Adds Snowbridge to Rococo runtime (#2522)

# Description Adds Snowbridge to the Rococo bridge hub runtime. Includes config changes required in Rococo asset hub. --------- Co-authored-by: Alistair Singh <alistair.singh7@gmail.com> Co-authored-by: ron <yrong1997@gmail.com> Co-authored-by: Vincent Geddes <vincent.geddes@hey.com> Co-authored-by: claravanstaden <Cats 4 life!>
2026-05-31 00:31:02 +00:00 · 2023-12-21 18:06:36 +02:00
parent 9f5221cc2f
commit 18d53dbf91
151 changed files with 19379 additions and 149 deletions
@@ -0,0 +1,52 @@
+[package]
+name = "snowbridge-beacon-primitives"
+description = "Snowbridge Beacon Primitives"
+version = "0.0.1"
+authors = ["Snowfork <contact@snowfork.com>"]
+edition = "2021"
+license = "Apache-2.0"
+
+[dependencies]
+serde = { version = "1.0.188", optional = true, features = ["derive"] }
+hex = { version = "0.4", default-features = false }
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false }
+scale-info = { version = "2.9.0", default-features = false, features = ["derive"] }
+rlp = { version = "0.5", default-features = false }
+
+frame-support = { path = "../../../../../substrate/frame/support", default-features = false }
+frame-system = { path = "../../../../../substrate/frame/system", default-features = false }
+sp-runtime = { path = "../../../../../substrate/primitives/runtime", default-features = false }
+sp-core = { path = "../../../../../substrate/primitives/core", default-features = false }
+sp-std = { path = "../../../../../substrate/primitives/std", default-features = false }
+sp-io = { path = "../../../../../substrate/primitives/io", default-features = false }
+
+ssz_rs = { version = "0.9.0", default-features = false }
+ssz_rs_derive = { version = "0.9.0", default-features = false }
+byte-slice-cast = { version = "1.2.1", default-features = false }
+
+snowbridge-ethereum = { path = "../../primitives/ethereum", default-features = false }
+static_assertions = { version = "1.1.0" }
+milagro_bls = { git = "https://github.com/snowfork/milagro_bls", default-features = false, rev = "a6d66e4eb89015e352fb1c9f7b661ecdbb5b2176" }
+
+[dev-dependencies]
+hex-literal = { version = "0.4.1" }
+
+[features]
+default = ["std"]
+std = [
+	"byte-slice-cast/std",
+	"codec/std",
+	"frame-support/std",
+	"frame-system/std",
+	"hex/std",
+	"milagro_bls/std",
+	"rlp/std",
+	"scale-info/std",
+	"serde",
+	"snowbridge-ethereum/std",
+	"sp-core/std",
+	"sp-io/std",
+	"sp-runtime/std",
+	"sp-std/std",
+	"ssz_rs/std",
+]
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use sp_std::{convert::TryInto, prelude::*};
+use ssz_rs::{Bitvector, Deserialize};
+
+pub fn decompress_sync_committee_bits<
+	const SYNC_COMMITTEE_SIZE: usize,
+	const SYNC_COMMITTEE_BITS_SIZE: usize,
+>(
+	input: [u8; SYNC_COMMITTEE_BITS_SIZE],
+) -> [u8; SYNC_COMMITTEE_SIZE] {
+	Bitvector::<{ SYNC_COMMITTEE_SIZE }>::deserialize(&input)
+		.expect("checked statically; qed")
+		.iter()
+		.map(|bit| u8::from(bit == true))
+		.collect::<Vec<u8>>()
+		.try_into()
+		.expect("checked statically; qed")
+}
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use crate::{PublicKey, Signature};
+use codec::{Decode, Encode};
+use frame_support::{ensure, PalletError};
+pub use milagro_bls::{
+	AggregatePublicKey, AggregateSignature, PublicKey as PublicKeyPrepared,
+	Signature as SignaturePrepared,
+};
+use scale_info::TypeInfo;
+use sp_core::H256;
+use sp_runtime::RuntimeDebug;
+use sp_std::prelude::*;
+
+#[derive(Copy, Clone, Encode, Decode, Eq, PartialEq, TypeInfo, RuntimeDebug, PalletError)]
+pub enum BlsError {
+	InvalidSignature,
+	InvalidPublicKey,
+	InvalidAggregatePublicKeys,
+	SignatureVerificationFailed,
+}
+
+/// fast_aggregate_verify optimized with aggregate key subtracting absent ones.
+pub fn fast_aggregate_verify(
+	aggregate_pubkey: &PublicKeyPrepared,
+	absent_pubkeys: &Vec<PublicKeyPrepared>,
+	message: H256,
+	signature: &Signature,
+) -> Result<(), BlsError> {
+	let agg_sig = prepare_aggregate_signature(signature)?;
+	let agg_key = prepare_aggregate_pubkey_from_absent(aggregate_pubkey, absent_pubkeys)?;
+	fast_aggregate_verify_pre_aggregated(agg_sig, agg_key, message)
+}
+
+/// Decompress one public key into a point in G1.
+pub fn prepare_milagro_pubkey(pubkey: &PublicKey) -> Result<PublicKeyPrepared, BlsError> {
+	PublicKeyPrepared::from_bytes_unchecked(&pubkey.0).map_err(|_| BlsError::InvalidPublicKey)
+}
+
+/// Prepare for G1 public keys.
+pub fn prepare_g1_pubkeys(pubkeys: &[PublicKey]) -> Result<Vec<PublicKeyPrepared>, BlsError> {
+	pubkeys
+		.iter()
+		// Deserialize one public key from compressed bytes
+		.map(prepare_milagro_pubkey)
+		.collect::<Result<Vec<PublicKeyPrepared>, BlsError>>()
+}
+
+/// Prepare for G1 AggregatePublicKey.
+pub fn prepare_aggregate_pubkey(
+	pubkeys: &[PublicKeyPrepared],
+) -> Result<AggregatePublicKey, BlsError> {
+	AggregatePublicKey::into_aggregate(pubkeys).map_err(|_| BlsError::InvalidPublicKey)
+}
+
+/// Prepare for G1 AggregatePublicKey.
+pub fn prepare_aggregate_pubkey_from_absent(
+	aggregate_key: &PublicKeyPrepared,
+	absent_pubkeys: &Vec<PublicKeyPrepared>,
+) -> Result<AggregatePublicKey, BlsError> {
+	let mut aggregate_pubkey = AggregatePublicKey::from_public_key(aggregate_key);
+	if !absent_pubkeys.is_empty() {
+		let absent_aggregate_key = prepare_aggregate_pubkey(absent_pubkeys)?;
+		aggregate_pubkey.point.sub(&absent_aggregate_key.point);
+	}
+	Ok(AggregatePublicKey { point: aggregate_pubkey.point })
+}
+
+/// Prepare for G2 AggregateSignature, normally more expensive than G1 operation.
+pub fn prepare_aggregate_signature(signature: &Signature) -> Result<AggregateSignature, BlsError> {
+	Ok(AggregateSignature::from_signature(
+		&SignaturePrepared::from_bytes(&signature.0).map_err(|_| BlsError::InvalidSignature)?,
+	))
+}
+
+/// fast_aggregate_verify_pre_aggregated which is the most expensive call in beacon light client.
+pub fn fast_aggregate_verify_pre_aggregated(
+	agg_sig: AggregateSignature,
+	aggregate_key: AggregatePublicKey,
+	message: H256,
+) -> Result<(), BlsError> {
+	ensure!(
+		agg_sig.fast_aggregate_verify_pre_aggregated(&message[..], &aggregate_key),
+		BlsError::SignatureVerificationFailed
+	);
+	Ok(())
+}
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+pub const MAX_PROOF_SIZE: u32 = 20;
+
+pub const FEE_RECIPIENT_SIZE: usize = 20;
+pub const EXTRA_DATA_SIZE: usize = 32;
+pub const LOGS_BLOOM_SIZE: usize = 256;
+
+pub const PUBKEY_SIZE: usize = 48;
+pub const SIGNATURE_SIZE: usize = 96;
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+#![cfg_attr(not(feature = "std"), no_std)]
+
+pub mod bits;
+pub mod bls;
+pub mod config;
+pub mod merkle_proof;
+pub mod receipt;
+pub mod ssz;
+pub mod types;
+pub mod updates;
+
+#[cfg(feature = "std")]
+mod serde_utils;
+
+pub use types::{
+	BeaconHeader, CompactBeaconState, CompactExecutionHeader, ExecutionHeaderState,
+	ExecutionPayloadHeader, FinalizedHeaderState, Fork, ForkData, ForkVersion, ForkVersions, Mode,
+	PublicKey, Signature, SigningData, SyncAggregate, SyncCommittee, SyncCommitteePrepared,
+};
+pub use updates::{CheckpointUpdate, ExecutionHeaderUpdate, NextSyncCommitteeUpdate, Update};
+
+pub use bits::decompress_sync_committee_bits;
+pub use bls::{
+	fast_aggregate_verify, prepare_aggregate_pubkey, prepare_aggregate_pubkey_from_absent,
+	prepare_aggregate_signature, prepare_g1_pubkeys, AggregatePublicKey, AggregateSignature,
+	BlsError, PublicKeyPrepared, SignaturePrepared,
+};
+pub use merkle_proof::verify_merkle_branch;
+pub use receipt::verify_receipt_proof;
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use sp_core::H256;
+use sp_io::hashing::sha2_256;
+
+/// Specified by <https://github.com/ethereum/consensus-specs/blob/fe9c1a8cbf0c2da8a4f349efdcd77dd7ac8445c4/specs/phase0/beacon-chain.md?plain=1#L742>
+/// with improvements from <https://github.com/ethereum/consensus-specs/blob/dev/ssz/merkle-proofs.md>
+pub fn verify_merkle_branch(
+	leaf: H256,
+	branch: &[H256],
+	index: usize,
+	depth: usize,
+	root: H256,
+) -> bool {
+	// verify the proof length
+	if branch.len() != depth {
+		return false
+	}
+	// verify the computed merkle root
+	root == compute_merkle_root(leaf, branch, index)
+}
+
+fn compute_merkle_root(leaf: H256, proof: &[H256], index: usize) -> H256 {
+	let mut value: [u8; 32] = leaf.into();
+	for (i, node) in proof.iter().enumerate() {
+		let mut data = [0u8; 64];
+		if generalized_index_bit(index, i) {
+			// right node
+			data[0..32].copy_from_slice(node.as_bytes());
+			data[32..64].copy_from_slice(&value);
+			value = sha2_256(&data);
+		} else {
+			// left node
+			data[0..32].copy_from_slice(&value);
+			data[32..64].copy_from_slice(node.as_bytes());
+			value = sha2_256(&data);
+		}
+	}
+	value.into()
+}
+
+/// Spec: <https://github.com/ethereum/consensus-specs/blob/fe9c1a8cbf0c2da8a4f349efdcd77dd7ac8445c4/ssz/merkle-proofs.md#get_generalized_index_bit>
+fn generalized_index_bit(index: usize, position: usize) -> bool {
+	index & (1 << position) > 0
+}
+
+/// Spec: <https://github.com/ethereum/consensus-specs/blob/fe9c1a8cbf0c2da8a4f349efdcd77dd7ac8445c4/specs/altair/light-client/sync-protocol.md#get_subtree_index>
+pub const fn subtree_index(generalized_index: usize) -> usize {
+	generalized_index % (1 << generalized_index_length(generalized_index))
+}
+
+/// Spec: <https://github.com/ethereum/consensus-specs/blob/fe9c1a8cbf0c2da8a4f349efdcd77dd7ac8445c4/ssz/merkle-proofs.md#get_generalized_index_length>
+pub const fn generalized_index_length(generalized_index: usize) -> usize {
+	match generalized_index.checked_ilog2() {
+		Some(v) => v as usize,
+		None => panic!("checked statically; qed"),
+	}
+}
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use sp_core::H256;
+use sp_io::hashing::keccak_256;
+use sp_std::prelude::*;
+
+use snowbridge_ethereum::{mpt, Receipt};
+
+pub fn verify_receipt_proof(
+	receipts_root: H256,
+	proof: &[Vec<u8>],
+) -> Option<Result<Receipt, rlp::DecoderError>> {
+	match apply_merkle_proof(proof) {
+		Some((root, data)) if root == receipts_root => Some(rlp::decode(&data)),
+		Some((_, _)) => None,
+		None => None,
+	}
+}
+
+fn apply_merkle_proof(proof: &[Vec<u8>]) -> Option<(H256, Vec<u8>)> {
+	let mut iter = proof.iter().rev();
+	let first_bytes = match iter.next() {
+		Some(b) => b,
+		None => return None,
+	};
+	let item_to_prove: mpt::ShortNode = rlp::decode(first_bytes).ok()?;
+
+	let final_hash: Option<[u8; 32]> = iter.try_fold(keccak_256(first_bytes), |acc, x| {
+		let node: Box<dyn mpt::Node> = x.as_slice().try_into().ok()?;
+		if (*node).contains_hash(acc.into()) {
+			return Some(keccak_256(x))
+		}
+		None
+	});
+
+	final_hash.map(|hash| (hash.into(), item_to_prove.value))
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use hex_literal::hex;
+
+	#[test]
+	fn test_verify_receipt_proof() {
+		let root: H256 =
+			hex!("fd5e397a84884641f53c496804f24b5276cbb8c5c9cfc2342246be8e3ce5ad02").into();
+
+		// Valid proof
+		let proof_receipt5 = vec!(
+			hex!("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").to_vec(),
+			hex!("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").to_vec(),
+			hex!("f904de20b904daf904d701830652f0b9010004200000000000000000000080020000000000010000000000010000000000000000000000000000000000000000000002000000080000000000000000200000000000000000000000000008000000220000000000400010000000000000000000000000000000000000000000000000000000000000040000000010000100000000000800000000004000000000000000000000000000080000004000000000020000000000020000000000000000000000000000000000000000000004000000000002000000000100000000000000000000000000001000000002000020000010200000000000010000000000000000000000000000000000000010000000f903ccf89b9421130f34829b4c343142047a28ce96ec07814b15f863a0ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3efa00000000000000000000000007d843005c7433c16b27ff939cb37471541561ebda0000000000000000000000000e9c1281aae66801fa35ec404d5f2aea393ff6988a000000000000000000000000000000000000000000000000000000005d09b7380f89b9421130f34829b4c343142047a28ce96ec07814b15f863a08c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925a00000000000000000000000007d843005c7433c16b27ff939cb37471541561ebda00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da0ffffffffffffffffffffffffffffffffffffffffffffffffffffffcc840c6920f89b94c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2f863a0ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3efa0000000000000000000000000e9c1281aae66801fa35ec404d5f2aea393ff6988a00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da000000000000000000000000000000000000000000000000003e973b5a5d1078ef87994e9c1281aae66801fa35ec404d5f2aea393ff6988e1a01c411e9a96e071241c2f21f7726b17ae89e3cab4c78be50e062b03a9fffbbad1b840000000000000000000000000000000000000000000000000000001f1420ad1d40000000000000000000000000000000000000000000000014ad400879d159a38f8fc94e9c1281aae66801fa35ec404d5f2aea393ff6988f863a0d78ad95fa46c994b6551d0da85fc275fe613ce37657fb8d5e3d130840159d822a00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488db88000000000000000000000000000000000000000000000000000000005d415f3320000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003e973b5a5d1078ef87a94c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2f842a07fcf532c15f0a6db0bd6d0e038bea71d30d808c7d98cb3bf7268a95bf5081b65a00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da000000000000000000000000000000000000000000000000003e973b5a5d1078e").to_vec(),
+		);
+		assert!(verify_receipt_proof(root, &proof_receipt5).is_some());
+
+		// Various invalid proofs
+		let proof_empty: Vec<Vec<u8>> = vec![];
+		let proof_missing_full_node = vec![proof_receipt5[0].clone(), proof_receipt5[2].clone()];
+		let proof_missing_short_node1 = vec![proof_receipt5[0].clone(), proof_receipt5[1].clone()];
+		let proof_missing_short_node2 = vec![proof_receipt5[0].clone()];
+		let proof_invalid_encoding = vec![proof_receipt5[2][2..].to_vec()];
+		let proof_no_full_node = vec![proof_receipt5[2].clone(), proof_receipt5[2].clone()];
+		assert!(verify_receipt_proof(root, &proof_empty).is_none());
+		assert!(verify_receipt_proof(root, &proof_missing_full_node).is_none());
+
+		assert_eq!(
+			verify_receipt_proof(root, &proof_missing_short_node1),
+			Some(Err(rlp::DecoderError::Custom("Unsupported receipt type")))
+		);
+
+		assert_eq!(
+			verify_receipt_proof(root, &proof_missing_short_node2),
+			Some(Err(rlp::DecoderError::Custom("Unsupported receipt type")))
+		);
+
+		assert!(verify_receipt_proof(root, &proof_invalid_encoding).is_none());
+		assert!(verify_receipt_proof(root, &proof_no_full_node).is_none());
+	}
+
+	#[test]
+	fn test_verify_receipt_proof_with_intermediate_short_node() {
+		let root: H256 =
+			hex!("d128e3a57142d2bf15bc0cbcac7ad54f40750d571b5c3097e425882c10c9ba66").into();
+
+		let proof_receipt263 = vec![
+			hex!("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").to_vec(),
+			hex!("f871a0246de222036ee6a03329b0105da0a6b3f916fc95a9ed5a403a581a0c4d74242ca0ac108a49a88b57a05ac34a108b39f1e45f6f167f2b9fbc8d52fb58e2e5a6af1ea0fcfe07ac2ccd3c28b6eab68d1bce112f6f6dbd9023e4ec3c05b96615aa803d798080808080808080808080808080").to_vec(),
