Add BEEFY finality pallet with basic functionality (#1606)

* pallet-bridge-beefy: initial commit

bridges/bin/rialto/runtime/Cargo.toml

@@ -19,6 +19,7 @@ bp-relayers = { path = "../../../primitives/relayers", default-features = false
 bp-rialto = { path = "../../../primitives/chain-rialto", default-features = false }
 bp-runtime = { path = "../../../primitives/runtime", default-features = false }
 bridge-runtime-common = { path = "../../runtime-common", default-features = false }
+pallet-bridge-beefy = { path = "../../../modules/beefy", default-features = false }
 pallet-bridge-grandpa = { path = "../../../modules/grandpa", default-features = false }
 pallet-bridge-messages = { path = "../../../modules/messages", default-features = false }
 pallet-bridge-relayers = { path = "../../../modules/relayers", default-features = false }
@@ -98,6 +99,7 @@ std = [
 	"pallet-balances/std",
 	"pallet-beefy/std",
 	"pallet-beefy-mmr/std",
+	"pallet-bridge-beefy/std",
 	"pallet-bridge-grandpa/std",
 	"pallet-bridge-messages/std",
 	"pallet-bridge-relayers/std",

bridges/bin/rialto/runtime/src/lib.rs

@@ -68,6 +68,7 @@ pub use frame_support::{
 
 pub use frame_system::Call as SystemCall;
 pub use pallet_balances::Call as BalancesCall;
+pub use pallet_bridge_beefy::Call as BridgeBeefyCall;
 pub use pallet_bridge_grandpa::Call as BridgeGrandpaCall;
 pub use pallet_bridge_messages::Call as MessagesCall;
 pub use pallet_sudo::Call as SudoCall;
@@ -474,6 +475,13 @@ impl pallet_bridge_messages::Config<WithMillauMessagesInstance> for Runtime {
 	type BridgedChainId = BridgedChainId;
 }
 
+pub type MillauBeefyInstance = ();
+impl pallet_bridge_beefy::Config<MillauBeefyInstance> for Runtime {
+	type MaxRequests = frame_support::traits::ConstU32<16>;
+	type CommitmentsToKeep = frame_support::traits::ConstU32<8>;
+	type BridgedChain = bp_millau::Millau;
+}
+
 construct_runtime!(
 	pub enum Runtime where
 		Block = Block,
@@ -506,6 +514,9 @@ construct_runtime!(
 		BridgeMillauGrandpa: pallet_bridge_grandpa::{Pallet, Call, Storage},
 		BridgeMillauMessages: pallet_bridge_messages::{Pallet, Call, Storage, Event<T>, Config<T>},
 
+		// Millau bridge modules (BEEFY based).
+		BridgeMillauBeefy: pallet_bridge_beefy::{Pallet, Call, Storage},
+
 		// Parachain modules.
 		ParachainsOrigin: polkadot_runtime_parachains::origin::{Pallet, Origin},
 		Configuration: polkadot_runtime_parachains::configuration::{Pallet, Call, Storage, Config<T>},

bridges/modules/beefy/Cargo.toml

@@ -0,0 +1,54 @@
+[package]
+name = "pallet-bridge-beefy"
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false }
+log = { version = "0.4.14", default-features = false }
+scale-info = { version = "2.0.1", default-features = false, features = ["derive"] }
+serde = { version = "1.0", optional = true }
+
+# Bridge Dependencies
+
+bp-beefy = { path = "../../primitives/beefy", default-features = false }
+bp-runtime = { path = "../../primitives/runtime", default-features = false }
+
+# Substrate Dependencies
+
+beefy-merkle-tree = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+frame-support = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+frame-system = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+primitive-types = { version = "0.12.0", default-features = false, features = ["impl-codec"] }
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-std = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+
+[dev-dependencies]
+beefy-primitives = { git = "https://github.com/paritytech/substrate", branch = "master" }
+mmr-lib = { package = "ckb-merkle-mountain-range", version = "0.3.2" }
+pallet-beefy-mmr = { git = "https://github.com/paritytech/substrate", branch = "master" }
+pallet-mmr = { git = "https://github.com/paritytech/substrate", branch = "master" }
+rand = "0.8"
+sp-io = { git = "https://github.com/paritytech/substrate", branch = "master" }
+bp-test-utils = { path = "../../primitives/test-utils" }
+
+[features]
+default = ["std"]
+std = [
+	"beefy-merkle-tree/std",
+	"bp-beefy/std",
+	"bp-runtime/std",
+	"codec/std",
+	"frame-support/std",
+	"frame-system/std",
+	"log/std",
+	"primitive-types/std",
+	"scale-info/std",
+	"serde",
+	"sp-core/std",
+	"sp-runtime/std",
+	"sp-std/std",
+]

