ckks_scheme_switching

Documentation

Overview

Package main showcases how lookup tables can complement fixed-point approximate homomorphic encryption to compute non-linear functions such as sign. The example starts by homomorphically decoding the ciphertext from the SIMD encoding to the coefficient encoding: IDFT(m(X)) -> m(X). It then evaluates a Lookup-Table (LUT) on each coefficient of m(X): m(X)[i] -> LUT(m(X)[i]) and repacks each LUT(m(X)[i]) in a single RLWE ciphertext: Repack(LUT(m(X)[i])) -> LUT(m(X)). Finally, it homomorphically switches LUT(m(X)) back to the SIMD domain: LUT(m(X)) -> IDFT(LUT(m(X))).