+			hex!("e4820001a04fff54398cad4d05ea6abfd8b0f3b4fe14c04d7ff5f5211c5b927d9cf72ac1d8").to_vec(),
+			hex!("f851a096d010643ca2d47412ca66898286b5f2412963b9ec051b33e570d575914c9c5ca028cd24c652989542fe89479ec6388eac4592432242af5ba97563b3ac7c71c019808080808080808080808080808080").to_vec(),
+			hex!("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").to_vec(),
+			hex!("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").to_vec(),
+		];
+		assert!(verify_receipt_proof(root, &proof_receipt263).is_some());
+	}
+}
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use sp_core::U256;
+
+use core::fmt::Formatter;
+use serde::{Deserialize, Deserializer};
+
+// helper to deserialize arbitrary arrays like [T; N]
+pub mod arrays {
+	use std::{convert::TryInto, marker::PhantomData};
+
+	use serde::{
+		de::{SeqAccess, Visitor},
+		ser::SerializeTuple,
+		Deserialize, Deserializer, Serialize, Serializer,
+	};
+
+	pub fn serialize<S: Serializer, T: Serialize, const N: usize>(
+		data: &[T; N],
+		ser: S,
+	) -> Result<S::Ok, S::Error> {
+		let mut s = ser.serialize_tuple(N)?;
+		for item in data {
+			s.serialize_element(item)?;
+		}
+		s.end()
+	}
+
+	struct ArrayVisitor<T, const N: usize>(PhantomData<T>);
+
+	impl<'de, T, const N: usize> Visitor<'de> for ArrayVisitor<T, N>
+	where
+		T: Deserialize<'de>,
+	{
+		type Value = [T; N];
+
+		fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+			formatter.write_str(&format!("an array of length {}", N))
+		}
+
+		#[inline]
+		fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+		where
+			A: SeqAccess<'de>,
+		{
+			// can be optimized using MaybeUninit
+			let mut data = Vec::with_capacity(N);
+			for _ in 0..N {
+				match (seq.next_element())? {
+					Some(val) => data.push(val),
+					None => return Err(serde::de::Error::invalid_length(N, &self)),
+				}
+			}
+			match data.try_into() {
+				Ok(arr) => Ok(arr),
+				Err(_) => unreachable!(),
+			}
+		}
+	}
+
+	pub fn deserialize<'de, D, T, const N: usize>(deserializer: D) -> Result<[T; N], D::Error>
+	where
+		D: Deserializer<'de>,
+		T: Deserialize<'de>,
+	{
+		deserializer.deserialize_tuple(N, ArrayVisitor::<T, N>(PhantomData))
+	}
+}
+
+pub(crate) fn from_hex_to_bytes<'de, D>(deserializer: D) -> Result<Vec<u8>, D::Error>
+where
+	D: Deserializer<'de>,
+{
+	let s = String::deserialize(deserializer)?;
+
+	let str_without_0x = match s.strip_prefix("0x") {
+		Some(val) => val,
+		None => &s,
+	};
+
+	let hex_bytes = match hex::decode(str_without_0x) {
+		Ok(bytes) => bytes,
+		Err(e) => return Err(serde::de::Error::custom(e.to_string())),
+	};
+
+	Ok(hex_bytes)
+}
+
+pub(crate) fn from_int_to_u256<'de, D>(deserializer: D) -> Result<U256, D::Error>
+where
+	D: Deserializer<'de>,
+{
+	let number = u128::deserialize(deserializer)?;
+
+	Ok(U256::from(number))
+}
+
+pub struct HexVisitor<const LENGTH: usize>();
+
+impl<'de, const LENGTH: usize> serde::de::Visitor<'de> for HexVisitor<LENGTH> {
+	type Value = [u8; LENGTH];
+
+	fn expecting(&self, formatter: &mut Formatter) -> sp_std::fmt::Result {
+		formatter.write_str("a hex string with an '0x' prefix")
+	}
+
+	fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+	where
+		E: serde::de::Error,
+	{
+		let stripped = match v.strip_prefix("0x") {
+			Some(stripped) => stripped,
+			None => v,
+		};
+
+		let decoded = match hex::decode(stripped) {
+			Ok(decoded) => decoded,
+			Err(e) => return Err(serde::de::Error::custom(e.to_string())),
+		};
+		if decoded.len() != LENGTH {
+			return Err(serde::de::Error::custom("publickey expected to be 48 characters"))
+		}
+
+		let data: Self::Value = decoded
+			.try_into()
+			.map_err(|_e| serde::de::Error::custom("hex data has unexpected length"))?;
+
+		Ok(data)
+	}
+}
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use crate::{
+	config::{EXTRA_DATA_SIZE, FEE_RECIPIENT_SIZE, LOGS_BLOOM_SIZE, PUBKEY_SIZE, SIGNATURE_SIZE},
+	types::{
+		BeaconHeader, ExecutionPayloadHeader, ForkData, SigningData, SyncAggregate, SyncCommittee,
+	},
+};
+use byte_slice_cast::AsByteSlice;
+use sp_core::H256;
+use sp_std::{vec, vec::Vec};
+use ssz_rs::{
+	prelude::{List, Vector},
+	Bitvector, Deserialize, DeserializeError, SimpleSerialize, SimpleSerializeError, Sized, U256,
+};
+use ssz_rs_derive::SimpleSerialize as SimpleSerializeDerive;
+
+#[derive(Default, SimpleSerializeDerive, Clone, Debug)]
+pub struct SSZBeaconBlockHeader {
+	pub slot: u64,
+	pub proposer_index: u64,
+	pub parent_root: [u8; 32],
+	pub state_root: [u8; 32],
+	pub body_root: [u8; 32],
+}
+
+impl From<BeaconHeader> for SSZBeaconBlockHeader {
+	fn from(beacon_header: BeaconHeader) -> Self {
+		SSZBeaconBlockHeader {
+			slot: beacon_header.slot,
+			proposer_index: beacon_header.proposer_index,
+			parent_root: beacon_header.parent_root.to_fixed_bytes(),
+			state_root: beacon_header.state_root.to_fixed_bytes(),
+			body_root: beacon_header.body_root.to_fixed_bytes(),
+		}
+	}
+}
+
+#[derive(Default, SimpleSerializeDerive, Clone)]
+pub struct SSZSyncCommittee<const COMMITTEE_SIZE: usize> {
+	pub pubkeys: Vector<Vector<u8, PUBKEY_SIZE>, COMMITTEE_SIZE>,
+	pub aggregate_pubkey: Vector<u8, PUBKEY_SIZE>,
+}
+
+impl<const COMMITTEE_SIZE: usize> From<SyncCommittee<COMMITTEE_SIZE>>
+	for SSZSyncCommittee<COMMITTEE_SIZE>
+{
+	fn from(sync_committee: SyncCommittee<COMMITTEE_SIZE>) -> Self {
+		let mut pubkeys_vec = Vec::new();
+
+		for pubkey in sync_committee.pubkeys.iter() {
+			// The only thing that can go wrong in the conversion from vec to Vector (ssz type) is
+			// that the Vector size is 0, or that the given data to create the Vector from does not
+			// match the expected size N. Because these sizes are statically checked (i.e.
+			// PublicKey's size is 48, and const PUBKEY_SIZE is 48, it is impossible for "try_from"
+			// to return an error condition.
+			let conv_pubkey = Vector::<u8, PUBKEY_SIZE>::try_from(pubkey.0.to_vec())
+				.expect("checked statically; qed");
+
+			pubkeys_vec.push(conv_pubkey);
+		}
+
+		let pubkeys = Vector::<Vector<u8, PUBKEY_SIZE>, { COMMITTEE_SIZE }>::try_from(pubkeys_vec)
+			.expect("checked statically; qed");
+
+		let aggregate_pubkey =
+			Vector::<u8, PUBKEY_SIZE>::try_from(sync_committee.aggregate_pubkey.0.to_vec())
+				.expect("checked statically; qed");
+
+		SSZSyncCommittee { pubkeys, aggregate_pubkey }
+	}
+}
+
+#[derive(Default, Debug, SimpleSerializeDerive, Clone)]
+pub struct SSZSyncAggregate<const COMMITTEE_SIZE: usize> {
+	pub sync_committee_bits: Bitvector<COMMITTEE_SIZE>,
+	pub sync_committee_signature: Vector<u8, SIGNATURE_SIZE>,
+}
+
+impl<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize>
+	From<SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>> for SSZSyncAggregate<COMMITTEE_SIZE>
+{
+	fn from(sync_aggregate: SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>) -> Self {
+		SSZSyncAggregate {
+			sync_committee_bits: Bitvector::<COMMITTEE_SIZE>::deserialize(
+				&sync_aggregate.sync_committee_bits,
+			)
+			.expect("checked statically; qed"),
+			sync_committee_signature: Vector::<u8, SIGNATURE_SIZE>::try_from(
+				sync_aggregate.sync_committee_signature.0.to_vec(),
+			)
+			.expect("checked statically; qed"),
+		}
+	}
+}
+
+#[derive(Default, SimpleSerializeDerive, Clone)]
+pub struct SSZForkData {
+	pub current_version: [u8; 4],
+	pub genesis_validators_root: [u8; 32],
+}
+
+impl From<ForkData> for SSZForkData {
+	fn from(fork_data: ForkData) -> Self {
+		SSZForkData {
+			current_version: fork_data.current_version,
+			genesis_validators_root: fork_data.genesis_validators_root,
+		}
+	}
+}
+
+#[derive(Default, SimpleSerializeDerive, Clone)]
+pub struct SSZSigningData {
+	pub object_root: [u8; 32],
+	pub domain: [u8; 32],
+}
+
+impl From<SigningData> for SSZSigningData {
+	fn from(signing_data: SigningData) -> Self {
+		SSZSigningData {
+			object_root: signing_data.object_root.into(),
+			domain: signing_data.domain.into(),
+		}
+	}
+}
+
+#[derive(Default, SimpleSerializeDerive, Clone, Debug)]
+pub struct SSZExecutionPayloadHeader {
+	pub parent_hash: [u8; 32],
+	pub fee_recipient: Vector<u8, FEE_RECIPIENT_SIZE>,
+	pub state_root: [u8; 32],
+	pub receipts_root: [u8; 32],
+	pub logs_bloom: Vector<u8, LOGS_BLOOM_SIZE>,
+	pub prev_randao: [u8; 32],
+	pub block_number: u64,
+	pub gas_limit: u64,
+	pub gas_used: u64,
+	pub timestamp: u64,
+	pub extra_data: List<u8, EXTRA_DATA_SIZE>,
+	pub base_fee_per_gas: U256,
+	pub block_hash: [u8; 32],
+	pub transactions_root: [u8; 32],
+	pub withdrawals_root: [u8; 32],
+}
+
+impl TryFrom<ExecutionPayloadHeader> for SSZExecutionPayloadHeader {
+	type Error = SimpleSerializeError;
+
+	fn try_from(payload: ExecutionPayloadHeader) -> Result<Self, Self::Error> {
+		Ok(SSZExecutionPayloadHeader {
+			parent_hash: payload.parent_hash.to_fixed_bytes(),
+			fee_recipient: Vector::<u8, FEE_RECIPIENT_SIZE>::try_from(
+				payload.fee_recipient.to_fixed_bytes().to_vec(),
+			)
+			.expect("checked statically; qed"),
+			state_root: payload.state_root.to_fixed_bytes(),
+			receipts_root: payload.receipts_root.to_fixed_bytes(),
+			// Logs bloom bytes size is not constrained, so here we do need to check the try_from
+			// error
+			logs_bloom: Vector::<u8, LOGS_BLOOM_SIZE>::try_from(payload.logs_bloom)
+				.map_err(|(_, err)| err)?,
+			prev_randao: payload.prev_randao.to_fixed_bytes(),
+			block_number: payload.block_number,
+			gas_limit: payload.gas_limit,
+			gas_used: payload.gas_used,
+			timestamp: payload.timestamp,
+			// Extra data bytes size is not constrained, so here we do need to check the try_from
+			// error
+			extra_data: List::<u8, EXTRA_DATA_SIZE>::try_from(payload.extra_data)
+				.map_err(|(_, err)| err)?,
+			base_fee_per_gas: U256::from_bytes_le(
+				payload
+					.base_fee_per_gas
+					.as_byte_slice()
+					.try_into()
+					.expect("checked in prep; qed"),
+			),
+			block_hash: payload.block_hash.to_fixed_bytes(),
+			transactions_root: payload.transactions_root.to_fixed_bytes(),
+			withdrawals_root: payload.withdrawals_root.to_fixed_bytes(),
+		})
+	}
+}
+
+pub fn hash_tree_root<T: SimpleSerialize>(mut object: T) -> Result<H256, SimpleSerializeError> {
+	match object.hash_tree_root() {
+		Ok(node) => {
+			let fixed_bytes: [u8; 32] =
+				node.as_ref().try_into().expect("Node is a newtype over [u8; 32]; qed");
+			Ok(fixed_bytes.into())
+		},
+		Err(err) => Err(err.into()),
+	}
+}
@@ -0,0 +1,512 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use codec::{Decode, Encode, MaxEncodedLen};
+use frame_support::{CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound};
+use scale_info::TypeInfo;
+use sp_core::{H160, H256, U256};
+use sp_runtime::RuntimeDebug;
+use sp_std::{boxed::Box, prelude::*};
+
+use crate::config::{PUBKEY_SIZE, SIGNATURE_SIZE};
+
+#[cfg(feature = "std")]
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+#[cfg(feature = "std")]
+use crate::serde_utils::HexVisitor;
+
+use crate::ssz::{
+	hash_tree_root, SSZBeaconBlockHeader, SSZExecutionPayloadHeader, SSZForkData, SSZSigningData,
+	SSZSyncAggregate, SSZSyncCommittee,
+};
+use ssz_rs::SimpleSerializeError;
+
+pub use crate::bits::decompress_sync_committee_bits;
+
+use crate::bls::{prepare_g1_pubkeys, prepare_milagro_pubkey, BlsError};
+use milagro_bls::PublicKey as PublicKeyPrepared;
+
+pub type ValidatorIndex = u64;
+pub type ForkVersion = [u8; 4];
+
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct ForkVersions {
+	pub genesis: Fork,
+	pub altair: Fork,
+	pub bellatrix: Fork,
+	pub capella: Fork,
+}
+
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Fork {
+	pub version: [u8; 4],
+	pub epoch: u64,
+}
+
+#[derive(Copy, Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct PublicKey(pub [u8; PUBKEY_SIZE]);
+
+impl Default for PublicKey {
+	fn default() -> Self {
+		PublicKey([0u8; PUBKEY_SIZE])
+	}
+}
+
+impl From<[u8; PUBKEY_SIZE]> for PublicKey {
+	fn from(v: [u8; PUBKEY_SIZE]) -> Self {
+		Self(v)
+	}
+}
+
+impl MaxEncodedLen for PublicKey {
+	fn max_encoded_len() -> usize {
+		PUBKEY_SIZE
+	}
+}
+
+#[cfg(feature = "std")]
+impl<'de> Deserialize<'de> for PublicKey {
+	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+	where
+		D: Deserializer<'de>,
+	{
+		deserializer.deserialize_str(HexVisitor::<PUBKEY_SIZE>()).map(|v| v.into())
+	}
+}
+
+#[cfg(feature = "std")]
+impl Serialize for PublicKey {
+	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+	where
+		S: Serializer,
+	{
+		serializer.serialize_bytes(&self.0)
+	}
+}
+
+#[derive(Copy, Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Signature(pub [u8; SIGNATURE_SIZE]);
+
+impl Default for Signature {
+	fn default() -> Self {
+		Signature([0u8; SIGNATURE_SIZE])
+	}
+}
+
+impl From<[u8; SIGNATURE_SIZE]> for Signature {
+	fn from(v: [u8; SIGNATURE_SIZE]) -> Self {
+		Self(v)
+	}
+}
+
+#[cfg(feature = "std")]
+impl<'de> Deserialize<'de> for Signature {
+	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+	where
+		D: Deserializer<'de>,
+	{
+		deserializer.deserialize_str(HexVisitor::<SIGNATURE_SIZE>()).map(|v| v.into())
+	}
+}
+
+#[derive(Copy, Clone, Default, Encode, Decode, TypeInfo, MaxEncodedLen)]
+pub struct ExecutionHeaderState {
+	pub beacon_block_root: H256,
+	pub beacon_slot: u64,
+	pub block_hash: H256,
+	pub block_number: u64,
+}
+
+#[derive(Copy, Clone, Default, Encode, Decode, TypeInfo, MaxEncodedLen)]
+pub struct FinalizedHeaderState {
+	pub beacon_block_root: H256,
+	pub beacon_slot: u64,
+}
+
+#[derive(Clone, Default, Encode, Decode, PartialEq, RuntimeDebug)]
+pub struct ForkData {
+	// 1 or 0 bit, indicates whether a sync committee participated in a vote
+	pub current_version: [u8; 4],
+	pub genesis_validators_root: [u8; 32],
+}
+
+impl ForkData {
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZForkData>(self.clone().into())
+	}
+}
+
+#[derive(Clone, Default, Encode, Decode, PartialEq, RuntimeDebug)]
+pub struct SigningData {
+	pub object_root: H256,
+	pub domain: H256,
+}
+
+impl SigningData {
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZSigningData>(self.clone().into())
+	}
+}
+
+/// Sync committee as it is stored in the runtime storage.
+#[derive(
+	Encode, Decode, PartialEqNoBound, CloneNoBound, RuntimeDebugNoBound, TypeInfo, MaxEncodedLen,
+)]
+#[cfg_attr(
+	feature = "std",
+	derive(Serialize, Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+#[codec(mel_bound())]
+pub struct SyncCommittee<const COMMITTEE_SIZE: usize> {
+	#[cfg_attr(feature = "std", serde(with = "crate::serde_utils::arrays"))]
+	pub pubkeys: [PublicKey; COMMITTEE_SIZE],
+	pub aggregate_pubkey: PublicKey,
+}
+
+impl<const COMMITTEE_SIZE: usize> Default for SyncCommittee<COMMITTEE_SIZE> {
+	fn default() -> Self {
+		SyncCommittee {
+			pubkeys: [Default::default(); COMMITTEE_SIZE],
+			aggregate_pubkey: Default::default(),
+		}
+	}
+}
+
+impl<const COMMITTEE_SIZE: usize> SyncCommittee<COMMITTEE_SIZE> {
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZSyncCommittee<COMMITTEE_SIZE>>(self.clone().into())
+	}
+}
+
+/// Prepared G1 public key of sync committee as it is stored in the runtime storage.
