Research On Designated Server Public Key Authenticated Encryption With Keyword Search In Cloud Storage

With the widespread popularity of digital and network technologies,cloud storage has become the mainstream method for data storage and sharing due to its efficient and convenient features.However,this convenience also brings security risks.Hacker attacks and improper operations by cloud server administrators may threaten the security of user data.In this case,data encryption has become an effective way for users to protect their data security,but encrypted data has the problem of low availability and inability to support traditional search methods.In order to solve the search requirements that traditional encryption schemes cannot achieve,public-key searchable encryption schemes have emerged,which can ensure the security of user data while achieving secure search of ciphertext.Since then,various public-key searchable schemes have been proposed,such as public-key authenticated searchable encryption schemes,certificateless searchable encryption schemes,and multi-keyword searchable encryption schemes.However,most existing public-key searchable encryption schemes cannot balance security and search efficiency,and do not support multi-user data sharing.Therefore,this paper focuses on the keyword security problem,low search efficiency problem,and multi-user data sharing requirements,and conducts research on public-key authenticated searchable encryption schemes,achieving the following main research results.In response to the keyword security issues in public-key searchable encryption schemes,this thesis proposes a designated server public-key authenticated searchable encryption scheme that satisfies multi-ciphertext indistinguishability security.The proposed scheme utilizes Diffie-Hellman shared key to generate keyword ciphertext and trapdoor,thus resisting internal keyword guessing attacks and multiple ciphertext attacks.Performance analysis and security comparison demonstrate that the proposed scheme meets higher security requirements compared to similar schemes and is not inferior in terms of computational efficiency.To address the issue of low search efficiency in existing public-key authentication searchable encryption schemes,this thesis puts forward a public key authentication searchable encryption scheme with logarithmic search time based on resisting internal keyword guessing attacks.In the keyword search stage,the scheme utilizes preprocessing of keyword ciphertext on the server side and ciphertext equivalence retrieval based on binary search to achieve keyword ciphertext search,which makes the search time have a logarithmic relationship with the number of keyword ciphertexts,and significantly improves the search efficiency compared with the existing schemes.In order to satisfy the multi-user data sharing requirements of public key authenticated searchable encryption schemes,this thesis presents a secure and efficient group-based public key authenticated searchable encryption scheme.This scheme not only maintains the efficient search feature of previous research,but also enables multiple users to share data in the group,and adds data decryption and verification functionality,thereby enhancing the practicality of the scheme.In terms of security,the scheme satisfies ciphertext indistinguishability and resists internal keyword guessing attacks.Experimental analysis shows that the proposed scheme is practical and efficient in multi-user data sharing scenarios.