Adds an offchain call to submit double vote reports (#966)

* Adds an offchain call to submit double vote reports

* Some tweaks

* Remove unnecessary IdentifyAccount impls

* Adds ValidateDoubleVoteReports to test runtime

* sp-application-crypto is only a dev dependency

polkadot/Cargo.lock

@@ -4355,6 +4355,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "sp-api",
+ "sp-application-crypto",
  "sp-core",
  "sp-inherents",
  "sp-io",

polkadot/primitives/src/parachain.rs

@@ -88,6 +88,17 @@ application_crypto::with_pair! {
 /// so we define it to be the same type as `SessionKey`. In the future it may have different crypto.
 pub type ValidatorSignature = validator_app::Signature;
 
+/// The key type ID for a fisherman key.
+pub const FISHERMAN_KEY_TYPE_ID: KeyTypeId = KeyTypeId(*b"fish");
+
+mod fisherman_app {
+	use application_crypto::{app_crypto, sr25519};
+	app_crypto!(sr25519, super::FISHERMAN_KEY_TYPE_ID);
+}
+
+/// Identity that fishermen use when generating reports.
+pub type FishermanId = fisherman_app::Public;
+
 /// Retriability for a given active para.
 #[derive(Clone, Eq, PartialEq, Encode, Decode)]
 #[cfg_attr(feature = "std", derive(Debug))]

polkadot/runtime/common/Cargo.toml

@@ -39,6 +39,7 @@ hex-literal = "0.2.1"
 keyring = { package = "sp-keyring", git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-trie = { git = "https://github.com/paritytech/substrate", branch = "master" }
 babe = { package = "pallet-babe", git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-application-crypto = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 randomness-collective-flip = { package = "pallet-randomness-collective-flip", git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 pallet-staking-reward-curve = { git = "https://github.com/paritytech/substrate", branch = "master" }
 treasury = { package = "pallet-treasury", git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }

polkadot/runtime/common/src/parachains.rs

@@ -57,7 +57,10 @@ use sp_runtime::transaction_validity::InvalidTransaction;
 
 use inherents::{ProvideInherent, InherentData, MakeFatalError, InherentIdentifier};
 
-use system::{ensure_none, ensure_signed};
+use system::{
+	ensure_none, ensure_signed,
+	offchain::SubmitSignedTransaction,
+};
 use crate::attestations::{self, IncludedBlocks};
 use crate::registrar::Registrar;
 
@@ -222,7 +225,7 @@ pub trait Trait: attestations::Trait + session::historical::Trait {
 	type Origin: From<Origin> + From<system::RawOrigin<Self::AccountId>>;
 
 	/// The outer call dispatch type.
-	type Call: Parameter + Dispatchable<Origin=<Self as Trait>::Origin>;
+	type Call: Parameter + Dispatchable<Origin=<Self as Trait>::Origin> + From<Call<Self>>;
 
 	/// Some way of interacting with balances for fees.
 	type ParachainCurrency: ParachainCurrency<Self::AccountId>;
@@ -290,6 +293,9 @@ pub trait Trait: attestations::Trait + session::historical::Trait {
 
 	/// A type that converts the opaque hash type to exact one.
 	type BlockHashConversion: Convert<Self::Hash, primitives::Hash>;
+
+	/// Submit a signed transaction.
+	type SubmitSignedTransaction: SubmitSignedTransaction<Self, <Self as Trait>::Call>;
 }
 
 /// Origin for the parachains module.
@@ -784,6 +790,21 @@ impl<T: Trait> Module<T> {
 		}
 	}
 
