2020-08-22 13:15:39 -07:00
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//! This module provides an implementation of a variant of (Turbo)[PLONK][plonk]
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//! that is designed specifically for the polynomial commitment scheme described
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//! in the [Halo][halo] paper.
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//!
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//! [halo]: https://eprint.iacr.org/2019/1021
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//! [plonk]: https://eprint.iacr.org/2019/953
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use crate::arithmetic::CurveAffine;
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use crate::polycommit::OpeningProof;
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use crate::transcript::Hasher;
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#[macro_use]
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mod circuit;
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mod domain;
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mod prover;
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mod srs;
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mod verifier;
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pub use circuit::*;
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pub use prover::*;
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pub use srs::*;
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pub use verifier::*;
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use domain::EvaluationDomain;
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/// This is a structured reference string (SRS) that is (deterministically)
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/// computed from a specific circuit and parameters for the polynomial
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/// commitment scheme.
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#[derive(Debug)]
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pub struct SRS<C: CurveAffine> {
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domain: EvaluationDomain<C::Scalar>,
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fixed_commitments: Vec<C>,
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fixed_polys: Vec<Vec<C::Scalar>>,
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fixed_cosets: Vec<Vec<C::Scalar>>,
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permutation_commitments: Vec<Vec<C>>,
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permutation_polys: Vec<Vec<Vec<C::Scalar>>>,
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permutation_cosets: Vec<Vec<Vec<C::Scalar>>>,
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meta: MetaCircuit<C::Scalar>,
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}
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/// This is an object which represents a (Turbo)PLONK proof.
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// This structure must never allow points at infinity.
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#[derive(Debug, Clone)]
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pub struct Proof<C: CurveAffine> {
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advice_commitments: Vec<C>,
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h_commitments: Vec<C>,
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permutation_product_commitments: Vec<C>,
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permutation_product_evals: Vec<C::Scalar>,
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permutation_product_inv_evals: Vec<C::Scalar>,
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permutation_evals: Vec<Vec<C::Scalar>>,
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advice_evals: Vec<C::Scalar>,
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fixed_evals: Vec<C::Scalar>,
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h_evals: Vec<C::Scalar>,
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f_commitment: C,
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q_evals: Vec<C::Scalar>,
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opening: OpeningProof<C>,
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}
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/// This is an error that could occur during proving or circuit synthesis.
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// TODO: these errors need to be cleaned up
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#[derive(Debug)]
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pub enum Error {
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/// This is an error that can occur during synthesis of the circuit, for
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/// example, when the witness is not present.
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SynthesisError,
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/// The structured reference string or the parameters are not compatible
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/// with the circuit being synthesized.
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IncompatibleParams,
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/// The constraint system is not satisfied.
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ConstraintSystemFailure,
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/// Out of bounds index passed to a backend
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BoundsFailure,
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}
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fn hash_point<C: CurveAffine, H: Hasher<C::Base>>(
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transcript: &mut H,
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point: &C,
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) -> Result<(), Error> {
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let tmp = point.get_xy();
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if bool::from(tmp.is_none()) {
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return Err(Error::SynthesisError);
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};
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let tmp = tmp.unwrap();
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transcript.absorb(tmp.0);
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transcript.absorb(tmp.1);
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Ok(())
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}
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#[test]
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fn test_proving() {
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use crate::arithmetic::{EqAffine, Field, Fp, Fq};
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use crate::polycommit::Params;
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use crate::transcript::DummyHash;
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use std::marker::PhantomData;
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const K: u32 = 5;
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2020-08-31 09:01:09 -07:00
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/// This represents an advice wire at a certain row in the MetaCircuit
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#[derive(Copy, Clone, Debug)]
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pub struct Variable(AdviceWire, usize);
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// Initialize the polynomial commitment parameters
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let params: Params<EqAffine> = Params::new::<DummyHash<Fq>>(K);
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struct PLONKConfig {
