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
In Cloud Computing, the application software and the databases are moved to large centralized data centers, where the management of the data and services may not be fully trustworthy. This unique paradigm brings many ...In Cloud Computing, the application software and the databases are moved to large centralized data centers, where the management of the data and services may not be fully trustworthy. This unique paradigm brings many new security challenges, which have not been well solved. Data access control is an effective way to ensure the big data security in the cloud. In this paper,we study the problem of fine-grained data access control in cloud computing.Based on CP-ABE scheme,we propose a novel access control policy to achieve fine-grainedness and implement the operation of user revocation effectively.The analysis results indicate that our scheme ensures the data security in cloud computing and reduces the cost of the data owner significantly.展开更多
Attribute-based encryption(ABE)is a technique used to encrypt data,it has the flexibility of access control,high security,and resistance to collusion attacks,and especially it is used in cloud security protection.Howe...Attribute-based encryption(ABE)is a technique used to encrypt data,it has the flexibility of access control,high security,and resistance to collusion attacks,and especially it is used in cloud security protection.However,a large number of bilinear mappings are used in ABE,and the calculation of bilinear pairing is time-consuming.So there is the problem of low efficiency.On the other hand,the decryption key is not uniquely associated with personal identification information,if the decryption key is maliciously sold,ABE is unable to achieve accountability for the user.In practical applications,shared message requires hierarchical sharing in most cases,in this paper,we present a message security hierarchy ABE scheme for this scenario.Firstly,attributes were grouped and weighted according to the importance of attributes,and then an access structure based on a threshold tree was constructed according to attribute weight.This method saved the computing time for decryption while ensuring security and on-demand access to information for users.In addition,with the help of computing power in the cloud,two-step decryption was used to complete the access,which relieved the computing and storage burden on the client side.Finally,we simulated and tested the scheme based on CP-ABE,and selected different security levels to test its performance.The security proof and the experimental simulation result showthat the proposed scheme has high efficiency and good performance,and the solution implements hierarchical access to the shared message.展开更多
In hybrid cloud computing, encrypted data access control can provide a fine-grained access method for organizations to enact policies closer to organizational policies. This paper presents an improved CP-ABE (cipherte...In hybrid cloud computing, encrypted data access control can provide a fine-grained access method for organizations to enact policies closer to organizational policies. This paper presents an improved CP-ABE (ciphertext-policy attribute-based encryption) scheme to construct an encrypted data access control solution that is suitable for mobile users in hybrid cloud system. In our improvement, we split the original decryption keys into a control key, a secret key and a set of transformation keys. The private cloud managed by the organization administrator takes charge of updating the transformation keys using the control key. It helps to handle the situation of flexible access management and attribute alteration. Meanwhile, the mobile user's single secret key remains unchanged as well as the ciphertext even if the data user's attribute has been revoked. In addition, we modify the access control list through adding the attributes with corresponding control key and transformation keys so as to manage user privileges depending upon the system version. Finally, the analysis shows that our scheme is secure, flexible and efficient to be applied in mobile hybrid cloud computing.展开更多
Cloud storage is a service involving cloud service providers providingstorage space to customers. Cloud storage services have numerous advantages,including convenience, high computation, and capacity, thereby attracti...Cloud storage is a service involving cloud service providers providingstorage space to customers. Cloud storage services have numerous advantages,including convenience, high computation, and capacity, thereby attracting usersto outsource data in the cloud. However, users outsource data directly via cloudstage services that are unsafe when outsourcing data is sensitive for users. Therefore, cipher text-policy attribute-based encryption is a promising cryptographicsolution in a cloud environment, and can be drawn up for access control by dataowners (DO) to define access policy. Unfortunately, an outsourced architectureapplied with attribute-based encryption introduces numerous challenges, including revocation. This issue is a threat to the data security of DO. Furthermore,highly secure and flexible cipher text-based attribute access control with role hierarchy user grouping in cloud storage is implemented by extending the KUNodes(revocation) storage identity-based encryption. Result is evaluated using Cloudsim, and our algorithm outperforms in terms of computational cost by consuming32 MB for 150-MB files.展开更多
