2021-11-16 19:26:15 -08:00
|
|
|
//! Async Halo2 batch verifier service
|
|
|
|
|
|
|
|
use std::{
|
|
|
|
convert::TryFrom,
|
|
|
|
fmt,
|
|
|
|
future::Future,
|
|
|
|
mem,
|
|
|
|
pin::Pin,
|
|
|
|
task::{Context, Poll},
|
|
|
|
};
|
|
|
|
|
|
|
|
use futures::future::{ready, Ready};
|
|
|
|
use once_cell::sync::Lazy;
|
|
|
|
use orchard::circuit::VerifyingKey;
|
|
|
|
use rand::{thread_rng, CryptoRng, RngCore};
|
|
|
|
use thiserror::Error;
|
|
|
|
use tokio::sync::broadcast::{channel, error::RecvError, Sender};
|
|
|
|
use tower::{util::ServiceFn, Service};
|
|
|
|
use tower_batch::{Batch, BatchControl};
|
|
|
|
use tower_fallback::Fallback;
|
|
|
|
|
|
|
|
#[cfg(test)]
|
|
|
|
mod tests;
|
|
|
|
|
|
|
|
lazy_static::lazy_static! {
|
|
|
|
pub static ref VERIFYING_KEY: VerifyingKey = VerifyingKey::build();
|
|
|
|
}
|
|
|
|
|
|
|
|
// === TEMPORARY BATCH HALO2 SUBSTITUTE ===
|
|
|
|
//
|
|
|
|
// These types are meant to be API compatible with the batch verification APIs
|
|
|
|
// in bellman::groth16::batch, reddsa::batch, redjubjub::batch, and
|
|
|
|
// ed25519-zebra::batch. Once Halo2 batch proof verification math and
|
|
|
|
// implementation is available, this code can be replaced with that.
|
|
|
|
|
|
|
|
/// A Halo2 verification item, used as the request type of the service.
|
|
|
|
#[derive(Clone, Debug)]
|
|
|
|
pub struct Item {
|
|
|
|
instances: Vec<orchard::circuit::Instance>,
|
|
|
|
proof: orchard::circuit::Proof,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl Item {
|
|
|
|
/// Perform non-batched verification of this `Item`.
|
|
|
|
///
|
|
|
|
/// This is useful (in combination with `Item::clone`) for implementing
|
|
|
|
/// fallback logic when batch verification fails.
|
|
|
|
pub fn verify_single(&self, vk: &VerifyingKey) -> Result<(), halo2::plonk::Error> {
|
|
|
|
self.proof.verify(vk, &self.instances[..])
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
#[derive(Default)]
|
|
|
|
pub struct BatchVerifier {
|
|
|
|
queue: Vec<Item>,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl BatchVerifier {
|
|
|
|
pub fn queue(&mut self, item: Item) {
|
|
|
|
self.queue.push(item);
|
|
|
|
}
|
|
|
|
|
|
|
|
pub fn verify<R: RngCore + CryptoRng>(
|
|
|
|
self,
|
|
|
|
_rng: R,
|
|
|
|
vk: &VerifyingKey,
|
|
|
|
) -> Result<(), halo2::plonk::Error> {
|
|
|
|
for item in self.queue {
|
|
|
|
item.verify_single(vk)?;
|
|
|
|
}
|
|
|
|
|
|
|
|
Ok(())
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// === END TEMPORARY BATCH HALO2 SUBSTITUTE ===
|
|
|
|
|
2021-11-16 21:54:14 -08:00
|
|
|
impl From<&zebra_chain::orchard::ShieldedData> for Item {
|
|
|
|
fn from(shielded_data: &zebra_chain::orchard::ShieldedData) -> Item {
|
2021-11-16 19:26:15 -08:00
|
|
|
use orchard::{circuit, note, primitives::redpallas, tree, value};
|
|
|
|
|
|
|
|
let anchor = tree::Anchor::from_bytes(shielded_data.shared_anchor.into()).unwrap();
|
|
|
|
|
|
|
|
let enable_spend = shielded_data
|
|
|
|
.flags
|
|
|
|
.contains(zebra_chain::orchard::Flags::ENABLE_SPENDS);
|
|
|
|
let enable_output = shielded_data
|
|
|
|
.flags
|
|
|
|
.contains(zebra_chain::orchard::Flags::ENABLE_OUTPUTS);
|
|
|
|
|
|
|
|
let instances = shielded_data
|
|
|
|
.actions()
|
|
|
|
.map(|action| {
|
|
|
|
circuit::Instance::from_parts(
|
|
|
|
anchor,
|
|
|
|
value::ValueCommitment::from_bytes(&action.cv.into()).unwrap(),
|
|
|
|
note::Nullifier::from_bytes(&action.nullifier.into()).unwrap(),
|
|
|
|
redpallas::VerificationKey::<redpallas::SpendAuth>::try_from(<[u8; 32]>::from(
|
|
|
|
action.rk,
|
|
|
|
))
|
|
|
|
.expect("should be a valid redpallas spendauth verification key"),
|
|
|
|
note::ExtractedNoteCommitment::from_bytes(&action.cm_x.into()).unwrap(),
|
|
|
|
enable_spend,
|
|
|
|
enable_output,
|
|
|
|
)
|
|
|
|
})
|
|
|
|
.collect();
|
|
|
|
|
|
|
|
Item {
|
|
|
|
instances,
|
2021-11-16 21:54:14 -08:00
|
|
|
proof: orchard::circuit::Proof::new(shielded_data.proof.0.clone()),
|
2021-11-16 19:26:15 -08:00
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// An error that may occur when verifying [Halo2 proofs of Zcash Orchard Action
|
|
|
|
/// descriptions][actions].