bridges/modules/beefy/src/lib.rs

@@ -0,0 +1,644 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! BEEFY bridge pallet.
+//!
+//! This pallet is an on-chain BEEFY light client for Substrate-based chains that are using the
+//! following pallets bundle: `pallet-mmr`, `pallet-beefy` and `pallet-beefy-mmr`.
+//!
+//! The pallet is able to verify MMR leaf proofs and BEEFY commitments, so it has access
+//! to the following data of the bridged chain:
+//!
+//! - header hashes
+//! - changes of BEEFY authorities
+//! - extra data of MMR leafs
+//!
+//! Given the header hash, other pallets are able to verify header-based proofs
+//! (e.g. storage proofs, transaction inclusion proofs, etc.).
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use bp_beefy::{ChainWithBeefy, InitializationData};
+use sp_std::{boxed::Box, prelude::*};
+
+// Re-export in crate namespace for `construct_runtime!`
+pub use pallet::*;
+
+mod utils;
+
+#[cfg(test)]
+mod mock;
+#[cfg(test)]
+mod mock_chain;
+
+/// The target that will be used when publishing logs related to this pallet.
+pub const LOG_TARGET: &str = "runtime::bridge-beefy";
+
+/// Configured bridged chain.
+pub type BridgedChain<T, I> = <T as Config<I>>::BridgedChain;
+/// Block number, used by configured bridged chain.
+pub type BridgedBlockNumber<T, I> = bp_runtime::BlockNumberOf<BridgedChain<T, I>>;
+/// Block hash, used by configured bridged chain.
+pub type BridgedBlockHash<T, I> = bp_runtime::HashOf<BridgedChain<T, I>>;
+
+/// Pallet initialization data.
+pub type InitializationDataOf<T, I> =
+	InitializationData<BridgedBlockNumber<T, I>, bp_beefy::MmrHashOf<BridgedChain<T, I>>>;
+/// BEEFY commitment hasher, used by configured bridged chain.
+pub type BridgedBeefyCommitmentHasher<T, I> = bp_beefy::BeefyCommitmentHasher<BridgedChain<T, I>>;
+/// BEEFY validator id, used by configured bridged chain.
+pub type BridgedBeefyAuthorityId<T, I> = bp_beefy::BeefyAuthorityIdOf<BridgedChain<T, I>>;
+/// BEEFY validator set, used by configured bridged chain.
+pub type BridgedBeefyAuthoritySet<T, I> = bp_beefy::BeefyAuthoritySetOf<BridgedChain<T, I>>;
+/// BEEFY authority set, used by configured bridged chain.
+pub type BridgedBeefyAuthoritySetInfo<T, I> = bp_beefy::BeefyAuthoritySetInfoOf<BridgedChain<T, I>>;
+/// BEEFY signed commitment, used by configured bridged chain.
+pub type BridgedBeefySignedCommitment<T, I> = bp_beefy::BeefySignedCommitmentOf<BridgedChain<T, I>>;
+/// MMR hashing algorithm, used by configured bridged chain.
+pub type BridgedMmrHashing<T, I> = bp_beefy::MmrHashingOf<BridgedChain<T, I>>;
+/// MMR hashing output type of `BridgedMmrHashing<T, I>`.
+pub type BridgedMmrHash<T, I> = bp_beefy::MmrHashOf<BridgedChain<T, I>>;
+/// The type of the MMR leaf extra data used by the configured bridged chain.
+pub type BridgedBeefyMmrLeafExtra<T, I> = bp_beefy::BeefyMmrLeafExtraOf<BridgedChain<T, I>>;
+/// BEEFY MMR proof type used by the pallet
+pub type BridgedMmrProof<T, I> = bp_beefy::MmrProofOf<BridgedChain<T, I>>;
+/// MMR leaf type, used by configured bridged chain.
+pub type BridgedBeefyMmrLeaf<T, I> = bp_beefy::BeefyMmrLeafOf<BridgedChain<T, I>>;
+/// Imported commitment data, stored by the pallet.
+pub type ImportedCommitment<T, I> = bp_beefy::ImportedCommitment<
+	BridgedBlockNumber<T, I>,
+	BridgedBlockHash<T, I>,
+	BridgedMmrHash<T, I>,
+>;
+
+/// Some high level info about the imported commitments.
+#[derive(codec::Encode, codec::Decode, scale_info::TypeInfo)]
+pub struct ImportedCommitmentsInfoData<BlockNumber> {
+	/// Best known block number, provided in a BEEFY commitment. However this is not
+	/// the best proven block. The best proven block is this block's parent.
+	best_block_number: BlockNumber,
+	/// The head of the `ImportedBlockNumbers` ring buffer.
+	next_block_number_index: u32,
+}
+
+#[frame_support::pallet]
+pub mod pallet {
+	use super::*;
+	use bp_runtime::{BasicOperatingMode, OwnedBridgeModule};
+	use frame_support::pallet_prelude::*;
+	use frame_system::pallet_prelude::*;
+
+	#[pallet::config]
+	pub trait Config<I: 'static = ()>: frame_system::Config {
+		/// The upper bound on the number of requests allowed by the pallet.
+		///
+		/// A request refers to an action which writes a header to storage.
+		///
+		/// Once this bound is reached the pallet will reject all commitments
+		/// until the request count has decreased.
+		#[pallet::constant]
+		type MaxRequests: Get<u32>;
+
+		/// Maximal number of imported commitments to keep in the storage.
+		///
+		/// The setting is there to prevent growing the on-chain state indefinitely. Note
+		/// the setting does not relate to block numbers - we will simply keep as much items
+		/// in the storage, so it doesn't guarantee any fixed timeframe for imported commitments.
+		#[pallet::constant]
+		type CommitmentsToKeep: Get<u32>;
+
+		/// The chain we are bridging to here.
+		type BridgedChain: ChainWithBeefy;
+	}
+
+	#[pallet::pallet]
+	#[pallet::without_storage_info]
+	pub struct Pallet<T, I = ()>(PhantomData<(T, I)>);
+
+	#[pallet::hooks]
+	impl<T: Config<I>, I: 'static> Hooks<BlockNumberFor<T>> for Pallet<T, I> {
+		fn on_initialize(_n: T::BlockNumber) -> frame_support::weights::Weight {
+			<RequestCount<T, I>>::mutate(|count| *count = count.saturating_sub(1));
+
+			Weight::from_ref_time(0)
+				.saturating_add(T::DbWeight::get().reads(1))
+				.saturating_add(T::DbWeight::get().writes(1))
+		}
+	}
+
+	impl<T: Config<I>, I: 'static> OwnedBridgeModule<T> for Pallet<T, I> {
+		const LOG_TARGET: &'static str = LOG_TARGET;
+		type OwnerStorage = PalletOwner<T, I>;
+		type OperatingMode = BasicOperatingMode;
+		type OperatingModeStorage = PalletOperatingMode<T, I>;
+	}
+
+	#[pallet::call]
+	impl<T: Config<I>, I: 'static> Pallet<T, I>
+	where
+		BridgedMmrHashing<T, I>: 'static + Send + Sync,
+	{
+		/// Initialize pallet with BEEFY authority set and best known finalized block number.
+		#[pallet::weight((T::DbWeight::get().reads_writes(2, 3), DispatchClass::Operational))]
+		pub fn initialize(
+			origin: OriginFor<T>,
+			init_data: InitializationDataOf<T, I>,
+		) -> DispatchResult {
+			Self::ensure_owner_or_root(origin)?;
+
+			let is_initialized = <ImportedCommitmentsInfo<T, I>>::exists();
+			ensure!(!is_initialized, <Error<T, I>>::AlreadyInitialized);
+
+			log::info!(target: LOG_TARGET, "Initializing bridge BEEFY pallet: {:?}", init_data);
+			Ok(initialize::<T, I>(init_data)?)
+		}
+
+		/// Change `PalletOwner`.
+		///
+		/// May only be called either by root, or by `PalletOwner`.
+		#[pallet::weight((T::DbWeight::get().reads_writes(1, 1), DispatchClass::Operational))]
+		pub fn set_owner(origin: OriginFor<T>, new_owner: Option<T::AccountId>) -> DispatchResult {
+			<Self as OwnedBridgeModule<_>>::set_owner(origin, new_owner)
+		}
+
+		/// Halt or resume all pallet operations.
+		///
+		/// May only be called either by root, or by `PalletOwner`.
+		#[pallet::weight((T::DbWeight::get().reads_writes(1, 1), DispatchClass::Operational))]
+		pub fn set_operating_mode(
+			origin: OriginFor<T>,
+			operating_mode: BasicOperatingMode,
+		) -> DispatchResult {
+			<Self as OwnedBridgeModule<_>>::set_operating_mode(origin, operating_mode)
+		}
+
+		/// Submit a commitment generated by BEEFY authority set.
+		///
+		/// It will use the underlying storage pallet to fetch information about the current
+		/// authority set and best finalized block number in order to verify that the commitment
+		/// is valid.
+		///
+		/// If successful in verification, it will update the underlying storage with the data
+		/// provided in the newly submitted commitment.
+		#[pallet::weight(0)]
+		pub fn submit_commitment(
+			origin: OriginFor<T>,
