Convert ECDSA Public Keys to EVM Addresses when building the merkle tree

pallets/dkg-metadata/Cargo.toml

@@ -37,6 +37,7 @@ sp-core = { workspace = true }
 sp-io = { workspace = true }
 sp-staking = { workspace = true }
 sp-keystore = { workspace = true }
+k256 = { version = "0.11.5", default-features = false, features = ["arithmetic", "ecdsa"] }
 
 [features]
 default = ["std"]

pallets/dkg-metadata/src/lib.rs

@@ -211,6 +211,13 @@ pub mod pallet {
 			+ Into<ecdsa::Public>
 			+ From<ecdsa::Public>
 			+ MaxEncodedLen;
+		/// Convert DKG AuthorityId to a form that would end up in the Merkle Tree.
+		///
+		/// For instance for ECDSA (secp256k1) we want to store uncompressed public keys (65 bytes)
+		/// and later to Ethereum Addresses (160 bits) to simplify using them on Ethereum chain,
+		/// but the rest of the Substrate codebase is storing them compressed (33 bytes) for
+		/// efficiency reasons.
+		type DKGAuthorityToMerkleLeaf: Convert<Self::DKGId, Vec<u8>>;
 		/// Jail lengths for misbehaviours
 		type KeygenJailSentence: Get<BlockNumberFor<Self>>;
 		type SigningJailSentence: Get<BlockNumberFor<Self>>;
@@ -1637,7 +1644,7 @@ impl<T: Config> Pallet<T> {
 		// Hash the external accounts into 32 byte chunks to form the base layer of the merkle tree
 		let mut base_layer: Vec<[u8; 32]> = voters
 			.iter()
-			.map(|account| account.to_raw_vec())
+			.map(|account| T::DKGAuthorityToMerkleLeaf::convert(account.clone()))
 			.map(|account| keccak_256(&account))
 			.collect();
 		// Pad base_layer to have length 2^height

pallets/dkg-metadata/src/mock.rs

@@ -29,8 +29,8 @@ use sp_runtime::{
 	impl_opaque_keys,
 	testing::TestXt,
 	traits::{
-		BlakeTwo256, ConvertInto, Extrinsic as ExtrinsicT, IdentifyAccount, IdentityLookup,
-		OpaqueKeys, Verify,
+		BlakeTwo256, Convert, ConvertInto, Extrinsic as ExtrinsicT, IdentifyAccount,
+		IdentityLookup, OpaqueKeys, Verify,
 	},
 	BuildStorage, Percent, Permill,
 };
@@ -141,6 +141,7 @@ parameter_types! {
 
 impl pallet_dkg_metadata::Config for Test {
 	type DKGId = DKGId;
+	type DKGAuthorityToMerkleLeaf = DKGEcdsaToEthereumAddress;
 	type RuntimeEvent = RuntimeEvent;
 	type OnAuthoritySetChangeHandler = ();
 	type OnDKGPublicKeyChangeHandler = ();
@@ -254,3 +255,23 @@ pub fn new_test_ext_raw_authorities(authorities: Vec<(AccountId, DKGId)>) -> Tes
 	ext.register_extension(KeystoreExt(Arc::new(MemoryKeystore::new()) as KeystorePtr));
 	ext
 }
+
+/// Convert DKG secp256k1 public keys into Ethereum addresses
+pub struct DKGEcdsaToEthereumAddress;
+impl Convert<dkg_runtime_primitives::crypto::AuthorityId, Vec<u8>> for DKGEcdsaToEthereumAddress {
+	fn convert(a: dkg_runtime_primitives::crypto::AuthorityId) -> Vec<u8> {
+		use k256::{ecdsa::VerifyingKey, elliptic_curve::sec1::ToEncodedPoint};
+		let _x = VerifyingKey::from_sec1_bytes(sp_core::crypto::ByteArray::as_slice(&a));
+		VerifyingKey::from_sec1_bytes(sp_core::crypto::ByteArray::as_slice(&a))
+			.map(|pub_key| {
+				// uncompress the key
+				let uncompressed = pub_key.to_encoded_point(false);
+				// convert to ETH address
+				sp_io::hashing::keccak_256(&uncompressed.as_bytes()[1..])[12..].to_vec()
+			})
+			.map_err(|_| {
+				log::error!(target: "runtime::dkg_proposals", "Invalid DKG PublicKey format!");
+			})
+			.unwrap_or_default()
+	}
+}

pallets/dkg-proposal-handler/src/mock.rs

@@ -287,6 +287,7 @@ parameter_types! {
 impl pallet_dkg_metadata::Config for Test {
 	type DKGId = DKGId;
 	type RuntimeEvent = RuntimeEvent;
+	type DKGAuthorityToMerkleLeaf = DKGEcdsaToEthereumAddress;
 	type OnAuthoritySetChangeHandler = ();
 	type OnDKGPublicKeyChangeHandler = ();
 	type OffChainAuthId = dkg_runtime_primitives::offchain::crypto::OffchainAuthId;

pallets/dkg-proposals/src/mock.rs

@@ -168,6 +168,7 @@ parameter_types! {
 
 impl pallet_dkg_metadata::Config for Test {
 	type DKGId = DKGId;
+	type DKGAuthorityToMerkleLeaf = DKGEcdsaToEthereumAddress;
 	type RuntimeEvent = RuntimeEvent;
 	type OnAuthoritySetChangeHandler = DKGProposals;
 	type OnDKGPublicKeyChangeHandler = ();

standalone/runtime/src/lib.rs

@@ -607,6 +607,7 @@ parameter_types! {
 
 impl pallet_dkg_metadata::Config for Runtime {
 	type DKGId = DKGId;
+	type DKGAuthorityToMerkleLeaf = pallet_dkg_proposals::DKGEcdsaToEthereumAddress;
 	type RuntimeEvent = RuntimeEvent;
 	type OnAuthoritySetChangeHandler = DKGProposals;
 	type OnDKGPublicKeyChangeHandler = ();