US 12,323,507 B2
Method and apparatus for hardware-based accelerated arithmetic operation on homomorphically encrypted message
Seong Cheon Park, Daejeon (KR); Hyun Woo Kim, Daejeon (KR); and Jung Chan Na, Daejeon (KR)
Assigned to Electronics and Telecommunications Research Institute, Daejeon (KR)
Filed by ELECTRONICS AND TELECOMMUNICATIONS RESEARCH INSTITUTE, Daejeon (KR)
Filed on Sep. 27, 2022, as Appl. No. 17/954,029.
Claims priority of application No. 10-2021-0163684 (KR), filed on Nov. 24, 2021; and application No. 10-2022-0045015 (KR), filed on Apr. 12, 2022.
Prior Publication US 2023/0163945 A1, May 25, 2023
Int. Cl. H04L 9/00 (2022.01); G06F 7/487 (2006.01); H04L 9/06 (2006.01)
CPC H04L 9/008 (2013.01) [G06F 7/4876 (2013.01); H04L 9/0618 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method of performing hardware-based modular multiplication on homomorphically encrypted messages, the method comprising:
performing a ciphertext division operation of receiving a plurality of homomorphically encrypted messages expressed in a polynomial form and a modulus for modular multiplication, decomposing the modulus into a product of a plurality of disjoint factors through a Chinese remainder theorem (CRT) operation, and extracting a divided ciphertext from a plurality of homomorphically encrypted messages based on each of the disjoint factors;
performing number theoretic transform (NTT) transformation on each coefficient of the divided ciphertext;
performing a pointwise multiplication operation between result values of the NTT transformation;
performing inverse number theoretic transform (INTT) transformation on a result value of the pointwise multiplication operation to obtain the divided ciphertext; and
merging the divided ciphertext obtained in the performing of the INTT transformation through an inverse Chinese remainder theorem (ICRT) operation to generate an output ciphertext;
wherein the performing of the ciphertext division operation includes decomposing the modulus into a product of disjoint factors less than or equal to a predetermined word size.