Research On Improvement Of Grey Wolf Optimizer And Its Application To Clustering Optimization

In recent years,people's requirements for data integrity and confidentiality have been increasing.Trusted cloud storage and the accessibility of data on the cloud have attracted researchers' attention.Searchable encryption technology has emerged as the times require.This technology allows data owners to store encrypted data in the cloud and use keywords to make the cloud server search the ciphertext and return the corresponding files.Searchable encryption technology allows data owners to perform controlled operations on ciphertext data while protecting data privacy.It is a hot topic in cryptography and applies to various fields such as industry,medical care,and the Internet of Things.With the increasing demand for search functions,some searchable encryption solutions with simple functions cannot meet higher requirements.For example,the confidentiality of corporate privacy data has different levels,which needs to restrict the personnel of the enterprise to only access the confidential data under its level;For another application scenario that requires time-limited sharing,the data owner allows his data to be shared at a specific time period,and once the validity period has expired,the data cannot be accessed by other users.Besides,due to the advancement of quantum algorithms and the rapid development of quantum computers,the security of modern public key cryptographic schemes based on classical number theory difficult problems has been seriously threatened.Therefore,it is particularly important to design a searchable encryption scheme that is feature-rich and can effectively resist quantum attacks.To solve the problems that the existing schemes cannot perform hierarchical control search and time validity period control search,and to ensure that the security of the scheme can be applied to the post-quantum cryptographic environment,this paper constructs an adaptive hierarchical searchable encryption scheme and a searchable encryption scheme with the validity period control of files based on the existing searchable encryption technology and lattice.The main innovations are reflected in the following aspects:(1)To address the problems of existing hierarchical searchable encryption schemes that cannot effectively resist quantum attacks,and cannot add or delete levels flexibly,we propose an adaptive hierarchical searchable encryption scheme based on error learning.This scheme divides users into clear hierarchies by constructing condition keys,so that users can only search for files under their hierarchy,and achieve effective hierarch access control;By designing a segmented index structure,its hierarchies can be added and deleted flexibly,so it has good self-adaptability which can meet the needs of different granularity access control;the operation of updates or deletions for users,files and hierarchy are easy to change,so the scheme is suitable in dynamic environments.(2)To solve the problems that the existing searchable encryption schemes cannot control the ciphertext retrieval by time validity period and most of the schemes cannot resist the quantum attack,we propose a lattice-based searchable encryption scheme with the validity period control of files.Our scheme converts time information into a lattice vector of time,and sets a different effective time for each file so that the data owner can have flexible and fine-grained control over the files;By embedding the time information into the ciphertext,the data owner only sets the validity period of the file once,and the life cycle of the ciphertext file can be maintained automatically without the need to revoke the access right of each expired file separately.As a result,the cloud server only returns valid files if the keywords match correctly and the search time is within the validity period of the files.Finally,the scheme has been proven to be resistant to selected keyword guessing attacks.