支持用户撤销的可验证密文检索方案

为解决恶意云服务器可能发送错误或者伪造的查询结果给用户，且授权用户可能在检索完成之后将密钥信息私自发送给非授权用户的问题，构造了一种支持用户撤销的可验证密文检索方案。首先，利用加密算法对用户文档加密、对关键词签名；其次，运用搜索算法对需要检索的文档进行检索；最后，运用验证算法和用户撤销算法对检索结果进行验证，以及对未检索文档进行再一次加密保护。分析结果表明，所提方案能够在保证数据完整性的前提下完成精确检索，且通过重加密机制实现了用户撤销，保证了系统的安全性，该方案满足不可区分性选择关键词攻击（IND-CKA）安全。

Verifiable ciphertext retrieval scheme with user revocation

The malicious cloud server may send incorrect or forged query results to the user, and the authorized user may send the key information privately to a non-authorized user after completing the retrieval. In order to solve the problems, a new verifiable ciphertext retrieval scheme with user revocation was constructed. Firstly, an encryption algorithm was used to encrypt the user documents and sign the keywords. Secondly, a searching algorithm was used to retrieve documents that needed to be retrieved. Finally, a verification algorithm and user revocation algorithm were used to verify the retrieval results and encrypt the unretrieved documents again. The analysis results show that, the proposed scheme can complete the accurate retrieval on the premise of guaranteeing the integrity of data, realize the user revocation through re-encryption scheme, and guarantee the security of system. Moreover, the proposed scheme satisfies the security of Indistinguishability-Chosen Keyword Attack (IND-CKA).