Cloud computing has become a significant computing model in the IT industry. In this emerging model,computing resources such as software, hardware, networking, and storage can be accessed anywhere in the world on a pa...Cloud computing has become a significant computing model in the IT industry. In this emerging model,computing resources such as software, hardware, networking, and storage can be accessed anywhere in the world on a pay-per-use basis. However, storing sensitive data on un-trusted servers is a challenging issue for this model. To guarantee confidentiality and proper access control of outsourced sensitive data, classical encryption techniques are used. However, such access control schemes are not feasible in cloud computing because of their lack of flexibility, scalability, and fine-grained access control. Instead, Attribute-Based Encryption（ABE） techniques are used in the cloud. This paper extensively surveys all ABE schemes and creates a comparison table for the key criteria for these schemes in cloud applications.展开更多
针对云平台下外包数据流不可信、验证范围不可控等问题,该文提出一种具有访问控制的外包数据流动态可验证方法.该方法的核心思想是利用任意的Hash函数、双陷门Hash函数和CP-ABE(Cipertext Policy-Attribute Based Encryption)算法构成...针对云平台下外包数据流不可信、验证范围不可控等问题,该文提出一种具有访问控制的外包数据流动态可验证方法.该方法的核心思想是利用任意的Hash函数、双陷门Hash函数和CP-ABE(Cipertext Policy-Attribute Based Encryption)算法构成一种具有访问控制的动态可认证数据结构(AC-MTAT).该可认证结构可以实现对外包数据流的实时增加、更新和细粒度动态验证.此外,该可认证数据结构不仅能够验证外包数据流的完整性,还能够验证数据流序列的正确性.由于在传统默克尔Hash树(MHT)中引入双陷门Hash函数,AC-MTAT的构建过程可以分为两个阶段:离线阶段和在线阶段.这样构建AC-MTAT所需的主要代价可以放在离线阶段完成,大大提高了AC-MTAT在线实时构建效率.该文首先给出AC-MTAT方案的形式化定义和具体构建算法;然后,对ACMTAT方案的安全性进行证明,证明其满足正确性、可验证安全性和访问安全性;最后,分析了方案的实现效率,并通过实现一个AC-MTAT原型来评估算法的耗费时间,实验结果显示作者的方案对于外包数据流的验证是高效的和可行的,而且与现有方案相比,该方案在实时增长、高效更新、可控验证以及对数据流的适应性等方面更有优势.展开更多
针对云计算环境下的安全性和隐私性问题,在CP-ABE的基础上提出MAH-ABE(Multiple and Hierarchical Attribute Based Encryption)访问控制模型,划分了公共领域和私人领域,私人领域采用CP,ABE密文访问控制,公共领域采用等级多信任机构来...针对云计算环境下的安全性和隐私性问题,在CP-ABE的基础上提出MAH-ABE(Multiple and Hierarchical Attribute Based Encryption)访问控制模型,划分了公共领域和私人领域,私人领域采用CP,ABE密文访问控制,公共领域采用等级多信任机构来管理属性和密钥,减少了管理复杂度.同时,该模型引入失效时间属性来执行属性更新操作.最后给出模型的安全性证明和仿真,表明该模型是高效灵活,细粒度并且安全的.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This research is supported by a grant from National Natural Science Foundation of China (No. 61170241, 61472097).This paper is funded by the International Exchange Program of Harbin Engineering University for Innovationoriented Talents Cultivation.
文摘In Cloud Computing, the application software and the databases are moved to large centralized data centers, where the management of the data and services may not be fully trustworthy. This unique paradigm brings many new security challenges, which have not been well solved. Data access control is an effective way to ensure the big data security in the cloud. In this paper,we study the problem of fine-grained data access control in cloud computing.Based on CP-ABE scheme,we propose a novel access control policy to achieve fine-grainedness and implement the operation of user revocation effectively.The analysis results indicate that our scheme ensures the data security in cloud computing and reduces the cost of the data owner significantly.
基金funded by the Funding of Nanjing Institute of Technology No.JXGG2021017the National Natural Science Foundation of China No.61701221.
文摘Attribute-based encryption(ABE)is a technique used to encrypt data,it has the flexibility of access control,high security,and resistance to collusion attacks,and especially it is used in cloud security protection.However,a large number of bilinear mappings are used in ABE,and the calculation of bilinear pairing is time-consuming.So there is the problem of low efficiency.On the other hand,the decryption key is not uniquely associated with personal identification information,if the decryption key is maliciously sold,ABE is unable to achieve accountability for the user.In practical applications,shared message requires hierarchical sharing in most cases,in this paper,we present a message security hierarchy ABE scheme for this scenario.Firstly,attributes were grouped and weighted according to the importance of attributes,and then an access structure based on a threshold tree was constructed according to attribute weight.This method saved the computing time for decryption while ensuring security and on-demand access to information for users.In addition,with the help of computing power in the cloud,two-step decryption was used to complete the access,which relieved the computing and storage burden on the client side.Finally,we simulated and tested the scheme based on CP-ABE,and selected different security levels to test its performance.The security proof and the experimental simulation result showthat the proposed scheme has high efficiency and good performance,and the solution implements hierarchical access to the shared message.
