Add generate and verify logic for AncestryProof (paritytech#4430)

Extracting the logic for generating and verifying ancestry proofs from
this PR: paritytech#1903 with small
adjustments

@Lederstrumpf I added you as a co-author to each commit. Please let me
know if you want me to also associate an e-mail address with your name

bridges/primitives/beefy/src/lib.rs

@@ -22,7 +22,7 @@
 pub use binary_merkle_tree::merkle_root;
 pub use pallet_beefy_mmr::BeefyEcdsaToEthereum;
 pub use pallet_mmr::{
-	primitives::{DataOrHash as MmrDataOrHash, Proof as MmrProof},
+	primitives::{DataOrHash as MmrDataOrHash, LeafProof as MmrProof},
 	verify_leaves_proof as verify_mmr_leaves_proof,
 };
 pub use sp_consensus_beefy::{

polkadot/node/service/src/fake_runtime_api.rs

@@ -272,11 +272,11 @@ sp_api::impl_runtime_apis! {
 		fn generate_proof(
 			_: Vec<BlockNumber>,
 			_: Option<BlockNumber>,
-		) -> Result<(Vec<sp_mmr_primitives::EncodableOpaqueLeaf>, sp_mmr_primitives::Proof<Hash>), sp_mmr_primitives::Error> {
+		) -> Result<(Vec<sp_mmr_primitives::EncodableOpaqueLeaf>, sp_mmr_primitives::LeafProof<Hash>), sp_mmr_primitives::Error> {
 			unimplemented!()
 		}
 
-		fn verify_proof(_: Vec<sp_mmr_primitives::EncodableOpaqueLeaf>, _: sp_mmr_primitives::Proof<Hash>)
+		fn verify_proof(_: Vec<sp_mmr_primitives::EncodableOpaqueLeaf>, _: sp_mmr_primitives::LeafProof<Hash>)
 			-> Result<(), sp_mmr_primitives::Error>
 		{
 			unimplemented!()
@@ -285,7 +285,7 @@ sp_api::impl_runtime_apis! {
 		fn verify_proof_stateless(
 			_: Hash,
 			_: Vec<sp_mmr_primitives::EncodableOpaqueLeaf>,
-			_: sp_mmr_primitives::Proof<Hash>
+			_: sp_mmr_primitives::LeafProof<Hash>
 		) -> Result<(), sp_mmr_primitives::Error> {
 			unimplemented!()
 		}

polkadot/runtime/rococo/src/lib.rs

@@ -2134,7 +2134,7 @@ sp_api::impl_runtime_apis! {
 		fn generate_proof(
 			block_numbers: Vec<BlockNumber>,
 			best_known_block_number: Option<BlockNumber>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<mmr::Hash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::LeafProof<mmr::Hash>), mmr::Error> {
 			Mmr::generate_proof(block_numbers, best_known_block_number).map(
 				|(leaves, proof)| {
 					(
@@ -2148,7 +2148,7 @@ sp_api::impl_runtime_apis! {
 			)
 		}
 
-		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::Proof<mmr::Hash>)
+		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::LeafProof<mmr::Hash>)
 			-> Result<(), mmr::Error>
 		{
 			let leaves = leaves.into_iter().map(|leaf|
@@ -2161,7 +2161,7 @@ sp_api::impl_runtime_apis! {
 		fn verify_proof_stateless(
 			root: mmr::Hash,
 			leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			proof: mmr::Proof<mmr::Hash>
+			proof: mmr::LeafProof<mmr::Hash>
 		) -> Result<(), mmr::Error> {
 			let nodes = leaves.into_iter().map(|leaf|mmr::DataOrHash::Data(leaf.into_opaque_leaf())).collect();
 			pallet_mmr::verify_leaves_proof::<mmr::Hashing, _>(root, nodes, proof)

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

@@ -1044,11 +1044,11 @@ sp_api::impl_runtime_apis! {
 		fn generate_proof(
 			_block_numbers: Vec<BlockNumber>,
 			_best_known_block_number: Option<BlockNumber>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<Hash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::LeafProof<Hash>), mmr::Error> {
 			Err(mmr::Error::PalletNotIncluded)
 		}
 
