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use std::{marker::PhantomData, sync::Arc};
use snarkvm_algorithms::traits::{MaskedMerkleParameters, CRH};
use snarkvm_fields::PrimeField;
use snarkvm_gadgets::{
algorithms::merkle_tree::compute_root,
integers::uint::UInt8,
traits::{
algorithms::{CRHGadget, MaskedCRHGadget},
alloc::AllocGadget,
eq::EqGadget,
},
};
use snarkvm_r1cs::{errors::SynthesisError, Assignment, ConstraintSynthesizer, ConstraintSystem};
pub trait POSWCircuitParameters {
const MASK_LENGTH: usize;
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct POSWCircuit<
F: PrimeField,
M: MaskedMerkleParameters,
HG: MaskedCRHGadget<M::H, F>,
CP: POSWCircuitParameters,
> {
pub leaves: Vec<Option<<M::H as CRH>::Output>>,
pub merkle_parameters: Arc<M>,
pub mask: Option<Vec<u8>>,
pub root: Option<<M::H as CRH>::Output>,
pub field_type: PhantomData<F>,
pub crh_gadget_type: PhantomData<HG>,
pub circuit_parameters_type: PhantomData<CP>,
}
impl<F: PrimeField, M: MaskedMerkleParameters, HG: MaskedCRHGadget<M::H, F>, CP: POSWCircuitParameters>
ConstraintSynthesizer<F> for POSWCircuit<F, M, HG, CP>
{
fn generate_constraints<CS: ConstraintSystem<F>>(&self, cs: &mut CS) -> Result<(), SynthesisError> {
let mask = self.mask.clone().unwrap_or_else(|| vec![0; CP::MASK_LENGTH]);
if mask.len() != CP::MASK_LENGTH {
return Err(SynthesisError::Unsatisfiable);
}
let mask_bytes = UInt8::alloc_input_vec_le(cs.ns(|| "mask"), &mask)?;
let crh_parameters =
<HG as CRHGadget<M::H, F>>::ParametersGadget::alloc(&mut cs.ns(|| "new_parameters"), || {
let crh_parameters = self.merkle_parameters.parameters();
Ok(crh_parameters)
})?;
let mask_crh_parameters =
<HG as CRHGadget<M::H, F>>::ParametersGadget::alloc(&mut cs.ns(|| "new_mask_parameters"), || {
let crh_parameters = self.merkle_parameters.mask_parameters();
Ok(crh_parameters)
})?;
let leaves_number = 2u32.pow(M::DEPTH as u32) as usize;
assert!(self.leaves.len() <= leaves_number);
let mut leaf_gadgets = self
.leaves
.iter()
.enumerate()
.map(|(i, l)| HG::OutputGadget::alloc(cs.ns(|| format!("leaf {}", i)), || l.as_ref().get()))
.collect::<Result<Vec<_>, _>>()?;
let empty_hash = self
.merkle_parameters
.hash_empty()
.map_err(|_| SynthesisError::Unsatisfiable)?;
for i in leaf_gadgets.len()..leaves_number {
leaf_gadgets.push(HG::OutputGadget::alloc(cs.ns(|| format!("leaf {}", i)), || {
Ok(empty_hash.clone())
})?);
}
let computed_root = compute_root::<M::H, HG, _, _, _>(
cs.ns(|| "compute masked root"),
&crh_parameters,
&mask_crh_parameters,
&mask_bytes,
&leaf_gadgets,
)?;
let public_computed_root =
HG::OutputGadget::alloc_input(cs.ns(|| "public computed root"), || self.root.as_ref().get())?;
computed_root.enforce_equal(cs.ns(|| "inputize computed root"), &public_computed_root)?;
Ok(())
}
}
#[cfg(test)]
mod test {
use std::{marker::PhantomData, sync::Arc};
use blake2::{digest::Digest, Blake2s};
use rand::thread_rng;
use snarkvm_algorithms::{
crh::PedersenCompressedCRH,
define_masked_merkle_tree_parameters,
snark::gm17::{create_random_proof, generate_random_parameters, prepare_verifying_key, verify_proof},
};
use snarkvm_curves::{
bls12_377::{Bls12_377, Fr},
edwards_bls12::{EdwardsProjective as Edwards, Fq},
};
use snarkvm_fields::ToConstraintField;
use snarkvm_gadgets::{algorithms::crh::PedersenCompressedCRHGadget, curves::edwards_bls12::EdwardsBls12Gadget};
use snarkvm_utilities::ToBytes;
use super::{POSWCircuit, POSWCircuitParameters};
struct TestPOSWCircuitParameters;
impl POSWCircuitParameters for TestPOSWCircuitParameters {
const MASK_LENGTH: usize = 32;
}
const NUM_WINDOWS: usize = 256;
const WINDOW_SIZE: usize = 4;
define_masked_merkle_tree_parameters!(EdwardsMaskedMerkleParameters, PedersenCompressedCRH<Edwards, NUM_WINDOWS, WINDOW_SIZE>, 4);
type HashGadget = PedersenCompressedCRHGadget<Edwards, Fq, EdwardsBls12Gadget>;
type EdwardsMaskedMerkleTree = MerkleTree<EdwardsMaskedMerkleParameters>;
#[test]
fn test_tree_proof() {
let mut rng = thread_rng();
let parameters = EdwardsMaskedMerkleParameters::setup(&mut rng);
let params = generate_random_parameters::<Bls12_377, _, _>(
&POSWCircuit::<_, EdwardsMaskedMerkleParameters, HashGadget, TestPOSWCircuitParameters> {
leaves: vec![None; 7],
merkle_parameters: Arc::new(parameters.clone()),
mask: None,
root: None,
field_type: PhantomData,
crh_gadget_type: PhantomData,
circuit_parameters_type: PhantomData,
},
&mut rng,
)
.unwrap();
let nonce = [1; 32];
let leaves = vec![vec![3u8; 32]; 7];
let tree = EdwardsMaskedMerkleTree::new(Arc::new(parameters.clone()), &leaves[..]).unwrap();
let root = tree.root();
let mut root_bytes = [0; 32];
root.write_le(&mut root_bytes[..]).unwrap();
let mut h = Blake2s::new();
h.update(nonce.as_ref());
h.update(root_bytes.as_ref());
let mask = h.finalize().to_vec();
let snark_leaves = tree.hashed_leaves().to_vec().into_iter().map(Some).collect();
let proof = create_random_proof(
&POSWCircuit::<_, EdwardsMaskedMerkleParameters, HashGadget, TestPOSWCircuitParameters> {
leaves: snark_leaves,
merkle_parameters: Arc::new(parameters),
mask: Some(mask.clone()),
root: Some(root),
field_type: PhantomData,
crh_gadget_type: PhantomData,
circuit_parameters_type: PhantomData,
},
¶ms,
&mut rng,
)
.unwrap();
let inputs = [ToConstraintField::<Fr>::to_field_elements(&mask[..]).unwrap(), vec![
root,
]]
.concat();
assert!(verify_proof(&prepare_verifying_key(params.vk), &proof, &inputs,).unwrap());
}
}