# Technique for Searching Data in a Cryptographically Protected SQL Database
## 6 Conclusions  
This paper presents a solution that provides a strong level of confidentiality when searching, inserting, modifying, and deleting the required sensitive data in a remote database whose data are encrypted. We have proposed a SQL query processing technique that allows the DBMS server to perform search functions over encrypted data in the same way as in an unencrypted database. This is achieved through the organization of automatic decryption by specially developed secure software of the appropriate data required for search, without the possibility of viewing these data itself. Decryption of the special software itself and its activation is also carried out automatically when accessing encrypted data in the corresponding query in an active legitimate session. Moreover, only a legitimate user who presented the corresponding key at the beginning of the session can perform such decryption. After the corresponding query is made, the decrypted special software is deleted automatically. The DBMS server cannot decrypt stored data encrypted with a strong cryptographic algorithm if these data were not requested by the application. At the same time, we guarantee the integrity of the used open stored procedures and special tables that store encrypted modules of special software and decryption keys, the relevance and completeness of the results returned to the application.  
Our technique involves separate processing of an SQL query on the side of the DBMS server and the application server (database proxy). At that, legitimate users are granted timely and uninterrupted access to the database. We offer a basis for implementing our solution on the Oracle DBMS server side, using both unmodified DBMS software and our own developed persistent stored modules.  
The results of the analysis of the feasibility and effectiveness of our approach, based on the evaluation of the performance of the proposed solution, show that proper security and privacy, despite the existing threats of data leakage from service providers, can be achieved with reasonable overhead.  
In the future, we plan to conduct an in-depth performance evaluation of the proposed solution, including a comparison with existing implementations, to show its practicality in various real-life situations. In addition, it is planned to study the proposed solution in more depth from the point of view of its security, namely, vulnerability to inference leakage due to access and search patterns, to which almost any implementation of an SE scheme is susceptible to a greater or lesser degree, and the security of the special software used itself.  
Conceptualization, V.Y.; methodology, V.Y. and V.V.; software, V.Y., V.V. and R.K.; formal analysis, M.K. and R.K.; investigation, V.Y., M.Y., V.V. and R.S.; writing--original draft preparation, V.Y., M.Y. and R.S.; writing--review and editing, V.Y., M.K. and M.Y.; funding acquisition, M.K. and R.S. All authors have read and agreed to the published version of the manuscript.  
The research work reported in this paper was, in part, supported by the National Centre for Research and Development, Poland, under grant no. POIR.04.01.04-00-0048/20.  
Not applicable.  
Not available.  
The authors declare no conflict of interest.