US 11,922,135 B2
Number-theoretic transform processing apparatus, number-theoretic transform processing method, and computer program product
Tomoko Yonemura, Kawasaki (JP)
Assigned to KABUSHIKI KAISHA TOSHIBA, Minato-ku (JP)
Filed by KABUSHIKI KAISHA TOSHIBA, Minato-ku (JP)
Filed on Aug. 28, 2020, as Appl. No. 17/005,390.
Claims priority of application No. 2020-038923 (JP), filed on Mar. 6, 2020.
Prior Publication US 2021/0279040 A1, Sep. 9, 2021
Int. Cl. H04L 9/30 (2006.01); G06F 7/72 (2006.01); G10L 21/0208 (2013.01)
CPC G06F 7/725 (2013.01) [G10L 21/0208 (2013.01); H04L 9/3093 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A number-theoretic transform processing apparatus for a noise in lattice-based cryptography, comprising:
a memory; and
a hardware processor coupled to the memory and configured to perform number-theoretic transform of the noise using a precomputation table including a combination of products of 2k+1 or less elements (where k is a positive integer) that belong to a subspace of a finite field Zq and indicate coefficients of the noise, with 2n or less number-theoretic transform constants selected from number-theoretic transform constants of {1, ω, ω2, . . . , ωn-1} and {γ, γω, γω2, . . . , yωn-1} (where ωn≡(mod q), γ2≡ω(mod q)), without performing a computation for the products included in the precomputation table, reducing a number of Zq multiplications in the number-theoretic transform of the noise over a polynomial ring Rq.