+#[derive(Clone, PartialEq, Eq, Encode, Decode, TypeInfo, MaxEncodedLen)]
+pub struct SyncCommitteePrepared<const COMMITTEE_SIZE: usize> {
+	pub root: H256,
+	pub pubkeys: Box<[PublicKeyPrepared; COMMITTEE_SIZE]>,
+	pub aggregate_pubkey: PublicKeyPrepared,
+}
+
+impl<const COMMITTEE_SIZE: usize> Default for SyncCommitteePrepared<COMMITTEE_SIZE> {
+	fn default() -> Self {
+		SyncCommitteePrepared {
+			root: H256::default(),
+			pubkeys: Box::new([PublicKeyPrepared::default(); COMMITTEE_SIZE]),
+			aggregate_pubkey: PublicKeyPrepared::default(),
+		}
+	}
+}
+
+impl<const COMMITTEE_SIZE: usize> TryFrom<&SyncCommittee<COMMITTEE_SIZE>>
+	for SyncCommitteePrepared<COMMITTEE_SIZE>
+{
+	type Error = BlsError;
+
+	fn try_from(sync_committee: &SyncCommittee<COMMITTEE_SIZE>) -> Result<Self, Self::Error> {
+		let g1_pubkeys = prepare_g1_pubkeys(&sync_committee.pubkeys)?;
+		let sync_committee_root = sync_committee.hash_tree_root().expect("checked statically; qed");
+
+		Ok(SyncCommitteePrepared::<COMMITTEE_SIZE> {
+			pubkeys: g1_pubkeys.try_into().expect("checked statically; qed"),
+			aggregate_pubkey: prepare_milagro_pubkey(&sync_committee.aggregate_pubkey)?,
+			root: sync_committee_root,
+		})
+	}
+}
+
+/// Beacon block header as it is stored in the runtime storage. The block root is the
+/// Merkleization of a BeaconHeader.
+#[derive(
+	Copy, Clone, Default, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo, MaxEncodedLen,
+)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct BeaconHeader {
+	// The slot for which this block is created. Must be greater than the slot of the block defined
+	// by parent root.
+	pub slot: u64,
+	// The index of the validator that proposed the block.
+	pub proposer_index: ValidatorIndex,
+	// The block root of the parent block, forming a block chain.
+	pub parent_root: H256,
+	// The hash root of the post state of running the state transition through this block.
+	pub state_root: H256,
+	// The hash root of the beacon block body
+	pub body_root: H256,
+}
+
+impl BeaconHeader {
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZBeaconBlockHeader>((*self).into())
+	}
+}
+
+#[derive(Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo)]
+#[cfg_attr(
+	feature = "std",
+	derive(Deserialize),
+	serde(
+		try_from = "IntermediateSyncAggregate",
+		deny_unknown_fields,
+		bound(serialize = ""),
+		bound(deserialize = "")
+	)
+)]
+#[codec(mel_bound())]
+pub struct SyncAggregate<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize> {
+	pub sync_committee_bits: [u8; COMMITTEE_BITS_SIZE],
+	pub sync_committee_signature: Signature,
+}
+
+impl<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize> Default
+	for SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>
+{
+	fn default() -> Self {
+		SyncAggregate {
+			sync_committee_bits: [0; COMMITTEE_BITS_SIZE],
+			sync_committee_signature: Default::default(),
+		}
+	}
+}
+
+impl<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize>
+	SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>
+{
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZSyncAggregate<COMMITTEE_SIZE>>(self.clone().into())
+	}
+}
+
+/// Serde deserialization helper for SyncAggregate
+#[cfg(feature = "std")]
+#[derive(Deserialize)]
+struct IntermediateSyncAggregate {
+	#[cfg_attr(feature = "std", serde(deserialize_with = "crate::serde_utils::from_hex_to_bytes"))]
+	pub sync_committee_bits: Vec<u8>,
+	pub sync_committee_signature: Signature,
+}
+
+#[cfg(feature = "std")]
+impl<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize>
+	TryFrom<IntermediateSyncAggregate> for SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>
+{
+	type Error = String;
+
+	fn try_from(other: IntermediateSyncAggregate) -> Result<Self, Self::Error> {
+		Ok(Self {
+			sync_committee_bits: other
+				.sync_committee_bits
+				.try_into()
+				.map_err(|_| "unexpected length".to_owned())?,
+			sync_committee_signature: other.sync_committee_signature,
+		})
+	}
+}
+
+/// ExecutionPayloadHeader
+/// <https://github.com/ethereum/annotated-spec/blob/master/capella/beacon-chain.md#executionpayloadheader>
+#[derive(
+	Default, Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo,
+)]
+#[cfg_attr(
+	feature = "std",
+	derive(Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+#[codec(mel_bound())]
+pub struct ExecutionPayloadHeader {
+	pub parent_hash: H256,
+	pub fee_recipient: H160,
+	pub state_root: H256,
+	pub receipts_root: H256,
+	#[cfg_attr(feature = "std", serde(deserialize_with = "crate::serde_utils::from_hex_to_bytes"))]
+	pub logs_bloom: Vec<u8>,
+	pub prev_randao: H256,
+	pub block_number: u64,
+	pub gas_limit: u64,
+	pub gas_used: u64,
+	pub timestamp: u64,
+	#[cfg_attr(feature = "std", serde(deserialize_with = "crate::serde_utils::from_hex_to_bytes"))]
+	pub extra_data: Vec<u8>,
+	#[cfg_attr(feature = "std", serde(deserialize_with = "crate::serde_utils::from_int_to_u256"))]
+	pub base_fee_per_gas: U256,
+	pub block_hash: H256,
+	pub transactions_root: H256,
+	pub withdrawals_root: H256,
+}
+
+impl ExecutionPayloadHeader {
+	pub fn hash_tree_root(&self) -> Result<H256, SimpleSerializeError> {
+		hash_tree_root::<SSZExecutionPayloadHeader>(self.clone().try_into()?)
+	}
+}
+
+#[derive(
+	Default,
+	Encode,
+	Decode,
+	CloneNoBound,
+	PartialEqNoBound,
+	RuntimeDebugNoBound,
+	TypeInfo,
+	MaxEncodedLen,
+)]
+pub struct CompactExecutionHeader {
+	pub parent_hash: H256,
+	#[codec(compact)]
+	pub block_number: u64,
+	pub state_root: H256,
+	pub receipts_root: H256,
+}
+
+impl From<ExecutionPayloadHeader> for CompactExecutionHeader {
+	fn from(execution_payload: ExecutionPayloadHeader) -> Self {
+		Self {
+			parent_hash: execution_payload.parent_hash,
+			block_number: execution_payload.block_number,
+			state_root: execution_payload.state_root,
+			receipts_root: execution_payload.receipts_root,
+		}
+	}
+}
+
+#[derive(
+	Default,
+	Encode,
+	Decode,
+	Copy,
+	Clone,
+	PartialEqNoBound,
+	RuntimeDebugNoBound,
+	TypeInfo,
+	MaxEncodedLen,
+)]
+pub struct CompactBeaconState {
+	#[codec(compact)]
+	pub slot: u64,
+	pub block_roots_root: H256,
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use hex_literal::hex;
+
+	#[test]
+	pub fn test_hash_beacon_header1() {
+		let hash_root = BeaconHeader {
+			slot: 3,
+			proposer_index: 2,
+			parent_root: hex!("796ea53efb534eab7777809cc5ee2d84e7f25024b9d0c4d7e5bcaab657e4bdbd")
+				.into(),
+			state_root: hex!("ba3ff080912be5c9c158b2e962c1b39a91bc0615762ba6fa2ecacafa94e9ae0a")
+				.into(),
+			body_root: hex!("a18d7fcefbb74a177c959160e0ee89c23546482154e6831237710414465dcae5")
+				.into(),
+		}
+		.hash_tree_root();
+
+		assert!(hash_root.is_ok());
+		assert_eq!(
+			hash_root.unwrap(),
+			hex!("7d42595818709e805dd2fa710a2d2c1f62576ef1ab7273941ac9130fb94b91f7").into()
+		);
+	}
+
+	#[test]
+	pub fn test_hash_beacon_header2() {
+		let hash_root = BeaconHeader {
+			slot: 3476424,
+			proposer_index: 314905,
+			parent_root: hex!("c069d7b49cffd2b815b0fb8007eb9ca91202ea548df6f3db60000f29b2489f28")
+				.into(),
+			state_root: hex!("444d293e4533501ee508ad608783a7d677c3c566f001313e8a02ce08adf590a3")
+				.into(),
+			body_root: hex!("6508a0241047f21ba88f05d05b15534156ab6a6f8e029a9a5423da429834e04a")
+				.into(),
+		}
+		.hash_tree_root();
+
+		assert!(hash_root.is_ok());
+		assert_eq!(
+			hash_root.unwrap(),
+			hex!("0aa41166ff01e58e111ac8c42309a738ab453cf8d7285ed8477b1c484acb123e").into()
+		);
+	}
+
+	#[test]
+	pub fn test_hash_fork_data() {
+		let hash_root = ForkData {
+			current_version: hex!("83f38a34"),
+			genesis_validators_root: hex!(
+				"22370bbbb358800f5711a10ea9845284272d8493bed0348cab87b8ab1e127930"
+			),
+		}
+		.hash_tree_root();
+
+		assert!(hash_root.is_ok());
+		assert_eq!(
+			hash_root.unwrap(),
+			hex!("57c12c4246bc7152b174b51920506bf943eff9c7ffa50b9533708e9cc1f680fc").into()
+		);
+	}
+
+	#[test]
+	pub fn test_hash_signing_data() {
+		let hash_root = SigningData {
+			object_root: hex!("63654cbe64fc07853f1198c165dd3d49c54fc53bc417989bbcc66da15f850c54")
+				.into(),
+			domain: hex!("037da907d1c3a03c0091b2254e1480d9b1783476e228ab29adaaa8f133e08f7a").into(),
+		}
+		.hash_tree_root();
+
+		assert!(hash_root.is_ok());
+		assert_eq!(
+			hash_root.unwrap(),
+			hex!("b9eb2caf2d691b183c2d57f322afe505c078cd08101324f61c3641714789a54e").into()
+		);
+	}
+
+	#[test]
+	pub fn test_hash_sync_aggregate() {
+		let hash_root = SyncAggregate::<512, 64>{
+				sync_committee_bits: hex!("cefffffefffffff767fffbedffffeffffeeffdffffdebffffff7f7dbdf7fffdffffbffcfffdff79dfffbbfefff2ffffff7ddeff7ffffc98ff7fbfffffffffff7"),
+				sync_committee_signature: hex!("8af1a8577bba419fe054ee49b16ed28e081dda6d3ba41651634685e890992a0b675e20f8d9f2ec137fe9eb50e838aa6117f9f5410e2e1024c4b4f0e098e55144843ce90b7acde52fe7b94f2a1037342c951dc59f501c92acf7ed944cb6d2b5f7").into(),
+		}.hash_tree_root();
+
+		assert!(hash_root.is_ok());
+		assert_eq!(
+			hash_root.unwrap(),
+			hex!("e6dcad4f60ce9ff8a587b110facbaf94721f06cd810b6d8bf6cffa641272808d").into()
+		);
+	}
+
+	#[test]
+	pub fn test_hash_execution_payload() {
+		let hash_root =
+            ExecutionPayloadHeader{
+                parent_hash: hex!("eadee5ab098dde64e9fd02ae5858064bad67064070679625b09f8d82dec183f7").into(),
+                fee_recipient: hex!("f97e180c050e5ab072211ad2c213eb5aee4df134").into(),
+                state_root: hex!("564fa064c2a324c2b5978d7fdfc5d4224d4f421a45388af1ed405a399c845dff").into(),
+                receipts_root: hex!("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421").into(),
+                logs_bloom: hex!("00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000").to_vec(),
+                prev_randao: hex!("6bf538bdfbdf1c96ff528726a40658a91d0bda0f1351448c4c4f3604db2a0ccf").into(),
+                block_number: 477434,
+                gas_limit: 8154925,
+                gas_used: 0,
+                timestamp: 1652816940,
+                extra_data: vec![],
+                base_fee_per_gas: U256::from(7_i16),
+                block_hash: hex!("cd8df91b4503adb8f2f1c7a4f60e07a1f1a2cbdfa2a95bceba581f3ff65c1968").into(),
+                transactions_root: hex!("7ffe241ea60187fdb0187bfa22de35d1f9bed7ab061d9401fd47e34a54fbede1").into(),
+				withdrawals_root: hex!("28ba1834a3a7b657460ce79fa3a1d909ab8828fd557659d4d0554a9bdbc0ec30").into(),
+			}.hash_tree_root();
+		assert!(hash_root.is_ok());
+	}
+}
+
+/// Operating modes for beacon client
+#[derive(Encode, Decode, Copy, Clone, PartialEq, RuntimeDebug, TypeInfo)]
+pub enum Mode {
+	Active,
+	Blocked,
+}
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use codec::{Decode, Encode};
+use frame_support::{CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound};
+use scale_info::TypeInfo;
+use sp_core::H256;
+use sp_std::prelude::*;
+
+use crate::types::{BeaconHeader, ExecutionPayloadHeader, SyncAggregate, SyncCommittee};
+
+#[derive(Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo)]
+#[cfg_attr(
+	feature = "std",
+	derive(serde::Serialize, serde::Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+pub struct CheckpointUpdate<const COMMITTEE_SIZE: usize> {
+	pub header: BeaconHeader,
+	pub current_sync_committee: SyncCommittee<COMMITTEE_SIZE>,
+	pub current_sync_committee_branch: Vec<H256>,
+	pub validators_root: H256,
+	pub block_roots_root: H256,
+	pub block_roots_branch: Vec<H256>,
+}
+
+impl<const COMMITTEE_SIZE: usize> Default for CheckpointUpdate<COMMITTEE_SIZE> {
+	fn default() -> Self {
+		CheckpointUpdate {
+			header: Default::default(),
+			current_sync_committee: Default::default(),
+			current_sync_committee_branch: Default::default(),
+			validators_root: Default::default(),
+			block_roots_root: Default::default(),
+			block_roots_branch: Default::default(),
+		}
+	}
+}
+
+#[derive(
+	Default, Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo,
+)]
+#[cfg_attr(
+	feature = "std",
+	derive(serde::Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+pub struct Update<const COMMITTEE_SIZE: usize, const COMMITTEE_BITS_SIZE: usize> {
+	/// A recent header attesting to the finalized header, using its `state_root`.
+	pub attested_header: BeaconHeader,
+	/// The signing data that the sync committee produced for this attested header, including
+	/// who participated in the vote and the resulting signature.
+	pub sync_aggregate: SyncAggregate<COMMITTEE_SIZE, COMMITTEE_BITS_SIZE>,
+	/// The slot at which the sync aggregate can be found, typically attested_header.slot + 1, if
+	/// the next slot block was not missed.
+	pub signature_slot: u64,
+	/// The next sync committee for the next sync committee period, if present.
+	pub next_sync_committee_update: Option<NextSyncCommitteeUpdate<COMMITTEE_SIZE>>,
+	/// The latest finalized header.
+	pub finalized_header: BeaconHeader,
+	/// The merkle proof testifying to the finalized header, using the `attested_header.state_root`
+	/// as tree root.
+	pub finality_branch: Vec<H256>,
+	/// The finalized_header's `block_roots` root in the beacon state, used for ancestry proofs.
+	pub block_roots_root: H256,
+	/// The merkle path to prove the `block_roots_root` value.
+	pub block_roots_branch: Vec<H256>,
+}
+
+#[derive(
+	Default, Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo,
+)]
+#[cfg_attr(
+	feature = "std",
+	derive(serde::Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+pub struct NextSyncCommitteeUpdate<const COMMITTEE_SIZE: usize> {
+	pub next_sync_committee: SyncCommittee<COMMITTEE_SIZE>,
+	pub next_sync_committee_branch: Vec<H256>,
+}
+
+#[derive(Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo)]
+#[cfg_attr(
+	feature = "std",
+	derive(serde::Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+pub struct ExecutionHeaderUpdate {
+	/// Header for the beacon block containing the execution payload
+	pub header: BeaconHeader,
+	/// Proof that `header` is an ancestor of a finalized header
+	pub ancestry_proof: Option<AncestryProof>,
+	/// Execution header to be imported
+	pub execution_header: ExecutionPayloadHeader,
+	/// Merkle proof that execution payload is contained within `header`
+	pub execution_branch: Vec<H256>,
+}
+
+#[derive(Encode, Decode, CloneNoBound, PartialEqNoBound, RuntimeDebugNoBound, TypeInfo)]
+#[cfg_attr(
+	feature = "std",
+	derive(serde::Deserialize),
+	serde(deny_unknown_fields, bound(serialize = ""), bound(deserialize = ""))
+)]
+pub struct AncestryProof {
+	/// Merkle proof that `header` is an ancestor of `finalized_header`
+	pub header_branch: Vec<H256>,
+	/// Root of a finalized block that has already been imported into the light client
+	pub finalized_block_root: H256,
+}
@@ -0,0 +1,60 @@
+[package]
+name = "snowbridge-core"
+description = "Snowbridge Core"
+version = "0.1.1"
+authors = ["Snowfork <contact@snowfork.com>"]
+edition = "2021"
+license = "Apache-2.0"
+
+[dependencies]
+serde = { version = "1.0.188", optional = true, features = ["alloc", "derive"], default-features = false }
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false }
+scale-info = { version = "2.9.0", default-features = false, features = ["derive"] }
+hex-literal = { version = "0.4.1" }
+
+polkadot-parachain-primitives = { path = "../../../../../polkadot/parachain", default-features = false }
+xcm = { package = "staging-xcm", path = "../../../../../polkadot/xcm", default-features = false }
+xcm-builder = { package = "staging-xcm-builder", path = "../../../../../polkadot/xcm/xcm-builder", default-features = false }
+
+frame-support = { path = "../../../../../substrate/frame/support", default-features = false }
+frame-system = { path = "../../../../../substrate/frame/system", default-features = false }
+sp-runtime = { path = "../../../../../substrate/primitives/runtime", default-features = false }
+sp-std = { path = "../../../../../substrate/primitives/std", default-features = false }
+sp-io = { path = "../../../../../substrate/primitives/io", default-features = false }
+sp-core = { path = "../../../../../substrate/primitives/core", default-features = false }
+sp-arithmetic = { path = "../../../../../substrate/primitives/arithmetic", default-features = false }
+
+snowbridge-beacon-primitives = { path = "../../primitives/beacon", default-features = false }
+
+ethabi = { git = "https://github.com/Snowfork/ethabi-decode.git", package = "ethabi-decode", branch = "master", default-features = false }
+
+[dev-dependencies]
+hex = { version = "0.4.3" }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"ethabi/std",
+	"frame-support/std",
+	"frame-system/std",
+	"polkadot-parachain-primitives/std",
+	"scale-info/std",
+	"serde/std",
+	"snowbridge-beacon-primitives/std",
+	"sp-arithmetic/std",
+	"sp-core/std",
+	"sp-io/std",
+	"sp-runtime/std",
+	"sp-std/std",
+	"xcm-builder/std",
+	"xcm/std",
+]
+serde = ["dep:serde", "scale-info/serde"]
+runtime-benchmarks = [
+	"frame-support/runtime-benchmarks",
+	"frame-system/runtime-benchmarks",
+	"polkadot-parachain-primitives/runtime-benchmarks",
+	"sp-runtime/runtime-benchmarks",
+	"xcm-builder/runtime-benchmarks",
+]
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! Types for representing inbound messages
+
+use codec::{Decode, Encode};
+use frame_support::PalletError;
+use scale_info::TypeInfo;
+use sp_core::{H160, H256};
+use sp_runtime::RuntimeDebug;
+use sp_std::vec::Vec;
+
+/// A trait for verifying inbound messages from Ethereum.