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a: AdviceWire,
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b: AdviceWire,
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c: AdviceWire,
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sa: FixedWire,
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sb: FixedWire,
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sc: FixedWire,
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sm: FixedWire,
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perm: usize,
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}
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trait StandardCS<FF: Field> {
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fn raw_multiply<F>(&mut self, f: F) -> Result<(Variable, Variable, Variable), Error>
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where
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F: FnOnce() -> Result<(FF, FF, FF), Error>;
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fn raw_add<F>(&mut self, f: F) -> Result<(Variable, Variable, Variable), Error>
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where
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F: FnOnce() -> Result<(FF, FF, FF), Error>;
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fn copy(&mut self, a: Variable, b: Variable) -> Result<(), Error>;
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}
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2020-08-22 13:15:39 -07:00
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struct MyCircuit<F: Field> {
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a: Option<F>,
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}
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2020-08-27 10:43:08 -07:00
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struct StandardPLONK<'a, F: Field, CS: ConstraintSystem<F> + 'a> {
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cs: &'a mut CS,
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config: PLONKConfig,
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current_gate: usize,
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_marker: PhantomData<F>,
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}
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impl<'a, FF: Field, CS: ConstraintSystem<FF>> StandardPLONK<'a, FF, CS> {
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fn new(cs: &'a mut CS, config: PLONKConfig) -> Self {
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StandardPLONK {
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cs,
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config,
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current_gate: 0,
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_marker: PhantomData,
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}
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}
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}
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impl<'a, FF: Field, CS: ConstraintSystem<FF>> StandardCS<FF> for StandardPLONK<'a, FF, CS> {
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fn raw_multiply<F>(&mut self, f: F) -> Result<(Variable, Variable, Variable), Error>
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where
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F: FnOnce() -> Result<(FF, FF, FF), Error>,
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{
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let index = self.current_gate;
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self.current_gate += 1;
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let mut value = None;
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self.cs.assign_advice(self.config.a, index, || {
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value = Some(f()?);
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Ok(value.ok_or(Error::SynthesisError)?.0)
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})?;
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self.cs.assign_advice(self.config.b, index, || {
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Ok(value.ok_or(Error::SynthesisError)?.1)
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})?;
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self.cs.assign_advice(self.config.c, index, || {
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Ok(value.ok_or(Error::SynthesisError)?.2)
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})?;
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self.cs
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.assign_fixed(self.config.sa, index, || Ok(FF::zero()))?;
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self.cs
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.assign_fixed(self.config.sb, index, || Ok(FF::zero()))?;
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self.cs
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.assign_fixed(self.config.sc, index, || Ok(FF::one()))?;
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self.cs
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.assign_fixed(self.config.sm, index, || Ok(FF::one()))?;
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Ok((
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Variable(self.config.a, index),
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Variable(self.config.b, index),
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Variable(self.config.c, index),
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))
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}
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fn raw_add<F>(&mut self, f: F) -> Result<(Variable, Variable, Variable), Error>
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where
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F: FnOnce() -> Result<(FF, FF, FF), Error>,
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{
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let index = self.current_gate;
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self.current_gate += 1;
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let mut value = None;
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self.cs.assign_advice(self.config.a, index, || {
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value = Some(f()?);
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Ok(value.ok_or(Error::SynthesisError)?.0)
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})?;
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self.cs.assign_advice(self.config.b, index, || {
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Ok(value.ok_or(Error::SynthesisError)?.1)
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})?;
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self.cs.assign_advice(self.config.c, index, || {
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Ok(value.ok_or(Error::SynthesisError)?.2)
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})?;
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self.cs
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.assign_fixed(self.config.sa, index, || Ok(FF::one()))?;
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self.cs
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.assign_fixed(self.config.sb, index, || Ok(FF::one()))?;
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self.cs
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.assign_fixed(self.config.sc, index, || Ok(FF::one()))?;
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self.cs
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.assign_fixed(self.config.sm, index, || Ok(FF::zero()))?;
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Ok((
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Variable(self.config.a, index),
