Decompose operation of ckks-hybrid-KS

FHE Questions
1

Hi!

Inside the function KeySwitchHYBRID::EvalKeySwitchPrecomputeCore in keyswitch-hybrid.cpp，I see the comment says Digit decomposition only does Zero-padding and split.

However in Algo3 Line2 of thesis Over 100x, there are some constants to multiply by.

I would like to know how does openFHE deal with the constant metioned above?
i.e. Are they omitted or merged with other constants?

Thanks for your help!

2

The constants are not needed. See KeySwitch keys reuse & optimization for hybrid key switching - #5 by Sijia for more details. This optimization was originally introduced in Section 3.3 of An Improved RNS Variant of the BFV Homomorphic Encryption Scheme