A BGV-Subroutined CKKS Bootstrapping Algorithm Without Sine Approximation

Jingjing Fan, Chi Zhang, Zejiu Tan, Zoe Lin Jiang, Man Ho Au, Siu Ming Yiu

Abstract: Bootstrapping plays a critical role in fully homomorphic encryption (FHE) systems like BGV, BFV, and CKKS, enabling versatile leveled multiplication. While BGV and BFV utilize a digit extraction-based approach for bootstrapping, CKKS employs a scaled sine function to approximate the modular reduction operation, followed by homomorphic evaluation of sine functions using polynomials. This method introduces a fixed lower bound on approximation error.

External IDs:doi:10.1007/978-981-95-3540-8_15