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Variable(self.config.b, index),
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Variable(self.config.c, index),
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))
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}
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fn copy(&mut self, a: Variable, b: Variable) -> Result<(), Error> {
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let left_wire = match a.0 {
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x if x == self.config.a => 0,
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x if x == self.config.b => 1,
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x if x == self.config.c => 2,
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_ => unreachable!(),
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};
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let right_wire = match b.0 {
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x if x == self.config.a => 0,
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x if x == self.config.b => 1,
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x if x == self.config.c => 2,
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_ => unreachable!(),
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};
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self.cs
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.copy(self.config.perm, left_wire, a.1, right_wire, b.1)
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}
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}
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impl<F: Field> Circuit<F> for MyCircuit<F> {
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type Config = PLONKConfig;
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fn configure(meta: &mut MetaCircuit<F>) -> PLONKConfig {
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let a = meta.advice_wire();
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let b = meta.advice_wire();
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let c = meta.advice_wire();
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let perm = meta.permutation(&[a, b, c]);
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let sa = meta.fixed_wire();
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let sb = meta.fixed_wire();
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let sc = meta.fixed_wire();
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let sm = meta.fixed_wire();
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2020-08-24 07:28:42 -07:00
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meta.create_gate(|meta| {
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let a = meta.query_advice(a, 0);
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let b = meta.query_advice(b, 0);
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let c = meta.query_advice(c, 0);
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let sa = meta.query_fixed(sa, 0);
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let sb = meta.query_fixed(sb, 0);
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let sc = meta.query_fixed(sc, 0);
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let sm = meta.query_fixed(sm, 0);
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a.clone() * sa + b.clone() * sb + a * b * sm + (c * sc * (-F::one()))
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});
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PLONKConfig {
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a,
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b,
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c,
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sa,
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sb,
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sc,
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sm,
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perm,
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}
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}
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fn synthesize(
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&self,
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cs: &mut impl ConstraintSystem<F>,
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config: PLONKConfig,
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) -> Result<(), Error> {
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let mut cs = StandardPLONK::new(cs, config);
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2020-08-22 15:10:27 -07:00
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for _ in 0..10 {
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let mut a_squared = None;
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2020-08-30 22:58:00 -07:00
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let (_, _, c0) = cs.raw_multiply(|| {
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2020-08-27 10:43:08 -07:00
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a_squared = self.a.map(|a| a.square());
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Ok((
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self.a.ok_or(Error::SynthesisError)?,
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self.a.ok_or(Error::SynthesisError)?,
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a_squared.ok_or(Error::SynthesisError)?,
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))
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})?;
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2020-08-31 09:01:09 -07:00
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let (_, b1, _) = cs.raw_add(|| {
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let fin = a_squared.and_then(|a2| self.a.map(|a| a + a2));
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Ok((
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self.a.ok_or(Error::SynthesisError)?,
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a_squared.ok_or(Error::SynthesisError)?,
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fin.ok_or(Error::SynthesisError)?,
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))
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})?;
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2020-08-31 09:01:09 -07:00
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cs.copy(b1, c0)?;
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}
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2020-08-22 13:15:39 -07:00
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Ok(())
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}
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}
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let circuit: MyCircuit<Fp> = MyCircuit {
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a: Some((-Fp::from_u64(2) + Fp::ROOT_OF_UNITY).pow(&[100, 0, 0, 0])),
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};
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2020-08-24 07:36:41 -07:00
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let empty_circuit: MyCircuit<Fp> = MyCircuit { a: None };
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// Initialize the SRS
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let srs = SRS::generate(¶ms, &empty_circuit).expect("SRS generation should not fail");
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// Create a proof
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let proof = Proof::create::<DummyHash<Fq>, DummyHash<Fp>, _>(¶ms, &srs, &circuit)
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.expect("proof generation should not fail");
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assert!(proof.verify::<DummyHash<Fq>, DummyHash<Fp>>(¶ms, &srs));
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|
|
}
|