+	/// Submit a double vote report.
+	pub fn submit_double_vote_report(
+		report: DoubleVoteReport<T::Proof>,
+	) -> Option<()> {
+		let call = Call::report_double_vote(report);
+
+		let res = T::SubmitSignedTransaction::submit_signed(call);
+
+		if res.iter().any(|(_, r)| r.is_ok()) {
+			Some(())
+		} else {
+			None
+		}
+	}
+
 	/// Dispatch some messages from a parachain.
 	fn dispatch_message(
 		id: ParaId,
@@ -1426,6 +1447,13 @@ impl<T> sp_std::fmt::Debug for ValidateDoubleVoteReports<T> where
 	}
 }
 
+impl<T> ValidateDoubleVoteReports<T> {
+	/// Create a new `ValidateDoubleVoteReports` struct.
+	pub fn new() -> Self {
+		ValidateDoubleVoteReports(sp_std::marker::PhantomData)
+	}
+}
+
 /// Custom validity error used while validating double vote reports.
 #[derive(RuntimeDebug)]
 #[repr(u8)]
@@ -1522,7 +1550,7 @@ mod tests {
 		Perbill, curve::PiecewiseLinear,
 		traits::{
 			BlakeTwo256, IdentityLookup, SaturatedConversion,
-			OpaqueKeys,
+			OpaqueKeys, Extrinsic as ExtrinsicT,
 		},
 		testing::TestXt,
 	};
@@ -1787,6 +1815,31 @@ mod tests {
 		pub const SlashPeriod: BlockNumber = 50;
 	}
 
+	// This is needed for a custom `AccountId` type which is `u64` in testing here.
+	pub mod test_keys {
+		use sp_core::crypto::KeyTypeId;
+
+		pub const KEY_TYPE: KeyTypeId = KeyTypeId(*b"test");
+
+		mod app {
+			use sp_application_crypto::{app_crypto, sr25519};
+			use super::super::Parachains;
+
+			app_crypto!(sr25519, super::KEY_TYPE);
+
+			impl sp_runtime::traits::IdentifyAccount for Public {
+				type AccountId = u64;
+
+				fn into_account(self) -> Self::AccountId {
+					Parachains::authorities().iter().position(|b| *b == self.0.clone().into()).unwrap() as u64
+				}
+			}
+		}
+
+		pub type ReporterId = app::Public;
+		pub type ReporterSignature = app::Signature;
+	}
+
 	impl Trait for Test {
 		type Origin = Origin;
 		type Call = Call;
@@ -1807,6 +1860,27 @@ mod tests {
 		type ReportOffence = Offences;
 		type BlockHashConversion = sp_runtime::traits::Identity;
 		type KeyOwnerProofSystem = Historical;
+		type SubmitSignedTransaction = system::offchain::TransactionSubmitter<
+			test_keys::ReporterId,
+			Test,
+			Extrinsic,
+		>;
+	}
+
+	type Extrinsic = TestXt<Call, ()>;
+
+	impl system::offchain::CreateTransaction<Test, Extrinsic> for Test {
+		type Public = test_keys::ReporterId;
+		type Signature = test_keys::ReporterSignature;
+
+		fn create_transaction<F: system::offchain::Signer<Self::Public, Self::Signature>>(
+			call: <Extrinsic as ExtrinsicT>::Call,
+			_public: Self::Public,
+			_account: <Test as system::Trait>::AccountId,
+			nonce: <Test as system::Trait>::Index,
+		) -> Option<(<Extrinsic as ExtrinsicT>::Call, <Extrinsic as ExtrinsicT>::SignaturePayload)> {
+			Some((call, (nonce, ())))
+		}
 	}
 
 	type Parachains = Module<Test>;

polkadot/runtime/common/src/registrar.rs

@@ -563,6 +563,15 @@ impl<T: Trait> ActiveParas for Module<T> {
 pub struct LimitParathreadCommits<T: Trait + Send + Sync>(sp_std::marker::PhantomData<T>) where
 	<T as system::Trait>::Call: IsSubType<Module<T>, T>;
 
