Dependency refactor

[mrain]

Description

closes: #109

• Remove jf-rescue crate, rescue hash function now resides in jf-primitives/rescue.
• Plonk constraint system definition and concrete constructions now live in a standalone crate jf-relation.
  • Basic and customized circuit gates are defined in jf-relation.
  • Customized/advanced circuit implementations are located in their own crates.
    • Plonk verifier related gadgets, transcript and plonk-verifier are now in jf-plonk/circuit.
    • Primitive gadgets, including commitment, el gamal etc. remains in jf-primitives/circuit.
    • Circuit for rescue hash function is now in jf-primitives/circuit/rescue.
• par-utils is moved to jf-utils.
• New dependency graph
  • jf-relation depends on jf-utils.
  • jf-primitives depends on jf-relation and jf-utils.
  • jf-plonk depends on all other crates.

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (main)
• Linked to GitHub issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• Wrote unit tests
• Updated relevant documentation in the code
• Added a relevant changelog entry to the Pending section in CHANGELOG.md
• Re-reviewed Files changed in the GitHub PR explorer

[alxiong]

👍 nice work.

here's some comments:

• plonk/src/circuit/* should be moved to jf-relation, those are not related to Plonk proof system, they are gadgets for plonk verifier (when you try to do proof recursion and prove that a Plonk proof is correct in circuit, therefore they belong with all the other gadgets)
• within jf-relation:
  • no need to have customized/ folder,
  • instead, put all gate impl (including basic.rs into relation/src/gadgets/*
  • merged relation/src/customized/gates.rs into relation/src/gates.rs
  • rename relation/src/customized/mod.rs to customized.rs ? (@chancharles92, @zhenfeizhang any better idea?) or we can also split them up and group them like arkwork or like plonky2
  • gadgets moved from plonk/ should be under /gadgets/transcript/ and gadgets/plonk_verifier/, just like gadgets/ecc/

[mrain]

👍 nice work.

here's some comments:

• plonk/src/circuit/* should be moved to jf-relation, those are not related to Plonk proof system, they are gadgets for plonk verifier (when you try to do proof recursion and prove that a Plonk proof is correct in circuit, therefore they belong with all the other gadgets)

Currently, circuit implementation of plonk verifier depends on struct VerifyingKey provided by jf-plonk. Moving it to jf-relation will cause circular dependency.

• within jf-relation:

  • no need to have customized/ folder,
  • instead, put all gate impl (including basic.rs into relation/src/gadgets/*
  • merged relation/src/customized/gates.rs into relation/src/gates.rs
  • rename relation/src/customized/mod.rs to customized.rs ? (@chancharles92, @zhenfeizhang any better idea?) or we can also split them up and group them like arkwork or like plonky2
  • gadgets moved from plonk/ should be under /gadgets/transcript/ and gadgets/plonk_verifier/, just like gadgets/ecc/

Good suggestion. Will do.

[zhenfeizhang]

• rename relation/src/customized/mod.rs to customized.rs ? (@chancharles92, @zhenfeizhang any better idea?) or we can also split them up and group them like arkwork or like plonky2

Good idea... now the customized is a bit large and it makes sense to group its components

[chancharles92]

• rename relation/src/customized/mod.rs to customized.rs ? (@chancharles92, @zhenfeizhang any better idea?) or we can also split them up and group them like arkwork or like plonky2

Agree with @zhenfeizhang , I prefer the approach used by arkworks and plonky2

[alxiong]

Currently, circuit implementation of plonk verifier depends on struct VerifyingKey provided by jf-plonk. Moving it to jf-relation will cause circular dependency.

Ah, I see, then just keep them where there are.

[alxiong]

I really like your reorg! great work! 🎉
Thank you for the big migration!

Some minor comments:

• relation/gadgets/basic.rs seems a bit strange, I would merge this file with relation/circuit.rs and call it relation/constraint_system.rs (which contains both the trait Circuit and struct PlonkCircuit) <-- I agree our usage of circuit/constraint_system/gadget/gates need to be re-checked later.

[alxiong]

LGTM!

[chancharles92]

Good job! Only 1 minor comment