+			commitment: BridgedBeefySignedCommitment<T, I>,
+			validator_set: BridgedBeefyAuthoritySet<T, I>,
+			mmr_leaf: Box<BridgedBeefyMmrLeaf<T, I>>,
+			mmr_proof: BridgedMmrProof<T, I>,
+		) -> DispatchResult
+		where
+			BridgedBeefySignedCommitment<T, I>: Clone,
+		{
+			Self::ensure_not_halted().map_err(Error::<T, I>::BridgeModule)?;
+			ensure_signed(origin)?;
+
+			ensure!(Self::request_count() < T::MaxRequests::get(), <Error<T, I>>::TooManyRequests);
+
+			// Ensure that the commitment is for a better block.
+			let commitments_info =
+				ImportedCommitmentsInfo::<T, I>::get().ok_or(Error::<T, I>::NotInitialized)?;
+			ensure!(
+				commitment.commitment.block_number > commitments_info.best_block_number,
+				Error::<T, I>::OldCommitment
+			);
+
+			// Verify commitment and mmr leaf.
+			let current_authority_set_info = CurrentAuthoritySetInfo::<T, I>::get();
+			let mmr_root = utils::verify_commitment::<T, I>(
+				&commitment,
+				&current_authority_set_info,
+				&validator_set,
+			)?;
+			utils::verify_beefy_mmr_leaf::<T, I>(&mmr_leaf, mmr_proof, mmr_root)?;
+
+			// Update request count.
+			RequestCount::<T, I>::mutate(|count| *count += 1);
+			// Update authority set if needed.
+			if mmr_leaf.beefy_next_authority_set.id > current_authority_set_info.id {
+				CurrentAuthoritySetInfo::<T, I>::put(mmr_leaf.beefy_next_authority_set);
+			}
+
+			// Import commitment.
+			let block_number_index = commitments_info.next_block_number_index;
+			let to_prune = ImportedBlockNumbers::<T, I>::try_get(block_number_index);
+			ImportedCommitments::<T, I>::insert(
+				commitment.commitment.block_number,
+				ImportedCommitment::<T, I> {
+					parent_number_and_hash: mmr_leaf.parent_number_and_hash,
+					mmr_root,
+				},
+			);
+			ImportedBlockNumbers::<T, I>::insert(
+				block_number_index,
+				commitment.commitment.block_number,
+			);
+			ImportedCommitmentsInfo::<T, I>::put(ImportedCommitmentsInfoData {
+				best_block_number: commitment.commitment.block_number,
+				next_block_number_index: (block_number_index + 1) % T::CommitmentsToKeep::get(),
+			});
+			if let Ok(old_block_number) = to_prune {
+				log::debug!(
+					target: LOG_TARGET,
+					"Pruning commitment for old block: {:?}.",
+					old_block_number
+				);
+				ImportedCommitments::<T, I>::remove(old_block_number);
+			}
+
+			log::info!(
+				target: LOG_TARGET,
+				"Successfully imported commitment for block {:?}",
+				commitment.commitment.block_number,
+			);
+
+			Ok(())
+		}
+	}
+
+	/// The current number of requests which have written to storage.
+	///
+	/// If the `RequestCount` hits `MaxRequests`, no more calls will be allowed to the pallet until
+	/// the request capacity is increased.
+	///
+	/// The `RequestCount` is decreased by one at the beginning of every block. This is to ensure
+	/// that the pallet can always make progress.
+	#[pallet::storage]
+	#[pallet::getter(fn request_count)]
+	pub type RequestCount<T: Config<I>, I: 'static = ()> = StorageValue<_, u32, ValueQuery>;
+
+	/// High level info about the imported commitments.
+	///
+	/// Contains the following info:
+	/// - best known block number of the bridged chain, finalized by BEEFY
+	/// - the head of the `ImportedBlockNumbers` ring buffer
+	#[pallet::storage]
+	pub type ImportedCommitmentsInfo<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, ImportedCommitmentsInfoData<BridgedBlockNumber<T, I>>>;
+
+	/// A ring buffer containing the block numbers of the commitments that we have imported,
+	/// ordered by the insertion time.
+	#[pallet::storage]
+	pub(super) type ImportedBlockNumbers<T: Config<I>, I: 'static = ()> =
+		StorageMap<_, Identity, u32, BridgedBlockNumber<T, I>>;
+
+	/// All the commitments that we have imported and haven't been pruned yet.
+	#[pallet::storage]
+	pub type ImportedCommitments<T: Config<I>, I: 'static = ()> =
+		StorageMap<_, Blake2_128Concat, BridgedBlockNumber<T, I>, ImportedCommitment<T, I>>;
+
+	/// The current BEEFY authority set at the bridged chain.
+	#[pallet::storage]
+	pub type CurrentAuthoritySetInfo<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, BridgedBeefyAuthoritySetInfo<T, I>, ValueQuery>;
+
+	/// Optional pallet owner.
+	///
+	/// Pallet owner has the right to halt all pallet operations and then resume it. If it is
+	/// `None`, then there are no direct ways to halt/resume pallet operations, but other
+	/// runtime methods may still be used to do that (i.e. `democracy::referendum` to update halt
+	/// flag directly or calling `halt_operations`).
+	#[pallet::storage]
+	pub type PalletOwner<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, T::AccountId, OptionQuery>;
+
+	/// The current operating mode of the pallet.
+	///
+	/// Depending on the mode either all, or no transactions will be allowed.
+	#[pallet::storage]
+	pub type PalletOperatingMode<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, BasicOperatingMode, ValueQuery>;
+
+	#[pallet::genesis_config]
+	pub struct GenesisConfig<T: Config<I>, I: 'static = ()> {
+		/// Optional module owner account.
+		pub owner: Option<T::AccountId>,
+		/// Optional module initialization data.
+		pub init_data: Option<InitializationDataOf<T, I>>,
+	}
+
+	#[cfg(feature = "std")]
+	impl<T: Config<I>, I: 'static> Default for GenesisConfig<T, I> {
+		fn default() -> Self {
+			Self { owner: None, init_data: None }
+		}
+	}
+
+	#[pallet::genesis_build]
+	impl<T: Config<I>, I: 'static> GenesisBuild<T, I> for GenesisConfig<T, I> {
+		fn build(&self) {
+			if let Some(ref owner) = self.owner {
+				<PalletOwner<T, I>>::put(owner);
+			}
+
+			if let Some(init_data) = self.init_data.clone() {
+				initialize::<T, I>(init_data)
+					.expect("invalid initialization data of BEEFY bridge pallet");
+			} else {
+				// Since the bridge hasn't been initialized we shouldn't allow anyone to perform
+				// transactions.
+				<PalletOperatingMode<T, I>>::put(BasicOperatingMode::Halted);
+			}
+		}
+	}
+
+	#[pallet::error]
+	pub enum Error<T, I = ()> {
+		/// The pallet has not been initialized yet.
+		NotInitialized,
+		/// The pallet has already been initialized.
+		AlreadyInitialized,
+		/// Invalid initial authority set.
+		InvalidInitialAuthoritySet,
+		/// There are too many requests for the current window to handle.
+		TooManyRequests,
+		/// The imported commitment is older than the best commitment known to the pallet.
+		OldCommitment,
+		/// The commitment is signed by unknown validator set.
+		InvalidCommitmentValidatorSetId,
+		/// The id of the provided validator set is invalid.
+		InvalidValidatorSetId,
+		/// The number of signatures in the commitment is invalid.
+		InvalidCommitmentSignaturesLen,
+		/// The number of validator ids provided is invalid.
+		InvalidValidatorSetLen,
+		/// There aren't enough correct signatures in the commitment to finalize the block.
+		NotEnoughCorrectSignatures,
+		/// MMR root is missing from the commitment.
+		MmrRootMissingFromCommitment,
+		/// MMR proof verification has failed.
+		MmrProofVerificationFailed,
+		/// The validators are not matching the merkle tree root of the authority set.
+		InvalidValidatorSetRoot,
+		/// Error generated by the `OwnedBridgeModule` trait.
+		BridgeModule(bp_runtime::OwnedBridgeModuleError),
+	}
+
+	/// Initialize pallet with given parameters.
+	pub(super) fn initialize<T: Config<I>, I: 'static>(
+		init_data: InitializationDataOf<T, I>,
+	) -> Result<(), Error<T, I>> {
+		if init_data.authority_set.len == 0 {
+			return Err(Error::<T, I>::InvalidInitialAuthoritySet)
+		}
+		CurrentAuthoritySetInfo::<T, I>::put(init_data.authority_set);
+
+		<PalletOperatingMode<T, I>>::put(init_data.operating_mode);