+impl<T: Trait + Send + Sync> LimitParathreadCommits<T> where
+	<T as system::Trait>::Call: IsSubType<Module<T>, T>
+{
+	/// Create a new `LimitParathreadCommits` struct.
+	pub fn new() -> Self {
+		LimitParathreadCommits(sp_std::marker::PhantomData)
+	}
+}
+
 impl<T: Trait + Send + Sync> sp_std::fmt::Debug for LimitParathreadCommits<T> where
 	<T as system::Trait>::Call: IsSubType<Module<T>, T>
 {
@@ -658,7 +667,7 @@ mod tests {
 	use sp_runtime::{
 		traits::{
 			BlakeTwo256, IdentityLookup, Dispatchable,
-			AccountIdConversion,
+			AccountIdConversion, Extrinsic as ExtrinsicT,
 		}, testing::{UintAuthorityId, TestXt}, KeyTypeId, Perbill, curve::PiecewiseLinear,
 	};
 	use primitives::{
@@ -840,6 +849,32 @@ mod tests {
 		type FullIdentificationOf = staking::ExposureOf<Self>;
 	}
 
+	// This is needed for a custom `AccountId` type which is `u64` in testing here.
+	pub mod test_keys {
+		use sp_core::crypto::KeyTypeId;
+
+		pub const KEY_TYPE: KeyTypeId = KeyTypeId(*b"test");
+
+		mod app {
+			use super::super::Parachains;
+			use sp_application_crypto::{app_crypto, sr25519};
+
+			app_crypto!(sr25519, super::KEY_TYPE);
+
+			impl sp_runtime::traits::IdentifyAccount for Public {
+				type AccountId = u64;
+
+				fn into_account(self) -> Self::AccountId {
+					let id = self.0.clone().into();
+					Parachains::authorities().iter().position(|b| *b == id).unwrap() as u64
+				}
+			}
+		}
+
+		pub type ReporterId = app::Public;
+		pub type ReporterSignature = app::Signature;
+	}
+
 	impl parachains::Trait for Test {
 		type Origin = Origin;
 		type Call = Call;
@@ -858,6 +893,27 @@ mod tests {
 		type IdentificationTuple = <Self::KeyOwnerProofSystem as KeyOwnerProofSystem<(KeyTypeId, Vec<u8>)>>::IdentificationTuple;
 		type ReportOffence = ();
 		type BlockHashConversion = sp_runtime::traits::Identity;
+		type SubmitSignedTransaction = system::offchain::TransactionSubmitter<
+			test_keys::ReporterId,
+			Test,
+			Extrinsic,
+		>;
+	}
+
+	type Extrinsic = TestXt<Call, ()>;
+
+	impl system::offchain::CreateTransaction<Test, Extrinsic> for Test {
+		type Public = test_keys::ReporterId;
+		type Signature = test_keys::ReporterSignature;
+
+		fn create_transaction<F: system::offchain::Signer<Self::Public, Self::Signature>>(
+			call: <Extrinsic as ExtrinsicT>::Call,
+			_public: Self::Public,
+			_account: <Test as system::Trait>::AccountId,
+			nonce: <Test as system::Trait>::Index,
+		) -> Option<(<Extrinsic as ExtrinsicT>::Call, <Extrinsic as ExtrinsicT>::SignaturePayload)> {
+			Some((call, (nonce, ())))
+		}
 	}
 