文摘In hybrid cloud computing, encrypted data access control can provide a fine-grained access method for organizations to enact policies closer to organizational policies. This paper presents an improved CP-ABE (ciphertext-policy attribute-based encryption) scheme to construct an encrypted data access control solution that is suitable for mobile users in hybrid cloud system. In our improvement, we split the original decryption keys into a control key, a secret key and a set of transformation keys. The private cloud managed by the organization administrator takes charge of updating the transformation keys using the control key. It helps to handle the situation of flexible access management and attribute alteration. Meanwhile, the mobile user's single secret key remains unchanged as well as the ciphertext even if the data user's attribute has been revoked. In addition, we modify the access control list through adding the attributes with corresponding control key and transformation keys so as to manage user privileges depending upon the system version. Finally, the analysis shows that our scheme is secure, flexible and efficient to be applied in mobile hybrid cloud computing.
文摘Cloud storage is a service involving cloud service providers providingstorage space to customers. Cloud storage services have numerous advantages,including convenience, high computation, and capacity, thereby attracting usersto outsource data in the cloud. However, users outsource data directly via cloudstage services that are unsafe when outsourcing data is sensitive for users. Therefore, cipher text-policy attribute-based encryption is a promising cryptographicsolution in a cloud environment, and can be drawn up for access control by dataowners (DO) to define access policy. Unfortunately, an outsourced architectureapplied with attribute-based encryption introduces numerous challenges, including revocation. This issue is a threat to the data security of DO. Furthermore,highly secure and flexible cipher text-based attribute access control with role hierarchy user grouping in cloud storage is implemented by extending the KUNodes(revocation) storage identity-based encryption. Result is evaluated using Cloudsim, and our algorithm outperforms in terms of computational cost by consuming32 MB for 150-MB files.
文摘Cloud computing has become a significant computing model in the IT industry. In this emerging model,computing resources such as software, hardware, networking, and storage can be accessed anywhere in the world on a pay-per-use basis. However, storing sensitive data on un-trusted servers is a challenging issue for this model. To guarantee confidentiality and proper access control of outsourced sensitive data, classical encryption techniques are used. However, such access control schemes are not feasible in cloud computing because of their lack of flexibility, scalability, and fine-grained access control. Instead, Attribute-Based Encryption（ABE） techniques are used in the cloud. This paper extensively surveys all ABE schemes and creates a comparison table for the key criteria for these schemes in cloud applications.
文摘针对云平台下外包数据流不可信、验证范围不可控等问题,该文提出一种具有访问控制的外包数据流动态可验证方法.该方法的核心思想是利用任意的Hash函数、双陷门Hash函数和CP-ABE(Cipertext Policy-Attribute Based Encryption)算法构成一种具有访问控制的动态可认证数据结构(AC-MTAT).该可认证结构可以实现对外包数据流的实时增加、更新和细粒度动态验证.此外,该可认证数据结构不仅能够验证外包数据流的完整性,还能够验证数据流序列的正确性.由于在传统默克尔Hash树(MHT)中引入双陷门Hash函数,AC-MTAT的构建过程可以分为两个阶段:离线阶段和在线阶段.这样构建AC-MTAT所需的主要代价可以放在离线阶段完成,大大提高了AC-MTAT在线实时构建效率.该文首先给出AC-MTAT方案的形式化定义和具体构建算法;然后,对ACMTAT方案的安全性进行证明,证明其满足正确性、可验证安全性和访问安全性;最后,分析了方案的实现效率,并通过实现一个AC-MTAT原型来评估算法的耗费时间,实验结果显示作者的方案对于外包数据流的验证是高效的和可行的,而且与现有方案相比,该方案在实时增长、高效更新、可控验证以及对数据流的适应性等方面更有优势.
文摘针对云计算环境下的安全性和隐私性问题,在CP-ABE的基础上提出MAH-ABE(Multiple and Hierarchical Attribute Based Encryption)访问控制模型,划分了公共领域和私人领域,私人领域采用CP,ABE密文访问控制,公共领域采用等级多信任机构来管理属性和密钥,减少了管理复杂度.同时,该模型引入失效时间属性来执行属性更新操作.最后给出模型的安全性证明和仿真,表明该模型是高效灵活,细粒度并且安全的.
