Efficient Protocols for Private Database Queries

  • Tushar Kanti SahaEmail author
  • Mayank
  • Takeshi Koshiba
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10359)


We consider the problem of processing private database queries over encrypted data in the cloud. To do this, we propose a protocol for conjunctive query and another for disjunctive query processing using somewhat homomorphic encryption in the semi-honest model. In 2016, Kim et al. [IEEE Trans. on Dependable and Secure Comput.] showed an FHE-based query processing with equality conditions over encrypted data. We improve the performance of processing private conjunctive and disjunctive queries with the low-depth equality circuits than Kim et al.’s circuits. To get the low-depth circuits, we modify the packing methods of Saha and Koshiba [APWConCSE 2016] to support an efficient batch computation for our protocols with a few multiplications. Our implementation shows that our protocols work faster than Kim et al.’s protocols for both conjunctive and disjunctive query processing along with a better security level. We are also able to provide security to both attributes and values appeared in the predicate of the conjunctive and disjunctive queries whereas Kim et al. provided the security to the values only.


Private Database Queries Conjunctive Disjunctive Packing method Homomorphic Encryption Batch technique 



This research is supported by KAKENHI Grant Numbers JP16H01705, JP17H01695, and JP24106008 for Scientific Research on Innovative Areas.


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Copyright information

© IFIP International Federation for Information Processing 2017

Authors and Affiliations

  1. 1.Division of Mathematics, Electronics, and Informatics, Graduate School of Science and EngineeringSaitama UniversitySaitamaJapan
  2. 2.Department of Computer Science and EngineeringIndian Institute of Technology (Banaras Hindu University)VaranasiIndia
  3. 3.Faculty of Education and Integrated Arts and SciencesWaseda UniversityTokyoJapan

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