 	parameter_types! {

polkadot/runtime/kusama/src/lib.rs

@@ -41,7 +41,7 @@ use sp_runtime::{
 	curve::PiecewiseLinear,
 	traits::{
 		BlakeTwo256, Block as BlockT, SignedExtension, OpaqueKeys, ConvertInto, IdentityLookup,
-		DispatchInfoOf,
+		DispatchInfoOf, Extrinsic as ExtrinsicT, SaturatedConversion,
 	},
 };
 #[cfg(feature = "runtime-benchmarks")]
@@ -53,7 +53,8 @@ use version::NativeVersion;
 use sp_core::OpaqueMetadata;
 use sp_staking::SessionIndex;
 use frame_support::{
-	parameter_types, construct_runtime, traits::{KeyOwnerProofSystem, SplitTwoWays, Randomness},
+	parameter_types, construct_runtime, debug,
+	traits::{KeyOwnerProofSystem, SplitTwoWays, Randomness},
 };
 use im_online::sr25519::AuthorityId as ImOnlineId;
 use authority_discovery_primitives::AuthorityId as AuthorityDiscoveryId;
@@ -539,6 +540,46 @@ impl parachains::Trait for Runtime {
 	type IdentificationTuple = <Self::KeyOwnerProofSystem as KeyOwnerProofSystem<(KeyTypeId, Vec<u8>)>>::IdentificationTuple;
 	type ReportOffence = Offences;
 	type BlockHashConversion = sp_runtime::traits::Identity;
+	type SubmitSignedTransaction = TransactionSubmitter<parachain::FishermanId, Runtime, UncheckedExtrinsic>;
+}
+
+impl system::offchain::CreateTransaction<Runtime, UncheckedExtrinsic> for Runtime {
+	type Public = <primitives::Signature as sp_runtime::traits::Verify>::Signer;
+	type Signature = primitives::Signature;
+
+	fn create_transaction<TSigner: system::offchain::Signer<Self::Public, Self::Signature>>(
+		call: <UncheckedExtrinsic as ExtrinsicT>::Call,
+		public: Self::Public,
+		account: <Runtime as system::Trait>::AccountId,
+		nonce: <Runtime as system::Trait>::Index,
+	) -> Option<(Call, <UncheckedExtrinsic as ExtrinsicT>::SignaturePayload)> {
+		let period = BlockHashCount::get()
+			.checked_next_power_of_two()
+			.map(|c| c / 2)
+			.unwrap_or(2) as u64;
+
+		let current_block = System::block_number()
+			.saturated_into::<u64>()
+			.saturating_sub(1);
+		let tip = 0;
+		let extra: SignedExtra = (
+			RestrictFunctionality,
+			system::CheckVersion::<Runtime>::new(),
+			system::CheckGenesis::<Runtime>::new(),
+			system::CheckEra::<Runtime>::from(generic::Era::mortal(period, current_block)),
+			system::CheckNonce::<Runtime>::from(nonce),
+			system::CheckWeight::<Runtime>::new(),
+			transaction_payment::ChargeTransactionPayment::<Runtime>::from(tip),
+			registrar::LimitParathreadCommits::<Runtime>::new(),
+			parachains::ValidateDoubleVoteReports::<Runtime>::new(),
+		);
+		let raw_payload = SignedPayload::new(call, extra).map_err(|e| {
+			debug::warn!("Unable to create signed payload: {:?}", e)
+		}).ok()?;
+		let signature = TSigner::sign(public, &raw_payload)?;
+		let (call, extra, _) = raw_payload.deconstruct();
+		Some((call, (account, signature, extra)))
+	}
 }
 
 parameter_types! {
@@ -769,6 +810,8 @@ pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signatu
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Nonce, Call>;
 /// Executive: handles dispatch to the various modules.
 pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Runtime, AllModules>;
+/// The payload being signed in the transactions.
+pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 
 sp_api::impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {

polkadot/runtime/polkadot/src/lib.rs

@@ -42,7 +42,7 @@ use sp_runtime::{
 	curve::PiecewiseLinear,
 	traits::{
 		BlakeTwo256, Block as BlockT, SignedExtension, OpaqueKeys, ConvertInto,
-		IdentityLookup, DispatchInfoOf,
+		DispatchInfoOf, IdentityLookup, Extrinsic as ExtrinsicT, SaturatedConversion,
 	},
 };
 #[cfg(feature = "runtime-benchmarks")]
@@ -54,7 +54,8 @@ use version::NativeVersion;
 use sp_core::OpaqueMetadata;
 use sp_staking::SessionIndex;
 use frame_support::{
-	parameter_types, construct_runtime, traits::{KeyOwnerProofSystem, SplitTwoWays, Randomness},
+	parameter_types, construct_runtime, debug,
+	traits::{KeyOwnerProofSystem, SplitTwoWays, Randomness},
 };
 use im_online::sr25519::AuthorityId as ImOnlineId;
 use authority_discovery_primitives::AuthorityId as AuthorityDiscoveryId;
@@ -545,6 +546,46 @@ impl parachains::Trait for Runtime {
 	type IdentificationTuple = <Self::KeyOwnerProofSystem as KeyOwnerProofSystem<(KeyTypeId, Vec<u8>)>>::IdentificationTuple;
 	type ReportOffence = Offences;
 	type BlockHashConversion = sp_runtime::traits::Identity;
+	type SubmitSignedTransaction = TransactionSubmitter<parachain::FishermanId, Runtime, UncheckedExtrinsic>;
+}
+
+impl system::offchain::CreateTransaction<Runtime, UncheckedExtrinsic> for Runtime {
+	type Public = <primitives::Signature as sp_runtime::traits::Verify>::Signer;
+	type Signature = primitives::Signature;
+
+	fn create_transaction<TSigner: system::offchain::Signer<Self::Public, Self::Signature>>(
+		call: <UncheckedExtrinsic as ExtrinsicT>::Call,
+		public: Self::Public,
+		account: <Runtime as system::Trait>::AccountId,
+		nonce: <Runtime as system::Trait>::Index,
+	) -> Option<(Call, <UncheckedExtrinsic as ExtrinsicT>::SignaturePayload)> {
+		let period = BlockHashCount::get()
+			.checked_next_power_of_two()
+			.map(|c| c / 2)
+			.unwrap_or(2) as u64;
+
+		let current_block = System::block_number()
+			.saturated_into::<u64>()
+			.saturating_sub(1);
+		let tip = 0;
+		let extra: SignedExtra = (
+			OnlyStakingAndClaims,
+			system::CheckVersion::<Runtime>::new(),
+			system::CheckGenesis::<Runtime>::new(),
+			system::CheckEra::<Runtime>::from(generic::Era::mortal(period, current_block)),
+			system::CheckNonce::<Runtime>::from(nonce),
+			system::CheckWeight::<Runtime>::new(),
+			transaction_payment::ChargeTransactionPayment::<Runtime>::from(tip),
+			registrar::LimitParathreadCommits::<Runtime>::new(),
+			parachains::ValidateDoubleVoteReports::<Runtime>::new(),
+		);
+		let raw_payload = SignedPayload::new(call, extra).map_err(|e| {
+			debug::warn!("Unable to create signed payload: {:?}", e)
+		}).ok()?;
+		let signature = TSigner::sign(public, &raw_payload)?;
+		let (call, extra, _) = raw_payload.deconstruct();
+		Some((call, (account, signature, extra)))
+	}
 }
 
 parameter_types! {
@@ -687,6 +728,8 @@ pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signatu
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Nonce, Call>;
 /// Executive: handles dispatch to the various modules.
 pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Runtime, AllModules>;
+/// The payload being signed in transactions.
+pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 
 sp_api::impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {

polkadot/runtime/test-runtime/src/lib.rs

@@ -41,7 +41,7 @@ use sp_runtime::{
 	curve::PiecewiseLinear,
 	traits::{
 		BlakeTwo256, Block as BlockT, StaticLookup, SignedExtension, OpaqueKeys, ConvertInto,
-		DispatchInfoOf,
+		DispatchInfoOf, Extrinsic as ExtrinsicT, SaturatedConversion,
 	},
 };
 use version::RuntimeVersion;
@@ -51,11 +51,12 @@ use version::NativeVersion;
 use sp_core::OpaqueMetadata;
 use sp_staking::SessionIndex;
 use frame_support::{
-	parameter_types, construct_runtime,
+	parameter_types, construct_runtime, debug,
 	traits::{KeyOwnerProofSystem, Randomness},
 };
 use pallet_transaction_payment_rpc_runtime_api::RuntimeDispatchInfo;
 use session::historical as session_historical;
+use system::offchain::TransactionSubmitter;
 
