Add Transaction::sign.

While I don't love the introduction of empty_signed, it's practically fine.

coordinator/src/tests/tributary/dkg.rs

@@ -1,11 +1,9 @@
 use core::time::Duration;
 
 use zeroize::Zeroizing;
-
 use rand_core::{RngCore, OsRng};
 
-use ciphersuite::{group::ff::Field, Ciphersuite, Ristretto};
-use schnorr::SchnorrSignature;
+use ciphersuite::{Ciphersuite, Ristretto};
 use frost::Participant;
 
 use tokio::time::sleep;
@@ -17,7 +15,7 @@ use processor_messages::{
   CoordinatorMessage,
 };
 
-use tributary::{Signed, Transaction as TransactionTrait, Tributary};
+use tributary::Tributary;
 
 use crate::{
   processor::MemProcessor,
@@ -39,41 +37,14 @@ async fn dkg_commitments_test() {
   let mut txs = vec![];
   // Create DKG commitments for each key
   for key in &keys {
-    let pub_key = Ristretto::generator() * **key;
-
     let attempt = 0;
     let mut commitments = vec![0; 256];
     OsRng.fill_bytes(&mut commitments);
 
-    // Create the TX with a null signature so we can get its sig hash
-    let tx = Transaction::DkgCommitments(
-      attempt,
-      commitments.clone(),
-      Signed {
-        signer: pub_key,
-        nonce: 0,
-        signature: SchnorrSignature::<Ristretto> {
-          R: Ristretto::generator(),
-          s: <Ristretto as Ciphersuite>::F::ZERO,
-        },
-      },
-    );
-
-    // Re-create it with the actual signature
-    // We could mutate the existing one, we'd just have to match to the DkgCommitments enum variant
-    txs.push(Transaction::DkgCommitments(
-      attempt,
-      commitments,
-      Signed {
-        signer: pub_key,
-        nonce: 0,
-        signature: SchnorrSignature::<Ristretto>::sign(
-          key,
-          Zeroizing::new(<Ristretto as Ciphersuite>::F::random(&mut OsRng)),
-          tx.sig_hash(spec.genesis()),
-        ),
-      },
-    ));
+    let mut tx =
+      Transaction::DkgCommitments(attempt, commitments.clone(), Transaction::empty_signed());
+    tx.sign(&mut OsRng, spec.genesis(), key, 0);
+    txs.push(tx);
   }
 
   let mut last_block = tributaries[0].1.tip();