update docs

docs/pages/developers/polkadot/token-gateway.mdx

@@ -23,6 +23,7 @@ Let's look at the pallet specific components of the configuration trait: <br/><b
  - `AssetIdFactory`: This type should be configured with a component that implements `pallet_token_gateway::types::CreateAssetId`. It should return a unique asset id each time the `AssetIdFactory::create_asset_id` is called.<br/><br/>
  - `NativeAssetId`: A constant value that represents the identifier of the native asset.<br/><br/>
  - `Decimals`: A constant that represents the precision of the native currency. <br/><br/>
+ - `EvmToSubstrate`: A type that allows conversion of an EVM account to a substrate account. <br/><br/>
 
 ## Calls
 
@@ -77,6 +78,8 @@ impl pallet_token_gateway::Config for Runtime {
     type AssetIdFactory = ();
     // The precision of the native asset
     type Decimals = Decimals;
+    // An implementation that converts an evm account to a substrate account
+    type EvmToSubstrate = ();
 }
 
 // Add the token gateway pallet to your ISMP router
@@ -166,6 +169,8 @@ pub struct TeleportParams<AssetId, Balance> {
 	pub token_gateway: Vec<u8>,
 	/// Relayer fee
 	pub relayer_fee: Balance,
+    /// Optional call data
+    pub call_data: Option<Vec<u8>>
 }
 ```
 Let's explore what each parameter holds: 

modules/pallets/token-gateway/src/lib.rs

@@ -40,10 +40,7 @@ use ismp::{
 };
 
 use sp_core::{Get, H160, U256};
-use sp_runtime::{
-	traits::{Dispatchable, Hash},
-	MultiSignature,
-};
+use sp_runtime::{traits::Dispatchable, MultiSignature};
 use token_gateway_primitives::{
 	token_gateway_id, token_governor_id, AssetMetadata, DeregisterAssets,
 };
@@ -636,7 +633,7 @@ where
 			// Verify signature against encoded runtime call
 			let nonce = frame_system::Pallet::<T>::account_nonce(beneficiary.clone());
 			let payload = (nonce, substrate_data.runtime_call.clone()).encode();
-			let message = <<T as frame_system::Config>::Hashing as Hash>::hash(&payload);
+			let message = sp_io::hashing::keccak_256(&payload);
 
 			let multi_signature = MultiSignature::decode(&mut &*substrate_data.signature)?;
 
@@ -662,10 +659,8 @@ where
 					}
 				},
 				MultiSignature::Ecdsa(sig) => {
-					let mut msg = [0u8; 32];
-					msg.copy_from_slice(message.as_ref());
-					let pub_key =
-						sp_io::crypto::secp256k1_ecdsa_recover(&sig.0, &msg).map_err(|_| {
+					let pub_key = sp_io::crypto::secp256k1_ecdsa_recover(&sig.0, &message)
+						.map_err(|_| {
 							anyhow!("Failed to recover ecdsa public key from signature")
 						})?;
 					let eth_address =

modules/pallets/token-gateway/src/types.rs

@@ -90,8 +90,8 @@ alloy_sol_macro::sol! {
 
 #[derive(Debug, Clone, Encode, Decode, scale_info::TypeInfo, PartialEq, Eq)]
 pub struct SubstrateCalldata {
-	/// A scale encoded encoded [MultiSignature](sp_runtime::MultiSignature) of the hash of the
-	/// encoded runtime call by the beneficiary account
+	/// A scale encoded encoded [MultiSignature](sp_runtime::MultiSignature) of the beneficiary's
+	/// account nonce and the encoded runtime call
 	pub signature: Vec<u8>,
 	/// Encoded Runtime call that should be executed
 	pub runtime_call: Vec<u8>,