 #[cfg(feature = "std")]
 pub use staking::StakerStatus;
@@ -348,6 +349,47 @@ impl parachains::Trait for Runtime {
 		>::IdentificationTuple;
 	type ReportOffence = Offences;
 	type BlockHashConversion = sp_runtime::traits::Identity;
+	type SubmitSignedTransaction = TransactionSubmitter<parachain::FishermanId, Runtime, UncheckedExtrinsic>;
+}
+
+impl system::offchain::CreateTransaction<Runtime, UncheckedExtrinsic> for Runtime {
+	type Public = <primitives::Signature as sp_runtime::traits::Verify>::Signer;
+	type Signature = primitives::Signature;
+
+	fn create_transaction<TSigner: system::offchain::Signer<Self::Public, Self::Signature>>(
+		call: <UncheckedExtrinsic as ExtrinsicT>::Call,
+		public: Self::Public,
+		account: <Runtime as system::Trait>::AccountId,
+		nonce: <Runtime as system::Trait>::Index,
+	) -> Option<(Call, <UncheckedExtrinsic as ExtrinsicT>::SignaturePayload)> {
+		let period = BlockHashCount::get()
+			.checked_next_power_of_two()
+			.map(|c| c / 2)
+			.unwrap_or(2) as u64;
+
+		let current_block = System::block_number()
+			.saturated_into::<u64>()
+			.saturating_sub(1);
+		let tip = 0;
+		let extra: SignedExtra = (
+			RestrictFunctionality,
+			system::CheckVersion::<Runtime>::new(),
+			system::CheckGenesis::<Runtime>::new(),
+			system::CheckEra::<Runtime>::from(generic::Era::mortal(period, current_block)),
+			system::CheckNonce::<Runtime>::from(nonce),
+			system::CheckWeight::<Runtime>::new(),
+			transaction_payment::ChargeTransactionPayment::<Runtime>::from(tip),
+			registrar::LimitParathreadCommits::<Runtime>::new(),
+			parachains::ValidateDoubleVoteReports::<Runtime>::new(),
+		);
+		let raw_payload = SignedPayload::new(call, extra).map_err(|e| {
+			debug::warn!("Unable to create signed payload: {:?}", e)
+		}).ok()?;
+		let signature = TSigner::sign(public, &raw_payload)?;
+		let (call, extra, _) = raw_payload.deconstruct();
+		let address = Indices::unlookup(account);
+		Some((call, (address, signature, extra)))
+	}
 }
 
 impl offences::Trait for Runtime {
@@ -467,7 +509,8 @@ pub type SignedExtra = (
 	system::CheckNonce<Runtime>,
 	system::CheckWeight<Runtime>,
 	transaction_payment::ChargeTransactionPayment::<Runtime>,
-	registrar::LimitParathreadCommits<Runtime>
+	registrar::LimitParathreadCommits<Runtime>,
+	parachains::ValidateDoubleVoteReports<Runtime>,
 );
 /// Unchecked extrinsic type as expected by this runtime.
 pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signature, SignedExtra>;
@@ -475,6 +518,8 @@ pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signatu
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Nonce, Call>;
 /// Executive: handles dispatch to the various modules.
 pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Runtime, AllModules>;
+/// The payload being signed in transactions.
+pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 
 pub type Hash = <Block as BlockT>::Hash;
 pub type Extrinsic = <Block as BlockT>::Extrinsic;

