US 12,273,453 B2
Isogeny calculation device, isogeny calculation method, and computer program product
Tomoko Yonemura, Kawasaki Kanagawa (JP)
Assigned to Kabushiki Kaisha Toshiba, Tokyo (JP)
Filed by KABUSHIKI KAISHA TOSHIBA, Tokyo (JP)
Filed on Feb. 26, 2023, as Appl. No. 18/174,634.
Claims priority of application No. 2022-106781 (JP), filed on Jul. 1, 2022.
Prior Publication US 2024/0007288 A1, Jan. 4, 2024
Int. Cl. H04L 9/32 (2006.01); H04L 9/08 (2006.01); H04L 9/30 (2006.01)
CPC H04L 9/3066 (2013.01) [H04L 9/085 (2013.01); H04L 9/3093 (2013.01); H04L 9/32 (2013.01); H04L 9/3263 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An isogeny calculation device comprising:
a memory configured to store, as a pre-calculated value, an intermediate value, among a plurality of intermediate values used for isogeny calculation, which is determined from an elliptic point T obtained by repeatedly performing L-point multiplication (where L is a positive integer) and M-isogeny (where M is a positive integer) on an elliptic point S serving as a kernel of the isogeny; and
an isogeny calculator configured to identify the elliptic point T serving as the kernel of the M-isogeny according to lower e digits (where e is a positive integer) of an L-adic representation of a secret key sk that determines the elliptic point S, read the pre-calculated value determined from the elliptic point T from the memory, and perform at least one of calculations of the L-point multiplication and the M-isogeny by using the pre-calculated value read from the memory.