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protogalaxy-poc/README.md
2023-07-31 21:10:37 +02:00

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# protogalaxy-poc [![Test](https://github.com/arnaucube/protogalaxy-poc/workflows/Test/badge.svg)](https://github.com/arnaucube/protogalaxy-poc/actions?query=workflow%3ATest)
Proof of concept implementation of ProtoGalaxy (https://eprint.iacr.org/2023/1106.pdf) using [arkworks](https://github.com/arkworks-rs).
> Experimental code, do not use in production.
Thanks to [Liam Eagen](https://twitter.com/LiamEagen) and [Ariel Gabizon](https://twitter.com/rel_zeta_tech) for their kind explanations.
This code has been done in the context of the research on folding schemes in [0xPARC](https://0xparc.org).
![protogalaxy img from Wikipedia](https://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Stellar_Fireworks_Finale.jpg/303px-Stellar_Fireworks_Finale.jpg)
(img: protogalaxies colliding, [from Wikipedia](https://en.wikipedia.org/wiki/File:Stellar_Fireworks_Finale.jpg))
## Details
Implementation of ProtoGalaxy's scheme described in section 4 of the paper.
Current version implements the folding on prover & verifier and it works for k-to-1 instances and with multiple iterations, but it is not optimized.
Next steps in terms of implementation include: F(X) O(n) construction following Claim 4.4, compute K(X) in O(kd log(kd)M + ndkC) as described in Claim 4.5, add tests folding in multiple iterations and also in a tree approach, add the decider and integrate with some existing R1CS tooling for the R1CS & witness generation.
### Usage
Example of folding k+1 instances:
```rust
// assume we have:
// an R1CS instance 'r1cs'
// a valid witness 'w' from our running instance
// k valid 'witnesses' to be fold
// compute the committed instance for our running witness
let phi = Pedersen::<G1Projective>::commit(&pedersen_params, &witness.w, &witness.r_w);
let instance = CommittedInstance::<G1Projective> {
phi,
betas: betas.clone(),
e: Fr::zero(),
};
// compute the k committed instances to be fold
let mut instances: Vec<CommittedInstance<G1Projective>> = Vec::new();
for i in 0..k {
let phi_i =
Pedersen::<G1Projective>::commit(&pedersen_params, &witnesses[i].w, &witnesses[i].r_w);
let instance_i = CommittedInstance::<G1Projective> {
phi: phi_i,
betas: betas.clone(),
e: Fr::zero(),
};
instances.push(instance_i);
}
// set the initial random betas
let beta = Fr::rand(&mut rng);
let betas = powers_of_beta(beta, t);
// Prover folds the instances and witnesses
let (F_coeffs, K_coeffs, folded_instance, folded_witness) = Folding::<G1Projective>::prover(
&mut transcript_p,
&r1cs,
// running instance
instance.clone(),
witness,
// incomming instances
instances.clone(),
witnesses,
);
// verifier folds the instances
let folded_instance_v = Folding::<G1Projective>::verifier(
&mut transcript_v,
&r1cs,
instance, // running instance
instances, // incomming instances
F_coeffs,
K_coeffs,
);
// check that the folded instance satisfies the relation
assert!(check_instance(&r2cs, folded_instance, folded_witness));
// now, the folded instance & witness can be folded again with k other instances.
```
(see the actual code for more details)