polkadot/runtime/westend/src/lib.rs

@@ -40,7 +40,7 @@ use sp_runtime::{
 	curve::PiecewiseLinear,
 	traits::{
 		BlakeTwo256, Block as BlockT, SignedExtension, OpaqueKeys, ConvertInto, IdentityLookup,
-		DispatchInfoOf,
+		DispatchInfoOf, StaticLookup, Extrinsic as ExtrinsicT, SaturatedConversion,
 	},
 };
 #[cfg(feature = "runtime-benchmarks")]
@@ -51,7 +51,10 @@ use grandpa::{AuthorityId as GrandpaId, fg_primitives};
 use version::NativeVersion;
 use sp_core::OpaqueMetadata;
 use sp_staking::SessionIndex;
-use frame_support::{parameter_types, construct_runtime, traits::{KeyOwnerProofSystem, Randomness}};
+use frame_support::{
+	parameter_types, construct_runtime, debug,
+	traits::{KeyOwnerProofSystem, Randomness},
+};
 use im_online::sr25519::AuthorityId as ImOnlineId;
 use authority_discovery_primitives::AuthorityId as AuthorityDiscoveryId;
 use system::offchain::TransactionSubmitter;
@@ -407,6 +410,46 @@ impl parachains::Trait for Runtime {
 	type IdentificationTuple = <Self::KeyOwnerProofSystem as KeyOwnerProofSystem<(KeyTypeId, Vec<u8>)>>::IdentificationTuple;
 	type ReportOffence = Offences;
 	type BlockHashConversion = sp_runtime::traits::Identity;
+	type SubmitSignedTransaction = TransactionSubmitter<parachain::FishermanId, Runtime, UncheckedExtrinsic>;
+}
+
+impl system::offchain::CreateTransaction<Runtime, UncheckedExtrinsic> for Runtime {
+	type Public = <primitives::Signature as sp_runtime::traits::Verify>::Signer;
+	type Signature = primitives::Signature;
+
+	fn create_transaction<TSigner: system::offchain::Signer<Self::Public, Self::Signature>>(
+		call: <UncheckedExtrinsic as ExtrinsicT>::Call,
+		public: Self::Public,
+		account: <Runtime as system::Trait>::AccountId,
+		nonce: <Runtime as system::Trait>::Index,
+	) -> Option<(Call, <UncheckedExtrinsic as ExtrinsicT>::SignaturePayload)> {
+		let period = BlockHashCount::get()
+			.checked_next_power_of_two()
+			.map(|c| c / 2)
+			.unwrap_or(2) as u64;
+
+		let current_block = System::block_number()
+			.saturated_into::<u64>()
+			.saturating_sub(1);
+		let tip = 0;
+		let extra: SignedExtra = (
+			RestrictFunctionality,
+			system::CheckVersion::<Runtime>::new(),
+			system::CheckGenesis::<Runtime>::new(),
+			system::CheckEra::<Runtime>::from(generic::Era::mortal(period, current_block)),
+			system::CheckNonce::<Runtime>::from(nonce),
+			system::CheckWeight::<Runtime>::new(),
+			transaction_payment::ChargeTransactionPayment::<Runtime>::from(tip),
+			registrar::LimitParathreadCommits::<Runtime>::new(),
+			parachains::ValidateDoubleVoteReports::<Runtime>::new(),
+		);
+		let raw_payload = SignedPayload::new(call, extra).map_err(|e| {
+			debug::warn!("Unable to create signed payload: {:?}", e)
+		}).ok()?;
+		let signature = TSigner::sign(public, &raw_payload)?;
+		let (call, extra, _) = raw_payload.deconstruct();
+		Some((call, (account, signature, extra)))
+	}
 }
 
 parameter_types! {
@@ -580,6 +623,8 @@ pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signatu
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Nonce, Call>;
 /// Executive: handles dispatch to the various modules.
 pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Runtime, AllModules>;
+/// The payload being signed in transactions.
+pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 
 sp_api::impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {