Minor work on the transaction signing task

processor/scheduler/primitives/src/lib.rs

@@ -10,11 +10,26 @@ use group::GroupEncoding;
 use serai_db::DbTxn;
 
 /// A signable transaction.
-pub trait SignableTransaction: 'static + Sized + Send + Sync {
+pub trait SignableTransaction: 'static + Sized + Send + Sync + Clone {
+  /// The ciphersuite used to sign this transaction.
+  type Ciphersuite: Cuphersuite;
+  /// The preprocess machine for the signing protocol for this transaction.
+  type PreprocessMachine: PreprocessMachine;
+
   /// Read a `SignableTransaction`.
   fn read(reader: &mut impl io::Read) -> io::Result<Self>;
   /// Write a `SignableTransaction`.
   fn write(&self, writer: &mut impl io::Write) -> io::Result<()>;
+
+  /// The ID for this transaction.
+  ///
+  /// This is an internal ID arbitrarily definable so long as it's unique.
+  ///
+  /// This same ID MUST be returned by the Eventuality for this transaction.
+  fn id(&self) -> [u8; 32];
+
+  /// Sign this transaction.
+  fn sign(self, keys: ThresholdKeys<Self::Ciphersuite>) -> Self::PreprocessMachine;
 }
 
 mod db {

processor/scheduler/utxo/standard/src/lib.rs

@@ -309,6 +309,8 @@ impl<S: ScannerFeed, P: TransactionPlanner<S, ()>> Scheduler<S, P> {
 }
 
 impl<S: ScannerFeed, P: TransactionPlanner<S, ()>> SchedulerTrait<S> for Scheduler<S, P> {
+  type SignableTransaction = P::SignableTransaction;
+
   fn activate_key(txn: &mut impl DbTxn, key: KeyFor<S>) {
     for coin in S::NETWORK.coins() {
       assert!(Db::<S>::outputs(txn, key, *coin).is_none());

processor/scheduler/utxo/transaction-chaining/src/lib.rs

@@ -368,6 +368,8 @@ impl<S: ScannerFeed, P: TransactionPlanner<S, EffectedReceivedOutputs<S>>> Sched
 impl<S: ScannerFeed, P: TransactionPlanner<S, EffectedReceivedOutputs<S>>> SchedulerTrait<S>
   for Scheduler<S, P>
 {
+  type SignableTransaction = P::SignableTransaction;
+
   fn activate_key(txn: &mut impl DbTxn, key: KeyFor<S>) {
     for coin in S::NETWORK.coins() {
       assert!(Db::<S>::outputs(txn, key, *coin).is_none());