mirror of https://github.com/zcash/halo2.git
Merge pull request #95 from zcash/mock-prover
Add MockProver for developing circuits
This commit is contained in:
commit
c968ea8091
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//! Tools for developing circuits.
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use ff::Field;
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use crate::{
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arithmetic::{FieldExt, Group},
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plonk::{permutation, Any, Assignment, Circuit, Column, ColumnType, ConstraintSystem, Error},
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poly::Rotation,
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};
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/// The reasons why a particular circuit is not satisfied.
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#[derive(Debug, PartialEq)]
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pub enum VerifyFailure {
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/// A gate was not satisfied for a particular row.
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Gate {
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/// The index of the gate that is not satisfied. These indices are assigned in the
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/// order in which `ConstraintSystem::create_gate` is called during
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/// `Circuit::configure`.
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gate_index: usize,
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/// The row on which this gate is not satisfied.
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row: usize,
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},
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/// A lookup input did not exist in its corresponding table.
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Lookup {
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/// The index of the lookup that is not satisfied. These indices are assigned in
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/// the order in which `ConstraintSystem::lookup` is called during
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/// `Circuit::configure`.
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lookup_index: usize,
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/// The row on which this lookup is not satisfied.
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row: usize,
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},
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/// A permutation did not preserve the original value of a cell.
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Permutation {
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/// The index of the permutation that is not satisfied. These indices are assigned
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/// in the order in which `ConstraintSystem::lookup` is called during
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/// `Circuit::configure`.
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perm_index: usize,
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/// The column in which this permutation is not satisfied.
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column: usize,
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/// The row on which this permutation is not satisfied.
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row: usize,
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},
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}
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/// A test prover for debugging circuits.
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///
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/// The normal proving process, when applied to a buggy circuit implementation, might
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/// return proofs that do not validate when they should, but it can't indicate anything
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/// other than "something is invalid". `MockProver` can be used to figure out _why_ these
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/// are invalid: it stores all the private inputs along with the circuit internals, and
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/// then checks every constraint manually.
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///
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/// # Examples
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///
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/// ```
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/// use halo2::{
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/// arithmetic::FieldExt,
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/// dev::{MockProver, VerifyFailure},
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/// pasta::Fp,
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/// plonk::{Advice, Assignment, Circuit, Column, ConstraintSystem, Error},
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/// };
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/// const K: u32 = 5;
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///
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/// struct MyConfig {
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/// a: Column<Advice>,
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/// b: Column<Advice>,
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/// c: Column<Advice>,
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/// }
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///
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/// struct MyCircuit {
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/// a: Option<u64>,
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/// b: Option<u64>,
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/// }
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///
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/// impl<F: FieldExt> Circuit<F> for MyCircuit {
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/// type Config = MyConfig;
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///
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/// fn configure(meta: &mut ConstraintSystem<F>) -> MyConfig {
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/// let a = meta.advice_column();
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/// let b = meta.advice_column();
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/// let c = meta.advice_column();
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///
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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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///
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/// // BUG: Should be a * b - c
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/// a * b + c
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/// });
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///
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/// MyConfig { a, b, c }
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/// }
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///
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/// fn synthesize(&self, cs: &mut impl Assignment<F>, config: MyConfig) -> Result<(), Error> {
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/// cs.assign_advice(config.a, 0, || {
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/// self.a.map(|v| F::from_u64(v)).ok_or(Error::SynthesisError)
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/// })?;
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/// cs.assign_advice(config.b, 0, || {
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/// self.b.map(|v| F::from_u64(v)).ok_or(Error::SynthesisError)
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/// })?;
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/// cs.assign_advice(config.c, 0, || {
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/// self.a
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/// .and_then(|a| self.b.map(|b| F::from_u64(a * b)))
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/// .ok_or(Error::SynthesisError)
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/// })
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/// }
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/// }
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///
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/// // Assemble the private inputs to the circuit.
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/// let circuit = MyCircuit {
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/// a: Some(2),
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/// b: Some(4),
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/// };
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///
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/// // This circuit has no public inputs.
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/// let aux = vec![];
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///
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/// let prover = MockProver::<Fp>::run(K, &circuit, aux).unwrap();
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/// assert_eq!(
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/// prover.verify(),
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/// Err(VerifyFailure::Gate {
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/// gate_index: 0,
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/// row: 0
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/// })
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/// );
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/// ```
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#[derive(Debug)]
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pub struct MockProver<F: Group> {
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n: u32,
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cs: ConstraintSystem<F>,
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// The fixed cells in the circuit, arranged as [column][row].
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fixed: Vec<Vec<F>>,
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// The advice cells in the circuit, arranged as [column][row].