+		ImportedCommitmentsInfo::<T, I>::put(ImportedCommitmentsInfoData {
+			best_block_number: init_data.best_block_number,
+			next_block_number_index: 0,
+		});
+
+		Ok(())
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use beefy_primitives::mmr::BeefyAuthoritySet;
+	use bp_runtime::{BasicOperatingMode, OwnedBridgeModuleError};
+	use bp_test_utils::generate_owned_bridge_module_tests;
+	use frame_support::{assert_noop, assert_ok, traits::Get};
+	use mock::*;
+	use mock_chain::*;
+	use sp_runtime::DispatchError;
+
+	fn next_block() {
+		use frame_support::traits::OnInitialize;
+
+		let current_number = frame_system::Pallet::<TestRuntime>::block_number();
+		frame_system::Pallet::<TestRuntime>::set_block_number(current_number + 1);
+		let _ = Pallet::<TestRuntime>::on_initialize(current_number);
+	}
+
+	fn import_header_chain(headers: Vec<HeaderAndCommitment>) {
+		for header in headers {
+			if header.commitment.is_some() {
+				assert_ok!(import_commitment(header));
+			}
+		}
+	}
+
+	#[test]
+	fn fails_to_initialize_if_already_initialized() {
+		run_test_with_initialize(32, || {
+			assert_noop!(
+				Pallet::<TestRuntime>::initialize(
+					RuntimeOrigin::root(),
+					InitializationData {
+						operating_mode: BasicOperatingMode::Normal,
+						best_block_number: 0,
+						authority_set: BeefyAuthoritySet { id: 0, len: 1, root: [0u8; 32].into() }
+					}
+				),
+				Error::<TestRuntime, ()>::AlreadyInitialized,
+			);
+		});
+	}
+
+	#[test]
+	fn fails_to_initialize_if_authority_set_is_empty() {
+		run_test(|| {
+			assert_noop!(
+				Pallet::<TestRuntime>::initialize(
+					RuntimeOrigin::root(),
+					InitializationData {
+						operating_mode: BasicOperatingMode::Normal,
+						best_block_number: 0,
+						authority_set: BeefyAuthoritySet { id: 0, len: 0, root: [0u8; 32].into() }
+					}
+				),
+				Error::<TestRuntime, ()>::InvalidInitialAuthoritySet,
+			);
+		});
+	}
+
+	#[test]
+	fn fails_to_import_commitment_if_halted() {
+		run_test_with_initialize(1, || {
+			assert_ok!(Pallet::<TestRuntime>::set_operating_mode(
+				RuntimeOrigin::root(),
+				BasicOperatingMode::Halted
+			));
+			assert_noop!(
+				import_commitment(ChainBuilder::new(1).append_finalized_header().to_header()),
+				Error::<TestRuntime, ()>::BridgeModule(OwnedBridgeModuleError::Halted),
+			);
+		})
+	}
+
+	#[test]
+	fn fails_to_import_commitment_if_too_many_requests() {
+		run_test_with_initialize(1, || {
+			let max_requests = <<TestRuntime as Config>::MaxRequests as Get<u32>>::get() as u64;
+			let mut chain = ChainBuilder::new(1);
+			for _ in 0..max_requests + 2 {
+				chain = chain.append_finalized_header();
+			}
+
+			// import `max_request` headers
+			for i in 0..max_requests {
+				assert_ok!(import_commitment(chain.header(i + 1)));
+			}
+
+			// try to import next header: it fails because we are no longer accepting commitments
+			assert_noop!(
+				import_commitment(chain.header(max_requests + 1)),
+				Error::<TestRuntime, ()>::TooManyRequests,
+			);
+
+			// when next block is "started", we allow import of next header
+			next_block();
+			assert_ok!(import_commitment(chain.header(max_requests + 1)));
+
+			// but we can't import two headers until next block and so on
+			assert_noop!(
+				import_commitment(chain.header(max_requests + 2)),
+				Error::<TestRuntime, ()>::TooManyRequests,
+			);
+		})
+	}
+
+	#[test]
+	fn fails_to_import_commitment_if_not_initialized() {
+		run_test(|| {
+			assert_noop!(
+				import_commitment(ChainBuilder::new(1).append_finalized_header().to_header()),
+				Error::<TestRuntime, ()>::NotInitialized,
+			);
+		})
+	}
+
+	#[test]
+	fn submit_commitment_works_with_long_chain_with_handoffs() {
+		run_test_with_initialize(3, || {
+			let chain = ChainBuilder::new(3)
+				.append_finalized_header()
+				.append_default_headers(16) // 2..17
+				.append_finalized_header() // 18
+				.append_default_headers(16) // 19..34
+				.append_handoff_header(9) // 35
+				.append_default_headers(8) // 36..43
+				.append_finalized_header() // 44
+				.append_default_headers(8) // 45..52
+				.append_handoff_header(17) // 53
+				.append_default_headers(4) // 54..57
+				.append_finalized_header() // 58
+				.append_default_headers(4); // 59..63
+			import_header_chain(chain.to_chain());
+
+			assert_eq!(
+				ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().best_block_number,
+				58
+			);
+			assert_eq!(CurrentAuthoritySetInfo::<TestRuntime>::get().id, 2);
+			assert_eq!(CurrentAuthoritySetInfo::<TestRuntime>::get().len, 17);
+
+			let imported_commitment = ImportedCommitments::<TestRuntime>::get(58).unwrap();
+			assert_eq!(
+				imported_commitment,
+				bp_beefy::ImportedCommitment {
+					parent_number_and_hash: (57, chain.header(57).header.hash()),
+					mmr_root: chain.header(58).mmr_root,
+				},
+			);
+		})
+	}
+
+	#[test]
+	fn commitment_pruning_works() {
+		run_test_with_initialize(3, || {
+			let commitments_to_keep = <TestRuntime as Config<()>>::CommitmentsToKeep::get();
+			let commitments_to_import: Vec<HeaderAndCommitment> = ChainBuilder::new(3)
+				.append_finalized_headers(commitments_to_keep as usize + 2)
+				.to_chain();
+
+			// import exactly `CommitmentsToKeep` commitments
+			for index in 0..commitments_to_keep {
+				next_block();
+				import_commitment(commitments_to_import[index as usize].clone())
+					.expect("must succeed");
+				assert_eq!(
+					ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().next_block_number_index,
+					(index + 1) % commitments_to_keep
+				);
+			}
+
+			// ensure that all commitments are in the storage
+			assert_eq!(
+				ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().best_block_number,
+				commitments_to_keep as TestBridgedBlockNumber
+			);
+			assert_eq!(
+				ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().next_block_number_index,
+				0
+			);
+			for index in 0..commitments_to_keep {
+				assert!(ImportedCommitments::<TestRuntime>::get(
+					index as TestBridgedBlockNumber + 1
+				)
+				.is_some());
+				assert_eq!(
+					ImportedBlockNumbers::<TestRuntime>::get(index),
+					Some(index + 1).map(Into::into)
+				);
+			}
+
+			// import next commitment
+			next_block();
+			import_commitment(commitments_to_import[commitments_to_keep as usize].clone())
+				.expect("must succeed");
+			assert_eq!(
+				ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().next_block_number_index,
+				1
+			);
+			assert!(ImportedCommitments::<TestRuntime>::get(
+				commitments_to_keep as TestBridgedBlockNumber + 1
+			)
+			.is_some());
+			assert_eq!(
+				ImportedBlockNumbers::<TestRuntime>::get(0),
+				Some(commitments_to_keep + 1).map(Into::into)
+			);
+			// the side effect of the import is that the commitment#1 is pruned
+			assert!(ImportedCommitments::<TestRuntime>::get(1).is_none());
+
+			// import next commitment
+			next_block();
+			import_commitment(commitments_to_import[commitments_to_keep as usize + 1].clone())
+				.expect("must succeed");
+			assert_eq!(
+				ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().next_block_number_index,
+				2
+			);
+			assert!(ImportedCommitments::<TestRuntime>::get(
+				commitments_to_keep as TestBridgedBlockNumber + 2
+			)
+			.is_some());
+			assert_eq!(
+				ImportedBlockNumbers::<TestRuntime>::get(1),
+				Some(commitments_to_keep + 2).map(Into::into)
+			);
+			// the side effect of the import is that the commitment#2 is pruned
+			assert!(ImportedCommitments::<TestRuntime>::get(1).is_none());
+			assert!(ImportedCommitments::<TestRuntime>::get(2).is_none());
+		});
+	}
+
+	generate_owned_bridge_module_tests!(BasicOperatingMode::Normal, BasicOperatingMode::Halted);
+}

