217 lines
7.7 KiB
Rust
217 lines
7.7 KiB
Rust
//! Async Groth16 batch verifier service
|
|
|
|
use std::{
|
|
fmt,
|
|
future::Future,
|
|
mem,
|
|
pin::Pin,
|
|
task::{Context, Poll},
|
|
};
|
|
|
|
use bellman::{
|
|
groth16::{batch, prepare_verifying_key, VerifyingKey},
|
|
VerificationError,
|
|
};
|
|
use bls12_381::Bls12;
|
|
use futures::future::{ready, Ready};
|
|
use once_cell::sync::Lazy;
|
|
use rand::thread_rng;
|
|
use tokio::sync::broadcast::{channel, error::RecvError, Sender};
|
|
use tower::{util::ServiceFn, Service};
|
|
use tower_batch::{Batch, BatchControl};
|
|
use tower_fallback::Fallback;
|
|
use zebra_chain::sapling::{Output, Spend};
|
|
|
|
mod hash_reader;
|
|
mod params;
|
|
#[cfg(test)]
|
|
mod tests;
|
|
|
|
use self::hash_reader::HashReader;
|
|
use params::PARAMS;
|
|
|
|
/// Global batch verification context for Groth16 proofs of Spend 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.
|
|
pub static SPEND_VERIFIER: Lazy<
|
|
Fallback<Batch<Verifier, Item>, ServiceFn<fn(Item) -> Ready<Result<(), VerificationError>>>>,
|
|
> = Lazy::new(|| {
|
|
Fallback::new(
|
|
Batch::new(
|
|
Verifier::new(&PARAMS.sapling.spend.vk),
|
|
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(&prepare_verifying_key(&PARAMS.sapling.spend.vk)))
|
|
}) as fn(_) -> _,
|
|
),
|
|
)
|
|
});
|
|
|
|
/// Global batch verification context for Groth16 proofs of Output 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.
|
|
pub static OUTPUT_VERIFIER: Lazy<
|
|
Fallback<Batch<Verifier, Item>, ServiceFn<fn(Item) -> Ready<Result<(), VerificationError>>>>,
|
|
> = Lazy::new(|| {
|
|
Fallback::new(
|
|
Batch::new(
|
|
Verifier::new(&PARAMS.sapling.output.vk),
|
|
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(&prepare_verifying_key(&PARAMS.sapling.output.vk)))
|
|
}) as fn(_) -> _,
|
|
),
|
|
)
|
|
});
|
|
|
|
/// A Groth16 verification item, used as the request type of the service.
|
|
pub type Item = batch::Item<Bls12>;
|
|
|
|
pub struct ItemWrapper(Item);
|
|
|
|
impl From<&Spend> for ItemWrapper {
|
|
fn from(spend: &Spend) -> Self {
|
|
Self(Item::from((
|
|
bellman::groth16::Proof::read(&spend.zkproof.0[..]).unwrap(),
|
|
spend.primary_inputs(),
|
|
)))
|
|
}
|
|
}
|
|
|
|
impl From<&Output> for ItemWrapper {
|
|
fn from(output: &Output) -> Self {
|
|
Self(Item::from((
|
|
bellman::groth16::Proof::read(&output.zkproof.0[..]).unwrap(),
|
|
output.primary_inputs(),
|
|
)))
|
|
}
|
|
}
|
|
|
|
impl From<ItemWrapper> for Item {
|
|
fn from(item_wrapper: ItemWrapper) -> Self {
|
|
item_wrapper.0
|
|
}
|
|
}
|
|
|
|
/// Groth16 signature verifier implementation
|
|
///
|
|
/// This is the core implementation for the batch verification logic of the groth
|
|
/// verifier. It handles batching incoming requests, driving batches to
|
|
/// completion, and reporting results.
|
|
pub struct Verifier {
|
|
batch: batch::Verifier<Bls12>,
|
|
// Making this 'static makes managing lifetimes much easier.
|
|
vk: &'static VerifyingKey<Bls12>,
|
|
/// Broadcast sender used to send the result of a batch verification to each
|
|
/// request source in the batch.
|
|
tx: Sender<Result<(), VerificationError>>,
|
|
}
|
|
|
|
impl Verifier {
|
|
fn new(vk: &'static VerifyingKey<Bls12>) -> Self {
|
|
let batch = batch::Verifier::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 = VerificationError;
|
|
type Future = Pin<Box<dyn Future<Output = Result<(), VerificationError>> + 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 groth16 proof");
|
|
metrics::counter!("proofs.groth16.verified", 1);
|
|
} else {
|
|
tracing::trace!(?result, "invalid groth16 proof");
|
|
metrics::counter!("proofs.groth16.invalid", 1);
|
|
}
|
|
|
|
result
|
|
}
|
|
Err(RecvError::Lagged(_)) => {
|
|
tracing::error!(
|
|
"missed channel updates, BROADCAST_BUFFER_SIZE is too low!!"
|
|
);
|
|
Err(VerificationError::InvalidProof)
|
|
}
|
|
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));
|
|
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));
|
|
}
|
|
}
|