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advice: Vec<Vec<F>>,
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// The aux cells in the circuit, arranged as [column][row].
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aux: Vec<Vec<F>>,
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permutations: Vec<permutation::keygen::Assembly>,
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}
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impl<F: Field + Group> Assignment<F> for MockProver<F> {
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fn assign_advice(
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&mut self,
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column: crate::plonk::Column<crate::plonk::Advice>,
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row: usize,
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to: impl FnOnce() -> Result<F, crate::plonk::Error>,
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) -> Result<(), crate::plonk::Error> {
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*self
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.advice
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.get_mut(column.index())
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.and_then(|v| v.get_mut(row))
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.ok_or(Error::BoundsFailure)? = to()?;
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Ok(())
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}
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fn assign_fixed(
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&mut self,
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column: crate::plonk::Column<crate::plonk::Fixed>,
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row: usize,
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to: impl FnOnce() -> Result<F, crate::plonk::Error>,
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) -> Result<(), crate::plonk::Error> {
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*self
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.fixed
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.get_mut(column.index())
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.and_then(|v| v.get_mut(row))
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.ok_or(Error::BoundsFailure)? = to()?;
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Ok(())
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}
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fn copy(
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&mut self,
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permutation: usize,
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left_column: usize,
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left_row: usize,
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right_column: usize,
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right_row: usize,
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) -> Result<(), crate::plonk::Error> {
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// Check bounds first
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if permutation >= self.permutations.len() {
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return Err(Error::BoundsFailure);
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}
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self.permutations[permutation].copy(left_column, left_row, right_column, right_row)
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}
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}
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impl<F: FieldExt> MockProver<F> {
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/// Runs a synthetic keygen-and-prove operation on the given circuit, collecting data
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/// about the constraints and their assignments.
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pub fn run<ConcreteCircuit: Circuit<F>>(
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k: u32,
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circuit: &ConcreteCircuit,
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aux: Vec<Vec<F>>,
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) -> Result<Self, Error> {
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let n = 1 << k;
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let mut cs = ConstraintSystem::default();
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let config = ConcreteCircuit::configure(&mut cs);
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let fixed = vec![vec![F::zero(); n as usize]; cs.num_fixed_columns];
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let advice = vec![vec![F::zero(); n as usize]; cs.num_advice_columns];
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let permutations = cs
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.permutations
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.iter()
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.map(|p| permutation::keygen::Assembly::new(n as usize, p))
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.collect();
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let mut prover = MockProver {
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n,
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cs,
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fixed,
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advice,
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aux,
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permutations,
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};
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circuit.synthesize(&mut prover, config)?;
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Ok(prover)
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}
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/// Returns `Ok(())` if this `MockProver` is satisfied, or an error indicating the
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/// first encountered reason that the circuit is not satisfied.
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pub fn verify(&self) -> Result<(), VerifyFailure> {
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let n = self.n as i32;
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// Check that all gates are satisfied for all rows.
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for (gate_index, gate) in self.cs.gates.iter().enumerate() {
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// We iterate from n..2n so we can just reduce to handle wrapping.
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for row in n..(2 * n) {
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fn load<'a, F: FieldExt, T: ColumnType>(
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n: i32,
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row: i32,
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queries: &'a [(Column<T>, Rotation)],
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cells: &'a [Vec<F>],
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) -> impl Fn(usize) -> F + 'a {
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move |index| {
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let (column, at) = &queries[index];
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let resolved_row = (row + at.0) % n;
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cells[column.index()][resolved_row as usize]
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}
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};
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if gate.evaluate(
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&load(n, row, &self.cs.fixed_queries, &self.fixed),
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&load(n, row, &self.cs.advice_queries, &self.advice),
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&load(n, row, &self.cs.aux_queries, &self.aux),
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&|a, b| a + &b,
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&|a, b| a * &b,
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&|a, scalar| a * scalar,
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) != F::zero()
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{
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return Err(VerifyFailure::Gate {
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gate_index,
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row: (row - n) as usize,
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});
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}
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}
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}
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// Check that all lookups exist in their respective tables.
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for (lookup_index, lookup) in self.cs.lookups.iter().enumerate() {
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for input_row in 0..n {
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let load = |column: &Column<Any>, row| match column.column_type() {
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Any::Fixed => self.fixed[column.index()][row as usize],
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Any::Advice => self.advice[column.index()][row as usize],
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Any::Aux => self.aux[column.index()][row as usize],
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};
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let inputs: Vec<_> = lookup
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.input_columns
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.iter()
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.map(|c| load(c, input_row))
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.collect();
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if !(0..n)
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.map(|table_row| lookup.table_columns.iter().map(move |c| load(c, table_row)))
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.any(|table_row| table_row.eq(inputs.iter().cloned()))
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{
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return Err(VerifyFailure::Lookup {
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lookup_index,
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row: input_row as usize,
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});
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}
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}
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}
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// Check that permutations preserve the original values of the cells.
