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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
// Copyright (c) DUSK NETWORK. All rights reserved.
//! Tools & traits for PLONK circuits
use crate::commitment_scheme::PublicParameters;
use crate::constraint_system::TurboComposer;
use crate::error::Error;
use crate::proof_system::{Proof, Prover, ProverKey, Verifier, VerifierKey};
#[cfg(feature = "canon")]
use canonical_derive::Canon;
use dusk_bls12_381::BlsScalar;
use dusk_bytes::{DeserializableSlice, Serializable, Write};
use dusk_jubjub::{JubJubAffine, JubJubExtended, JubJubScalar};
use parity_scale_codec::{Decode, Encode};
use sp_std::vec;
use sp_std::vec::Vec;
#[derive(Default, Debug, Clone, PartialEq, Decode, Encode)]
#[cfg_attr(feature = "canon", derive(Canon))]
/// Structure that represents a PLONK Circuit Public Input converted into it's
/// &\[[`BlsScalar`]\] repr.
pub struct PublicInputValue(pub(crate) Vec<BlsScalar>);
impl From<BlsScalar> for PublicInputValue {
fn from(scalar: BlsScalar) -> Self {
Self(vec![scalar])
}
}
impl From<JubJubScalar> for PublicInputValue {
fn from(scalar: JubJubScalar) -> Self {
Self(vec![scalar.into()])
}
}
impl From<JubJubAffine> for PublicInputValue {
fn from(point: JubJubAffine) -> Self {
Self(vec![point.get_x(), point.get_y()])
}
}
impl From<JubJubExtended> for PublicInputValue {
fn from(point: JubJubExtended) -> Self {
JubJubAffine::from(point).into()
}
}
#[derive(Debug, Clone, PartialEq, Decode, Encode)]
/// Collection of structs/objects that the Verifier will use in order to
/// de/serialize data needed for Circuit proof verification.
/// This structure can be seen as a link between the [`Circuit`] public input
/// positions and the [`VerifierKey`] that the Verifier needs to use.
pub struct VerifierData {
key: VerifierKey,
public_inputs_indexes: Vec<u32>,
}
impl VerifierData {
/// Creates a new `VerifierData` from a [`VerifierKey`] and the public
/// input positions of the circuit that it represents.
pub const fn new(
key: VerifierKey,
public_inputs_indexes: Vec<u32>,
) -> Self {
Self {
key,
public_inputs_indexes,
}
}
/// Returns a reference to the contained [`VerifierKey`].
pub const fn key(&self) -> &VerifierKey {
&self.key
}
/// Returns a reference to the contained Public Input positions.
pub fn public_inputs_indexes(&self) -> &[u32] {
&self.public_inputs_indexes
}
/// Deserializes the `VerifierData` into a vector of bytes.
#[allow(unused_must_use)]
pub fn to_var_bytes(&self) -> Vec<u8> {
let mut buff = vec![
0u8;
VerifierKey::SIZE
+ u32::SIZE
+ self.public_inputs_indexes.len() * u32::SIZE
];
let mut writer = &mut buff[..];
writer.write(&self.key.to_bytes());
writer.write(&(self.public_inputs_indexes.len() as u32).to_bytes());
self.public_inputs_indexes.iter().copied().for_each(|pos| {
// Omit the result since disk_bytes write can't fail here
// due to the fact that we're writing into a vector basically.
let _ = writer.write(&(pos as u32).to_bytes());
});
buff
}
/// Serializes `VerifierData` from a slice of bytes.
pub fn from_slice(mut buf: &[u8]) -> Result<Self, Error> {
let key = VerifierKey::from_reader(&mut buf)?;
let pos_num = u32::from_reader(&mut buf)? as usize;
let mut public_inputs_indexes = vec![];
for _ in 0..pos_num {
public_inputs_indexes.push(u32::from_reader(&mut buf)?);
}
Ok(Self {
key,
public_inputs_indexes,
})
}
}
/// Trait that should be implemented for any circuit function to provide to it
/// the capabilities of automatically being able to generate, and verify proofs
/// as well as compile the circuit.
