Practical Packing Method in Somewhat Homomorphic Encryption

2014 ◽  
pp. 34-50 ◽  
Author(s):  
Masaya Yasuda ◽  
Takeshi Shimoyama ◽  
Jun Kogure ◽  
Kazuhiro Yokoyama ◽  
Takeshi Koshiba
Keyword(s):  
Homomorphic Encryption ◽  
Packing Method ◽  
Somewhat Homomorphic Encryption

scholarly journals New packing method in somewhat homomorphic encryption and its applications

2015 ◽  
Vol 8 (13) ◽  
pp. 2194-2213 ◽  
Author(s):  
Masaya Yasuda ◽  
Takeshi Shimoyama ◽  
Jun Kogure ◽  
Kazuhiro Yokoyama ◽  
Takeshi Koshiba
Keyword(s):  
Homomorphic Encryption ◽  
Packing Method ◽  
Somewhat Homomorphic Encryption

scholarly journals Efficient Secure Matrix Multiplication Over LWE-Based Homomorphic Encryption

2016 ◽  
Vol 67 (1) ◽  
pp. 69-83 ◽  
Author(s):  
Dung Hoang Duong ◽  
Pradeep Kumar Mishra ◽  
Masaya Yasuda
Keyword(s):  
Homomorphic Encryption ◽  
Matrix Multiplication ◽  
New Method ◽  
Inner Product ◽  
Encryption Scheme ◽  
Data Confidentiality ◽  
Computation Cost ◽  
Packing Method ◽  
Somewhat Homomorphic Encryption

Abstract Homomorphic encryption enables various calculations while preserving the data confidentiality. In this paper, we apply the somewhat homomorphic encryption scheme proposed by Brakerski and Vaikuntanathan (CRYPTO 2011) to secure matrix multiplication between two matrices. To reduce both the ciphertext size and the computation cost, we propose a new method to pack a matrix into a single ciphertexts so that it also enables efficient matrix multiplication over the packed ciphertexts. Our packing method generalizes Yasuda et al.’s methods (Security Comm. Networks 2015 and ACISP 2015), which are for secure inner product. We also implement our methods and give a comparison with previous packing methods.

scholarly journals Efficient Private Conjunctive Query Protocol Over Encrypted Data

Cryptography ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Tushar Kanti Saha ◽  
Takeshi Koshiba
Keyword(s):  
Homomorphic Encryption ◽  
Data Access ◽  
Conjunctive Query ◽  
Conjunctive Queries ◽  
Private Data ◽  
Binary Format ◽  
Main Technique ◽  
Batch Technique ◽  
Outsourced Database ◽  
Packing Method

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.

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