Natural Science Foundation of Jiangsu Province under Grant No.BK2009426+1 种基金Major State Basic Research Development Program of China under Grant No.2011CB302903Key University Science Research Project of Jiangsu Province under Grant No.11KJA520002
文摘In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption and decryption operations that depend at least linearly on the number of attributes involved in the access policy. We propose an efficient multi-authority CP-ABE scheme in which the authorities need not interact to generate public information during the system initialization phase. Our scheme has constant ciphertext length and a constant number of pairing computations. Our scheme can be proven CPA-secure in random oracle model under the decision q-BDHE assumption. When user's attributes revocation occurs, the scheme transfers most re-encryption work to the cloud service provider, reducing the data owner's computational cost on the premise of security. Finally the analysis and simulation result show that the schemes proposed in this thesis ensure the privacy and secure access of sensitive data stored in the cloud server, and be able to cope with the dynamic changes of users' access privileges in large-scale systems. Besides, the multi-authority ABE eliminates the key escrow problem, achieves the length of ciphertext optimization and enhances the effi ciency of the encryption and decryption operations.
基金Supported by the National Natural Science Foundation of China(No.60970111,60903189,60903020)the National High Technology Research and Development Programme of China(No.2009AA012418)+1 种基金the National Basic Research Program of China(No.2007CB311201)the Foundation of NLMC(No.9140C1103020803)
文摘An accountable authority attribute-based encryption （A-ABE） scheme is presented in this paper. The notion of accountable authority identity-based encryption （A-IBE） was first introduced by Goyal at Crypto＇07. It is a novel approach to mitigate the （inherent） key escrow problem in identity-based cryptosystems. In this work, the concept of accountable authority to attribute-based encryption （ABE） setting is generalized for the first time, and then a construction is given. The scheme non-trivially integrates an A-IBE scheme proposed by Libert et al. with an ABE scheme. In our construction, a user will be identified by a pair （ id, o~）, where id denotes the user＇ s identity and ω denotes the set of attributes associated to the user. In addition, our construction is shown to be secure under some reasonable assumptions.
基金supported by grants from the School of Social Development and Public Policy,Fudan University the Youth Project of the National Social Science Fund of China（15CSH030） the Major Project of the National Natural Science Foundation of China（71490733）
文摘China＇s aging society and the family-based model of basic aged care determine that children＇s support for their parents directly affects the standard of living of the majority of the aging population. Existing theories indicate that in this era of social transition, the implications of filial piety have shifted from the traditional emphasis on the parent- child generational relationship and children＇s duty to obey their parents to a dual mode in which family love coexists with the authority of the elders. Using data from the Chinese General Social Survey of 2006, we explore the ways in which the two basic dimensions of authoritarian filial piety and reciprocal filial piety connect with various types of filial behavior. The results of our multivariate linear model show that on average, authoritarian filial piety, which emphasizes authority relationships and children＇s duty, increases children＇s financial support for their parents, while reciprocal filial piety, stressing family love and generational equality, significantly increases children＇s emotional support for their parents. A comparison of the basic dimensions of filial piety shows that neither significantly increases children＇s physical support for their parents. Further analysis of the interaction effect indicates that the link between authoritarian filial piety and financial support is more significant among younger groups. In addition, for males, a marginally significant positive relation exists between authoritarian filial piety and physical support for their parents.
