Replace bincode with borsh (#452)

* Add SignalsConfig to chain_spec

* Correct multiexp feature flagging for rand_core std

* Remove bincode for borsh

Replaces a non-canonical encoding with a canonical encoding which additionally
should be faster.

Also fixes an issue where we used bincode in transcripts where it cannot be
trusted.

This ended up fixing a myriad of other bugs observed, unfortunately.
Accordingly, it either has to be merged or the bug fixes from it must be ported
to a new PR.

* Make serde optional, minimize usage

* Make borsh an optional dependency of substrate/ crates

* Remove unused dependencies

* Use [u8; 64] where possible in the processor messages

* Correct borsh feature flagging

tests/processor/Cargo.toml

@@ -32,6 +32,7 @@ scale = { package = "parity-scale-codec", version = "3" }
 serai-client = { path = "../../substrate/client" }
 serai-message-queue = { path = "../../message-queue" }
 
+borsh = { version = "1", features = ["de_strict_order"] }
 serde = { version = "1", default-features = false }
 serde_json = { version = "1", default-features = false }
 

tests/processor/src/lib.rs

@@ -224,7 +224,7 @@ impl Coordinator {
           to: Service::Processor(self.network),
           intent: msg.intent(),
         },
-        serde_json::to_string(&msg).unwrap().into_bytes(),
+        borsh::to_vec(&msg).unwrap(),
       )
       .await;
     self.next_send_id += 1;
@@ -242,7 +242,7 @@ impl Coordinator {
     assert_eq!(msg.id, self.next_recv_id);
     self.queue.ack(Service::Processor(self.network), msg.id).await;
     self.next_recv_id += 1;
-    serde_json::from_slice(&msg.msg).unwrap()
+    borsh::from_slice(&msg.msg).unwrap()
   }
 
   pub async fn add_block(&self, ops: &DockerOperations) -> ([u8; 32], Vec<u8>) {

tests/processor/src/tests/batch.rs

@@ -26,7 +26,7 @@ pub(crate) async fn recv_batch_preprocesses(
   substrate_key: &[u8; 32],
   batch: &Batch,
   attempt: u32,
-) -> (SubstrateSignId, HashMap<Participant, Vec<u8>>) {
+) -> (SubstrateSignId, HashMap<Participant, [u8; 64]>) {
   let id = SubstrateSignId {
     key: *substrate_key,
     id: SubstrateSignableId::Batch((batch.network, batch.id).encode().try_into().unwrap()),
@@ -87,7 +87,7 @@ pub(crate) async fn sign_batch(
   coordinators: &mut [Coordinator],
   key: [u8; 32],
   id: SubstrateSignId,
-  preprocesses: HashMap<Participant, Vec<u8>>,
+  preprocesses: HashMap<Participant, [u8; 64]>,
 ) -> SignedBatch {
   assert_eq!(preprocesses.len(), THRESHOLD);
 

tests/processor/src/tests/key_gen.rs

@@ -4,7 +4,7 @@ use dkg::{Participant, ThresholdParams, tests::clone_without};
 
 use serai_client::{
   primitives::{NetworkId, BlockHash, PublicKey},
-  validator_sets::primitives::{Session, KeyPair, ValidatorSet},
+  validator_sets::primitives::{Session, ValidatorSet, KeyPair},
 };
 
 use messages::{SubstrateContext, key_gen::KeyGenId, CoordinatorMessage, ProcessorMessage};
@@ -122,8 +122,10 @@ pub(crate) async fn key_gen(coordinators: &mut [Coordinator], network: NetworkId
     network_latest_finalized_block: BlockHash([0; 32]),
   };
 
-  let key_pair =
-    (PublicKey::from_raw(substrate_key.unwrap()), network_key.clone().unwrap().try_into().unwrap());
+  let key_pair = KeyPair(
+    PublicKey::from_raw(substrate_key.unwrap()),
+    network_key.clone().unwrap().try_into().unwrap(),
+  );
 
   for coordinator in coordinators {
     coordinator