Research On Forward-secure Symmetric Searchable Encryption Technolog

Cloud storage has the advantage of on-demand storage,pay as you use and convenient access,so more and more individuals or enterprises choose to store their data on the cloud server.Because the cloud may suffer from internal or external attacks,it will lead to the disclosure of user private data stored on the cloud server.In order to ensure the privacy of data,the data is encrypted before being uploaded to the cloud server,and then store the encrypted data on the cloud server.However,the traditional encryption technology will make the data lose the ability of direct search.In order to solve the problem,searchable symmetric encryption technology came into being.Forward security is an important security feature of searchable encryption.The searchable encryption scheme with forward security can resist file injection attacks.And ensure that the data stored on the cloud server will not disclose file information due to updates.This thesis mainly studies the forward secure searchable symmetric encryption technology,and puts forward two schemes:(1)Due to software and hardware,the cloud server may return incorrect search results to the data user.In order to verify the correctness of search results,a fully verifiable forward secure searchable symmetric encryption scheme is proposed.In the proposed scheme,in order to achieve forward security,the secure index is constructed based on hash chain.For each update,the data owner randomly chooses a string as a new state to generate the new trapdoor.The new trapdoor cannot match previous trapdoors.In order to achieve the full verifiability while still maintaining forward security,the authentication tag is designed.The tag has the incremental property and supports the verification on the basis of efficient data update.Finally,the specific safety analysis and experiment results prove that the proposed scheme is safe and efficient.(2)The attribute-value type database is different from the traditional file system,most of the current forward secure searchable symmetric encryption schemes are not applicable.In order to solve the problem,a forward secure searchable symmetric encryption scheme based on attribute-value type database is proposed.The scheme generates a hash chain for each keyword of each attribute,and uses bitmap index to represent the file identifier.The dynamic update of the file is realized by XOR operation of bitmap index.Compared with the other schemes,the proposed scheme will not disclose the specific update operation to the cloud server.In this way,the privacy of data can be further protected.The scheme can also realize fine-grained search.When the user executes search operations,she/he only gets a matched attribute value instead of the whole record.As a result,the communication cost is reduced and the disclosure of user’s private is minimized.In addition,the proposed scheme can realize condition search,which can search the value of another attribute on the condition that a certain attribute value contains keyword.Finally,the specific safety analysis and experiment results prove that the proposed scheme is safe and efficient.