-		fn verify_proof(_leaves: Vec<mmr::EncodableOpaqueLeaf>, _proof: mmr::Proof<Hash>)
+		fn verify_proof(_leaves: Vec<mmr::EncodableOpaqueLeaf>, _proof: mmr::LeafProof<Hash>)
 			-> Result<(), mmr::Error>
 		{
 			Err(mmr::Error::PalletNotIncluded)
@@ -1057,7 +1057,7 @@ sp_api::impl_runtime_apis! {
 		fn verify_proof_stateless(
 			_root: Hash,
 			_leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			_proof: mmr::Proof<Hash>
+			_proof: mmr::LeafProof<Hash>
 		) -> Result<(), mmr::Error> {
 			Err(mmr::Error::PalletNotIncluded)
 		}

polkadot/runtime/westend/src/lib.rs

@@ -2013,7 +2013,7 @@ sp_api::impl_runtime_apis! {
 		fn generate_proof(
 			block_numbers: Vec<BlockNumber>,
 			best_known_block_number: Option<BlockNumber>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<mmr::Hash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::LeafProof<mmr::Hash>), mmr::Error> {
 			Mmr::generate_proof(block_numbers, best_known_block_number).map(
 				|(leaves, proof)| {
 					(
@@ -2027,7 +2027,7 @@ sp_api::impl_runtime_apis! {
 			)
 		}
 
-		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::Proof<mmr::Hash>)
+		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::LeafProof<mmr::Hash>)
 			-> Result<(), mmr::Error>
 		{
 			let leaves = leaves.into_iter().map(|leaf|
@@ -2040,7 +2040,7 @@ sp_api::impl_runtime_apis! {
 		fn verify_proof_stateless(
 			root: mmr::Hash,
 			leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			proof: mmr::Proof<mmr::Hash>
+			proof: mmr::LeafProof<mmr::Hash>
 		) -> Result<(), mmr::Error> {
 			let nodes = leaves.into_iter().map(|leaf|mmr::DataOrHash::Data(leaf.into_opaque_leaf())).collect();
 			pallet_mmr::verify_leaves_proof::<mmr::Hashing, _>(root, nodes, proof)

substrate/bin/node/runtime/src/lib.rs

@@ -3094,7 +3094,7 @@ impl_runtime_apis! {
 		fn generate_proof(
 			block_numbers: Vec<BlockNumber>,
 			best_known_block_number: Option<BlockNumber>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<mmr::Hash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::LeafProof<mmr::Hash>), mmr::Error> {
 			Mmr::generate_proof(block_numbers, best_known_block_number).map(
 				|(leaves, proof)| {
 					(
@@ -3108,7 +3108,7 @@ impl_runtime_apis! {
 			)
 		}
 
-		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::Proof<mmr::Hash>)
+		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::LeafProof<mmr::Hash>)
 			-> Result<(), mmr::Error>
 		{
 			let leaves = leaves.into_iter().map(|leaf|
@@ -3121,7 +3121,7 @@ impl_runtime_apis! {
 		fn verify_proof_stateless(
 			root: mmr::Hash,
 			leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			proof: mmr::Proof<mmr::Hash>
+			proof: mmr::LeafProof<mmr::Hash>
 		) -> Result<(), mmr::Error> {
 			let nodes = leaves.into_iter().map(|leaf|mmr::DataOrHash::Data(leaf.into_opaque_leaf())).collect();
 			pallet_mmr::verify_leaves_proof::<mmr::Hashing, _>(root, nodes, proof)

substrate/client/merkle-mountain-range/rpc/src/lib.rs

@@ -36,7 +36,7 @@ use sp_core::{
 	offchain::{storage::OffchainDb, OffchainDbExt, OffchainStorage},
 	Bytes,
 };
-use sp_mmr_primitives::{Error as MmrError, Proof};
+use sp_mmr_primitives::{Error as MmrError, LeafProof};
 use sp_runtime::traits::{Block as BlockT, NumberFor};
 