bridges/modules/beefy/src/mock.rs

@@ -0,0 +1,226 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate as beefy;
+use crate::{
+	utils::get_authorities_mmr_root, BridgedBeefyAuthoritySet, BridgedBeefyAuthoritySetInfo,
+	BridgedBeefyCommitmentHasher, BridgedBeefyMmrLeafExtra, BridgedBeefySignedCommitment,
+	BridgedMmrHash, BridgedMmrHashing, BridgedMmrProof,
+};
+
+use bp_beefy::{BeefyValidatorSignatureOf, ChainWithBeefy, Commitment, MmrDataOrHash};
+use bp_runtime::{BasicOperatingMode, Chain};
+use codec::Encode;
+use frame_support::{construct_runtime, parameter_types, weights::Weight};
+use sp_core::{sr25519::Signature, Pair};
+use sp_runtime::{
+	testing::{Header, H256},
+	traits::{BlakeTwo256, Hash, IdentityLookup},
+	Perbill,
+};
+
+pub use beefy_primitives::crypto::{AuthorityId as BeefyId, Pair as BeefyPair};
+use sp_core::crypto::Wraps;
+use sp_runtime::traits::Keccak256;
+
+pub type TestAccountId = u64;
+pub type TestBridgedBlockNumber = u64;
+pub type TestBridgedBlockHash = H256;
+pub type TestBridgedHeader = Header;
+pub type TestBridgedAuthoritySetInfo = BridgedBeefyAuthoritySetInfo<TestRuntime, ()>;
+pub type TestBridgedValidatorSet = BridgedBeefyAuthoritySet<TestRuntime, ()>;
+pub type TestBridgedCommitment = BridgedBeefySignedCommitment<TestRuntime, ()>;
+pub type TestBridgedValidatorSignature = BeefyValidatorSignatureOf<TestBridgedChain>;
+pub type TestBridgedCommitmentHasher = BridgedBeefyCommitmentHasher<TestRuntime, ()>;
+pub type TestBridgedMmrHashing = BridgedMmrHashing<TestRuntime, ()>;
+pub type TestBridgedMmrHash = BridgedMmrHash<TestRuntime, ()>;
+pub type TestBridgedBeefyMmrLeafExtra = BridgedBeefyMmrLeafExtra<TestRuntime, ()>;
+pub type TestBridgedMmrProof = BridgedMmrProof<TestRuntime, ()>;
+pub type TestBridgedRawMmrLeaf = beefy_primitives::mmr::MmrLeaf<
+	TestBridgedBlockNumber,
+	TestBridgedBlockHash,
+	TestBridgedMmrHash,
+	TestBridgedBeefyMmrLeafExtra,
+>;
+pub type TestBridgedMmrNode = MmrDataOrHash<Keccak256, TestBridgedRawMmrLeaf>;
+
+type TestBlock = frame_system::mocking::MockBlock<TestRuntime>;
+type TestUncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<TestRuntime>;
+
+construct_runtime! {
+	pub enum TestRuntime where
+		Block = TestBlock,
+		NodeBlock = TestBlock,
+		UncheckedExtrinsic = TestUncheckedExtrinsic,
+	{
+		System: frame_system::{Pallet, Call, Config, Storage, Event<T>},
+		Beefy: beefy::{Pallet},
+	}
+}
+
+parameter_types! {
+	pub const BlockHashCount: u64 = 250;
+	pub const MaximumBlockWeight: Weight = Weight::from_ref_time(1024);
+	pub const MaximumBlockLength: u32 = 2 * 1024;
+	pub const AvailableBlockRatio: Perbill = Perbill::one();
+}
+
+impl frame_system::Config for TestRuntime {
+	type RuntimeOrigin = RuntimeOrigin;
+	type Index = u64;
+	type RuntimeCall = RuntimeCall;
+	type BlockNumber = u64;
+	type Hash = H256;
+	type Hashing = BlakeTwo256;
+	type AccountId = TestAccountId;
+	type Lookup = IdentityLookup<Self::AccountId>;
+	type Header = Header;
+	type RuntimeEvent = ();
+	type BlockHashCount = BlockHashCount;
+	type Version = ();
+	type PalletInfo = PalletInfo;
+	type AccountData = ();
+	type OnNewAccount = ();
+	type OnKilledAccount = ();
+	type BaseCallFilter = frame_support::traits::Everything;
+	type SystemWeightInfo = ();
+	type DbWeight = ();
+	type BlockWeights = ();
+	type BlockLength = ();
+	type SS58Prefix = ();
+	type OnSetCode = ();
+	type MaxConsumers = frame_support::traits::ConstU32<16>;
+}
+
+impl beefy::Config for TestRuntime {
+	type MaxRequests = frame_support::traits::ConstU32<16>;
+	type BridgedChain = TestBridgedChain;
+	type CommitmentsToKeep = frame_support::traits::ConstU32<16>;
+}
+
+#[derive(Debug)]
+pub struct TestBridgedChain;
+
+impl Chain for TestBridgedChain {
+	type BlockNumber = TestBridgedBlockNumber;
+	type Hash = H256;
+	type Hasher = BlakeTwo256;
+	type Header = <TestRuntime as frame_system::Config>::Header;
+
+	type AccountId = TestAccountId;
+	type Balance = u64;
+	type Index = u64;
+	type Signature = Signature;
+
+	fn max_extrinsic_size() -> u32 {
+		unreachable!()
+	}
+	fn max_extrinsic_weight() -> Weight {
+		unreachable!()
+	}
+}
+
+impl ChainWithBeefy for TestBridgedChain {
+	type CommitmentHasher = Keccak256;
+	type MmrHashing = Keccak256;
+	type MmrHash = <Keccak256 as Hash>::Output;
+	type BeefyMmrLeafExtra = ();
+	type AuthorityId = BeefyId;
+	type Signature = beefy_primitives::crypto::AuthoritySignature;
+	type AuthorityIdToMerkleLeaf = pallet_beefy_mmr::BeefyEcdsaToEthereum;
+}
+
+/// Run test within test runtime.
+pub fn run_test<T>(test: impl FnOnce() -> T) -> T {
+	sp_io::TestExternalities::new(Default::default()).execute_with(test)
+}
+
+/// Initialize pallet and run test.
+pub fn run_test_with_initialize<T>(initial_validators_count: u32, test: impl FnOnce() -> T) -> T {
+	run_test(|| {
+		let validators = validator_ids(0, initial_validators_count);
+		let authority_set = authority_set_info(0, &validators);
+
+		crate::Pallet::<TestRuntime>::initialize(
+			RuntimeOrigin::root(),
+			bp_beefy::InitializationData {
+				operating_mode: BasicOperatingMode::Normal,
+				best_block_number: 0,
+				authority_set,
+			},
+		)
+		.expect("initialization data is correct");
+
+		test()
+	})
+}
+
+/// Import given commitment.
+pub fn import_commitment(
+	header: crate::mock_chain::HeaderAndCommitment,
+) -> sp_runtime::DispatchResult {
+	crate::Pallet::<TestRuntime>::submit_commitment(
+		RuntimeOrigin::signed(1),
+		header
+			.commitment
+			.expect("thou shall not call import_commitment on header without commitment"),
+		header.validator_set,
+		Box::new(header.leaf),
+		header.leaf_proof,
+	)
+}
+
+pub fn validator_pairs(index: u32, count: u32) -> Vec<BeefyPair> {
+	(index..index + count)
+		.map(|index| {
+			let mut seed = [1u8; 32];
+			seed[0..8].copy_from_slice(&(index as u64).encode());
+			BeefyPair::from_seed(&seed)
+		})
+		.collect()
+}
+
+/// Return identifiers of validators, starting at given index.
+pub fn validator_ids(index: u32, count: u32) -> Vec<BeefyId> {
+	validator_pairs(index, count).into_iter().map(|pair| pair.public()).collect()
+}
+
+pub fn authority_set_info(id: u64, validators: &Vec<BeefyId>) -> TestBridgedAuthoritySetInfo {
+	let merkle_root = get_authorities_mmr_root::<TestRuntime, (), _>(validators.iter());
+
+	TestBridgedAuthoritySetInfo { id, len: validators.len() as u32, root: merkle_root }
+}
+
+/// Sign BEEFY commitment.
+pub fn sign_commitment(
+	commitment: Commitment<TestBridgedBlockNumber>,
+	validator_pairs: &[BeefyPair],
+	signature_count: usize,
+) -> TestBridgedCommitment {
+	let total_validators = validator_pairs.len();
+	let random_validators =
+		rand::seq::index::sample(&mut rand::thread_rng(), total_validators, signature_count);
+
+	let commitment_hash = TestBridgedCommitmentHasher::hash(&commitment.encode());
+	let mut signatures = vec![None; total_validators];
+	for validator_idx in random_validators.iter() {
+		let validator = &validator_pairs[validator_idx];
+		signatures[validator_idx] =
+			Some(validator.as_inner_ref().sign_prehashed(commitment_hash.as_fixed_bytes()).into());
+	}
+
+	TestBridgedCommitment { commitment, signatures }
+}

