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Article

Efficient Private Conjunctive Query Protocol Over Encrypted Data

1
Department of Computer Science and Engineering, Jatiya Kabi Kazi Nazrul Islam University, Trishal, Mymensingh 2224, Bangladesh
2
Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo 169-8050, Japan
*
Author to whom correspondence should be addressed.
Appeared at Progress in Cryptology-AFRICACRYPT 2017 (Africacrypt2017). We extend the contribution of the paper by adding another efficient protocol for PCQ processing using an N-ary encoding, its homomorphic evaluation, and showing the corresponding results.
Received: 15 December 2020 / Revised: 7 January 2021 / Accepted: 12 January 2021 / Published: 18 January 2021
Conjunctive queries play a key role in retrieving data from a database. In a database, a query containing many conditions in its predicate, connected by an “and/&/∧” operator, is called a conjunctive query. Retrieving the outcome of a conjunctive query from thousands of records is a heavy computational task. Private data access to an outsourced database is required to keep the database secure from adversaries; thus, private conjunctive queries (PCQs) are indispensable. Cheon, Kim, and Kim (CKK) proposed a PCQ protocol using search-and-compute circuits in which they used somewhat homomorphic encryption (SwHE) for their protocol security. As their protocol is far from being able to be used practically, we propose a practical batch private conjunctive query (BPCQ) protocol by applying a batch technique for processing conjunctive queries over an outsourced database, in which both database and queries are encoded in binary format. As a main technique in our protocol, we develop a new data-packing method to pack many data into a single polynomial with the batch technique. We further enhance the performances of the binary-encoded BPCQ protocol by replacing the binary encoding with N-ary encoding. Finally, we compare the performance to assess the results obtained by the binary-encoded BPCQ protocol and the N-ary-encoded BPCQ protocol. View Full-Text
Keywords: private conjunctive query; encrypted data; packing method; homomorphic encryption private conjunctive query; encrypted data; packing method; homomorphic encryption
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MDPI and ACS Style

Saha, T.K.; Koshiba, T. Efficient Private Conjunctive Query Protocol Over Encrypted Data. Cryptography 2021, 5, 2. https://0-doi-org.brum.beds.ac.uk/10.3390/cryptography5010002

AMA Style

Saha TK, Koshiba T. Efficient Private Conjunctive Query Protocol Over Encrypted Data. Cryptography. 2021; 5(1):2. https://0-doi-org.brum.beds.ac.uk/10.3390/cryptography5010002

Chicago/Turabian Style

Saha, Tushar K., and Takeshi Koshiba. 2021. "Efficient Private Conjunctive Query Protocol Over Encrypted Data" Cryptography 5, no. 1: 2. https://0-doi-org.brum.beds.ac.uk/10.3390/cryptography5010002

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