区块链上基于云辅助的密文策略属性基数据共享加密方案

针对云存储的集中化带来的数据安全和隐私保护问题，该文提出一种区块链上基于云辅助的密文策略属性基(CP-ABE)数据共享加密方案。该方案采用基于属性加密技术对加密数据文件的对称密钥进行加密，并上传到云服务器，实现了数据安全以及细粒度访问控制；采用可搜索加密技术对关键字进行加密，并将关键字密文上传到区块链(BC)中，由区块链进行关键字搜索保证了关键字密文的安全，有效地解决现有的云存储共享系统所存在的安全问题。该方案能够满足选择明文攻击下的不可区分性、陷门不可区分性和抗串联性。最后，通过性能评估，验证了该方案的有效性。

Cloud-Assisted Ciphertext Policy Attribute Based Eencryption Data Sharing Encryption Scheme Based on BlockChain

To solve the problem of data security and privacy preservation brought by the centralization of cloud storage, a cloud-assisted Ciphertext Policy Attribute Based Eencryption(CP-ABE) data sharing encryption scheme based on BlockChain(BC) is proposed. In this scheme, the symmetric key of the encrypted file is encrypted by attribute-based encryption and the encrypted file is uploaded to cloud server for realizing the data security and fine-grained access control. Searchable encryption technology is adopted to encrypt the keyword, and the keyword ciphertext is uploaded to the BlockChain. Keyword search is executed by the BlockChain to ensure the security of keyword ciphertext, which effectively solves the security problems existing in the cloud storage and sharing system. This scheme can satisfy the indiscernibility, trap indiscernibility and series resistance under the selective plaintext attack. Finally, the effectiveness of the scheme is verified by performance evaluation.