 pub use sp_mmr_primitives::MmrApi as MmrRuntimeApi;
@@ -52,17 +52,17 @@ pub struct LeavesProof<BlockHash> {
 	pub block_hash: BlockHash,
 	/// SCALE-encoded vector of `LeafData`.
 	pub leaves: Bytes,
-	/// SCALE-encoded proof data. See [sp_mmr_primitives::Proof].
+	/// SCALE-encoded proof data. See [sp_mmr_primitives::LeafProof].
 	pub proof: Bytes,
 }
 
 impl<BlockHash> LeavesProof<BlockHash> {
 	/// Create new `LeavesProof` from a given vector of `Leaf` and a
-	/// [sp_mmr_primitives::Proof].
+	/// [sp_mmr_primitives::LeafProof].
 	pub fn new<Leaf, MmrHash>(
 		block_hash: BlockHash,
 		leaves: Vec<Leaf>,
-		proof: Proof<MmrHash>,
+		proof: LeafProof<MmrHash>,
 	) -> Self
 	where
 		Leaf: Encode,
@@ -258,7 +258,7 @@ mod tests {
 	fn should_serialize_leaf_proof() {
 		// given
 		let leaf = vec![1_u8, 2, 3, 4];
-		let proof = Proof {
+		let proof = LeafProof {
 			leaf_indices: vec![1],
 			leaf_count: 9,
 			items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
@@ -281,7 +281,7 @@ mod tests {
 		// given
 		let leaf_a = vec![1_u8, 2, 3, 4];
 		let leaf_b = vec![2_u8, 2, 3, 4];
-		let proof = Proof {
+		let proof = LeafProof {
 			leaf_indices: vec![1, 2],
 			leaf_count: 9,
 			items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
@@ -306,7 +306,7 @@ mod tests {
 			block_hash: H256::repeat_byte(0),
 			leaves: Bytes(vec![vec![1_u8, 2, 3, 4]].encode()),
 			proof: Bytes(
-				Proof {
+				LeafProof {
 					leaf_indices: vec![1],
 					leaf_count: 9,
 					items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
@@ -333,7 +333,7 @@ mod tests {
 			block_hash: H256::repeat_byte(0),
 			leaves: Bytes(vec![vec![1_u8, 2, 3, 4], vec![2_u8, 2, 3, 4]].encode()),
 			proof: Bytes(
-				Proof {
+				LeafProof {
 					leaf_indices: vec![1, 2],
 					leaf_count: 9,
 					items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],

substrate/client/merkle-mountain-range/src/test_utils.rs

@@ -309,11 +309,11 @@ sp_api::mock_impl_runtime_apis! {
 			&self,
 			_block_numbers: Vec<u64>,
 			_best_known_block_number: Option<u64>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<MmrHash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::LeafProof<MmrHash>), mmr::Error> {
 			Err(mmr::Error::PalletNotIncluded)
 		}
 
-		fn verify_proof(_leaves: Vec<mmr::EncodableOpaqueLeaf>, _proof: mmr::Proof<MmrHash>)
+		fn verify_proof(_leaves: Vec<mmr::EncodableOpaqueLeaf>, _proof: mmr::LeafProof<MmrHash>)
 			-> Result<(), mmr::Error>
 		{
 			Err(mmr::Error::PalletNotIncluded)
@@ -322,7 +322,7 @@ sp_api::mock_impl_runtime_apis! {
 		fn verify_proof_stateless(
 			_root: MmrHash,
 			_leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			_proof: mmr::Proof<MmrHash>
+			_proof: mmr::LeafProof<MmrHash>
 		) -> Result<(), mmr::Error> {
 			Err(mmr::Error::PalletNotIncluded)
 		}

