关键词: 密文策略基于属性加密体制, 可证明安全, 重加密, 密钥泄漏, 属性撤销

Abstract:

In order to solve the confidentiality issues such as key exposure and attribute revocation of data stored in cloud server, an advanced anonymous privacy-preserving scheme based on Ciphertext-Policy Attributed-Based Encryption (CP_ABE) was proposed by considering confidentiality of data storage and indistinguishability of access. First, the scheme constructed a forward-secure irreversible key-update algorithm to solve key exposure. On the basis of the classified user-group and the advanced Subset-Difference algorithm, fine-grained attribute revocation was implemented with the help of cloud data re-encryption algorithm. The potential interests of user would be concealed when k-anonymity l-diversity data request was introduced based on the homomorphic encryption algorithm. The backward-security of key exposure was realized on the basis of secondary encryption inserted in data response. Under the l-Bilinear Diffie-Hellman Exponent Problem (l-BDHE) assumption, selective security of the proposed scheme was proved in the standard model. The performance advantage of the proposed scheme was demonstrated respectively in terms of efficiency, key length and security.

Key words: Ciphertext-Policy Attributed-Based Encryption (CP_ABE), provable security, re-encryption, key exposure, attribute revocation