bridges/modules/beefy/src/mock_chain.rs

@@ -0,0 +1,299 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Utilities to build bridged chain and BEEFY+MMR structures.
+
+use crate::{
+	mock::{
+		sign_commitment, validator_pairs, BeefyPair, TestBridgedBlockNumber, TestBridgedCommitment,
+		TestBridgedHeader, TestBridgedMmrHash, TestBridgedMmrHashing, TestBridgedMmrNode,
+		TestBridgedMmrProof, TestBridgedRawMmrLeaf, TestBridgedValidatorSet,
+		TestBridgedValidatorSignature, TestRuntime,
+	},
+	utils::get_authorities_mmr_root,
+};
+
+use beefy_primitives::mmr::{BeefyNextAuthoritySet, MmrLeafVersion};
+use bp_beefy::{BeefyPayload, Commitment, ValidatorSetId, MMR_ROOT_PAYLOAD_ID};
+use codec::Encode;
+use pallet_mmr::NodeIndex;
+use rand::Rng;
+use sp_core::Pair;
+use sp_runtime::traits::{Hash, Header as HeaderT};
+use std::collections::HashMap;
+
+#[derive(Debug, Clone)]
+pub struct HeaderAndCommitment {
+	pub header: TestBridgedHeader,
+	pub commitment: Option<TestBridgedCommitment>,
+	pub validator_set: TestBridgedValidatorSet,
+	pub leaf: TestBridgedRawMmrLeaf,
+	pub leaf_proof: TestBridgedMmrProof,
+	pub mmr_root: TestBridgedMmrHash,
+}
+
+impl HeaderAndCommitment {
+	pub fn customize_signatures(
+		&mut self,
+		f: impl FnOnce(&mut Vec<Option<TestBridgedValidatorSignature>>),
+	) {
+		if let Some(commitment) = &mut self.commitment {
+			f(&mut commitment.signatures);
+		}
+	}
+
+	pub fn customize_commitment(
+		&mut self,
+		f: impl FnOnce(&mut Commitment<TestBridgedBlockNumber>),
+		validator_pairs: &[BeefyPair],
+		signature_count: usize,
+	) {
+		if let Some(mut commitment) = self.commitment.take() {
+			f(&mut commitment.commitment);
+			self.commitment =
+				Some(sign_commitment(commitment.commitment, validator_pairs, signature_count));
+		}
+	}
+}
+
+pub struct ChainBuilder {
+	headers: Vec<HeaderAndCommitment>,
+	validator_set_id: ValidatorSetId,
+	validator_keys: Vec<BeefyPair>,
+	mmr: mmr_lib::MMR<TestBridgedMmrNode, BridgedMmrHashMerge, BridgedMmrStorage>,
+}
+
+struct BridgedMmrStorage {
+	nodes: HashMap<NodeIndex, TestBridgedMmrNode>,
+}
+
+impl mmr_lib::MMRStore<TestBridgedMmrNode> for BridgedMmrStorage {
+	fn get_elem(&self, pos: NodeIndex) -> mmr_lib::Result<Option<TestBridgedMmrNode>> {
+		Ok(self.nodes.get(&pos).cloned())
+	}
+
+	fn append(&mut self, pos: NodeIndex, elems: Vec<TestBridgedMmrNode>) -> mmr_lib::Result<()> {
+		for (i, elem) in elems.into_iter().enumerate() {
+			self.nodes.insert(pos + i as NodeIndex, elem);
+		}
+		Ok(())
+	}
+}
+
+impl ChainBuilder {
+	/// Creates new chain builder with given validator set size.
+	pub fn new(initial_validators_count: u32) -> Self {
+		ChainBuilder {
+			headers: Vec::new(),
+			validator_set_id: 0,
+			validator_keys: validator_pairs(0, initial_validators_count),
+			mmr: mmr_lib::MMR::new(0, BridgedMmrStorage { nodes: HashMap::new() }),
+		}
+	}
+
+	/// Get header with given number.
+	pub fn header(&self, number: TestBridgedBlockNumber) -> HeaderAndCommitment {
+		self.headers[number as usize - 1].clone()
+	}
+
+	/// Returns single built header.
+	pub fn to_header(&self) -> HeaderAndCommitment {
+		assert_eq!(self.headers.len(), 1);
+		self.headers[0].clone()
+	}
+
+	/// Returns built chain.
+	pub fn to_chain(&self) -> Vec<HeaderAndCommitment> {
+		self.headers.clone()
+	}
+
+	/// Appends header, that has been finalized by BEEFY (so it has a linked signed commitment).
+	pub fn append_finalized_header(self) -> Self {
+		let next_validator_set_id = self.validator_set_id;
+		let next_validator_keys = self.validator_keys.clone();
+		HeaderBuilder::with_chain(self, next_validator_set_id, next_validator_keys).finalize()
+	}
+
+	/// Append multiple finalized headers at once.
+	pub fn append_finalized_headers(mut self, count: usize) -> Self {
+		for _ in 0..count {
+			self = self.append_finalized_header();
+		}
+		self
+	}
+
+	/// Appends header, that enacts new validator set.
+	///
+	/// Such headers are explicitly finalized by BEEFY.
+	pub fn append_handoff_header(self, next_validators_len: u32) -> Self {
+		let new_validator_set_id = self.validator_set_id + 1;
+		let new_validator_pairs =
+			validator_pairs(rand::thread_rng().gen::<u32>() % (u32::MAX / 2), next_validators_len);
+
+		HeaderBuilder::with_chain(self, new_validator_set_id, new_validator_pairs).finalize()
+	}
+
+	/// Append several default header without commitment.
+	pub fn append_default_headers(mut self, count: usize) -> Self {
+		for _ in 0..count {
+			let next_validator_set_id = self.validator_set_id;
+			let next_validator_keys = self.validator_keys.clone();
+			self =
+				HeaderBuilder::with_chain(self, next_validator_set_id, next_validator_keys).build()
+		}
+		self
+	}
+}
+
+/// Custom header builder.
+pub struct HeaderBuilder {
+	chain: ChainBuilder,
+	header: TestBridgedHeader,
+	leaf: TestBridgedRawMmrLeaf,
+	leaf_proof: Option<TestBridgedMmrProof>,
+	next_validator_set_id: ValidatorSetId,
+	next_validator_keys: Vec<BeefyPair>,
+}
+
+impl HeaderBuilder {
+	fn with_chain(
+		chain: ChainBuilder,
+		next_validator_set_id: ValidatorSetId,
+		next_validator_keys: Vec<BeefyPair>,
+	) -> Self {
+		// we're starting with header#1, since header#0 is always finalized
+		let header_number = chain.headers.len() as TestBridgedBlockNumber + 1;
+		let header = TestBridgedHeader::new(
+			header_number,
+			Default::default(),
+			Default::default(),
+			chain.headers.last().map(|h| h.header.hash()).unwrap_or_default(),
+			Default::default(),
+		);
+
+		let next_validators =
+			next_validator_keys.iter().map(|pair| pair.public()).collect::<Vec<_>>();
+		let next_validators_mmr_root =
+			get_authorities_mmr_root::<TestRuntime, (), _>(next_validators.iter());
+		let leaf = beefy_primitives::mmr::MmrLeaf {
+			version: MmrLeafVersion::new(1, 0),
+			parent_number_and_hash: (header.number().saturating_sub(1), *header.parent_hash()),
+			beefy_next_authority_set: BeefyNextAuthoritySet {
+				id: next_validator_set_id,
+				len: next_validators.len() as u32,
+				root: next_validators_mmr_root,
+			},
+			leaf_extra: (),
+		};
+
+		HeaderBuilder {
+			chain,
+			header,
+			leaf,
+			leaf_proof: None,
+			next_validator_keys,
+			next_validator_set_id,
+		}
+	}
+
+	/// Customize generated proof of header MMR leaf.
+	///
+	/// Can only be called once.
+	pub fn customize_proof(
+		mut self,
+		f: impl FnOnce(TestBridgedMmrProof) -> TestBridgedMmrProof,
+	) -> Self {
+		assert!(self.leaf_proof.is_none());
+
+		let leaf_hash = TestBridgedMmrHashing::hash(&self.leaf.encode());
+		let node = TestBridgedMmrNode::Hash(leaf_hash);
+		let leaf_position = self.chain.mmr.push(node).unwrap();
+
+		let proof = self.chain.mmr.gen_proof(vec![leaf_position]).unwrap();
+		// genesis has no leaf => leaf index is header number minus 1
+		let leaf_index = *self.header.number() - 1;
+		let leaf_count = *self.header.number();
+		self.leaf_proof = Some(f(TestBridgedMmrProof {
+			leaf_index,
+			leaf_count,
+			items: proof.proof_items().iter().map(|i| i.hash()).collect(),
+		}));
+
+		self
+	}
+
+	/// Build header without commitment.
+	pub fn build(mut self) -> ChainBuilder {
+		if self.leaf_proof.is_none() {
+			self = self.customize_proof(|proof| proof);
+		}
+
+		let validators =
+			self.chain.validator_keys.iter().map(|pair| pair.public()).collect::<Vec<_>>();
+		self.chain.headers.push(HeaderAndCommitment {
+			header: self.header,
+			commitment: None,
+			validator_set: TestBridgedValidatorSet::new(validators, self.chain.validator_set_id)
+				.unwrap(),
+			leaf: self.leaf,
+			leaf_proof: self.leaf_proof.expect("guaranteed by the customize_proof call above; qed"),
+			mmr_root: self.chain.mmr.get_root().unwrap().hash(),
+		});
+
+		self.chain.validator_set_id = self.next_validator_set_id;
+		self.chain.validator_keys = self.next_validator_keys;
+
+		self.chain
+	}
+
+	/// Build header with commitment.
+	pub fn finalize(self) -> ChainBuilder {
+		let validator_count = self.chain.validator_keys.len();
+		let current_validator_set_id = self.chain.validator_set_id;
+		let current_validator_set_keys = self.chain.validator_keys.clone();
+		let mut chain = self.build();
+
+		let last_header = chain.headers.last_mut().expect("added by append_header; qed");
+		last_header.commitment = Some(sign_commitment(
+			Commitment {
+				payload: BeefyPayload::from_single_entry(
+					MMR_ROOT_PAYLOAD_ID,
+					chain.mmr.get_root().unwrap().hash().encode(),
+				),
+				block_number: *last_header.header.number(),
+				validator_set_id: current_validator_set_id,
+			},
+			&current_validator_set_keys,
+			validator_count * 2 / 3 + 1,
+		));
+
+		chain
+	}
+}
+
+/// Default Merging & Hashing behavior for MMR.
+pub struct BridgedMmrHashMerge;
+
+impl mmr_lib::Merge for BridgedMmrHashMerge {
+	type Item = TestBridgedMmrNode;
+
+	fn merge(left: &Self::Item, right: &Self::Item) -> Self::Item {
+		let mut concat = left.hash().as_ref().to_vec();
+		concat.extend_from_slice(right.hash().as_ref());
+
+		TestBridgedMmrNode::Hash(TestBridgedMmrHashing::hash(&concat))
+	}
+}