substrate/frame/merkle-mountain-range/src/lib.rs

@@ -260,15 +260,15 @@ pub mod pallet {
 
 /// Stateless MMR proof verification for batch of leaves.
 ///
-/// This function can be used to verify received MMR [primitives::Proof] (`proof`)
+/// This function can be used to verify received MMR [primitives::LeafProof] (`proof`)
 /// for given leaves set (`leaves`) against a known MMR root hash (`root`).
 /// Note, the leaves should be sorted such that corresponding leaves and leaf indices have the
 /// same position in both the `leaves` vector and the `leaf_indices` vector contained in the
-/// [primitives::Proof].
+/// [primitives::LeafProof].
 pub fn verify_leaves_proof<H, L>(
 	root: H::Output,
 	leaves: Vec<mmr::Node<H, L>>,
-	proof: primitives::Proof<H::Output>,
+	proof: primitives::LeafProof<H::Output>,
 ) -> Result<(), primitives::Error>
 where
 	H: traits::Hash,
@@ -342,7 +342,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 	pub fn generate_proof(
 		block_numbers: Vec<BlockNumberFor<T>>,
 		best_known_block_number: Option<BlockNumberFor<T>>,
-	) -> Result<(Vec<LeafOf<T, I>>, primitives::Proof<HashOf<T, I>>), primitives::Error> {
+	) -> Result<(Vec<LeafOf<T, I>>, primitives::LeafProof<HashOf<T, I>>), primitives::Error> {
 		// check whether best_known_block_number provided, else use current best block
 		let best_known_block_number =
 			best_known_block_number.unwrap_or_else(|| <frame_system::Pallet<T>>::block_number());
@@ -362,11 +362,6 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		mmr.generate_proof(leaf_indices)
 	}
 
-	/// Return the on-chain MMR root hash.
-	pub fn mmr_root() -> HashOf<T, I> {
-		RootHash::<T, I>::get()
-	}
-
 	/// Verify MMR proof for given `leaves`.
 	///
 	/// This method is safe to use within the runtime code.
@@ -375,7 +370,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 	/// or the proof is invalid.
 	pub fn verify_leaves(
 		leaves: Vec<LeafOf<T, I>>,
-		proof: primitives::Proof<HashOf<T, I>>,
+		proof: primitives::LeafProof<HashOf<T, I>>,
 	) -> Result<(), primitives::Error> {
 		if proof.leaf_count > NumberOfLeaves::<T, I>::get() ||
 			proof.leaf_count == 0 ||
@@ -393,4 +388,37 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			Err(primitives::Error::Verify.log_debug("The proof is incorrect."))
 		}
 	}
+
+	pub fn generate_ancestry_proof(
+		prev_block_number: BlockNumberFor<T>,
+		best_known_block_number: Option<BlockNumberFor<T>>,
+	) -> Result<primitives::AncestryProof<HashOf<T, I>>, Error> {
+		// check whether best_known_block_number provided, else use current best block
+		let best_known_block_number =
+			best_known_block_number.unwrap_or_else(|| <frame_system::Pallet<T>>::block_number());
+
+		let leaf_count = Self::block_num_to_leaf_index(best_known_block_number)?.saturating_add(1);
+		let prev_leaf_count = Self::block_num_to_leaf_index(prev_block_number)?.saturating_add(1);
+
+		let mmr: ModuleMmr<mmr::storage::OffchainStorage, T, I> = mmr::Mmr::new(leaf_count);
+		mmr.generate_ancestry_proof(prev_leaf_count)
+	}
+
+	pub fn verify_ancestry_proof(
+		ancestry_proof: primitives::AncestryProof<HashOf<T, I>>,
+	) -> Result<(), Error> {
+		let mmr: ModuleMmr<mmr::storage::OffchainStorage, T, I> =
+			mmr::Mmr::new(ancestry_proof.leaf_count);
+		let is_valid = mmr.verify_ancestry_proof(ancestry_proof)?;
+		if is_valid {
+			Ok(())
+		} else {
+			Err(Error::Verify.log_debug("The ancestry proof is incorrect."))
+		}
+	}
+
+	/// Return the on-chain MMR root hash.
+	pub fn mmr_root() -> HashOf<T, I> {
+		RootHash::<T, I>::get()
+	}
 }