|
|
|
|
///
|
|
|
|
/// [actions]: https://zips.z.cash/protocol/protocol.pdf#actiondesc
|
|
|
|
// TODO: if halo2::plonk::Error gets the std::error::Error trait derived on it,
|
|
|
|
// remove this and just wrap `halo2::plonk::Error` as an enum variant of
|
|
|
|
// `crate::transaction::Error`, which does the trait derivation via `thiserror`
|
|
|
|
#[derive(Clone, Debug, Error, Eq, PartialEq)]
|
|
|
|
pub enum Halo2Error {
|
|
|
|
#[error("the constraint system is not satisfied")]
|
|
|
|
ConstraintSystemFailure,
|
|
|
|
#[error("unknown Halo2 error")]
|
|
|
|
Other,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl From<halo2::plonk::Error> for Halo2Error {
|
|
|
|
fn from(err: halo2::plonk::Error) -> Halo2Error {
|
|
|
|
match err {
|
|
|
|
halo2::plonk::Error::ConstraintSystemFailure => Halo2Error::ConstraintSystemFailure,
|
|
|
|
_ => Halo2Error::Other,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Global batch verification context for Halo2 proofs of Action statements.
|
|
|
|
///
|
|
|
|
/// This service transparently batches contemporaneous proof verifications,
|
|
|
|
/// handling batch failures by falling back to individual verification.
|
|
|
|
///
|
|
|
|
/// Note that making a `Service` call requires mutable access to the service, so
|
|
|
|
/// you should call `.clone()` on the global handle to create a local, mutable
|
|
|
|
/// handle.
|
|
|
|
#[allow(dead_code)]
|
|
|
|
pub static VERIFIER: Lazy<
|
|
|
|
Fallback<Batch<Verifier, Item>, ServiceFn<fn(Item) -> Ready<Result<(), Halo2Error>>>>,
|
|
|
|
> = Lazy::new(|| {
|
|
|
|
Fallback::new(
|
|
|
|
Batch::new(
|
|
|
|
Verifier::new(&VERIFYING_KEY),
|
|
|
|
super::MAX_BATCH_SIZE,
|
|
|
|
super::MAX_BATCH_LATENCY,
|
|
|
|
),
|
|
|
|
// We want to fallback to individual verification if batch verification
|
|
|
|
// fails, so we need a Service to use. The obvious way to do this would
|
|
|
|
// be to write a closure that returns an async block. But because we
|
|
|
|
// have to specify the type of a static, we need to be able to write the
|
|
|
|
// type of the closure and its return value, and both closures and async
|
|
|
|
// blocks have eldritch types whose names cannot be written. So instead,
|
|
|
|
// we use a Ready to avoid an async block and cast the closure to a
|
|
|
|
// function (which is possible because it doesn't capture any state).
|
|
|
|
tower::service_fn(
|
|
|
|
(|item: Item| ready(item.verify_single(&VERIFYING_KEY).map_err(Halo2Error::from)))
|
|
|
|
as fn(_) -> _,
|
|
|
|
),
|
|
|
|
)
|
|
|
|
});
|
|
|
|
|
|
|
|
/// Halo2 proof verifier implementation
|
|
|
|
///
|
|
|
|
/// This is the core implementation for the batch verification logic of the
|
|
|
|
/// Halo2 verifier. It handles batching incoming requests, driving batches to
|
|
|
|
/// completion, and reporting results.
