Title
Faster Packed Homomorphic Operations and Efficient Circuit Bootstrapping for TFHE.
Abstract
In this paper, we present several methods to improve the evaluation of homomorphic functions in TFHE, both for fully and for leveled homomorphic encryption. We propose two methods to manipulate packed data, in order to decrease the ciphertext expansion and optimize the evaluation of look-up tables and arbitrary functions in RingGSW based homomorphic schemes. We also extend the automata logic, introduced in [12,19], to the efficient leveled evaluation of weighted automata, and present a new homomorphic counter called TBSR, that supports all the elementary operations that occur in a multiplication. These improvements speed-up the evaluation of most arithmetic functions in a packed leveled mode, with a noise overhead that remains additive. We finally present a new circuit bootstrapping that converts LWE into low-noise RingGSW ciphertexts in just 137 ms, which makes the leveled mode of TFHE composable, and which is fast enough to speed-up arithmetic functions, compared to the gate-by-gate bootstrapping given in [12]. Finally, we propose concrete parameter sets and timing comparison for all our constructions.
Year
DOI
Venue
2017
10.1007/978-3-319-70694-8_14
ADVANCES IN CRYPTOLOGY - ASIACRYPT 2017, PT I
Keywords
Field
DocType
FHE,Leveled,Bootstrapping,LWE,GSW,Packing,Weighted automata,Arithmetic
Homomorphic encryption,Discrete mathematics,Arithmetic function,Computer science,Bootstrapping,Automaton,Ciphertext expansion,Multiplication
Conference
Volume
ISSN
Citations 
10624
0302-9743
10
PageRank 
References 
Authors
0.49
15
4
Name
Order
Citations
PageRank
Ilaria Chillotti1925.14
Nicolas Gama241224.04
Mariya Georgieva3945.51
Malika Izabachène423112.13