bridges/modules/beefy/src/utils.rs

@@ -0,0 +1,363 @@
+use crate::{
+	BridgedBeefyAuthorityId, BridgedBeefyAuthoritySet, BridgedBeefyAuthoritySetInfo,
+	BridgedBeefyCommitmentHasher, BridgedBeefyMmrLeaf, BridgedBeefySignedCommitment, BridgedChain,
+	BridgedMmrHash, BridgedMmrHashing, BridgedMmrProof, Config, Error, LOG_TARGET,
+};
+use bp_beefy::{merkle_root, verify_mmr_leaves_proof, BeefyVerify, MmrDataOrHash, MmrProof};
+use codec::Encode;
+use frame_support::ensure;
+use sp_runtime::traits::{Convert, Hash};
+use sp_std::{vec, vec::Vec};
+
+type BridgedMmrDataOrHash<T, I> = MmrDataOrHash<BridgedMmrHashing<T, I>, BridgedBeefyMmrLeaf<T, I>>;
+/// A way to encode validator id to the BEEFY merkle tree leaf.
+type BridgedBeefyAuthorityIdToMerkleLeaf<T, I> =
+	bp_beefy::BeefyAuthorityIdToMerkleLeafOf<BridgedChain<T, I>>;
+
+/// Get the MMR root for a collection of validators.
+pub(crate) fn get_authorities_mmr_root<
+	'a,
+	T: Config<I>,
+	I: 'static,
+	V: Iterator<Item = &'a BridgedBeefyAuthorityId<T, I>>,
+>(
+	authorities: V,
+) -> BridgedMmrHash<T, I> {
+	let merkle_leafs = authorities
+		.cloned()
+		.map(BridgedBeefyAuthorityIdToMerkleLeaf::<T, I>::convert)
+		.collect::<Vec<_>>();
+	merkle_root::<BridgedMmrHashing<T, I>, _>(merkle_leafs)
+}
+
+fn verify_authority_set<T: Config<I>, I: 'static>(
+	authority_set_info: &BridgedBeefyAuthoritySetInfo<T, I>,
+	authority_set: &BridgedBeefyAuthoritySet<T, I>,
+) -> Result<(), Error<T, I>> {
+	ensure!(authority_set.id() == authority_set_info.id, Error::<T, I>::InvalidValidatorSetId);
+	ensure!(
+		authority_set.len() == authority_set_info.len as usize,
+		Error::<T, I>::InvalidValidatorSetLen
+	);
+
+	// Ensure that the authority set that signed the commitment is the expected one.
+	let root = get_authorities_mmr_root::<T, I, _>(authority_set.validators().iter());
+	ensure!(root == authority_set_info.root, Error::<T, I>::InvalidValidatorSetRoot);
+
+	Ok(())
+}
+
+/// Number of correct signatures, required from given validators set to accept signed
+/// commitment.
+///
+/// We're using 'conservative' approach here, where signatures of `2/3+1` validators are
+/// required..
+pub(crate) fn signatures_required<T: Config<I>, I: 'static>(validators_len: usize) -> usize {
+	validators_len - validators_len.saturating_sub(1) / 3
+}
+
+fn verify_signatures<T: Config<I>, I: 'static>(
+	commitment: &BridgedBeefySignedCommitment<T, I>,
+	authority_set: &BridgedBeefyAuthoritySet<T, I>,
+) -> Result<(), Error<T, I>> {
+	ensure!(
+		commitment.signatures.len() == authority_set.len(),
+		Error::<T, I>::InvalidCommitmentSignaturesLen
+	);
+
+	// Ensure that the commitment was signed by enough authorities.
+	let msg = commitment.commitment.encode();
+	let mut missing_signatures = signatures_required::<T, I>(authority_set.len());
+	for (idx, (authority, maybe_sig)) in
+		authority_set.validators().iter().zip(commitment.signatures.iter()).enumerate()
+	{
+		if let Some(sig) = maybe_sig {
+			if BeefyVerify::<BridgedBeefyCommitmentHasher<T, I>>::verify(sig, &msg, authority) {
+				missing_signatures = missing_signatures.saturating_sub(1);
+				if missing_signatures == 0 {
+					break
+				}
+			} else {
+				log::debug!(
+					target: LOG_TARGET,
+					"Signed commitment contains incorrect signature of validator {} ({:?}): {:?}",
+					idx,
+					authority,
+					sig,
+				);
+			}
+		}
+	}
+	ensure!(missing_signatures == 0, Error::<T, I>::NotEnoughCorrectSignatures);
+
+	Ok(())
+}
+
+/// Extract MMR root from commitment payload.
+fn extract_mmr_root<T: Config<I>, I: 'static>(
+	commitment: &BridgedBeefySignedCommitment<T, I>,
+) -> Result<BridgedMmrHash<T, I>, Error<T, I>> {
+	commitment
+		.commitment
+		.payload
+		.get_decoded(&bp_beefy::MMR_ROOT_PAYLOAD_ID)
+		.ok_or(Error::MmrRootMissingFromCommitment)
+}
+
+pub(crate) fn verify_commitment<T: Config<I>, I: 'static>(
+	commitment: &BridgedBeefySignedCommitment<T, I>,
+	authority_set_info: &BridgedBeefyAuthoritySetInfo<T, I>,
+	authority_set: &BridgedBeefyAuthoritySet<T, I>,
+) -> Result<BridgedMmrHash<T, I>, Error<T, I>> {
+	// Ensure that the commitment is signed by the best known BEEFY validator set.
+	ensure!(
+		commitment.commitment.validator_set_id == authority_set_info.id,
+		Error::<T, I>::InvalidCommitmentValidatorSetId
+	);
+	ensure!(
+		commitment.signatures.len() == authority_set_info.len as usize,
+		Error::<T, I>::InvalidCommitmentSignaturesLen
+	);
+
+	verify_authority_set(authority_set_info, authority_set)?;
+	verify_signatures(commitment, authority_set)?;
+
+	extract_mmr_root(commitment)
+}
+
+/// Verify MMR proof of given leaf.
+pub(crate) fn verify_beefy_mmr_leaf<T: Config<I>, I: 'static>(
+	mmr_leaf: &BridgedBeefyMmrLeaf<T, I>,
+	mmr_proof: BridgedMmrProof<T, I>,
+	mmr_root: BridgedMmrHash<T, I>,
+) -> Result<(), Error<T, I>> {
+	let mmr_proof_leaf_index = mmr_proof.leaf_index;
+	let mmr_proof_leaf_count = mmr_proof.leaf_count;
+	let mmr_proof_length = mmr_proof.items.len();
+
+	// Verify the mmr proof for the provided leaf.
+	let mmr_leaf_hash = BridgedMmrHashing::<T, I>::hash(&mmr_leaf.encode());
+	verify_mmr_leaves_proof(
+		mmr_root,
+		vec![BridgedMmrDataOrHash::<T, I>::Hash(mmr_leaf_hash)],
+		MmrProof::into_batch_proof(mmr_proof),
+	)
+	.map_err(|e| {
+		log::error!(
+			target: LOG_TARGET,
+			"MMR proof of leaf {:?} (root: {:?}, leaf: {}, leaf count: {}, len: {}) \
+				verification has failed with error: {:?}",
+			mmr_leaf_hash,
+			mmr_root,
+			mmr_proof_leaf_index,
+			mmr_proof_leaf_count,
+			mmr_proof_length,
+			e,
+		);
+
+		Error::<T, I>::MmrProofVerificationFailed
+	})
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use crate::{mock::*, mock_chain::*, *};
+	use beefy_primitives::ValidatorSet;
+	use bp_beefy::{BeefyPayload, MMR_ROOT_PAYLOAD_ID};
+	use frame_support::{assert_noop, assert_ok};
+
+	#[test]
+	fn submit_commitment_checks_metadata() {
+		run_test_with_initialize(8, || {
+			// Fails if `commitment.commitment.validator_set_id` differs.
+			let mut header = ChainBuilder::new(8).append_finalized_header().to_header();
+			header.customize_commitment(
+				|commitment| {
+					commitment.validator_set_id += 1;
+				},
+				&validator_pairs(0, 8),
+				6,
+			);
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::InvalidCommitmentValidatorSetId,
+			);
+
+			// Fails if `commitment.signatures.len()` differs.
+			let mut header = ChainBuilder::new(8).append_finalized_header().to_header();
+			header.customize_signatures(|signatures| {
+				signatures.pop();
+			});
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::InvalidCommitmentSignaturesLen,
+			);
+		});
+	}
+
+	#[test]
+	fn submit_commitment_checks_validator_set() {
+		run_test_with_initialize(8, || {
+			// Fails if `ValidatorSet::id` differs.
+			let mut header = ChainBuilder::new(8).append_finalized_header().to_header();
+			header.validator_set = ValidatorSet::new(validator_ids(0, 8), 1).unwrap();
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::InvalidValidatorSetId,
+			);
+
+			// Fails if `ValidatorSet::len()` differs.
+			let mut header = ChainBuilder::new(8).append_finalized_header().to_header();
+			header.validator_set = ValidatorSet::new(validator_ids(0, 5), 0).unwrap();
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::InvalidValidatorSetLen,
+			);
+
+			// Fails if the validators differ.
+			let mut header = ChainBuilder::new(8).append_finalized_header().to_header();
+			header.validator_set = ValidatorSet::new(validator_ids(3, 8), 0).unwrap();
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::InvalidValidatorSetRoot,
+			);
+		});
+	}
+
+	#[test]
+	fn submit_commitment_checks_signatures() {
+		run_test_with_initialize(20, || {
+			// Fails when there aren't enough signatures.
+			let mut header = ChainBuilder::new(20).append_finalized_header().to_header();
+			header.customize_signatures(|signatures| {
+				let first_signature_idx = signatures.iter().position(Option::is_some).unwrap();
+				signatures[first_signature_idx] = None;
+			});
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::NotEnoughCorrectSignatures,
+			);
+
+			// Fails when there aren't enough correct signatures.
+			let mut header = ChainBuilder::new(20).append_finalized_header().to_header();
+			header.customize_signatures(|signatures| {
+				let first_signature_idx = signatures.iter().position(Option::is_some).unwrap();
+				let last_signature_idx = signatures.len() -
+					signatures.iter().rev().position(Option::is_some).unwrap() -
+					1;
+				signatures[first_signature_idx] = signatures[last_signature_idx].clone();
+			});
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::NotEnoughCorrectSignatures,
+			);
+
+			// Returns Ok(()) when there are enough signatures, even if some are incorrect.
+			let mut header = ChainBuilder::new(20).append_finalized_header().to_header();
+			header.customize_signatures(|signatures| {
+				let first_signature_idx = signatures.iter().position(Option::is_some).unwrap();
+				let first_missing_signature_idx =
+					signatures.iter().position(Option::is_none).unwrap();
+				signatures[first_missing_signature_idx] = signatures[first_signature_idx].clone();
+			});
+			assert_ok!(import_commitment(header));
+		});
+	}
+
+	#[test]
+	fn submit_commitment_checks_mmr_proof() {
+		run_test_with_initialize(1, || {
+			let validators = validator_pairs(0, 1);
+
+			// Fails if leaf is not for parent.
+			let mut header = ChainBuilder::new(1).append_finalized_header().to_header();
+			header.leaf.parent_number_and_hash.0 += 1;
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::MmrProofVerificationFailed,
+			);
+
+			// Fails if mmr proof is incorrect.
+			let mut header = ChainBuilder::new(1).append_finalized_header().to_header();
+			header.leaf_proof.leaf_index += 1;
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::MmrProofVerificationFailed,
+			);
+
+			// Fails if mmr root is incorrect.
+			let mut header = ChainBuilder::new(1).append_finalized_header().to_header();
+			// Replace MMR root with zeroes.
+			header.customize_commitment(
+				|commitment| {
+					commitment.payload =
+						BeefyPayload::from_single_entry(MMR_ROOT_PAYLOAD_ID, [0u8; 32].encode());
+				},
+				&validators,
+				1,
+			);
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::MmrProofVerificationFailed,
+			);
+		});
+	}
+
+	#[test]
+	fn submit_commitment_extracts_mmr_root() {
+		run_test_with_initialize(1, || {
+			let validators = validator_pairs(0, 1);
+
+			// Fails if there is no mmr root in the payload.
+			let mut header = ChainBuilder::new(1).append_finalized_header().to_header();
+			// Remove MMR root from the payload.
+			header.customize_commitment(
+				|commitment| {
+					commitment.payload = BeefyPayload::from_single_entry(*b"xy", vec![]);
+				},
+				&validators,
+				1,
+			);
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::MmrRootMissingFromCommitment,
+			);
+
+			// Fails if mmr root can't be decoded.
+			let mut header = ChainBuilder::new(1).append_finalized_header().to_header();
+			// MMR root is a 32-byte array and we have replaced it with single byte
+			header.customize_commitment(
+				|commitment| {
+					commitment.payload =
+						BeefyPayload::from_single_entry(MMR_ROOT_PAYLOAD_ID, vec![42]);
+				},
+				&validators,
+				1,
+			);
+			assert_noop!(
+				import_commitment(header),
+				Error::<TestRuntime, ()>::MmrRootMissingFromCommitment,
+			);
+		});
+	}
+
+	#[test]
+	fn submit_commitment_stores_valid_data() {
+		run_test_with_initialize(20, || {
+			let header = ChainBuilder::new(20).append_handoff_header(30).to_header();
+			assert_ok!(import_commitment(header.clone()));
+
+			assert_eq!(ImportedCommitmentsInfo::<TestRuntime>::get().unwrap().best_block_number, 1);
+			assert_eq!(CurrentAuthoritySetInfo::<TestRuntime>::get().id, 1);
+			assert_eq!(CurrentAuthoritySetInfo::<TestRuntime>::get().len, 30);
+			assert_eq!(
+				ImportedCommitments::<TestRuntime>::get(1).unwrap(),
+				bp_beefy::ImportedCommitment {
+					parent_number_and_hash: (0, [0; 32].into()),
+					mmr_root: header.mmr_root,
+				},
+			);
+		});
+	}
+}

bridges/primitives/beefy/Cargo.toml

@@ -0,0 +1,48 @@
+[package]
+name = "bp-beefy"
+description = "Primitives of pallet-bridge-beefy module."
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive", "bit-vec"] }
+scale-info = { version = "2.0.1", default-features = false, features = ["bit-vec", "derive"] }
+serde = { version = "1.0", optional = true }
+static_assertions = "1.1"
+
+# Bridge Dependencies
+
+bp-runtime = { path = "../runtime", default-features = false }
+
+# Substrate Dependencies
+
+beefy-merkle-tree = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+beefy-primitives = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+frame-support = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+pallet-beefy-mmr = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+pallet-mmr = { 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 }
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-io = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-std = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+
+[features]
+default = ["std"]
+std = [
+	"beefy-primitives/std",
+	"bp-runtime/std",
+	"codec/std",
+	"frame-support/std",
+	"pallet-beefy-mmr/std",
+	"pallet-mmr/std",
+	"scale-info/std",
+	"serde",
+	"sp-application-crypto/std",
+	"sp-core/std",
+	"sp-io/std",
+	"sp-runtime/std",
+	"sp-std/std"
+]

