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
由于目前云存储的访问控制策略中密文与密钥长度过大,引发存储与通信代价过高,并且针对用户权限撤销需要频繁地重新加密对称密钥或者重新加密原始数据,导致系统安全性差、效率低下的问题,提出了一种安全可靠的,基于CP-ABE(ciphertext-po...由于目前云存储的访问控制策略中密文与密钥长度过大,引发存储与通信代价过高,并且针对用户权限撤销需要频繁地重新加密对称密钥或者重新加密原始数据,导致系统安全性差、效率低下的问题,提出了一种安全可靠的,基于CP-ABE(ciphertext-policy attribute based encryption)的访问控制方案。该方案不仅可以固定密文与密钥的长度,具有较高的计算效率,而且支持用户权限的撤销功能,并且在密钥与密文传送的过程中使用了签名机制,防止传输过程遭受破坏。通过理论与实验证明,该方案可以抵抗选择密文攻击、合谋攻击等常见的攻击。与现有的方案相比,该方案具有较高的计算效率,并且更容易实现。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.
文摘由于目前云存储的访问控制策略中密文与密钥长度过大,引发存储与通信代价过高,并且针对用户权限撤销需要频繁地重新加密对称密钥或者重新加密原始数据,导致系统安全性差、效率低下的问题,提出了一种安全可靠的,基于CP-ABE(ciphertext-policy attribute based encryption)的访问控制方案。该方案不仅可以固定密文与密钥的长度,具有较高的计算效率,而且支持用户权限的撤销功能,并且在密钥与密文传送的过程中使用了签名机制,防止传输过程遭受破坏。通过理论与实验证明,该方案可以抵抗选择密文攻击、合谋攻击等常见的攻击。与现有的方案相比,该方案具有较高的计算效率,并且更容易实现。