+pub trait Verifier {
+	fn verify(event: &Log, proof: &Proof) -> Result<(), VerificationError>;
+}
+
+#[derive(Clone, Encode, Decode, RuntimeDebug, PalletError, TypeInfo)]
+#[cfg_attr(feature = "std", derive(PartialEq))]
+pub enum VerificationError {
+	/// Execution header is missing
+	HeaderNotFound,
+	/// Event log was not found in the verified transaction receipt
+	LogNotFound,
+	/// Event log has an invalid format
+	InvalidLog,
+	/// Unable to verify the transaction receipt with the provided proof
+	InvalidProof,
+}
+
+pub type MessageNonce = u64;
+
+/// A bridge message from the Gateway contract on Ethereum
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Message {
+	/// Event log emitted by Gateway contract
+	pub event_log: Log,
+	/// Inclusion proof for a transaction receipt containing the event log
+	pub proof: Proof,
+}
+
+const MAX_TOPICS: usize = 4;
+
+#[derive(Clone, RuntimeDebug)]
+pub enum LogValidationError {
+	TooManyTopics,
+}
+
+/// Event log
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Log {
+	pub address: H160,
+	pub topics: Vec<H256>,
+	pub data: Vec<u8>,
+}
+
+impl Log {
+	pub fn validate(&self) -> Result<(), LogValidationError> {
+		if self.topics.len() > MAX_TOPICS {
+			return Err(LogValidationError::TooManyTopics)
+		}
+		Ok(())
+	}
+}
+
+/// Inclusion proof for a transaction receipt
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Proof {
+	// The block hash of the block in which the receipt was included.
+	pub block_hash: H256,
+	// The index of the transaction (and receipt) within the block.
+	pub tx_index: u32,
+	// Proof keys and values (receipts tree)
+	pub data: (Vec<Vec<u8>>, Vec<Vec<u8>>),
+}
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! # Core
+//!
+//! Common traits and types
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(test)]
+mod tests;
+
+pub mod inbound;
+pub mod operating_mode;
+pub mod outbound;
+pub mod pricing;
+pub mod ringbuffer;
+
+pub use polkadot_parachain_primitives::primitives::{
+	Id as ParaId, IsSystem, Sibling as SiblingParaId,
+};
+pub use ringbuffer::{RingBufferMap, RingBufferMapImpl};
+pub use sp_core::U256;
+
+use codec::{Decode, Encode, MaxEncodedLen};
+use frame_support::traits::Contains;
+use hex_literal::hex;
+use scale_info::TypeInfo;
+use sp_core::H256;
+use sp_io::hashing::keccak_256;
+use sp_runtime::{traits::AccountIdConversion, RuntimeDebug};
+use sp_std::prelude::*;
+use xcm::prelude::{
+	Junction::Parachain,
+	Junctions::{Here, X1},
+	MultiLocation,
+};
+use xcm_builder::{DescribeAllTerminal, DescribeFamily, DescribeLocation, HashedDescription};
+
+/// The ID of an agent contract
+pub type AgentId = H256;
+pub use operating_mode::BasicOperatingMode;
+
+pub use pricing::{PricingParameters, Rewards};
+
+pub fn sibling_sovereign_account<T>(para_id: ParaId) -> T::AccountId
+where
+	T: frame_system::Config,
+{
+	SiblingParaId::from(para_id).into_account_truncating()
+}
+
+pub fn sibling_sovereign_account_raw(para_id: ParaId) -> [u8; 32] {
+	SiblingParaId::from(para_id).into_account_truncating()
+}
+
+pub struct AllowSiblingsOnly;
+impl Contains<MultiLocation> for AllowSiblingsOnly {
+	fn contains(location: &MultiLocation) -> bool {
+		matches!(location, MultiLocation { parents: 1, interior: X1(Parachain(_)) })
+	}
+}
+
+pub fn gwei(x: u128) -> U256 {
+	U256::from(1_000_000_000u128).saturating_mul(x.into())
+}
+
+pub fn meth(x: u128) -> U256 {
+	U256::from(1_000_000_000_000_000u128).saturating_mul(x.into())
+}
+
+pub fn eth(x: u128) -> U256 {
+	U256::from(1_000_000_000_000_000_000u128).saturating_mul(x.into())
+}
+
+pub const ROC: u128 = 1_000_000_000_000;
+
+/// Identifier for a message channel
+#[derive(
+	Clone, Copy, Encode, Decode, PartialEq, Eq, Default, RuntimeDebug, MaxEncodedLen, TypeInfo,
+)]
+pub struct ChannelId([u8; 32]);
+
+/// Deterministically derive a ChannelId for a sibling parachain
+/// Generator: keccak256("para" + big_endian_bytes(para_id))
+///
+/// The equivalent generator on the Solidity side is in
+/// contracts/src/Types.sol:into().
+fn derive_channel_id_for_sibling(para_id: ParaId) -> ChannelId {
+	let para_id: u32 = para_id.into();
+	let para_id_bytes: [u8; 4] = para_id.to_be_bytes();
+	let prefix: [u8; 4] = *b"para";
+	let preimage: Vec<u8> = prefix.into_iter().chain(para_id_bytes).collect();
+	keccak_256(&preimage).into()
+}
+
+impl ChannelId {
+	pub const fn new(id: [u8; 32]) -> Self {
+		ChannelId(id)
+	}
+}
+
+impl From<ParaId> for ChannelId {
+	fn from(value: ParaId) -> Self {
+		derive_channel_id_for_sibling(value)
+	}
+}
+
+impl From<[u8; 32]> for ChannelId {
+	fn from(value: [u8; 32]) -> Self {
+		ChannelId(value)
+	}
+}
+
+impl From<ChannelId> for [u8; 32] {
+	fn from(value: ChannelId) -> Self {
+		value.0
+	}
+}
+
+impl<'a> From<&'a [u8; 32]> for ChannelId {
+	fn from(value: &'a [u8; 32]) -> Self {
+		ChannelId(*value)
+	}
+}
+
+impl From<H256> for ChannelId {
+	fn from(value: H256) -> Self {
+		ChannelId(value.into())
+	}
+}
+
+impl AsRef<[u8]> for ChannelId {
+	fn as_ref(&self) -> &[u8] {
+		&self.0
+	}
+}
+
+#[derive(Clone, Encode, Decode, RuntimeDebug, MaxEncodedLen, TypeInfo)]
+pub struct Channel {
+	/// ID of the agent contract deployed on Ethereum
+	pub agent_id: AgentId,
+	/// ID of the parachain who will receive or send messages using this channel
+	pub para_id: ParaId,
+}
+
+pub trait StaticLookup {
+	/// Type to lookup from.
+	type Source;
+	/// Type to lookup into.
+	type Target;
+	/// Attempt a lookup.
+	fn lookup(s: Self::Source) -> Option<Self::Target>;
+}
+
+/// Channel for high-priority governance commands
+pub const PRIMARY_GOVERNANCE_CHANNEL: ChannelId =
+	ChannelId::new(hex!("0000000000000000000000000000000000000000000000000000000000000001"));
+
+/// Channel for lower-priority governance commands
+pub const SECONDARY_GOVERNANCE_CHANNEL: ChannelId =
+	ChannelId::new(hex!("0000000000000000000000000000000000000000000000000000000000000002"));
+
+pub struct DescribeHere;
+impl DescribeLocation for DescribeHere {
+	fn describe_location(l: &MultiLocation) -> Option<Vec<u8>> {
+		match (l.parents, l.interior) {
+			(0, Here) => Some(Vec::<u8>::new().encode()),
+			_ => None,
+		}
+	}
+}
+
+/// Creates an AgentId from a MultiLocation. An AgentId is a unique mapping to a Agent contract on
+/// Ethereum which acts as the sovereign account for the MultiLocation.
+pub type AgentIdOf = HashedDescription<H256, (DescribeHere, DescribeFamily<DescribeAllTerminal>)>;
@@ -0,0 +1,25 @@
+use codec::{Decode, Encode, MaxEncodedLen};
+use scale_info::TypeInfo;
+use sp_runtime::RuntimeDebug;
+
+/// Basic operating modes for a bridges module (Normal/Halted).
+#[derive(Encode, Decode, Clone, Copy, PartialEq, Eq, RuntimeDebug, TypeInfo, MaxEncodedLen)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub enum BasicOperatingMode {
+	/// Normal mode, when all operations are allowed.
+	Normal,
+	/// The pallet is halted. All non-governance operations are disabled.
+	Halted,
+}
+
+impl Default for BasicOperatingMode {
+	fn default() -> Self {
+		Self::Normal
+	}
+}
+
+impl BasicOperatingMode {
+	pub fn is_halted(&self) -> bool {
+		*self == BasicOperatingMode::Halted
+	}
+}
@@ -0,0 +1,413 @@
+use codec::{Decode, Encode};
+use frame_support::PalletError;
+use scale_info::TypeInfo;
+use sp_arithmetic::traits::{BaseArithmetic, Unsigned};
+use sp_core::{RuntimeDebug, H256};
+pub use v1::{AgentExecuteCommand, Command, Initializer, Message, OperatingMode, QueuedMessage};
+
+/// Enqueued outbound messages need to be versioned to prevent data corruption
+/// or loss after forkless runtime upgrades
+#[derive(Encode, Decode, TypeInfo, Clone, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(PartialEq))]
+pub enum VersionedQueuedMessage {
+	V1(QueuedMessage),
+}
+
+impl TryFrom<VersionedQueuedMessage> for QueuedMessage {
+	type Error = ();
+	fn try_from(x: VersionedQueuedMessage) -> Result<Self, Self::Error> {
+		use VersionedQueuedMessage::*;
+		match x {
+			V1(x) => Ok(x),
+		}
+	}
+}
+
+impl<T: Into<QueuedMessage>> From<T> for VersionedQueuedMessage {
+	fn from(x: T) -> Self {
+		VersionedQueuedMessage::V1(x.into())
+	}
+}
+
+mod v1 {
+	use crate::{pricing::UD60x18, ChannelId};
+	use codec::{Decode, Encode};
+	use ethabi::Token;
+	use scale_info::TypeInfo;
+	use sp_core::{RuntimeDebug, H160, H256, U256};
+	use sp_std::{borrow::ToOwned, vec, vec::Vec};
+
+	/// A message which can be accepted by implementations of `/[`SendMessage`\]`
+	#[derive(Encode, Decode, TypeInfo, Clone, RuntimeDebug)]
+	#[cfg_attr(feature = "std", derive(PartialEq))]
+	pub struct Message {
+		/// ID for this message. One will be automatically generated if not provided.
+		///
+		/// When this message is created from an XCM message, the ID should be extracted
+		/// from the `SetTopic` instruction.
+		///
+		/// The ID plays no role in bridge consensus, and is purely meant for message tracing.
+		pub id: Option<H256>,
+		/// The message channel ID
+		pub channel_id: ChannelId,
+		/// The stable ID for a receiving gateway contract
+		pub command: Command,
+	}
+
+	/// The operating mode of Channels and Gateway contract on Ethereum.
+	#[derive(Copy, Clone, Encode, Decode, PartialEq, Eq, RuntimeDebug, TypeInfo)]
+	pub enum OperatingMode {
+		/// Normal operations. Allow sending and receiving messages.
+		Normal,
+		/// Reject outbound messages. This allows receiving governance messages but does now allow
+		/// enqueuing of new messages from the Ethereum side. This can be used to close off an
+		/// deprecated channel or pause the bridge for upgrade operations.
+		RejectingOutboundMessages,
+	}
+
+	/// A command which is executable by the Gateway contract on Ethereum
+	#[derive(Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
+	#[cfg_attr(feature = "std", derive(PartialEq))]
+	pub enum Command {
+		/// Execute a sub-command within an agent for a consensus system in Polkadot
+		AgentExecute {
+			/// The ID of the agent
+			agent_id: H256,
+			/// The sub-command to be executed
+			command: AgentExecuteCommand,
+		},
+		/// Upgrade the Gateway contract
+		Upgrade {
+			/// Address of the new implementation contract
+			impl_address: H160,
+			/// Codehash of the implementation contract
+			impl_code_hash: H256,
+			/// Optionally invoke an initializer in the implementation contract
+			initializer: Option<Initializer>,
+		},
+		/// Create an agent representing a consensus system on Polkadot
+		CreateAgent {
+			/// The ID of the agent, derived from the `MultiLocation` of the consensus system on
+			/// Polkadot
+			agent_id: H256,
+		},
+		/// Create bidirectional messaging channel to a parachain
+		CreateChannel {
+			/// The ID of the channel
+			channel_id: ChannelId,
+			/// The agent ID of the parachain
+			agent_id: H256,
+			/// Initial operating mode
+			mode: OperatingMode,
+		},
+		/// Update the configuration of a channel
+		UpdateChannel {
+			/// The ID of the channel
+			channel_id: ChannelId,
+			/// The new operating mode
+			mode: OperatingMode,
+		},
+		/// Set the global operating mode of the Gateway contract
+		SetOperatingMode {
+			/// The new operating mode
+			mode: OperatingMode,
+		},
+		/// Transfer ether from an agent contract to a recipient account
+		TransferNativeFromAgent {
+			/// The agent ID
+			agent_id: H256,
+			/// The recipient of the ether
+			recipient: H160,
+			/// The amount to transfer
+			amount: u128,
+		},
+		/// Set token fees of the Gateway contract
+		SetTokenTransferFees {
+			/// The fee(DOT) for the cost of creating asset on AssetHub
+			create_asset_xcm: u128,
+			/// The fee(DOT) for the cost of sending asset on AssetHub
+			transfer_asset_xcm: u128,
+			/// The fee(Ether) for register token to discourage spamming
+			register_token: U256,
+		},
+		/// Set pricing parameters
+		SetPricingParameters {
+			// ETH/DOT exchange rate
+			exchange_rate: UD60x18,
+			// Cost of delivering a message from Ethereum to BridgeHub, in ROC/KSM/DOT
+			delivery_cost: u128,
+		},
+	}
+
+	impl Command {
+		/// Compute the enum variant index
+		pub fn index(&self) -> u8 {
+			match self {
+				Command::AgentExecute { .. } => 0,
+				Command::Upgrade { .. } => 1,
+				Command::CreateAgent { .. } => 2,
+				Command::CreateChannel { .. } => 3,
+				Command::UpdateChannel { .. } => 4,
+				Command::SetOperatingMode { .. } => 5,
+				Command::TransferNativeFromAgent { .. } => 6,
+				Command::SetTokenTransferFees { .. } => 7,
+				Command::SetPricingParameters { .. } => 8,
+			}
+		}
+
+		/// ABI-encode the Command.
+		pub fn abi_encode(&self) -> Vec<u8> {
+			match self {
+				Command::AgentExecute { agent_id, command } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::FixedBytes(agent_id.as_bytes().to_owned()),
+						Token::Bytes(command.abi_encode()),
+					])]),
+				Command::Upgrade { impl_address, impl_code_hash, initializer, .. } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::Address(*impl_address),
+						Token::FixedBytes(impl_code_hash.as_bytes().to_owned()),
+						initializer
+							.clone()
+							.map_or(Token::Bytes(vec![]), |i| Token::Bytes(i.params)),
+					])]),
+				Command::CreateAgent { agent_id } =>
+					ethabi::encode(&[Token::Tuple(vec![Token::FixedBytes(
+						agent_id.as_bytes().to_owned(),
+					)])]),
+				Command::CreateChannel { channel_id, agent_id, mode } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::FixedBytes(channel_id.as_ref().to_owned()),
+						Token::FixedBytes(agent_id.as_bytes().to_owned()),
+						Token::Uint(U256::from((*mode) as u64)),
+					])]),
+				Command::UpdateChannel { channel_id, mode } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::FixedBytes(channel_id.as_ref().to_owned()),
+						Token::Uint(U256::from((*mode) as u64)),
+					])]),
+				Command::SetOperatingMode { mode } =>
+					ethabi::encode(&[Token::Tuple(vec![Token::Uint(U256::from((*mode) as u64))])]),
+				Command::TransferNativeFromAgent { agent_id, recipient, amount } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::FixedBytes(agent_id.as_bytes().to_owned()),
+						Token::Address(*recipient),
+						Token::Uint(U256::from(*amount)),
+					])]),
+				Command::SetTokenTransferFees {
+					create_asset_xcm,
+					transfer_asset_xcm,
+					register_token,
+				} => ethabi::encode(&[Token::Tuple(vec![
+					Token::Uint(U256::from(*create_asset_xcm)),
+					Token::Uint(U256::from(*transfer_asset_xcm)),
+					Token::Uint(*register_token),
+				])]),
+				Command::SetPricingParameters { exchange_rate, delivery_cost } =>
+					ethabi::encode(&[Token::Tuple(vec![
+						Token::Uint(exchange_rate.clone().into_inner()),
+						Token::Uint(U256::from(*delivery_cost)),
+					])]),
+			}
+		}
+	}
+
+	/// Representation of a call to the initializer of an implementation contract.
+	/// The initializer has the following ABI signature: `initialize(bytes)`.
+	#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+	pub struct Initializer {
+		/// ABI-encoded params of type `bytes` to pass to the initializer
+		pub params: Vec<u8>,
+		/// The initializer is allowed to consume this much gas at most.