bridges/primitives/beefy/src/lib.rs

@@ -0,0 +1,152 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Primitives that are used to interact with BEEFY bridge pallet.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+#![warn(missing_docs)]
+
+pub use beefy_merkle_tree::{merkle_root, Keccak256 as BeefyKeccak256};
+pub use beefy_primitives::{
+	crypto::{AuthorityId as EcdsaValidatorId, AuthoritySignature as EcdsaValidatorSignature},
+	known_payloads::MMR_ROOT_ID as MMR_ROOT_PAYLOAD_ID,
+	mmr::{BeefyAuthoritySet, MmrLeafVersion},
+	BeefyAuthorityId, BeefyVerify, Commitment, Payload as BeefyPayload, SignedCommitment,
+	ValidatorSet, ValidatorSetId, BEEFY_ENGINE_ID,
+};
+pub use pallet_beefy_mmr::BeefyEcdsaToEthereum;
+pub use pallet_mmr::{
+	primitives::{DataOrHash as MmrDataOrHash, Proof as MmrProof},
+	verify_leaves_proof as verify_mmr_leaves_proof,
+};
+
+use bp_runtime::{BasicOperatingMode, BlockNumberOf, Chain, HashOf};
+use codec::{Decode, Encode};
+use frame_support::Parameter;
+use scale_info::TypeInfo;
+use sp_runtime::{
+	traits::{Convert, MaybeSerializeDeserialize},
+	RuntimeDebug,
+};
+use sp_std::prelude::*;
+
+/// Substrate-based chain with BEEFY && MMR pallets deployed.
+///
+/// Both BEEFY and MMR pallets and their clients may be configured to use different
+/// primitives. Some of types can be configured in low-level pallets, but are constrained
+/// when BEEFY+MMR bundle is used.
+pub trait ChainWithBeefy: Chain {
+	/// The hashing algorithm used to compute the digest of the BEEFY commitment.
+	///
+	/// Corresponds to the hashing algorithm, used by `beefy_gadget::BeefyKeystore`.
+	type CommitmentHasher: sp_runtime::traits::Hash;
+
+	/// The hashing algorithm used to build the MMR.
+	///
+	/// The same algorithm is also used to compute merkle roots in BEEFY
+	/// (e.g. validator addresses root in leaf data).
+	///
+	/// Corresponds to the `Hashing` field of the `pallet-mmr` configuration.
+	type MmrHashing: sp_runtime::traits::Hash<Output = Self::MmrHash>;
+
+	/// The output type of the hashing algorithm used to build the MMR.
+	///
+	/// This type is actually stored in the MMR.
+
+	/// Corresponds to the `Hash` field of the `pallet-mmr` configuration.
+	type MmrHash: sp_std::hash::Hash
+		+ Parameter
+		+ Copy
+		+ AsRef<[u8]>
+		+ Default
+		+ MaybeSerializeDeserialize;
+
+	/// The type expected for the MMR leaf extra data.
+	type BeefyMmrLeafExtra: Parameter;
+
+	/// A way to identify a BEEFY validator.
+	///
+	/// Corresponds to the `BeefyId` field of the `pallet-beefy` configuration.
+	type AuthorityId: BeefyAuthorityId + Parameter;
+
+	/// The signature type used by BEEFY.
+	///
+	/// Corresponds to the `BeefyId` field of the `pallet-beefy` configuration.
+	type Signature: BeefyVerify<Self::CommitmentHasher, Signer = Self::AuthorityId> + Parameter;
+
+	/// A way to convert validator id to its raw representation in the BEEFY merkle tree.
+	///
+	/// Corresponds to the `BeefyAuthorityToMerkleLeaf` field of the `pallet-beefy-mmr`
+	/// configuration.
+	type AuthorityIdToMerkleLeaf: Convert<Self::AuthorityId, Vec<u8>>;
+}
+
+/// BEEFY validator id used by given Substrate chain.
+pub type BeefyAuthorityIdOf<C> = <C as ChainWithBeefy>::AuthorityId;
+/// BEEFY validator set, containing both validator identifiers and the numeric set id.
+pub type BeefyAuthoritySetOf<C> = ValidatorSet<BeefyAuthorityIdOf<C>>;
+/// BEEFY authority set, containing both validator identifiers and the numeric set id.
+pub type BeefyAuthoritySetInfoOf<C> = beefy_primitives::mmr::BeefyAuthoritySet<MmrHashOf<C>>;
+/// BEEFY validator signature used by given Substrate chain.
+pub type BeefyValidatorSignatureOf<C> = <C as ChainWithBeefy>::Signature;
+/// Signed BEEFY commitment used by given Substrate chain.
+pub type BeefySignedCommitmentOf<C> =
+	SignedCommitment<BlockNumberOf<C>, BeefyValidatorSignatureOf<C>>;
+/// Hash algorithm, used to compute the digest of the BEEFY commitment before signing it.
+pub type BeefyCommitmentHasher<C> = <C as ChainWithBeefy>::CommitmentHasher;
+/// Hash algorithm used in Beefy MMR construction by given Substrate chain.
+pub type MmrHashingOf<C> = <C as ChainWithBeefy>::MmrHashing;
+/// Hash type, used in MMR construction by given Substrate chain.
+pub type MmrHashOf<C> = <C as ChainWithBeefy>::MmrHash;
+/// BEEFY MMR proof type used by the given Substrate chain.
+pub type MmrProofOf<C> = MmrProof<MmrHashOf<C>>;
+/// The type of the MMR leaf extra data used by the given Substrate chain.
+pub type BeefyMmrLeafExtraOf<C> = <C as ChainWithBeefy>::BeefyMmrLeafExtra;
+/// A way to convert a validator id to its raw representation in the BEEFY merkle tree, used by
+/// the given Substrate chain.
+pub type BeefyAuthorityIdToMerkleLeafOf<C> = <C as ChainWithBeefy>::AuthorityIdToMerkleLeaf;
+/// Actual type of leafs in the BEEFY MMR.
+pub type BeefyMmrLeafOf<C> = beefy_primitives::mmr::MmrLeaf<
+	BlockNumberOf<C>,
+	HashOf<C>,
+	MmrHashOf<C>,
+	BeefyMmrLeafExtraOf<C>,
+>;
+
+/// Data required for initializing the BEEFY pallet.
+///
+/// Provides the initial context that the bridge needs in order to know
+/// where to start the sync process from.
+#[derive(Encode, Decode, RuntimeDebug, PartialEq, Clone, TypeInfo)]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
+pub struct InitializationData<BlockNumber, Hash> {
+	/// Pallet operating mode.
+	pub operating_mode: BasicOperatingMode,
+	/// Number of the best block, finalized by BEEFY.
+	pub best_block_number: BlockNumber,
+	/// BEEFY authority set that will be finalizing descendants of the `best_beefy_block_number`
+	/// block.
+	pub authority_set: BeefyAuthoritySet<Hash>,
+}
+
+/// Basic data, stored by the pallet for every imported commitment.
+#[derive(Encode, Decode, RuntimeDebug, PartialEq, TypeInfo)]
+pub struct ImportedCommitment<BlockNumber, BlockHash, MmrHash> {
+	/// Block number and hash of the finalized block parent.
+	pub parent_number_and_hash: (BlockNumber, BlockHash),
+	/// MMR root at the imported block.
+	pub mmr_root: MmrHash,
+}

bridges/primitives/chain-millau/Cargo.toml

@@ -10,6 +10,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 # Bridge Dependencies
 
+bp-beefy = { path = "../beefy", default-features = false }
 bp-messages = { path = "../messages", default-features = false }
 bp-runtime = { path = "../runtime", default-features = false }
 fixed-hash = { version = "0.7.0", default-features = false }
@@ -34,6 +35,7 @@ sp-trie = { git = "https://github.com/paritytech/substrate", branch = "master",
 [features]
 default = ["std"]
 std = [
+	"bp-beefy/std",
 	"bp-messages/std",
 	"bp-runtime/std",
 	"fixed-hash/std",

bridges/primitives/chain-millau/src/lib.rs

@@ -20,6 +20,7 @@
 
 mod millau_hash;
 
+use bp_beefy::ChainWithBeefy;
 use bp_messages::{
 	InboundMessageDetails, LaneId, MessageNonce, MessagePayload, OutboundMessageDetails,
 };
@@ -41,6 +42,7 @@ use sp_trie::{LayoutV0, LayoutV1, TrieConfiguration};
 
 #[cfg(feature = "std")]
 use serde::{Deserialize, Serialize};
+use sp_runtime::traits::Keccak256;
 
 pub use millau_hash::MillauHash;
 
@@ -155,6 +157,16 @@ impl Chain for Millau {
 	}
 }
 
+impl ChainWithBeefy for Millau {
+	type CommitmentHasher = Keccak256;
+	type MmrHashing = Keccak256;
+	type MmrHash = <Keccak256 as sp_runtime::traits::Hash>::Output;
+	type BeefyMmrLeafExtra = ();
+	type AuthorityId = bp_beefy::EcdsaValidatorId;
+	type Signature = bp_beefy::EcdsaValidatorSignature;
+	type AuthorityIdToMerkleLeaf = bp_beefy::BeefyEcdsaToEthereum;
+}
+
 /// Millau Hasher (Blake2-256 ++ Keccak-256) implementation.
 #[derive(PartialEq, Eq, Clone, Copy, RuntimeDebug, TypeInfo)]
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize))]