The Research Of Searchable Encryption Technology On Cloud Database

Cloud computing is a multi-server virtual server to provide users with services.It can save costs while ensuring the diversity of services,is the current computer field of research issues.It has many challenges while providing almost unlimited storage capacity,powerful computing power and economic benefits.Among them,the security issue has become the biggest challenge facing cloud computing.As the server in the cloud environment is considered as an untrusted server and doesn't have the privilege to obtain the secret key,the cloud server can't operate the encrypted data and limit the data processing capability of the cloud platform.Addresses the above issues,this thesis studies the searchable encryption algorithm,which allows the cloud server to operate on the ciphertext data while ensuring the privacy of users so as to realize various conditions inquiries.In order to query ciphertext of database in cloud environment,a new order-preserving encryption based on coding tree is proposed.The order-preserving ciphertext is generated according to the search path of the ciphertext in the coding tree.Because of the ciphertext variability,an update strategy is designed to quickly perform ciphertext updates when data is updated.By this way the efficiency and reliability of encryption is ensured.Experimental results show that our encryption algorithm can reduce the number of client-server communication and greatly improves the efficiency of generating ciphertext.For the order-preserving encryption algorithm only supports the limitations of ciphertext size comparison,homomorphic encryption algorithm is introduced to support ciphertext addition and multiplication.A combined encryption scheme based on onion encryption model is proposed.It uses adjustable encryption of query perception to meet the needs of ciphertext operation in different query scenarios.Experimental results show that the combined encryption scheme can provide a variety of functional ciphertext and take into account the encryption performance and ciphertext security.Based on the above research,a database encryption system is developed by using Java language,and we deploy it in cloud environment.Experiments show that the cloud data server can guarantee higher query traffic after using the encryption system to meet the requirements of the actual application environment.The encryption scheme designed in this thesis can protect the data while supporting a variety of complex cloud database query function,with strong theoretical and practical value.