+		pub maximum_required_gas: u64,
+	}
+
+	/// A Sub-command executable within an agent
+	#[derive(Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
+	#[cfg_attr(feature = "std", derive(PartialEq))]
+	pub enum AgentExecuteCommand {
+		/// Transfer ERC20 tokens
+		TransferToken {
+			/// Address of the ERC20 token
+			token: H160,
+			/// The recipient of the tokens
+			recipient: H160,
+			/// The amount of tokens to transfer
+			amount: u128,
+		},
+	}
+
+	impl AgentExecuteCommand {
+		fn index(&self) -> u8 {
+			match self {
+				AgentExecuteCommand::TransferToken { .. } => 0,
+			}
+		}
+
+		/// ABI-encode the sub-command
+		pub fn abi_encode(&self) -> Vec<u8> {
+			match self {
+				AgentExecuteCommand::TransferToken { token, recipient, amount } =>
+					ethabi::encode(&[
+						Token::Uint(self.index().into()),
+						Token::Bytes(ethabi::encode(&[
+							Token::Address(*token),
+							Token::Address(*recipient),
+							Token::Uint(U256::from(*amount)),
+						])),
+					]),
+			}
+		}
+	}
+
+	/// Message which is awaiting processing in the MessageQueue pallet
+	#[derive(Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
+	#[cfg_attr(feature = "std", derive(PartialEq))]
+	pub struct QueuedMessage {
+		/// Message ID
+		pub id: H256,
+		/// Channel ID
+		pub channel_id: ChannelId,
+		/// Command to execute in the Gateway contract
+		pub command: Command,
+	}
+}
+
+#[cfg_attr(feature = "std", derive(PartialEq, Debug))]
+/// Fee for delivering message
+pub struct Fee<Balance>
+where
+	Balance: BaseArithmetic + Unsigned + Copy,
+{
+	/// Fee to cover cost of processing the message locally
+	pub local: Balance,
+	/// Fee to cover cost processing the message remotely
+	pub remote: Balance,
+}
+
+impl<Balance> Fee<Balance>
+where
+	Balance: BaseArithmetic + Unsigned + Copy,
+{
+	pub fn total(&self) -> Balance {
+		self.local.saturating_add(self.remote)
+	}
+}
+
+impl<Balance> From<(Balance, Balance)> for Fee<Balance>
+where
+	Balance: BaseArithmetic + Unsigned + Copy,
+{
+	fn from((local, remote): (Balance, Balance)) -> Self {
+		Self { local, remote }
+	}
+}
+
+/// A trait for sending messages to Ethereum
+pub trait SendMessage: SendMessageFeeProvider {
+	type Ticket: Clone + Encode + Decode;
+
+	/// Validate an outbound message and return a tuple:
+	/// 1. Ticket for submitting the message
+	/// 2. Delivery fee
+	fn validate(
+		message: &Message,
+	) -> Result<(Self::Ticket, Fee<<Self as SendMessageFeeProvider>::Balance>), SendError>;
+
+	/// Submit the message ticket for eventual delivery to Ethereum
+	fn deliver(ticket: Self::Ticket) -> Result<H256, SendError>;
+}
+
+pub trait Ticket: Encode + Decode + Clone {
+	fn message_id(&self) -> H256;
+}
+
+/// A trait for getting the local costs associated with sending a message.
+pub trait SendMessageFeeProvider {
+	type Balance: BaseArithmetic + Unsigned + Copy;
+
+	/// The local component of the message processing fees in native currency
+	fn local_fee() -> Self::Balance;
+}
+
+/// Reasons why sending to Ethereum could not be initiated
+#[derive(Copy, Clone, Encode, Decode, PartialEq, Eq, RuntimeDebug, PalletError, TypeInfo)]
+pub enum SendError {
+	/// Message is too large to be safely executed on Ethereum
+	MessageTooLarge,
+	/// The bridge has been halted for maintenance
+	Halted,
+	/// Invalid Channel
+	InvalidChannel,
+}
+
+pub trait GasMeter {
+	/// All the gas used for submitting a message to Ethereum, minus the cost of dispatching
+	/// the command within the message
+	const MAXIMUM_BASE_GAS: u64;
+
+	fn maximum_gas_used_at_most(command: &Command) -> u64 {
+		Self::MAXIMUM_BASE_GAS + Self::maximum_dispatch_gas_used_at_most(command)
+	}
+
+	/// Measures the maximum amount of gas a command payload will require to dispatch, AFTER
+	/// validation & verification.
+	fn maximum_dispatch_gas_used_at_most(command: &Command) -> u64;
+}
+
+/// A meter that assigns a constant amount of gas for the execution of a command
+///
+/// The gas figures are extracted from this report:
+/// > forge test --match-path test/Gateway.t.sol --gas-report
+///
+/// A healthy buffer is added on top of these figures to account for:
+/// * The EIP-150 63/64 rule
+/// * Future EVM upgrades that may increase gas cost
+pub struct ConstantGasMeter;
+
+impl GasMeter for ConstantGasMeter {
+	// The base transaction cost, which includes:
+	// 21_000 transaction cost, roughly worst case 64_000 for calldata, and 100_000
+	// for message verification
+	const MAXIMUM_BASE_GAS: u64 = 185_000;
+
+	fn maximum_dispatch_gas_used_at_most(command: &Command) -> u64 {
+		match command {
+			Command::CreateAgent { .. } => 275_000,
+			Command::CreateChannel { .. } => 100_000,
+			Command::UpdateChannel { .. } => 50_000,
+			Command::TransferNativeFromAgent { .. } => 60_000,
+			Command::SetOperatingMode { .. } => 40_000,
+			Command::AgentExecute { command, .. } => match command {
+				// Execute IERC20.transferFrom
+				//
+				// Worst-case assumptions are important:
+				// * No gas refund for clearing storage slot of source account in ERC20 contract
+				// * Assume dest account in ERC20 contract does not yet have a storage slot
+				// * ERC20.transferFrom possibly does other business logic besides updating balances
+				AgentExecuteCommand::TransferToken { .. } => 100_000,
+			},
+			Command::Upgrade { initializer, .. } => {
+				let initializer_max_gas = match *initializer {
+					Some(Initializer { maximum_required_gas, .. }) => maximum_required_gas,
+					None => 0,
+				};
+				// total maximum gas must also include the gas used for updating the proxy before
+				// the the initializer is called.
+				50_000 + initializer_max_gas
+			},
+			Command::SetTokenTransferFees { .. } => 60_000,
+			Command::SetPricingParameters { .. } => 60_000,
+		}
+	}
+}
+
+impl GasMeter for () {
+	const MAXIMUM_BASE_GAS: u64 = 1;
+
+	fn maximum_dispatch_gas_used_at_most(_: &Command) -> u64 {
+		1
+	}
+}
+
+pub const ETHER_DECIMALS: u8 = 18;
@@ -0,0 +1,67 @@
+use codec::{Decode, Encode, MaxEncodedLen};
+use scale_info::TypeInfo;
+use sp_arithmetic::traits::{BaseArithmetic, Unsigned, Zero};
+use sp_core::U256;
+use sp_runtime::{FixedU128, RuntimeDebug};
+use sp_std::prelude::*;
+
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, MaxEncodedLen, TypeInfo)]
+pub struct PricingParameters<Balance> {
+	/// ETH/DOT exchange rate
+	pub exchange_rate: FixedU128,
+	/// Relayer rewards
+	pub rewards: Rewards<Balance>,
+	/// Ether (wei) fee per gas unit
+	pub fee_per_gas: U256,
+}
+
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, MaxEncodedLen, TypeInfo)]
+pub struct Rewards<Balance> {
+	/// Local reward in DOT
+	pub local: Balance,
+	/// Remote reward in ETH (wei)
+	pub remote: U256,
+}
+
+#[derive(RuntimeDebug)]
+pub struct InvalidPricingParameters;
+
+impl<Balance> PricingParameters<Balance>
+where
+	Balance: BaseArithmetic + Unsigned + Copy,
+{
+	pub fn validate(&self) -> Result<(), InvalidPricingParameters> {
+		if self.exchange_rate == FixedU128::zero() {
+			return Err(InvalidPricingParameters)
+		}
+		if self.fee_per_gas == U256::zero() {
+			return Err(InvalidPricingParameters)
+		}
+		if self.rewards.local.is_zero() {
+			return Err(InvalidPricingParameters)
+		}
+		if self.rewards.remote.is_zero() {
+			return Err(InvalidPricingParameters)
+		}
+		Ok(())
+	}
+}
+
+/// Holder for fixed point number implemented in <https://github.com/PaulRBerg/prb-math>
+#[derive(Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
+#[cfg_attr(feature = "std", derive(PartialEq))]
+pub struct UD60x18(U256);
+
+impl From<FixedU128> for UD60x18 {
+	fn from(value: FixedU128) -> Self {
+		// Both FixedU128 and UD60x18 have 18 decimal places
+		let inner: u128 = value.into_inner();
+		UD60x18(inner.into())
+	}
+}
+
+impl UD60x18 {
+	pub fn into_inner(self) -> U256 {
+		self.0
+	}
+}
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use codec::FullCodec;
+use core::{cmp::Ord, marker::PhantomData, ops::Add};
+use frame_support::storage::{types::QueryKindTrait, StorageMap, StorageValue};
+use sp_core::{Get, GetDefault};
+use sp_runtime::traits::{One, Zero};
+
+/// Trait object presenting the ringbuffer interface.
+pub trait RingBufferMap<Key, Value, QueryKind>
+where
+	Key: FullCodec,
+	Value: FullCodec,
+	QueryKind: QueryKindTrait<Value, GetDefault>,
+{
+	/// Insert a map entry.
+	fn insert(k: Key, v: Value);
+
+	/// Check if map contains a key
+	fn contains_key(k: Key) -> bool;
+
+	/// Get the value of the key
+	fn get(k: Key) -> QueryKind::Query;
+}
+
+pub struct RingBufferMapImpl<Index, B, CurrentIndex, Intermediate, M, QueryKind>(
+	PhantomData<(Index, B, CurrentIndex, Intermediate, M, QueryKind)>,
+);
+
+/// Ringbuffer implementation based on `RingBufferTransient`
+impl<Key, Value, Index, B, CurrentIndex, Intermediate, M, QueryKind>
+	RingBufferMap<Key, Value, QueryKind>
+	for RingBufferMapImpl<Index, B, CurrentIndex, Intermediate, M, QueryKind>
+where
+	Key: FullCodec + Clone,
+	Value: FullCodec,
+	Index: Ord + One + Zero + Add<Output = Index> + Copy + FullCodec + Eq,
+	B: Get<Index>,
+	CurrentIndex: StorageValue<Index, Query = Index>,
+	Intermediate: StorageMap<Index, Key, Query = Key>,
+	M: StorageMap<Key, Value, Query = QueryKind::Query>,
+	QueryKind: QueryKindTrait<Value, GetDefault>,
+{
+	/// Insert a map entry.
+	fn insert(k: Key, v: Value) {
+		let bound = B::get();
+		let mut current_index = CurrentIndex::get();
+
+		// Adding one here as bound denotes number of items but our index starts with zero.
+		if (current_index + Index::one()) >= bound {
+			current_index = Index::zero();
+		} else {
+			current_index = current_index + Index::one();
+		}
+
+		// Deleting earlier entry if it exists
+		if Intermediate::contains_key(current_index) {
+			let older_key = Intermediate::get(current_index);
+			M::remove(older_key);
+		}
+
+		Intermediate::insert(current_index, k.clone());
+		CurrentIndex::set(current_index);
+		M::insert(k, v);
+	}
+
+	/// Check if map contains a key
+	fn contains_key(k: Key) -> bool {
+		M::contains_key(k)
+	}
+
+	/// Get the value associated with key
+	fn get(k: Key) -> M::Query {
+		M::get(k)
+	}
+}
@@ -0,0 +1,13 @@
+use crate::{ChannelId, ParaId};
+use hex_literal::hex;
+
+const EXPECT_CHANNEL_ID: [u8; 32] =
+	hex!("c173fac324158e77fb5840738a1a541f633cbec8884c6a601c567d2b376a0539");
+
+// The Solidity equivalent code is tested in Gateway.t.sol:testDeriveChannelID
+#[test]
+fn generate_channel_id() {
+	let para_id: ParaId = 1000.into();
+	let channel_id: ChannelId = para_id.into();
+	assert_eq!(channel_id, EXPECT_CHANNEL_ID.into());
+}
@@ -0,0 +1,14 @@
+#[cfg(test)]
+mod tests {
+	use frame_support::traits::Contains;
+	use snowbridge_core::AllowSiblingsOnly;
+	use xcm::prelude::{Junction::Parachain, Junctions::X1, MultiLocation};
+
+	#[test]
+	fn allow_siblings_predicate_only_allows_siblings() {
+		let sibling = MultiLocation::new(1, X1(Parachain(1000)));
+		let child = MultiLocation::new(0, X1(Parachain(1000)));
+		assert!(AllowSiblingsOnly::contains(&sibling), "Sibling returns true.");
+		assert!(!AllowSiblingsOnly::contains(&child), "Child returns false.");
+	}
+}
@@ -0,0 +1,2 @@
+[target.wasm32-unknown-unknown]
+runner = 'wasm-bindgen-test-runner'
@@ -0,0 +1,51 @@
+[package]
+name = "snowbridge-ethereum"
+description = "Snowbridge Ethereum"
+version = "0.1.0"
+authors = ["Snowfork <contact@snowfork.com>"]
+edition = "2021"
+license = "Apache-2.0"
+
+[dependencies]
+serde = { version = "1.0.188", optional = true, features = ["derive"] }
+serde-big-array = { version = "0.3.2", optional = true, features = ["const-generics"] }
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = ["derive"] }
+scale-info = { version = "2.9.0", default-features = false, features = ["derive"] }
+ethbloom = { version = "0.13.0", default-features = false }
+ethereum-types = { version = "0.14.1", default-features = false, features = ["codec", "rlp", "serialize"] }
+hex = { package = "rustc-hex", version = "2.1.0", default-features = false }
+hex-literal = { version = "0.4.1", default-features = false }
+parity-bytes = { version = "0.1.2", default-features = false }
+rlp = { version = "0.5.2", default-features = false }
+
+sp-io = { path = "../../../../../substrate/primitives/io", default-features = false }
+sp-std = { path = "../../../../../substrate/primitives/std", default-features = false }
+sp-core = { path = "../../../../../substrate/primitives/core", default-features = false }
+sp-runtime = { path = "../../../../../substrate/primitives/runtime", default-features = false }
+
+ethabi = { git = "https://github.com/snowfork/ethabi-decode.git", package = "ethabi-decode", branch = "master", default-features = false }
+
+[dev-dependencies]
+wasm-bindgen-test = "0.3.19"
+rand = "0.8.5"
+serde_json = "1.0.96"
+
+[features]
+default = ["std"]
+expensive_tests = []
+std = [
+	"codec/std",
+	"ethabi/std",
+	"ethbloom/std",
+	"ethereum-types/std",
+	"hex/std",
+	"parity-bytes/std",
+	"rlp/std",
+	"scale-info/std",
+	"serde",
+	"serde-big-array",
+	"sp-core/std",
+	"sp-io/std",
+	"sp-runtime/std",
+	"sp-std/std",
+]
@@ -0,0 +1,414 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use codec::{Decode, Encode};
+use ethbloom::Bloom as EthBloom;
+use hex_literal::hex;
+use parity_bytes::Bytes;
+use rlp::RlpStream;
+use scale_info::TypeInfo;
+use sp_io::hashing::keccak_256;
+use sp_runtime::RuntimeDebug;
+use sp_std::{convert::TryInto, prelude::*};
+
+#[cfg(feature = "std")]
+use serde::{Deserialize, Serialize};
+
+#[cfg(feature = "std")]
+use serde_big_array::BigArray;
+
+use ethereum_types::{Address, H256, H64, U256};
+
+use crate::{mpt, receipt};
+
+/// Complete block header id.
+#[derive(Clone, Copy, Default, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct HeaderId {
+	/// Header number.
+	pub number: u64,
+	/// Header hash.
+	pub hash: H256,
+}
+
+const EMPTY_OMMERS_HASH: [u8; 32] =
+	hex!("1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347");
+
+/// An Ethereum block header.
+#[derive(Clone, Default, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct Header {
+	/// Parent block hash.
+	pub parent_hash: H256,
+	/// Block timestamp.
+	pub timestamp: u64,
+	/// Block number.
+	pub number: u64,
+	/// Block author.
+	pub author: Address,
+
+	/// Transactions root.
+	pub transactions_root: H256,
+	/// Block ommers hash.
+	pub ommers_hash: H256,
+	/// Block extra data.
+	pub extra_data: Bytes,
+
+	/// State root.
+	pub state_root: H256,
+	/// Block receipts root.
+	pub receipts_root: H256,
+	/// Block bloom.
+	pub logs_bloom: Bloom,
+	/// Gas used for contracts execution.
+	pub gas_used: U256,
+	/// Block gas limit.
+	pub gas_limit: U256,
+
+	/// Block difficulty.
+	pub difficulty: U256,
+	/// Vector of post-RLP-encoded fields.
+	pub seal: Vec<Bytes>,
+
+	// Base fee per gas (EIP-1559), only in headers from the London hardfork onwards.
+	pub base_fee: Option<U256>,
+}
+
+impl Header {
+	/// Compute hash of this header (keccak of the RLP with seal).
+	pub fn compute_hash(&self) -> H256 {
+		keccak_256(&self.rlp(true)).into()
+	}
+
+	/// Compute hash of the truncated header i.e. excluding seal.
+	pub fn compute_partial_hash(&self) -> H256 {
+		keccak_256(&self.rlp(false)).into()
+	}
+
+	pub fn check_receipt_proof(
+		&self,
+		proof: &[Vec<u8>],
+	) -> Option<Result<receipt::Receipt, rlp::DecoderError>> {
+		match self.apply_merkle_proof(proof) {
+			Some((root, data)) if root == self.receipts_root => Some(rlp::decode(&data)),
+			Some((_, _)) => None,
+			None => None,
+		}
+	}
+
+	pub fn apply_merkle_proof(&self, proof: &[Vec<u8>]) -> Option<(H256, Vec<u8>)> {
+		let mut iter = proof.iter().rev();
+		let first_bytes = match iter.next() {
+			Some(b) => b,
+			None => return None,
+		};
+		let item_to_prove: mpt::ShortNode = rlp::decode(first_bytes).ok()?;
+
+		let final_hash: Option<[u8; 32]> = iter.try_fold(keccak_256(first_bytes), |acc, x| {
+			let node: Box<dyn mpt::Node> = x.as_slice().try_into().ok()?;
+			if (*node).contains_hash(acc.into()) {
+				return Some(keccak_256(x))
+			}
+			None
+		});
+
+		final_hash.map(|hash| (hash.into(), item_to_prove.value))
+	}
+
+	pub fn mix_hash(&self) -> Option<H256> {
+		let bytes: Bytes = self.decoded_seal_field(0, 32)?;
+		let size = bytes.len();
+		let mut mix_hash = [0u8; 32];
+		for i in 0..size {
+			mix_hash[31 - i] = bytes[size - 1 - i];
+		}
+		Some(mix_hash.into())
+	}
+
+	pub fn nonce(&self) -> Option<H64> {
+		let bytes: Bytes = self.decoded_seal_field(1, 8)?;
+		let size = bytes.len();
+		let mut nonce = [0u8; 8];
+		for i in 0..size {
+			nonce[7 - i] = bytes[size - 1 - i];
+		}
+		Some(nonce.into())
+	}
+
+	pub fn has_ommers(&self) -> bool {
+		self.ommers_hash != EMPTY_OMMERS_HASH.into()
+	}
+
+	fn decoded_seal_field(&self, index: usize, max_len: usize) -> Option<Bytes> {
+		let bytes: Bytes = rlp::decode(self.seal.get(index)?).ok()?;
+		if bytes.len() > max_len {
+			return None
+		}
+		Some(bytes)
+	}
+
+	/// Returns header RLP with or without seals.
