Title
Efficient Sorting Of Homomorphic Encrypted Data With K-Way Sorting Network
Abstract
In this study, we propose an efficient sorting method for encrypted data using fully homomorphic encryption (FHE). The proposed method extends the existing 2-way sorting method by applying the k-way sorting network for any prime k to reduce the depth in terms of comparison operation from O(log(2)(2) n) to O(k log(k)(2) n), thereby improving performance for k slightly larger than 2, such as k = 5. We apply this method to approximate FHE which is widely used due to its efficiency of homomorphic arithmetic operations. In order to build up the k-way sorting network, the k-sorter, which sorts k-numbers with a minimal comparison depth, is used as a building block. The approximate homomorphic comparison, which is the only type of comparison working on approximate HIE, cannot he used for the construction of the k-sorter as it is because the result of the comparison is not binary, unlike the comparison in conventional bit-wise FHEs. To overcome this problem, we propose an efficient k-sorter construction utilizing the features of approximate homomorphic comparison. Also, we propose an efficient construction of a k-way sorting network using cryptographic SIMD operations. To use the proposed method most efficiently, we propose an estimation formula that finds the appropriate k that is expected to reduce the total time cost when the parameters of the approximating comparisons and the performance of the operations provided by the approximate FHE are given. We also show the implementation results of the proposed method, and it shows that sorting 5(6) = 15625 data using 5-way sorting network can be about 23.3% faster than sorting 2(14) = 16384 data using 2-way.
Year
DOI
Venue
2021
10.1109/TIFS.2021.3106167
IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY
Keywords
DocType
Volume
Approximate homomorphic encryption, sorting network, parallel algorithm
Journal
16
ISSN
Citations 
PageRank 
1556-6013
0
0.34
References 
Authors
0
5
Name
Order
Citations
PageRank
Seungwan Hong1124.70
Seunghong Kim200.34
Jiheon Choi300.34
Younho Lee440525.13
Jung Hee Cheon51787129.74