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for (perm_index, assembly) in self.permutations.iter().enumerate() {
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// Original values of columns involved in the permutation
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let original = self.cs.permutations[perm_index]
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.get_columns()
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.iter()
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.map(|c| self.advice[c.index()].clone())
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.collect::<Vec<_>>();
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// Iterate over each column of the permutation
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for (column, values) in assembly.mapping.iter().enumerate() {
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// Iterate over each row of the column to check that the cell's
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// value is preserved by the mapping.
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for (row, cell) in values.iter().enumerate() {
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let original_cell = original[column][row];
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let permuted_cell = original[cell.0][cell.1];
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if original_cell != permuted_cell {
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return Err(VerifyFailure::Permutation {
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perm_index,
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column,
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row,
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});
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}
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}
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}
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}
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Ok(())
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}
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}
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@ -19,4 +19,5 @@ pub mod plonk;
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pub mod poly;
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pub mod transcript;
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pub mod dev;
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pub mod model;
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10
src/plonk.rs
10
src/plonk.rs
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@ -14,7 +14,7 @@ use crate::transcript::ChallengeScalar;
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mod circuit;
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mod keygen;
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mod lookup;
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mod permutation;
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pub(crate) mod permutation;
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mod vanishing;
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mod prover;
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@ -119,6 +119,7 @@ type ChallengeX<F> = ChallengeScalar<F, X>;
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#[test]
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fn test_proving() {
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use crate::arithmetic::{Curve, FieldExt};
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use crate::dev::MockProver;
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use crate::pasta::{EqAffine, Fp, Fq};
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use crate::poly::commitment::{Blind, Params};
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use crate::transcript::DummyHash;
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@ -462,6 +463,13 @@ fn test_proving() {
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.commit_lagrange(&pubinputs, Blind::default())
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.to_affine();
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// Check this circuit is satisfied.
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let prover = match MockProver::run(K, &circuit, vec![pubinputs.to_vec()]) {
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Ok(prover) => prover,
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Err(e) => panic!("{:?}", e),
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};
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assert_eq!(prover.verify(), Ok(()));
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for _ in 0..100 {
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// Create a proof
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let proof = Proof::create::<DummyHash<Fq>, DummyHash<Fp>, _>(
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@ -104,7 +104,7 @@ where
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permutations: cs
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.permutations
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.iter()
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.map(|p| permutation::keygen::Assembly::new(params, p))
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.map(|p| permutation::keygen::Assembly::new(params.n as usize, p))
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.collect(),
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_marker: std::marker::PhantomData,
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};
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@ -37,6 +37,10 @@ impl Argument {
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// - z(omega^{-1} X) \prod (p(X) + \delta^i \beta X + \gamma)
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std::cmp::max(self.columns.len() + 1, 2)
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}
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pub(crate) fn get_columns(&self) -> Vec<Column<Advice>> {
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self.columns.clone()
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}
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}
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/// The verifying key for a single permutation argument.
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@ -14,20 +14,21 @@ pub(crate) struct AssemblyHelper<C: CurveAffine> {
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deltaomega: Vec<Vec<C::Scalar>>,
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}
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#[derive(Debug)]
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pub(crate) struct Assembly {
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mapping: Vec<Vec<(usize, usize)>>,
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pub(crate) mapping: Vec<Vec<(usize, usize)>>,
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aux: Vec<Vec<(usize, usize)>>,
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sizes: Vec<Vec<usize>>,
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}
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impl Assembly {
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pub(crate) fn new<C: CurveAffine>(params: &Params<C>, p: &Argument) -> Self {
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pub(crate) fn new(n: usize, p: &Argument) -> Self {
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// Initialize the copy vector to keep track of copy constraints in all
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// the permutation arguments.
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let mut columns = vec![];
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for i in 0..p.columns.len() {
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// Computes [(i, 0), (i, 1), ..., (i, n - 1)]
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columns.push((0..params.n).map(|j| (i, j as usize)).collect());
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columns.push((0..n).map(|j| (i, j)).collect());
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}
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// Before any equality constraints are applied, every cell in the permutation is
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@ -36,7 +37,7 @@ impl Assembly {
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Assembly {
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mapping: columns.clone(),
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aux: columns,
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sizes: vec![vec![1usize; params.n as usize]; p.columns.len()],
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sizes: vec![vec![1usize; n]; p.columns.len()],
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}
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}
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