+	/// For EIP-1559 baseFee addition refer to:
+	/// <https://github.com/openethereum/openethereum/blob/193b25a22d5ff07759c6431129e95235510516f9/crates/ethcore/types/src/header.rs#L341>
+	fn rlp(&self, with_seal: bool) -> Bytes {
+		let mut s = RlpStream::new();
+
+		let stream_length_without_seal = if self.base_fee.is_some() { 14 } else { 13 };
+
+		if with_seal {
+			s.begin_list(stream_length_without_seal + self.seal.len());
+		} else {
+			s.begin_list(stream_length_without_seal);
+		}
+
+		s.append(&self.parent_hash);
+		s.append(&self.ommers_hash);
+		s.append(&self.author);
+		s.append(&self.state_root);
+		s.append(&self.transactions_root);
+		s.append(&self.receipts_root);
+		s.append(&EthBloom::from(self.logs_bloom.0));
+		s.append(&self.difficulty);
+		s.append(&self.number);
+		s.append(&self.gas_limit);
+		s.append(&self.gas_used);
+		s.append(&self.timestamp);
+		s.append(&self.extra_data);
+
+		if with_seal {
+			for b in &self.seal {
+				s.append_raw(b, 1);
+			}
+		}
+
+		if let Some(base_fee) = self.base_fee {
+			s.append(&base_fee);
+		}
+
+		s.out().to_vec()
+	}
+}
+
+/// Logs bloom.
+#[derive(Clone, Debug, Encode, Decode, TypeInfo)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct Bloom(#[cfg_attr(feature = "std", serde(with = "BigArray"))] [u8; 256]);
+
+impl<'a> From<&'a [u8; 256]> for Bloom {
+	fn from(buffer: &'a [u8; 256]) -> Bloom {
+		Bloom(*buffer)
+	}
+}
+
+impl PartialEq<Bloom> for Bloom {
+	fn eq(&self, other: &Bloom) -> bool {
+		self.0.iter().zip(other.0.iter()).all(|(l, r)| l == r)
+	}
+}
+
+impl Default for Bloom {
+	fn default() -> Self {
+		Bloom([0; 256])
+	}
+}
+
+impl rlp::Decodable for Bloom {
+	fn decode(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		let v: Vec<u8> = rlp.as_val()?;
+		match v.len() {
+			256 => {
+				let mut bytes = [0u8; 256];
+				bytes.copy_from_slice(&v);
+				Ok(Self(bytes))
+			},
+			_ => Err(rlp::DecoderError::Custom("Expected 256 bytes")),
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+
+	use super::*;
+
+	#[test]
+	fn bloom_decode_rlp() {
+		let raw_bloom = hex!(
+			"
+			b901000420000000000000000000008002000000000001000000000001000000000000000000
+			0000000000000000000000000002000000080000000000000000200000000000000000000000
+			0000080000002200000000004000100000000000000000000000000000000000000000000000
+			0000000000000004000000001000010000000000080000000000400000000000000000000000
+			0000080000004000000000020000000000020000000000000000000000000000000000000000
+			0000040000000000020000000001000000000000000000000000000010000000020000200000
+			10200000000000010000000000000000000000000000000000000010000000
+		"
+		);
+		let expected_bytes = &raw_bloom[3..];
+		let bloom: Bloom = rlp::decode(&raw_bloom).unwrap();
+		assert_eq!(bloom.0, expected_bytes);
+	}
+
+	#[test]
+	fn header_compute_hash_poa() {
+		// PoA header
+		let header = Header {
+			parent_hash: Default::default(),
+			timestamp: 0,
+			number: 0,
+			author: Default::default(),
+			transactions_root: hex!(
+				"56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"
+			)
+			.into(),
+			ommers_hash: hex!("1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347")
+				.into(),
+			extra_data: vec![],
+			state_root: hex!("eccf6b74c2bcbe115c71116a23fe963c54406010c244d9650526028ad3e32cce")
+				.into(),
+			receipts_root: hex!("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
+				.into(),
+			logs_bloom: Default::default(),
+			gas_used: Default::default(),
+			gas_limit: 0x222222.into(),
+			difficulty: 0x20000.into(),
+			seal: vec![vec![0x80], {
+				let mut vec = vec![0xb8, 0x41];
+				vec.resize(67, 0);
+				vec
+			}],
+			base_fee: None,
+		};
+		assert_eq!(
+			header.compute_hash().as_bytes(),
+			hex!("9ff57c7fa155853586382022f0982b71c51fa313a0942f8c456300896643e890"),
+		);
+	}
+
+	#[test]
+	fn header_compute_hash_pow() {
+		// <https://etherscan.io/block/11090290>
+		let nonce = hex!("6935bbe7b63c4f8e").to_vec();
+		let mix_hash =
+			hex!("be3adfb0087be62b28b716e2cdf3c79329df5caa04c9eee035d35b5d52102815").to_vec();
+		let header = Header {
+			parent_hash: hex!("bede0bddd6f32c895fc505ffe0c39d9bde58e9a5272f31a3dee448b796edcbe3")
+				.into(),
+			timestamp: 1603160977,
+			number: 11090290,
+			author: hex!("ea674fdde714fd979de3edf0f56aa9716b898ec8").into(),
+			transactions_root: hex!(
+				"56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"
+			)
+			.into(),
+			ommers_hash: hex!("1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347")
+				.into(),
+			extra_data: hex!("65746865726d696e652d61736961312d33").to_vec(),
+			state_root: hex!("7dcb8aca872b712bad81df34a89d4efedc293566ffc3eeeb5cbcafcc703e42c9")
+				.into(),
+			receipts_root: hex!("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
+				.into(),
+			logs_bloom: Default::default(),
+			gas_used: 0.into(),
+			gas_limit: 0xbe8c19.into(),
+			difficulty: 0xbc140caa61087i64.into(),
+			seal: vec![rlp::encode(&mix_hash).to_vec(), rlp::encode(&nonce).to_vec()],
+			base_fee: None,
+		};
+		assert_eq!(
+			header.compute_hash().as_bytes(),
+			hex!("0f9bdc91c2e0140acb873330742bda8c8181fa3add91fe7ae046251679cedef7"),
+		);
+	}
+
+	#[test]
+	fn header_pow_seal_fields_extracted_correctly() {
+		let nonce: H64 = hex!("6935bbe7b63c4f8e").into();
+		let mix_hash: H256 =
+			hex!("be3adfb0087be62b28b716e2cdf3c79329df5caa04c9eee035d35b5d52102815").into();
+		let header = Header {
+			seal: vec![
+				rlp::encode(&mix_hash.0.to_vec()).to_vec(),
+				rlp::encode(&nonce.0.to_vec()).to_vec(),
+			],
+			..Default::default()
+		};
+
+		assert_eq!(header.nonce().unwrap(), nonce);
+		assert_eq!(header.mix_hash().unwrap(), mix_hash);
+	}
+
+	#[test]
+	fn header_pow_seal_fields_return_none_for_invalid_values() {
+		let nonce = hex!("696935bbe7b63c4f8e").to_vec();
+		let mix_hash =
+			hex!("bebe3adfb0087be62b28b716e2cdf3c79329df5caa04c9eee035d35b5d52102815").to_vec();
+		let mut header = Header {
+			seal: vec![rlp::encode(&mix_hash).to_vec(), rlp::encode(&nonce).to_vec()],
+			..Default::default()
+		};
+		assert_eq!(header.nonce(), None);
+		assert_eq!(header.mix_hash(), None);
+
+		header.seal = Vec::new();
+		assert_eq!(header.nonce(), None);
+		assert_eq!(header.mix_hash(), None);
+	}
+
+	#[test]
+	fn header_check_receipt_proof() {
+		let header = Header {
+			receipts_root: hex!("fd5e397a84884641f53c496804f24b5276cbb8c5c9cfc2342246be8e3ce5ad02")
+				.into(),
+			..Default::default()
+		};
+
+		// Valid proof
+		let proof_receipt5 = vec!(
+			hex!("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").to_vec(),
+			hex!("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").to_vec(),
+			hex!("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").to_vec(),
+		);
+		assert!(header.check_receipt_proof(&proof_receipt5).is_some());
+
+		// Various invalid proofs
+		let proof_empty: Vec<Vec<u8>> = vec![];
+		let proof_missing_full_node = vec![proof_receipt5[0].clone(), proof_receipt5[2].clone()];
+		let proof_missing_short_node1 = vec![proof_receipt5[0].clone(), proof_receipt5[1].clone()];
+		let proof_missing_short_node2 = vec![proof_receipt5[0].clone()];
+		let proof_invalid_encoding = vec![proof_receipt5[2][2..].to_vec()];
+		let proof_no_full_node = vec![proof_receipt5[2].clone(), proof_receipt5[2].clone()];
+		assert!(header.check_receipt_proof(&proof_empty).is_none());
+		assert!(header.check_receipt_proof(&proof_missing_full_node).is_none());
+
+		assert_eq!(
+			header.check_receipt_proof(&proof_missing_short_node1),
+			Some(Err(rlp::DecoderError::Custom("Unsupported receipt type")))
+		);
+
+		assert_eq!(
+			header.check_receipt_proof(&proof_missing_short_node2),
+			Some(Err(rlp::DecoderError::Custom("Unsupported receipt type")))
+		);
+
+		assert!(header.check_receipt_proof(&proof_invalid_encoding).is_none());
+		assert!(header.check_receipt_proof(&proof_no_full_node).is_none());
+	}
+
+	#[test]
+	fn header_check_receipt_proof_with_intermediate_short_node() {
+		let header = Header {
+			receipts_root: hex!("d128e3a57142d2bf15bc0cbcac7ad54f40750d571b5c3097e425882c10c9ba66")
+				.into(),
+			..Default::default()
+		};
+
+		let proof_receipt263 = vec![
+			hex!("f90131a00d3cb8d3f57ac1c0e12918a2ebe0cafed8c273577b9dd73e7ed1079b403ef494a0678b9835b834f8a287c0dd33a8fca9146e456ca688555ed4ec1361a2180b778da0fe42da181a46677a043b3d9d4b8bb05a6a17b7b5c010c17e7c1d31cfb7c4f911a0c89f0e2c53241cdb578e1f2b4caf6ba36e00500bdc57fecd66b84a6a58394c19a086c3c1fae5a0575940b5d38e111c469d07883106c26856f3ef608469a2081f13a06c5992ff00aab6226a70a032fd2f571ba22f797321f45e2daa73020d638d21b0a050861e9503ef68728f6c90a44f7fe1bceb2a9bdab6957bbe7136166bd849561ea006aa6eaca8a07e57176e9aa41e6a09edfb7678d1a112404e0ec779d7e567e82ea0bb0b430d303ba21b0af11c487b8a218bd75db54c98940b3f11bad8ff47cad3ef8080808080808080").to_vec(),
+			hex!("f871a0246de222036ee6a03329b0105da0a6b3f916fc95a9ed5a403a581a0c4d74242ca0ac108a49a88b57a05ac34a108b39f1e45f6f167f2b9fbc8d52fb58e2e5a6af1ea0fcfe07ac2ccd3c28b6eab68d1bce112f6f6dbd9023e4ec3c05b96615aa803d798080808080808080808080808080").to_vec(),
+			hex!("e4820001a04fff54398cad4d05ea6abfd8b0f3b4fe14c04d7ff5f5211c5b927d9cf72ac1d8").to_vec(),
+			hex!("f851a096d010643ca2d47412ca66898286b5f2412963b9ec051b33e570d575914c9c5ca028cd24c652989542fe89479ec6388eac4592432242af5ba97563b3ac7c71c019808080808080808080808080808080").to_vec(),
+			hex!("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").to_vec(),
+			hex!("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").to_vec(),
+		];
+		assert!(header.check_receipt_proof(&proof_receipt263).is_some());
+	}
+}
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+#![cfg_attr(not(feature = "std"), no_std)]
+
+pub mod header;
+pub mod log;
+pub mod mpt;
+pub mod receipt;
+
+pub use ethereum_types::{Address, H160, H256, H64, U256};
+
+pub use header::{Bloom, Header, HeaderId};
+pub use log::Log;
+pub use receipt::Receipt;
+
+#[derive(Debug)]
+pub enum DecodeError {
+	// Unexpected RLP data
+	InvalidRLP(rlp::DecoderError),
+	// Data does not match expected ABI
+	InvalidABI(ethabi::Error),
+	// Invalid message payload
+	InvalidPayload,
+}
+
+impl From<rlp::DecoderError> for DecodeError {
+	fn from(err: rlp::DecoderError) -> Self {
+		DecodeError::InvalidRLP(err)
+	}
+}
+
+impl From<ethabi::Error> for DecodeError {
+	fn from(err: ethabi::Error) -> Self {
+		DecodeError::InvalidABI(err)
+	}
+}
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use codec::{Decode, Encode};
+use ethereum_types::{H160, H256};
+use sp_std::prelude::*;
+
+#[derive(Clone, Debug, Encode, Decode, PartialEq, Eq)]
+pub struct Log {
+	pub address: H160,
+	pub topics: Vec<H256>,
+	pub data: Vec<u8>,
+}
+
+impl rlp::Decodable for Log {
+	/// We need to implement rlp::Decodable manually as the derive macro RlpDecodable
+	/// didn't seem to generate the correct code for parsing our logs.
+	fn decode(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		let mut iter = rlp.iter();
+
+		let address: H160 = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected log address")),
+		};
+
+		let topics: Vec<H256> = match iter.next() {
+			Some(data) => data.as_list()?,
+			None => return Err(rlp::DecoderError::Custom("Expected log topics")),
+		};
+
+		let data: Vec<u8> = match iter.next() {
+			Some(data) => data.data()?.to_vec(),
+			None => return Err(rlp::DecoderError::Custom("Expected log data")),
+		};
+
+		Ok(Self { address, topics, data })
+	}
+}
+
+#[cfg(test)]
+mod tests {
+
+	use super::Log;
+	use hex_literal::hex;
+
+	const RAW_LOG: [u8; 605] = hex!(
+		"
+		f9025a941cfd66659d44cfe2e627c5742ba7477a3284cffae1a0266413be5700ce8dd5ac6b9a7dfb
+		abe99b3e45cae9a68ac2757858710b401a38b9022000000000000000000000000000000000000000
+		00000000000000000000000060000000000000000000000000000000000000000000000000000000
+		00000000c00000000000000000000000000000000000000000000000000000000000000100000000
+		00000000000000000000000000000000000000000000000000000000283163466436363635394434
+		34636665324536323763353734324261373437376133323834634666410000000000000000000000
+		00000000000000000000000000000000000000000000000000000000000000000000000000000000
+		000000000773656e6445544800000000000000000000000000000000000000000000000000000000
+		00000000000000000000000000000000000000000000000000000001000000000000000000000000
+		00cffeaaf7681c89285d65cfbe808b80e50269657300000000000000000000000000000000000000
+		000000000000000000000000a0000000000000000000000000000000000000000000000000000000
+		0000000000000000000000000000000000000000000000000000000000000000000000000a000000
+		00000000000000000000000000000000000000000000000000000000020000000000000000000000
+		00000000000000000000000000000000000000002f3146524d4d3850456957585961783772705336
+		5834585a5831614141785357783143724b5479725659685632346667000000000000000000000000
+		0000000000
+	"
+	);
+
+	#[test]
+	fn decode_log() {
+		let log: Log = rlp::decode(&RAW_LOG).unwrap();
+		assert_eq!(log.address.as_bytes(), hex!["1cfd66659d44cfe2e627c5742ba7477a3284cffa"]);
+		assert_eq!(
+			log.topics[0].as_bytes(),
+			hex!["266413be5700ce8dd5ac6b9a7dfbabe99b3e45cae9a68ac2757858710b401a38"]
+		);
+	}
+}
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! Helper types to work with Ethereum's Merkle Patricia Trie nodes
+
+use ethereum_types::H256;
+use sp_std::{convert::TryFrom, prelude::*};
+
+pub trait Node {
+	fn contains_hash(&self, hash: H256) -> bool;
+}
+
+impl TryFrom<&[u8]> for Box<dyn Node> {
+	type Error = rlp::DecoderError;
+
+	fn try_from(bytes: &[u8]) -> Result<Box<dyn Node>, Self::Error> {
+		let rlp = rlp::Rlp::new(bytes);
+		match rlp.item_count()? {
+			2 => {
+				let node: ShortNode = rlp.as_val()?;
+				Ok(Box::new(node))
+			},
+			17 => {
+				let node: FullNode = rlp.as_val()?;
+				Ok(Box::new(node))
+			},
+			_ => Err(rlp::DecoderError::Custom("Invalid number of list elements")),
+		}
+	}
+}
+
+/// Intermediate trie node with children (refers to node with same name in Geth).
+/// This struct only handles the proof representation, i.e. a child is either empty
+/// or a 32-byte hash of its subtree.
+pub struct FullNode {
+	pub children: Vec<Option<H256>>,
+}
+
+impl rlp::Decodable for FullNode {
+	fn decode(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		let children: Vec<Option<H256>> = rlp
+			.iter()
+			.map(|item| {
+				let v: Vec<u8> = item.as_val()?;
+				match v.len() {
+					0 => Ok(None),
+					32 => {
+						let mut bytes = [0u8; 32];
+						bytes.copy_from_slice(&v);
+						Ok(Some(bytes.into()))
+					},
+					_ => Err(rlp::DecoderError::Custom("Expected 32-byte hash or empty child")),
+				}
+			})
+			.collect::<Result<_, rlp::DecoderError>>()?;
+
+		Ok(Self { children })
+	}
+}
+
+impl Node for FullNode {
+	fn contains_hash(&self, hash: H256) -> bool {
+		self.children.iter().any(|h| Some(hash) == *h)
+	}
+}
+
+/// Trie node where `value` is either the RLP-encoded item we're
+/// proving or an intermediate hash (refers to node with same name in Geth)
+/// Proof verification should return `value`. `key` is an implementation
+/// detail of the trie.
