refactor: move some types from common to backend (post-split)(plonk-0)

[duguorong009]

Description

• move some types/funcs of plonk from halo2_common to halo2_backend

Related issues

• [post frontend-backend split] Move types/functions from common to frontend/backend #266

Changes

• move the following types/mods from halo2_common::plonk to halo2_backend::plonk
  • Challenge*
  • Transcript

[ed255]

LGTM!

[CPerezz]

LGTM.

But I want to take a second and think/consider moving the transcript to it's own crate such that it can be reused by other libs.

This is a good example on what we would need: https://github.com/dalek-cryptography/merlin
Although is fixed for keccak. Where we need to abstract the hashing algo.

What do you think @ed255 @kilic @han0110 ?

[duguorong009]

LGTM.

But I want to take a second and think/consider moving the transcript to it's own crate such that it can be reused by other libs.

This is a good example on what we would need: https://github.com/dalek-cryptography/merlin Although is fixed for keccak. Where we need to abstract the hashing algo.

What do you think @ed255 @kilic @han0110 ?

From my side, I think it is good idea.
For the best, I think you should create new issue for discussion. And gets the feedback, suggestions, etc. @CPerezz

On the other hand, I believe we can merge this small PR. @CPerezz
Maybe, is it better to keep the transcript module in halo2_common crate?
Or move it to halo2_backend crate & take care of it later?

[ed255]

From my side, I think it is good idea. For the best, I think you should create new issue for discussion. And gets the feedback, suggestions, etc. @CPerezz

On the other hand, I believe we can merge this small PR. @CPerezz Maybe, is it better to keep the transcript module in halo2_common crate? Or move it to halo2_backend crate & take care of it later?

I think we can move it to halo2_backend now and take care of it later. The same applies to poly: it was temporarily in halo2_common and then moved to halo2_backend via #272 and at the same time we discussed the possibility of moving it to its own crate.