/// # Example
///
/// ```
/// use fullcodec_plonk::prelude::*;
/// use rand::SeedableRng;
/// use rand_xorshift::XorShiftRng;
///
/// fn main() -> Result<(), Error> {
/// // Implements a circuit that checks:
/// // 1) a + b = c where C is a PI
/// // 2) a <= 2^6
/// // 3) b <= 2^5
/// // 4) a * b = d where D is a PI
/// // 5) JubJub::GENERATOR * e(JubJubScalar) = f where F is a PI
/// #[derive(Debug, Default)]
/// pub struct TestCircuit {
/// a: BlsScalar,
/// b: BlsScalar,
/// c: BlsScalar,
/// d: BlsScalar,
/// e: JubJubScalar,
/// f: JubJubAffine,
/// }
///
/// impl Circuit for TestCircuit {
/// const CIRCUIT_ID: [u8; 32] = [0xff; 32];
/// fn gadget(
/// &mut self,
/// composer: &mut TurboComposer,
/// ) -> Result<(), Error> {
/// // Add fixed witness zero
/// let zero = TurboComposer::constant_zero();
/// let a = composer.append_witness(self.a);
/// let b = composer.append_witness(self.b);
///
/// // Make first constraint a + b = c
/// let constraint = Constraint::new()
/// .left(1)
/// .right(1)
/// .public(-self.c)
/// .a(a)
/// .b(b);
///
/// composer.append_gate(constraint);
///
/// // Check that a and b are in range
/// composer.component_range(a, 1 << 6);
/// composer.component_range(b, 1 << 5);
///
/// // Make second constraint a * b = d
/// let constraint = Constraint::new()
/// .mult(1)
/// .output(1)
/// .public(-self.d)
/// .a(a)
/// .b(b);
///
/// composer.append_gate(constraint);
///
/// let e = composer.append_witness(self.e);
/// let scalar_mul_result =
/// composer.component_mul_generator(
/// e, dusk_jubjub::GENERATOR_EXTENDED,
/// );
/// // Apply the constrain
/// composer
/// .assert_equal_public_point(scalar_mul_result, self.f);
/// Ok(())
/// }
///
/// fn public_inputs(&self) -> Vec<PublicInputValue> {
/// vec![self.c.into(), self.d.into(), self.f.into()]
/// }
///
/// fn padded_gates(&self) -> usize {
/// 1 << 11
/// }
/// }
///
/// let rng = XorShiftRng::from_seed([
/// 0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37,
/// 0x32, 0x54, 0x06, 0xbc, 0xe5,
/// ]);
///
/// let pp = PublicParameters::setup(1 << 12, rng)?;
/// // Initialize the circuit
/// let mut circuit = TestCircuit::default();
/// // Compile the circuit
/// let (pk, vd) = circuit.compile(&pp)?;
///
/// // Prover POV
/// let proof = {
/// let mut circuit = TestCircuit {
/// a: BlsScalar::from(20u64),
/// b: BlsScalar::from(5u64),
/// c: BlsScalar::from(25u64),
/// d: BlsScalar::from(100u64),
/// e: JubJubScalar::from(2u64),
/// f: JubJubAffine::from(
/// dusk_jubjub::GENERATOR_EXTENDED * JubJubScalar::from(2u64),
/// ),
/// };
///
/// circuit.prove(&pp, &pk, b"Test")
/// }?;
///
/// // Verifier POV
/// let public_inputs: Vec<PublicInputValue> = vec![
/// BlsScalar::from(25u64).into(),
/// BlsScalar::from(100u64).into(),
/// JubJubAffine::from(
/// dusk_jubjub::GENERATOR_EXTENDED * JubJubScalar::from(2u64),
/// )
/// .into(),
/// ];
///
/// TestCircuit::verify(
/// &pp,
/// &vd,
/// &proof,
/// &public_inputs,
/// b"Test",
/// )
/// }
pub trait Circuit
where
Self: Sized,
{
/// Circuit identifier associated constant.
const CIRCUIT_ID: [u8; 32];
/// Gadget implementation used to fill the composer.
fn gadget(&mut self, composer: &mut TurboComposer) -> Result<(), Error>;
/// Compiles the circuit by using a function that returns a `Result`
/// with the `ProverKey`, `VerifierKey` and the circuit size.
fn compile(
&mut self,
pub_params: &PublicParameters,
) -> Result<(ProverKey, VerifierData), Error> {
// Setup PublicParams
let (ck, _) = pub_params.trim(self.padded_gates())?;
// Generate & save `ProverKey` with some random values.
let mut prover = Prover::new(b"CircuitCompilation");
self.gadget(prover.composer_mut())?;
let public_inputs_indexes =
prover.composer_mut().public_input_indexes();
prover.preprocess(&ck)?;
// Generate & save `VerifierKey` with some random values.
let mut verifier = Verifier::new(b"CircuitCompilation");
self.gadget(verifier.composer_mut())?;
verifier.preprocess(&ck)?;
Ok((
prover
.prover_key
.expect("Unexpected error. Missing ProverKey in compilation"),
VerifierData::new(
verifier.verifier_key.expect(
"Unexpected error. Missing VerifierKey in compilation",
),
public_inputs_indexes,
),
))
}
/// Generates a proof using the provided `CircuitInputs` & `ProverKey`
/// instances.
fn prove(
&mut self,
pub_params: &PublicParameters,
prover_key: &ProverKey,
transcript_init: &'static [u8],
) -> Result<Proof, Error> {
let (ck, _) = pub_params.trim(self.padded_gates())?;
// New Prover instance
let mut prover = Prover::new(transcript_init);
// Fill witnesses for Prover
self.gadget(prover.composer_mut())?;
// Add ProverKey to Prover
prover.prover_key = Some(prover_key.clone());
prover.prove(&ck)
}
/// Verify the provided proof for the compiled verifier data
fn verify(
pub_params: &PublicParameters,
verifier_data: &VerifierData,
proof: &Proof,
public_inputs: &[PublicInputValue],
transcript_init: &'static [u8],
) -> Result<(), Error> {
let gates = verifier_data.key().padded_gates();
let pi_indexes = verifier_data.public_inputs_indexes();
let mut dense_pi = vec![BlsScalar::zero(); gates as usize];
public_inputs
.iter()
.map(|pi| pi.0.clone())
.flatten()
.zip(pi_indexes.iter().cloned())
.for_each(|(value, pos)| {
dense_pi[pos as usize] = -value;
});
let mut verifier = Verifier::new(transcript_init);
verifier.verifier_key.replace(*verifier_data.key());
let opening_key = pub_params.opening_key();
verifier.verify(proof, opening_key, &dense_pi)
}
/// Return the list of public inputs generated by the gadget
fn public_inputs(&self) -> Vec<PublicInputValue>;
/// Returns the Circuit size padded to the next power of two.
fn padded_gates(&self) -> usize;
}