+pub struct ShortNode {
+	pub key: Vec<u8>,
+	pub value: Vec<u8>,
+}
+
+impl rlp::Decodable for ShortNode {
+	fn decode(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		let mut iter = rlp.iter();
+
+		let key: Vec<u8> = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected key bytes")),
+		};
+
+		let value: Vec<u8> = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected value bytes")),
+		};
+
+		Ok(Self { key, value })
+	}
+}
+
+impl Node for ShortNode {
+	fn contains_hash(&self, hash: H256) -> bool {
+		self.value == hash.0
+	}
+}
+
+#[cfg(test)]
+mod tests {
+
+	use super::*;
+	use hex_literal::hex;
+
+	const RAW_PROOF: [&[u8]; 3] = [
+        &hex!("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"),
+        &hex!("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"),
+        &hex!("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"),
+    ];
+
+	#[test]
+	fn decode_full_node() {
+		let node1: FullNode = rlp::decode(RAW_PROOF[0]).unwrap();
+		let node2: FullNode = rlp::decode(RAW_PROOF[1]).unwrap();
+		assert_eq!(node1.children.len(), 17);
+		assert_eq!(node2.children.len(), 17);
+		assert_eq!(node1.children.iter().filter(|c| c.is_none()).count(), 8);
+		assert_eq!(node2.children.iter().filter(|c| c.is_none()).count(), 2);
+
+		let result: Result<FullNode, rlp::DecoderError> = rlp::decode(RAW_PROOF[2]);
+		assert!(result.is_err());
+	}
+
+	#[test]
+	fn decode_short_node() {
+		// key + item value
+		let node: ShortNode = rlp::decode(RAW_PROOF[2]).unwrap();
+		assert_eq!(node.key, vec![32]);
+		assert!(!node.value.is_empty());
+
+		// key + item hash
+		let node: ShortNode = rlp::decode(&hex!(
+			"e4820001a04fff54398cad4d05ea6abfd8b0f3b4fe14c04d7ff5f5211c5b927d9cf72ac1d8"
+		))
+		.unwrap();
+		assert_eq!(node.key, vec![0, 1]);
+		assert_eq!(
+			node.value,
+			hex!("4fff54398cad4d05ea6abfd8b0f3b4fe14c04d7ff5f5211c5b927d9cf72ac1d8").to_vec()
+		);
+	}
+}
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+use crate::{Bloom, Log};
+use codec::{Decode, Encode};
+use sp_runtime::RuntimeDebug;
+use sp_std::prelude::*;
+
+#[derive(Clone, Default, Encode, Decode, PartialEq, RuntimeDebug)]
+pub struct Receipt {
+	pub post_state_or_status: Vec<u8>,
+	pub cumulative_gas_used: u64,
+	pub bloom: Bloom,
+	pub logs: Vec<Log>,
+}
+
+impl Receipt {
+	pub fn contains_log(&self, log: &Log) -> bool {
+		self.logs.iter().any(|l| l == log)
+	}
+
+	fn decode_list(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		let mut iter = rlp.iter();
+
+		let post_state_or_status: Vec<u8> = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected receipt post state or status")),
+		};
+
+		let cumulative_gas_used: u64 = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected receipt cumulative gas used")),
+		};
+
+		let bloom: Bloom = match iter.next() {
+			Some(data) => data.as_val()?,
+			None => return Err(rlp::DecoderError::Custom("Expected receipt bloom")),
+		};
+
+		let logs: Vec<Log> = match iter.next() {
+			Some(data) => data.as_list()?,
+			None => return Err(rlp::DecoderError::Custom("Expected receipt logs")),
+		};
+
+		Ok(Self { post_state_or_status, cumulative_gas_used, bloom, logs })
+	}
+}
+
+impl rlp::Decodable for Receipt {
+	fn decode(rlp: &rlp::Rlp) -> Result<Self, rlp::DecoderError> {
+		if rlp.is_data() {
+			// Typed receipt
+			let data = rlp.as_raw();
+			match data[0] {
+				// 1 = EIP-2930, 2 = EIP-1559
+				1 | 2 => {
+					let receipt_rlp = &rlp::Rlp::new(&data[1..]);
+					if !receipt_rlp.is_list() {
+						return Err(rlp::DecoderError::RlpExpectedToBeList)
+					}
+					Self::decode_list(&rlp::Rlp::new(&data[1..]))
+				},
+				_ => Err(rlp::DecoderError::Custom("Unsupported receipt type")),
+			}
+		} else if rlp.is_list() {
+			// Legacy receipt
+			Self::decode_list(rlp)
+		} else {
+			Err(rlp::DecoderError::RlpExpectedToBeList)
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+
+	use super::Receipt;
+	use hex_literal::hex;
+
+	const RAW_RECEIPT: [u8; 1242] = hex!(
+		"
+		f904d701830652f0b901000420000000000000000000008002000000000001000000000001000000
+		00000000000000000000000000000000000000020000000800000000000000002000000000000000
+		00000000000008000000220000000000400010000000000000000000000000000000000000000000
+		00000000000000000004000000001000010000000000080000000000400000000000000000000000
+		00000800000040000000000200000000000200000000000000000000000000000000000000000000
+		04000000000002000000000100000000000000000000000000001000000002000020000010200000
+		000000010000000000000000000000000000000000000010000000f903ccf89b9421130f34829b4c
+		343142047a28ce96ec07814b15f863a0ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a116
+		28f55a4df523b3efa00000000000000000000000007d843005c7433c16b27ff939cb37471541561e
+		bda0000000000000000000000000e9c1281aae66801fa35ec404d5f2aea393ff6988a00000000000
+		0000000000000000000000000000000000000000000005d09b7380f89b9421130f34829b4c343142
+		047a28ce96ec07814b15f863a08c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200a
+		c8c7c3b925a00000000000000000000000007d843005c7433c16b27ff939cb37471541561ebda000
+		00000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da0ffffffffffffffff
+		ffffffffffffffffffffffffffffffffffffffcc840c6920f89b94c02aaa39b223fe8d0a0e5c4f27
+		ead9083c756cc2f863a0ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523
+		b3efa0000000000000000000000000e9c1281aae66801fa35ec404d5f2aea393ff6988a000000000
+		00000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da00000000000000000000000
+		0000000000000000000000000003e973b5a5d1078ef87994e9c1281aae66801fa35ec404d5f2aea3
+		93ff6988e1a01c411e9a96e071241c2f21f7726b17ae89e3cab4c78be50e062b03a9fffbbad1b840
+		000000000000000000000000000000000000000000000000000001f1420ad1d40000000000000000
+		000000000000000000000000000000014ad400879d159a38f8fc94e9c1281aae66801fa35ec404d5
+		f2aea393ff6988f863a0d78ad95fa46c994b6551d0da85fc275fe613ce37657fb8d5e3d130840159
+		d822a00000000000000000000000007a250d5630b4cf539739df2c5dacb4c659f2488da000000000
+		00000000000000007a250d5630b4cf539739df2c5dacb4c659f2488db88000000000000000000000
+		000000000000000000000000000000000005d415f332000000000000000000000000000000000000
+		00000000000000000000000000000000000000000000000000000000000000000000000000000000
+		00000000000000000000000000000000000000000000000000000000000003e973b5a5d1078ef87a
+		94c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2f842a07fcf532c15f0a6db0bd6d0e038bea71d
+		30d808c7d98cb3bf7268a95bf5081b65a00000000000000000000000007a250d5630b4cf539739df
+		2c5dacb4c659f2488da000000000000000000000000000000000000000000000000003e973b5a5d1
+		078e
+	"
+	);
+
+	#[test]
+	fn decode_legacy_receipt() {
+		let receipt: Receipt = rlp::decode(&RAW_RECEIPT).unwrap();
+		assert_eq!(receipt.post_state_or_status, vec!(1));
+		assert_eq!(receipt.cumulative_gas_used, 414448);
+		assert_eq!(
+			receipt.bloom,
+			(&hex!(
+				"
+				042000000000000000000000800200000000000100000000000100000000000000000000
+				000000000000000000000000020000000800000000000000002000000000000000000000
+				000000080000002200000000004000100000000000000000000000000000000000000000
+				000000000000000000000400000000100001000000000008000000000040000000000000
+				000000000000000800000040000000000200000000000200000000000000000000000000
+				000000000000000000040000000000020000000001000000000000000000000000000010
+				000000020000200000102000000000000100000000000000000000000000000000000000
+				10000000
+			"
+			))
+				.into(),
+		);
+		assert_eq!(receipt.logs.len(), 6);
+	}
+}
@@ -0,0 +1,61 @@
+[package]
+name = "snowbridge-router-primitives"
+description = "Snowbridge Router Primitives"
+version = "0.1.1"
+authors = ["Snowfork <contact@snowfork.com>"]
+edition = "2021"
+license = "Apache-2.0"
+
+[dependencies]
+serde = { version = "1.0.188", optional = true, features = ["derive"] }
+codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false }
+scale-info = { version = "2.9.0", default-features = false, features = ["derive"] }
+log = { version = "0.4.20", default-features = false }
+
+frame-support = { path = "../../../../../substrate/frame/support", default-features = false }
+frame-system = { path = "../../../../../substrate/frame/system", default-features = false }
+sp-core = { path = "../../../../../substrate/primitives/core", default-features = false }
+sp-io = { path = "../../../../../substrate/primitives/io", default-features = false }
+sp-runtime = { path = "../../../../../substrate/primitives/runtime", default-features = false }
+sp-std = { path = "../../../../../substrate/primitives/std", default-features = false }
+
+xcm = { package = "staging-xcm", path = "../../../../../polkadot/xcm", default-features = false }
+xcm-builder = { package = "staging-xcm-builder", path = "../../../../../polkadot/xcm/xcm-builder", default-features = false }
+xcm-executor = { package = "staging-xcm-executor", path = "../../../../../polkadot/xcm/xcm-executor", default-features = false }
+
+snowbridge-core = { path = "../../primitives/core", default-features = false }
+
+ethabi = { git = "https://github.com/Snowfork/ethabi-decode.git", package = "ethabi-decode", branch = "master", default-features = false }
+
+hex-literal = { version = "0.4.1" }
+
+[dev-dependencies]
+hex = { package = "rustc-hex", version = "2.1.0" }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"ethabi/std",
+	"frame-support/std",
+	"frame-system/std",
+	"log/std",
+	"scale-info/std",
+	"serde",
+	"snowbridge-core/std",
+	"sp-core/std",
+	"sp-io/std",
+	"sp-runtime/std",
+	"sp-std/std",
+	"xcm-builder/std",
+	"xcm-executor/std",
+	"xcm/std",
+]
+runtime-benchmarks = [
+	"frame-support/runtime-benchmarks",
+	"frame-system/runtime-benchmarks",
+	"snowbridge-core/runtime-benchmarks",
+	"sp-runtime/runtime-benchmarks",
+	"xcm-builder/runtime-benchmarks",
+	"xcm-executor/runtime-benchmarks",
+]
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! Converts messages from Ethereum to XCM messages
+
+#[cfg(test)]
+mod tests;
+
+use codec::{Decode, Encode};
+use core::marker::PhantomData;
+use frame_support::{traits::tokens::Balance as BalanceT, weights::Weight, PalletError};
+use scale_info::TypeInfo;
+use sp_core::{Get, RuntimeDebug, H160};
+use sp_io::hashing::blake2_256;
+use sp_runtime::MultiAddress;
+use sp_std::prelude::*;
+use xcm::prelude::{Junction::AccountKey20, *};
+use xcm_executor::traits::ConvertLocation;
+
+const MINIMUM_DEPOSIT: u128 = 1;
+
+/// Messages from Ethereum are versioned. This is because in future,
+/// we may want to evolve the protocol so that the ethereum side sends XCM messages directly.
+/// Instead having BridgeHub transcode the messages into XCM.
+#[derive(Clone, Encode, Decode, RuntimeDebug)]
+pub enum VersionedMessage {
+	V1(MessageV1),
+}
+
+/// For V1, the ethereum side sends messages which are transcoded into XCM. These messages are
+/// self-contained, in that they can be transcoded using only information in the message.
+#[derive(Clone, Encode, Decode, RuntimeDebug)]
+pub struct MessageV1 {
+	/// EIP-155 chain id of the origin Ethereum network
+	pub chain_id: u64,
+	/// The command originating from the Gateway contract
+	pub command: Command,
+}
+
+#[derive(Clone, Encode, Decode, RuntimeDebug)]
+pub enum Command {
+	/// Register a wrapped token on the AssetHub `ForeignAssets` pallet
+	RegisterToken {
+		/// The address of the ERC20 token to be bridged over to AssetHub
+		token: H160,
+		/// XCM execution fee on AssetHub
+		fee: u128,
+	},
+	/// Send a token to AssetHub or another parachain
+	SendToken {
+		/// The address of the ERC20 token to be bridged over to AssetHub
+		token: H160,
+		/// The destination for the transfer
+		destination: Destination,
+		/// Amount to transfer
+		amount: u128,
+		/// XCM execution fee on AssetHub
+		fee: u128,
+	},
+}
+
+/// Destination for bridged tokens
+#[derive(Clone, Encode, Decode, RuntimeDebug)]
+pub enum Destination {
+	/// The funds will be deposited into account `id` on AssetHub
+	AccountId32 { id: [u8; 32] },
+	/// The funds will deposited into the sovereign account of destination parachain `para_id` on
+	/// AssetHub, Account `id` on the destination parachain will receive the funds via a
+	/// reserve-backed transfer. See <https://github.com/paritytech/xcm-format#depositreserveasset>
+	ForeignAccountId32 {
+		para_id: u32,
+		id: [u8; 32],
+		/// XCM execution fee on final destination
+		fee: u128,
+	},
+	/// The funds will deposited into the sovereign account of destination parachain `para_id` on
+	/// AssetHub, Account `id` on the destination parachain will receive the funds via a
+	/// reserve-backed transfer. See <https://github.com/paritytech/xcm-format#depositreserveasset>
+	ForeignAccountId20 {
+		para_id: u32,
+		id: [u8; 20],
+		/// XCM execution fee on final destination
+		fee: u128,
+	},
+}
+
+pub struct MessageToXcm<
+	CreateAssetCall,
+	CreateAssetDeposit,
+	InboundQueuePalletInstance,
+	AccountId,
+	Balance,
+> where
+	CreateAssetCall: Get<CallIndex>,
+	CreateAssetDeposit: Get<u128>,
+	Balance: BalanceT,
+{
+	_phantom: PhantomData<(
+		CreateAssetCall,
+		CreateAssetDeposit,
+		InboundQueuePalletInstance,
+		AccountId,
+		Balance,
+	)>,
+}
+
+/// Reason why a message conversion failed.
+#[derive(Copy, Clone, TypeInfo, PalletError, Encode, Decode, RuntimeDebug)]
+pub enum ConvertMessageError {
+	/// The message version is not supported for conversion.
+	UnsupportedVersion,
+}
+
+/// convert the inbound message to xcm which will be forwarded to the destination chain
+pub trait ConvertMessage {
+	type Balance: BalanceT + From<u128>;
+	type AccountId;
+	/// Converts a versioned message into an XCM message and an optional topicID
+	fn convert(message: VersionedMessage) -> Result<(Xcm<()>, Self::Balance), ConvertMessageError>;
+}
+
+pub type CallIndex = [u8; 2];
+
+impl<CreateAssetCall, CreateAssetDeposit, InboundQueuePalletInstance, AccountId, Balance>
+	ConvertMessage
+	for MessageToXcm<
+		CreateAssetCall,
+		CreateAssetDeposit,
+		InboundQueuePalletInstance,
+		AccountId,
+		Balance,
+	> where
+	CreateAssetCall: Get<CallIndex>,
+	CreateAssetDeposit: Get<u128>,
+	InboundQueuePalletInstance: Get<u8>,
+	Balance: BalanceT + From<u128>,
+	AccountId: Into<[u8; 32]>,
+{
+	type Balance = Balance;
+	type AccountId = AccountId;
+
+	fn convert(message: VersionedMessage) -> Result<(Xcm<()>, Self::Balance), ConvertMessageError> {
+		use Command::*;
+		use VersionedMessage::*;
+		match message {
+			V1(MessageV1 { chain_id, command: RegisterToken { token, fee } }) =>
+				Ok(Self::convert_register_token(chain_id, token, fee)),
+			V1(MessageV1 { chain_id, command: SendToken { token, destination, amount, fee } }) =>
+				Ok(Self::convert_send_token(chain_id, token, destination, amount, fee)),
+		}
+	}
+}
+
+impl<CreateAssetCall, CreateAssetDeposit, InboundQueuePalletInstance, AccountId, Balance>
+	MessageToXcm<CreateAssetCall, CreateAssetDeposit, InboundQueuePalletInstance, AccountId, Balance>
+where
+	CreateAssetCall: Get<CallIndex>,
+	CreateAssetDeposit: Get<u128>,
+	InboundQueuePalletInstance: Get<u8>,
+	Balance: BalanceT + From<u128>,
+	AccountId: Into<[u8; 32]>,
+{
+	fn convert_register_token(chain_id: u64, token: H160, fee: u128) -> (Xcm<()>, Balance) {
+		let network = Ethereum { chain_id };
+		let xcm_fee: MultiAsset = (MultiLocation::parent(), fee).into();
+		let deposit: MultiAsset = (MultiLocation::parent(), CreateAssetDeposit::get()).into();
+
+		let total_amount = fee + CreateAssetDeposit::get();
+		let total: MultiAsset = (MultiLocation::parent(), total_amount).into();
+
+		let bridge_location: MultiLocation = (Parent, Parent, GlobalConsensus(network)).into();
+
+		let owner = GlobalConsensusEthereumConvertsFor::<[u8; 32]>::from_chain_id(&chain_id);
+		let asset_id = Self::convert_token_address(network, token);
+		let create_call_index: [u8; 2] = CreateAssetCall::get();
+		let inbound_queue_pallet_index = InboundQueuePalletInstance::get();
+
+		let xcm: Xcm<()> = vec![
+			// Teleport required fees.
