Make sign asynchronous

Some relation to https://github.com/serai-dex/serai/issues/95.

substrate/tendermint/machine/src/ext.rs

@@ -1,6 +1,8 @@
 use core::{hash::Hash, fmt::Debug};
 use std::sync::Arc;
 
+use async_trait::async_trait;
+
 use parity_scale_codec::{Encode, Decode};
 
 use crate::{SignedMessage, commit_msg};
@@ -31,6 +33,7 @@ pub struct BlockNumber(pub u64);
 pub struct Round(pub u32);
 
 /// A signature scheme used by validators.
+#[async_trait]
 pub trait SignatureScheme: Send + Sync {
   // Type used to identify validators.
   type ValidatorId: ValidatorId;
@@ -43,7 +46,7 @@ pub trait SignatureScheme: Send + Sync {
   type AggregateSignature: Signature;
 
   /// Sign a signature with the current validator's private key.
-  fn sign(&self, msg: &[u8]) -> Self::Signature;
+  async fn sign(&self, msg: &[u8]) -> Self::Signature;
   /// Verify a signature from the validator in question.
   #[must_use]
   fn verify(&self, validator: Self::ValidatorId, msg: &[u8], sig: &Self::Signature) -> bool;
@@ -121,7 +124,7 @@ impl<B: sp_runtime::traits::Block> Block for B {
 }
 
 /// Trait representing the distributed system Tendermint is providing consensus over.
-#[async_trait::async_trait]
+#[async_trait]
 pub trait Network: Send + Sync {
   // Type used to identify validators.
   type ValidatorId: ValidatorId;

substrate/tendermint/machine/src/lib.rs

@@ -157,7 +157,9 @@ impl<N: Network + 'static> TendermintMachine<N> {
   fn timeout(&self, step: Step) -> Instant {
     let mut round_time = Duration::from_secs(N::BLOCK_TIME.into());
     round_time *= self.round.0 + 1;
-    let step_time = round_time / 3; // TODO: Non-uniform timeouts
+    // TODO: Non-uniform timeouts. Proposal has to validate the block which will take much longer
+    // than any other step
+    let step_time = round_time / 3;
 
     let offset = match step {
       Step::Propose => step_time,
@@ -382,7 +384,7 @@ impl<N: Network + 'static> TendermintMachine<N> {
             }
 
             if broadcast {
-              let sig = machine.signer.sign(&msg.encode());
+              let sig = machine.signer.sign(&msg.encode()).await;
               machine.network.write().await.broadcast(SignedMessage { msg, sig }).await;
             }
           }
@@ -435,10 +437,10 @@ impl<N: Network + 'static> TendermintMachine<N> {
       if let Some(Data::Proposal(_, block)) = self.log.get(msg.round, proposer, Step::Propose) {
         // Check if it has gotten a sufficient amount of precommits
         // Use a junk signature since message equality disregards the signature
-        if self
-          .log
-          .has_consensus(msg.round, Data::Precommit(Some((block.id(), self.signer.sign(&[])))))
-        {
+        if self.log.has_consensus(
+          msg.round,
+          Data::Precommit(Some((block.id(), self.signer.sign(&[]).await))),
+        ) {
           return Ok(Some(block.clone()));
         }
       }
@@ -549,7 +551,8 @@ impl<N: Network + 'static> TendermintMachine<N> {
               block.id(),
               self
                 .signer
-                .sign(&commit_msg(self.canonical_end_time(self.round), block.id().as_ref())),
+                .sign(&commit_msg(self.canonical_end_time(self.round), block.id().as_ref()))
+                .await,
             ))));
             return Ok(None);
           }

substrate/tendermint/machine/tests/ext.rs

@@ -3,6 +3,8 @@ use std::{
   time::{UNIX_EPOCH, SystemTime, Duration},
 };
 
+use async_trait::async_trait;
+
 use parity_scale_codec::{Encode, Decode};
 
 use tokio::{sync::RwLock, time::sleep};
@@ -13,12 +15,13 @@ type TestValidatorId = u16;
 type TestBlockId = [u8; 4];
 
 struct TestSignatureScheme(u16);
+#[async_trait]
 impl SignatureScheme for TestSignatureScheme {
   type ValidatorId = TestValidatorId;
   type Signature = [u8; 32];
   type AggregateSignature = Vec<[u8; 32]>;
 
-  fn sign(&self, msg: &[u8]) -> [u8; 32] {
+  async fn sign(&self, msg: &[u8]) -> [u8; 32] {
     let mut sig = [0; 32];
     sig[.. 2].copy_from_slice(&self.0.to_le_bytes());
     sig[2 .. (2 + 30.min(msg.len()))].copy_from_slice(&msg[.. 30.min(msg.len())]);
@@ -81,7 +84,7 @@ impl Block for TestBlock {
 
 struct TestNetwork(u16, Arc<RwLock<Vec<TendermintHandle<Self>>>>);
 
-#[async_trait::async_trait]
+#[async_trait]
 impl Network for TestNetwork {
   type ValidatorId = TestValidatorId;
   type SignatureScheme = TestSignatureScheme;