|
|
|
|
pub struct Verifier {
|
|
|
|
/// The sync Halo2 batch verifier.
|
|
|
|
batch: BatchVerifier,
|
|
|
|
// Making this 'static makes managing lifetimes much easier.
|
|
|
|
vk: &'static VerifyingKey,
|
|
|
|
/// Broadcast sender used to send the result of a batch verification to each
|
|
|
|
/// request source in the batch.
|
|
|
|
tx: Sender<Result<(), Halo2Error>>,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl Verifier {
|
|
|
|
#[allow(dead_code)]
|
|
|
|
fn new(vk: &'static VerifyingKey) -> Self {
|
|
|
|
let batch = BatchVerifier::default();
|
|
|
|
let (tx, _) = channel(super::BROADCAST_BUFFER_SIZE);
|
|
|
|
Self { batch, vk, tx }
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
impl fmt::Debug for Verifier {
|
|
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
|
|
let name = "Verifier";
|
|
|
|
f.debug_struct(name)
|
|
|
|
.field("batch", &"..")
|
|
|
|
.field("vk", &"..")
|
|
|
|
.field("tx", &self.tx)
|
|
|
|
.finish()
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
impl Service<BatchControl<Item>> for Verifier {
|
|
|
|
type Response = ();
|
|
|
|
type Error = Halo2Error;
|
|
|
|
type Future = Pin<Box<dyn Future<Output = Result<(), Halo2Error>> + Send + 'static>>;
|
|
|
|
|
|
|
|
fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
|
|
|
|
Poll::Ready(Ok(()))
|
|
|
|
}
|
|
|
|
|
|
|
|
fn call(&mut self, req: BatchControl<Item>) -> Self::Future {
|
|
|
|
match req {
|
|
|
|
BatchControl::Item(item) => {
|
|
|
|
tracing::trace!("got item");
|
|
|
|
self.batch.queue(item);
|
|
|
|
let mut rx = self.tx.subscribe();
|
|
|
|
Box::pin(async move {
|
|
|
|
match rx.recv().await {
|
|
|
|
Ok(result) => {
|
|
|
|
if result.is_ok() {
|
|
|
|
tracing::trace!(?result, "verified halo2 proof");
|
|
|
|
metrics::counter!("proofs.halo2.verified", 1);
|
|
|
|
} else {
|
|
|
|
tracing::trace!(?result, "invalid halo2 proof");
|
|
|
|
metrics::counter!("proofs.halo2.invalid", 1);
|
|
|
|
}
|
|
|
|
|
|
|
|
result
|
|
|
|
}
|
|
|
|
Err(RecvError::Lagged(_)) => {
|
|
|
|
tracing::error!(
|
|
|
|
"missed channel updates, BROADCAST_BUFFER_SIZE is too low!!"
|
|
|
|
);
|
|
|
|
// This is the enum variant that
|
|
|
|
// orchard::circuit::Proof.verify() returns on
|
|
|
|
// evaluation failure.
|
|
|
|
Err(Halo2Error::ConstraintSystemFailure)
|
|
|
|
}
|
|
|
|
Err(RecvError::Closed) => panic!("verifier was dropped without flushing"),
|
|
|
|
}
|
|
|
|
})
|
|
|
|
}
|
|
|
|
|
|
|
|
BatchControl::Flush => {
|
|
|
|
tracing::trace!("got flush command");
|
|
|
|
let batch = mem::take(&mut self.batch);
|
|
|
|
let _ = self.tx.send(
|
|
|
|
batch
|
|
|
|
.verify(thread_rng(), self.vk)
|
|
|
|
.map_err(Halo2Error::from),
|
|
|
|
);
|
|
|
|
Box::pin(async { Ok(()) })
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
impl Drop for Verifier {
|
|
|
|
fn drop(&mut self) {
|
|
|
|
// We need to flush the current batch in case there are still any pending futures.
|
|
|
|
let batch = mem::take(&mut self.batch);
|
|
|
|
let _ = self.tx.send(
|
|
|
|
batch
|
|
|
|
.verify(thread_rng(), self.vk)
|
|
|
|
.map_err(Halo2Error::from),
|
|
|
|
);
|
|
|
|
}
|
|
|
|
}
|