+			ReceiveTeleportedAsset(total.into()),
+			// Pay for execution.
+			BuyExecution { fees: xcm_fee, weight_limit: Unlimited },
+			// Fund the snowbridge sovereign with the required deposit for creation.
+			DepositAsset { assets: Definite(deposit.into()), beneficiary: bridge_location },
+			// Only our inbound-queue pallet is allowed to invoke `UniversalOrigin`
+			DescendOrigin(X1(PalletInstance(inbound_queue_pallet_index))),
+			// Change origin to the bridge.
+			UniversalOrigin(GlobalConsensus(network)),
+			// Call create_asset on foreign assets pallet.
+			Transact {
+				origin_kind: OriginKind::Xcm,
+				require_weight_at_most: Weight::from_parts(400_000_000, 8_000),
+				call: (
+					create_call_index,
+					asset_id,
+					MultiAddress::<[u8; 32], ()>::Id(owner),
+					MINIMUM_DEPOSIT,
+				)
+					.encode()
+					.into(),
+			},
+			RefundSurplus,
+			// Clear the origin so that remaining assets in holding
+			// are claimable by the physical origin (BridgeHub)
+			ClearOrigin,
+		]
+		.into();
+
+		(xcm, total_amount.into())
+	}
+
+	fn convert_send_token(
+		chain_id: u64,
+		token: H160,
+		destination: Destination,
+		amount: u128,
+		asset_hub_fee: u128,
+	) -> (Xcm<()>, Balance) {
+		let network = Ethereum { chain_id };
+		let asset_hub_fee_asset: MultiAsset = (MultiLocation::parent(), asset_hub_fee).into();
+		let asset: MultiAsset = (Self::convert_token_address(network, token), amount).into();
+
+		let (dest_para_id, beneficiary, dest_para_fee) = match destination {
+			// Final destination is a 32-byte account on AssetHub
+			Destination::AccountId32 { id } => (
+				None,
+				MultiLocation { parents: 0, interior: X1(AccountId32 { network: None, id }) },
+				0,
+			),
+			// Final destination is a 32-byte account on a sibling of AssetHub
+			Destination::ForeignAccountId32 { para_id, id, fee } => (
+				Some(para_id),
+				MultiLocation { parents: 0, interior: X1(AccountId32 { network: None, id }) },
+				// Total fee needs to cover execution on AssetHub and Sibling
+				fee,
+			),
+			// Final destination is a 20-byte account on a sibling of AssetHub
+			Destination::ForeignAccountId20 { para_id, id, fee } => (
+				Some(para_id),
+				MultiLocation { parents: 0, interior: X1(AccountKey20 { network: None, key: id }) },
+				// Total fee needs to cover execution on AssetHub and Sibling
+				fee,
+			),
+		};
+
+		let total_fees = asset_hub_fee.saturating_add(dest_para_fee);
+		let total_fee_asset: MultiAsset = (MultiLocation::parent(), total_fees).into();
+		let inbound_queue_pallet_index = InboundQueuePalletInstance::get();
+
+		let mut instructions = vec![
+			ReceiveTeleportedAsset(total_fee_asset.into()),
+			BuyExecution { fees: asset_hub_fee_asset, weight_limit: Unlimited },
+			DescendOrigin(X1(PalletInstance(inbound_queue_pallet_index))),
+			UniversalOrigin(GlobalConsensus(network)),
+			ReserveAssetDeposited(asset.clone().into()),
+			ClearOrigin,
+		];
+
+		match dest_para_id {
+			Some(dest_para_id) => {
+				let dest_para_fee_asset: MultiAsset =
+					(MultiLocation::parent(), dest_para_fee).into();
+
+				instructions.extend(vec![
+					// Perform a deposit reserve to send to destination chain.
+					DepositReserveAsset {
+						assets: Definite(vec![dest_para_fee_asset.clone(), asset.clone()].into()),
+						dest: MultiLocation { parents: 1, interior: X1(Parachain(dest_para_id)) },
+						xcm: vec![
+							// Buy execution on target.
+							BuyExecution { fees: dest_para_fee_asset, weight_limit: Unlimited },
+							// Deposit asset to beneficiary.
+							DepositAsset { assets: Definite(asset.into()), beneficiary },
+						]
+						.into(),
+					},
+				]);
+			},
+			None => {
+				instructions.extend(vec![
+					// Deposit asset to beneficiary.
+					DepositAsset { assets: Definite(asset.into()), beneficiary },
+				]);
+			},
+		}
+
+		(instructions.into(), total_fees.into())
+	}
+
+	// Convert ERC20 token address to a Multilocation that can be understood by Assets Hub.
+	fn convert_token_address(network: NetworkId, token: H160) -> MultiLocation {
+		MultiLocation {
+			parents: 2,
+			interior: X2(
+				GlobalConsensus(network),
+				AccountKey20 { network: None, key: token.into() },
+			),
+		}
+	}
+}
+
+pub struct GlobalConsensusEthereumConvertsFor<AccountId>(PhantomData<AccountId>);
+impl<AccountId> ConvertLocation<AccountId> for GlobalConsensusEthereumConvertsFor<AccountId>
+where
+	AccountId: From<[u8; 32]> + Clone,
+{
+	fn convert_location(location: &MultiLocation) -> Option<AccountId> {
+		if let MultiLocation { interior: X1(GlobalConsensus(Ethereum { chain_id })), .. } = location
+		{
+			Some(Self::from_chain_id(chain_id).into())
+		} else {
+			None
+		}
+	}
+}
+
+impl<AccountId> GlobalConsensusEthereumConvertsFor<AccountId> {
+	pub fn from_chain_id(chain_id: &u64) -> [u8; 32] {
+		(b"ethereum-chain", chain_id).using_encoded(blake2_256)
+	}
+}
@@ -0,0 +1,41 @@
+use super::GlobalConsensusEthereumConvertsFor;
+use crate::inbound::CallIndex;
+use frame_support::parameter_types;
+use hex_literal::hex;
+use xcm::v3::prelude::*;
+use xcm_executor::traits::ConvertLocation;
+
+const NETWORK: NetworkId = Ethereum { chain_id: 11155111 };
+
+parameter_types! {
+	pub EthereumNetwork: NetworkId = NETWORK;
+
+	pub const CreateAssetCall: CallIndex = [1, 1];
+	pub const CreateAssetExecutionFee: u128 = 123;
+	pub const CreateAssetDeposit: u128 = 891;
+	pub const SendTokenExecutionFee: u128 = 592;
+}
+
+#[test]
+fn test_contract_location_with_network_converts_successfully() {
+	let expected_account: [u8; 32] =
+		hex!("ce796ae65569a670d0c1cc1ac12515a3ce21b5fbf729d63d7b289baad070139d");
+	let contract_location = MultiLocation { parents: 2, interior: X1(GlobalConsensus(NETWORK)) };
+
+	let account =
+		GlobalConsensusEthereumConvertsFor::<[u8; 32]>::convert_location(&contract_location)
+			.unwrap();
+
+	assert_eq!(account, expected_account);
+}
+
+#[test]
+fn test_contract_location_with_incorrect_location_fails_convert() {
+	let contract_location =
+		MultiLocation { parents: 2, interior: X2(GlobalConsensus(Polkadot), Parachain(1000)) };
+
+	assert_eq!(
+		GlobalConsensusEthereumConvertsFor::<[u8; 32]>::convert_location(&contract_location),
+		None,
+	);
+}
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+#![cfg_attr(not(feature = "std"), no_std)]
+
+pub mod inbound;
+pub mod outbound;
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! Converts XCM messages into simpler commands that can be processed by the Gateway contract
+
+#[cfg(test)]
+mod tests;
+
+use core::slice::Iter;
+
+use codec::{Decode, Encode};
+
+use frame_support::{ensure, traits::Get};
+use snowbridge_core::{
+	outbound::{AgentExecuteCommand, Command, Message, SendMessage},
+	ChannelId, ParaId,
+};
+use sp_core::{H160, H256};
+use sp_std::{iter::Peekable, marker::PhantomData, prelude::*};
+use xcm::v3::prelude::*;
+use xcm_executor::traits::{ConvertLocation, ExportXcm};
+
+pub struct EthereumBlobExporter<
+	UniversalLocation,
+	EthereumNetwork,
+	OutboundQueue,
+	AgentHashedDescription,
+>(PhantomData<(UniversalLocation, EthereumNetwork, OutboundQueue, AgentHashedDescription)>);
+
+impl<UniversalLocation, EthereumNetwork, OutboundQueue, AgentHashedDescription> ExportXcm
+	for EthereumBlobExporter<UniversalLocation, EthereumNetwork, OutboundQueue, AgentHashedDescription>
+where
+	UniversalLocation: Get<InteriorMultiLocation>,
+	EthereumNetwork: Get<NetworkId>,
+	OutboundQueue: SendMessage<Balance = u128>,
+	AgentHashedDescription: ConvertLocation<H256>,
+{
+	type Ticket = (Vec<u8>, XcmHash);
+
+	fn validate(
+		network: NetworkId,
+		_channel: u32,
+		universal_source: &mut Option<InteriorMultiLocation>,
+		destination: &mut Option<InteriorMultiLocation>,
+		message: &mut Option<Xcm<()>>,
+	) -> SendResult<Self::Ticket> {
+		let expected_network = EthereumNetwork::get();
+		let universal_location = UniversalLocation::get();
+
+		if network != expected_network {
+			log::trace!(target: "xcm::ethereum_blob_exporter", "skipped due to unmatched bridge network {network:?}.");
+			return Err(SendError::NotApplicable)
+		}
+
+		let dest = destination.take().ok_or(SendError::MissingArgument)?;
+		if dest != Here {
+			log::trace!(target: "xcm::ethereum_blob_exporter", "skipped due to unmatched remote destination {dest:?}.");
+			return Err(SendError::NotApplicable)
+		}
+
+		let (local_net, local_sub) = universal_source
+			.take()
+			.ok_or_else(|| {
+				log::error!(target: "xcm::ethereum_blob_exporter", "universal source not provided.");
+				SendError::MissingArgument
+			})?
+			.split_global()
+			.map_err(|()| {
+				log::error!(target: "xcm::ethereum_blob_exporter", "could not get global consensus from universal source '{universal_source:?}'.");
+				SendError::Unroutable
+			})?;
+
+		if Ok(local_net) != universal_location.global_consensus() {
+			log::trace!(target: "xcm::ethereum_blob_exporter", "skipped due to unmatched relay network {local_net:?}.");
+			return Err(SendError::NotApplicable)
+		}
+
+		let para_id = match local_sub {
+			X1(Parachain(para_id)) => para_id,
+			_ => {
+				log::error!(target: "xcm::ethereum_blob_exporter", "could not get parachain id from universal source '{local_sub:?}'.");
+				return Err(SendError::MissingArgument)
+			},
+		};
+
+		let message = message.take().ok_or_else(|| {
+			log::error!(target: "xcm::ethereum_blob_exporter", "xcm message not provided.");
+			SendError::MissingArgument
+		})?;
+
+		let mut converter = XcmConverter::new(&message, &expected_network);
+		let (agent_execute_command, message_id) = converter.convert().map_err(|err|{
+			log::error!(target: "xcm::ethereum_blob_exporter", "unroutable due to pattern matching error '{err:?}'.");
+			SendError::Unroutable
+		})?;
+
+		let source_location: MultiLocation = MultiLocation { parents: 1, interior: local_sub };
+		let agent_id = match AgentHashedDescription::convert_location(&source_location) {
+			Some(id) => id,
+			None => {
+				log::error!(target: "xcm::ethereum_blob_exporter", "unroutable due to not being able to create agent id. '{source_location:?}'");
+				return Err(SendError::Unroutable)
+			},
+		};
+
+		let channel_id: ChannelId = ParaId::from(para_id).into();
+
+		let outbound_message = Message {
+			id: Some(message_id.into()),
+			channel_id,
+			command: Command::AgentExecute { agent_id, command: agent_execute_command },
+		};
+
+		// validate the message
+		let (ticket, fee) = OutboundQueue::validate(&outbound_message).map_err(|err| {
+			log::error!(target: "xcm::ethereum_blob_exporter", "OutboundQueue validation of message failed. {err:?}");
+			SendError::Unroutable
+		})?;
+
+		// convert fee to MultiAsset
+		let fee = MultiAsset::from((MultiLocation::parent(), fee.total())).into();
+
+		Ok(((ticket.encode(), message_id), fee))
+	}
+
+	fn deliver(blob: (Vec<u8>, XcmHash)) -> Result<XcmHash, SendError> {
+		let ticket: OutboundQueue::Ticket = OutboundQueue::Ticket::decode(&mut blob.0.as_ref())
+			.map_err(|_| {
+				log::trace!(target: "xcm::ethereum_blob_exporter", "undeliverable due to decoding error");
+				SendError::NotApplicable
+			})?;
+
+		let message_id = OutboundQueue::deliver(ticket).map_err(|_| {
+			log::error!(target: "xcm::ethereum_blob_exporter", "OutboundQueue submit of message failed");
+			SendError::Transport("other transport error")
+		})?;
+
+		log::info!(target: "xcm::ethereum_blob_exporter", "message delivered {message_id:#?}.");
+		Ok(message_id.into())
+	}
+}
+
+/// Errors that can be thrown to the pattern matching step.
+#[derive(PartialEq, Debug)]
+enum XcmConverterError {
+	UnexpectedEndOfXcm,
+	EndOfXcmMessageExpected,
+	WithdrawAssetExpected,
+	DepositAssetExpected,
+	NoReserveAssets,
+	FilterDoesNotConsumeAllAssets,
+	TooManyAssets,
+	ZeroAssetTransfer,
+	BeneficiaryResolutionFailed,
+	AssetResolutionFailed,
+	InvalidFeeAsset,
+	SetTopicExpected,
+}
+
+macro_rules! match_expression {
+	($expression:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )?, $value:expr $(,)?) => {
+		match $expression {
+			$( $pattern )|+ $( if $guard )? => Some($value),
+			_ => None,
+		}
+	};
+}
+
+struct XcmConverter<'a, Call> {
+	iter: Peekable<Iter<'a, Instruction<Call>>>,
+	ethereum_network: &'a NetworkId,
+}
+impl<'a, Call> XcmConverter<'a, Call> {
+	fn new(message: &'a Xcm<Call>, ethereum_network: &'a NetworkId) -> Self {
+		Self { iter: message.inner().iter().peekable(), ethereum_network }
+	}
+
+	fn convert(&mut self) -> Result<(AgentExecuteCommand, [u8; 32]), XcmConverterError> {
+		// Get withdraw/deposit and make native tokens create message.
+		let result = self.native_tokens_unlock_message()?;
+
+		// All xcm instructions must be consumed before exit.
+		if self.next().is_ok() {
+			return Err(XcmConverterError::EndOfXcmMessageExpected)
+		}
+
+		Ok(result)
+	}
+
+	fn native_tokens_unlock_message(
+		&mut self,
+	) -> Result<(AgentExecuteCommand, [u8; 32]), XcmConverterError> {
+		use XcmConverterError::*;
+
+		// Get the reserve assets from WithdrawAsset.
+		let reserve_assets =
+			match_expression!(self.next()?, WithdrawAsset(reserve_assets), reserve_assets)
+				.ok_or(WithdrawAssetExpected)?;
+
+		// Check if clear origin exists and skip over it.
+		if match_expression!(self.peek(), Ok(ClearOrigin), ()).is_some() {
+			let _ = self.next();
+		}
+
+		// Get the fee asset item from BuyExecution or continue parsing.
+		let fee_asset = match_expression!(self.peek(), Ok(BuyExecution { fees, .. }), fees);
+		if fee_asset.is_some() {
+			let _ = self.next();
+		}
+
+		let (deposit_assets, beneficiary) = match_expression!(
+			self.next()?,
+			DepositAsset { assets, beneficiary },
+			(assets, beneficiary)
+		)
+		.ok_or(DepositAssetExpected)?;
+
+		// assert that the beneficiary is AccountKey20.
+		let recipient = match_expression!(
+			beneficiary,
+			MultiLocation { parents: 0, interior: X1(AccountKey20 { network, key }) }
+				if self.network_matches(network),
+			H160(*key)
+		)
+		.ok_or(BeneficiaryResolutionFailed)?;
+
+		// Make sure there are reserved assets.
+		if reserve_assets.len() == 0 {
+			return Err(NoReserveAssets)
+		}
+
+		// Check the the deposit asset filter matches what was reserved.
+		if reserve_assets.inner().iter().any(|asset| !deposit_assets.matches(asset)) {
+			return Err(FilterDoesNotConsumeAllAssets)
+		}
+
+		// We only support a single asset at a time.
+		ensure!(reserve_assets.len() == 1, TooManyAssets);
+		let reserve_asset = reserve_assets.get(0).ok_or(AssetResolutionFailed)?;
+
+		// If there was a fee specified verify it.
+		if let Some(fee_asset) = fee_asset {
+			// The fee asset must be the same as the reserve asset.
+			if fee_asset.id != reserve_asset.id || fee_asset.fun > reserve_asset.fun {
+				return Err(InvalidFeeAsset)
+			}
+		}
+
+		let (token, amount) = match_expression!(
+			reserve_asset,
+			MultiAsset {
+				id: Concrete(MultiLocation { parents: 0, interior: X1(AccountKey20 { network , key })}),
+				fun: Fungible(amount)
+			} if self.network_matches(network),
+			(H160(*key), *amount)
+		)
+		.ok_or(AssetResolutionFailed)?;
+
+		// transfer amount must be greater than 0.
+		ensure!(amount > 0, ZeroAssetTransfer);
+
+		// Check if there is a SetTopic and skip over it if found.
+		let topic_id = match_expression!(self.next()?, SetTopic(id), id).ok_or(SetTopicExpected)?;
+
+		Ok((AgentExecuteCommand::TransferToken { token, recipient, amount }, *topic_id))
+	}
+
+	fn next(&mut self) -> Result<&'a Instruction<Call>, XcmConverterError> {
+		self.iter.next().ok_or(XcmConverterError::UnexpectedEndOfXcm)
+	}
+
+	fn peek(&mut self) -> Result<&&'a Instruction<Call>, XcmConverterError> {
+		self.iter.peek().ok_or(XcmConverterError::UnexpectedEndOfXcm)
+	}
+
+	fn network_matches(&self, network: &Option<NetworkId>) -> bool {
+		if let Some(network) = network {
+			network == self.ethereum_network
+		} else {
+			true
+		}
+	}
+}