Trouble using FHECKKSRNS::EvalLinearTransform

Library Questions
1

Hello,

I am trying to use the following method in an application: FHECKKSRNS::EvalLinearTransform
(link: https://github.com/openfheorg/openfhe-development/blob/v1.3.1/src/pke/lib/scheme/ckksrns/ckksrns-fhe.cpp#L1611)

However, I am having trouble with it as it appears like nothing in the FHECKKSRNS type is exposed on any public CryptoContext<DCRTPoly> interface.

I have tried static_pointer_cast/dynamic_cast approaches on both the context and scheme pointers, and downcasting the scheme object itself but nothing worked so far.

Could you advise the recommended way to invoke EvalLinearTransform from user code?

Thanks!

2

You are right, currently the EvalLinearTransform methods are particularized for the bootstrapping use and only callable in FHECKKSRNS.

I can create an issue to expose it in a later OpenFHE version. But until then, for your application it is probably the easiest to copy the code for EvalLinearTransform (and relevant functions such as MakeAuxPlaintext, EvalAddExtInPlace, etc) and remove the bootstrapping-dependent parts (m_bootPrecomMap).

3

Thank you for your answer! I will copy the relevant bits of code then. It would be great to have it available in a future version :slight_smile: