feat: broadcast barrier

state-chain/cf-integration-tests/src/threshold_signing.rs

@@ -76,6 +76,7 @@ impl KeyUtils for EthKeyComponents {
 }
 
 pub struct ThresholdSigner<KeyComponents, SigVerification> {
+	previous_key_components: Option<KeyComponents>,
 	key_components: KeyComponents,
 	proposed_key_components: Option<KeyComponents>,
 	_phantom: PhantomData<SigVerification>,
@@ -90,8 +91,14 @@ where
 		if key == current_key {
 			return self.key_components.sign(message)
 		}
-		let next_key = self.proposed_key_components.as_ref().unwrap().agg_key();
-		if key == next_key {
+		if self.previous_key_components.is_some() &&
+			self.previous_key_components.as_ref().unwrap().agg_key() == key
+		{
+			return self.previous_key_components.as_ref().unwrap().sign(message)
+		}
+		if self.proposed_key_components.is_some() &&
+			self.proposed_key_components.as_ref().unwrap().agg_key() == key
+		{
 			self.proposed_key_components.as_ref().unwrap().sign(message)
 		} else {
 			panic!("Unknown key");
@@ -108,6 +115,7 @@ where
 	// Rotate to the current proposed key and clear the proposed key
 	pub fn use_proposed_key(&mut self) {
 		if self.proposed_key_components.is_some() {
+			self.previous_key_components = Some(self.key_components.clone());
 			self.key_components =
 				self.proposed_key_components.as_ref().expect("No key has been proposed").clone();
 			self.proposed_key_components = None;
@@ -120,6 +128,7 @@ pub type EthThresholdSigner = ThresholdSigner<EthKeyComponents, SchnorrVerificat
 impl Default for EthThresholdSigner {
 	fn default() -> Self {
 		ThresholdSigner {
+			previous_key_components: None,
 			key_components: EthKeyComponents::generate(GENESIS_KEY_SEED, GENESIS_EPOCH),
 			proposed_key_components: None,
 			_phantom: PhantomData,
@@ -134,6 +143,7 @@ pub type DotThresholdSigner = ThresholdSigner<DotKeyComponents, PolkadotSignatur
 impl Default for DotThresholdSigner {
 	fn default() -> Self {
 		Self {
+			previous_key_components: None,
 			key_components: DotKeyComponents::generate(GENESIS_KEY_SEED, GENESIS_EPOCH),
 			proposed_key_components: None,
 			_phantom: PhantomData,
@@ -171,6 +181,7 @@ pub type BtcThresholdSigner = ThresholdSigner<BtcKeyComponents, btc::Signature>;
 impl Default for BtcThresholdSigner {
 	fn default() -> Self {
 		Self {
+			previous_key_components: None,
 			key_components: BtcKeyComponents::generate(GENESIS_KEY_SEED, GENESIS_EPOCH),
 			proposed_key_components: None,
 			_phantom: PhantomData,

state-chain/chains/src/dot.rs

@@ -308,12 +308,6 @@ impl ChainCrypto for PolkadotCrypto {
 		EncodedPolkadotPayload(Blake2_256::hash(&agg_key.aliased_ref()[..]).to_vec())
 	}
 
-	/// Once authored, polkadot extrinsic must be signed by the key whose nonce was incorporated
-	/// into the extrinsic.
-	fn sign_with_specific_key() -> bool {
-		true
-	}
-
 	fn maybe_broadcast_barriers_on_rotation(
 		rotation_broadcast_id: BroadcastId,
 	) -> Vec<BroadcastId> {

state-chain/chains/src/lib.rs

@@ -179,14 +179,6 @@ pub trait ChainCrypto {
 		true
 	}
 
-	/// Determines whether threshold signatures are made with a specific fixed key, or whether the
-	/// key is refreshed if we need to retry the signature.
-	///
-	/// By default, this is true for Utxo-based chains, false otherwise.
-	fn sign_with_specific_key() -> bool {
-		Self::UtxoChain::get()
-	}
-
 	/// Determines whether the chain crypto supports key handover.
 	///
 	/// By default, this is true for Utxo-based chains, false otherwise.

state-chain/chains/src/mocks.rs

@@ -23,7 +23,6 @@ pub enum ChainChoice {
 
 thread_local! {
 	static MOCK_KEY_HANDOVER_IS_REQUIRED: RefCell<bool> = RefCell::new(true);
-	static MOCK_SIGN_WITH_SPECIFIC_KEY: RefCell<bool> = RefCell::new(false);
 	static MOCK_VALID_METADATA: RefCell<bool> = RefCell::new(true);
 	static MOCK_BROADCAST_BARRIERS: RefCell<ChainChoice> = RefCell::new(ChainChoice::Ethereum);
 }
@@ -56,20 +55,6 @@ impl Get<ChainChoice> for MockBroadcastBarriers {
 	}
 }
 
-pub struct MockFixedKeySigningRequests;
-
-impl MockFixedKeySigningRequests {
-	pub fn set(value: bool) {
-		MOCK_SIGN_WITH_SPECIFIC_KEY.with(|v| *v.borrow_mut() = value);
-	}
-}
-
-impl Get<bool> for MockFixedKeySigningRequests {
-	fn get() -> bool {
-		MOCK_SIGN_WITH_SPECIFIC_KEY.with(|v| *v.borrow())
-	}
-}
-
 #[derive(Debug, Clone, Default, PartialEq, Eq, Encode, Decode, TypeInfo)]
 pub struct MockEthereumTransactionMetadata;
 
@@ -267,10 +252,6 @@ impl ChainCrypto for MockEthereumChainCrypto {
 		new_key != &BAD_AGG_KEY_POST_HANDOVER
 	}
 
-	fn sign_with_specific_key() -> bool {
-		MockFixedKeySigningRequests::get()
-	}
-
 	fn key_handover_is_required() -> bool {
 		MockKeyHandoverIsRequired::get()
 	}

state-chain/pallets/cf-threshold-signature/src/lib.rs

@@ -422,11 +422,7 @@ pub mod pallet {
 								request_id,
 								attempt_count.wrapping_add(1),
 								payload,
-								if <T::TargetChainCrypto as ChainCrypto>::sign_with_specific_key() {
-									RequestType::SpecificKey(key, epoch)
-								} else {
-									RequestType::CurrentKey
-								},
+								RequestType::SpecificKey(key, epoch),
 							));
 							Event::<T, I>::RetryRequested { request_id, ceremony_id }
 						},
@@ -810,14 +806,11 @@ where
 	type ValidatorId = T::ValidatorId;
 
 	fn request_signature(payload: PayloadFor<T, I>) -> RequestId {
-		let request_type = if <T::TargetChainCrypto as ChainCrypto>::sign_with_specific_key() {
-			T::KeyProvider::active_epoch_key().defensive_map_or_else(
-				|| RequestType::CurrentKey,
-				|EpochKey { key, epoch_index, .. }| RequestType::SpecificKey(key, epoch_index),
-			)
-		} else {
-			RequestType::CurrentKey
-		};
+		let request_type = T::KeyProvider::active_epoch_key().defensive_map_or_else(
+			|| RequestType::SpecificKey(Default::default(), Default::default()),
+			|EpochKey { key, epoch_index, .. }| RequestType::SpecificKey(key, epoch_index),
+		);
+
 		Self::inner_request_signature(payload, request_type)
 	}
 

state-chain/pallets/cf-threshold-signature/src/tests.rs

@@ -4,7 +4,7 @@ use crate::{
 	self as pallet_cf_threshold_signature, mock::*, AttemptCount, CeremonyContext, CeremonyId,
 	Error, PalletOffence, RequestContext, RequestId, ThresholdSignatureResponseTimeout,
 };
-use cf_chains::mocks::{MockAggKey, MockEthereumChainCrypto, MockFixedKeySigningRequests};
+use cf_chains::mocks::{MockAggKey, MockEthereumChainCrypto};
 use cf_traits::{
 	mocks::{key_provider::MockKeyProvider, signer_nomination::MockNominator},
 	AsyncResult, Chainflip, EpochKey, KeyProvider, ThresholdSigner,
@@ -479,8 +479,6 @@ fn test_retries_for_immutable_key() {
 				..
 			} = EthereumThresholdSigner::pending_ceremonies(ceremony_id).unwrap();
 
-			MockFixedKeySigningRequests::set(true);
-
 			// Pretend the key has been updated to the next one.
 			MockKeyProvider::<MockEthereumChainCrypto>::add_key(MockAggKey(*b"NEXT"));