feat: Inbound Transaction Verification (#785)

* doc: added callout to axelar dest chain gmp msg

* doc: add gmp verification tx docs

* doc: added link to video for validateContractCall

* chore: added reference to cosmos gmp doc, reworded based on team feedback

* chore: rephrased integrations to axelar are set TO connections to Axleaxelar are initiated via gateway

src/layouts/navigation.ts

@@ -79,6 +79,10 @@ export const getNavigation = (section) => {
               title: "Monitor Transaction State",
               href: "/dev/general-message-passing/monitoring",
             },
+            {
+              title: "Verify GMP Transaction",
+              href: "/dev/general-message-passing/verify-gmp-tx",
+            },
             {
               title: "Debug",
               children: [

src/pages/dev/general-message-passing/overview.mdx

@@ -13,6 +13,11 @@ With GMP, you can:
   **NOTE:** The security of your contracts is limited to the security of the chains they integrate with. Since blockchains can have different security practices, we recommend doing due diligence on all chains your contract will be deployed to.
 </Callout>
 
+<Callout emoji="🚨">
+  **NOTE:** GMP Transactions using `callContractWithToken` sent to the Axelar chain itself are not yet supported. Axelar only supports GMP call without token from Axelar to chain X. Transactions sent to the Axelar chain as the destination chain will be stuck until support is rolled out.
+</Callout>
+
+
 ### Prerequisites
 - For GMP to work, chains A and B must be EVM or Cosmos with a deployed Axelar Gateway contract. We're adding new chains and chain technology stacks all of the time. This document primarily focuses on EVM chains and Solidity code, but you can [learn about interacting with Cosmos GMP](./cosmos-gmp).
 - The application's executable contract must be deployed on the destination contract.

src/pages/dev/general-message-passing/verify-gmp-tx.mdx

@@ -0,0 +1,45 @@
+# GMP Message Verification
+
+Axelar enables messages to be sent between two different blockchains. When a message is sent from a source chain to a destination chain, Axelar verifies that the incoming message on the destination chain is the authentic message that was sent on the source chain, having passed through the Axelar blockchain and confirmed by Axelar's validators.
+
+## Ethereum Virtual Machine (EVM)
+
+On EVM based chains such as Ethereum or Avalanche, connections to Axelar are initiated via the [Gateway Contract](https://github.com/axelarnetwork/axelar-cgp-solidity/blob/main/contracts/AxelarGateway.sol). The Gateway is used on both the source and the destination chain. On the source chain it is used to trigger the interchain transaction, on the destination chain it is triggered by the [Axelar Executable](https://github.com/axelarnetwork/axelar-gmp-sdk-solidity/blob/main/contracts/executable/AxelarExecutable.sol) to [validate](https://github.com/axelarnetwork/axelar-cgp-solidity/blob/2023fadee722c3896f1071c2a9d578436643c5a7/contracts/AxelarGateway.sol#L233) an incoming GMP message. 
+
+#### Validate Contract Call
+The `validateContractCall()` function is called on every inbound GMP message to ensure that the incoming message is authentic. This function receives the relevant parameters of a GMP call including;
+1. `CommandId`: A unique id for interchain messages
+2. `SourceChain`: The source chain of the GMP message
+3. `SourceAddress`: The source address of the contract call
+4. `PayloadHash`: A hash of the GMP message that was sent with the call
+
+Using this information it confirms that the inbound call has indeed been verified by the Axelar network and that this data is the authentic data passed in from the source chain rather than a malicious execution with invalid data on the destination chain.
+
+Once this function has been called the transaction is marked as _Executed_ on the destination chain to avoid double execution.
+
+Please watch [here](https://www.youtube.com/watch?v=qF9cVhcD2CY) for more information on validating incoming messages.
+
+## Cosmos
+
+On Cosmos, [validation](/dev/cosmos-gmp#establishing-a-path-of-trust) is conducted on Axelar before calling a destination contract. 
+
+### Evm -> Cosmos 
+
+For messages coming from [EVM to Cosmos](https://github.com/axelarnetwork/evm-cosmos-gmp-sample/tree/main/cosmwasm-integration#authenticate-the-sender), Axelar users a unique sender to handle communication `axelar1dv4u5k73pzqrxlzujxg3qp8kvc3pje7jtdvu72npnt5zhq05ejcsn5qme5`. Then on the destination chain itself Axelar derives a unique caller to execute the transaction. On your contract you simply must ensure that the address triggering the transaction is the unique Axelar address to know that this is the authentic call coming from the Axelar network. The Axelar account is derived via the `DeriveIntermediateSender` sender function.
+
+```
+func DeriveIntermediateSender(channel, originalSender, bech32Prefix string) (string, error) {
+	senderStr := fmt.Sprintf("%s/%s", channel, originalSender)
+	senderHash32 := address.Hash(types.SenderPrefix, []byte(senderStr))
+	sender := sdk.AccAddress(senderHash32[:])
+	return sdk.Bech32ifyAddressBytes(bech32Prefix, sender)
+}
+```
+
+For the Neutron blockchain for example to derive the Axelar account you pass in `channel-2`, `axelar1dv4u5k73pzqrxlzujxg3qp8kvc3pje7jtdvu72npnt5zhq05ejcsn5qme5` , `neutron` to the `DeriveIntermediateSender` function.
+
+### IBC Hooks
+
+If you’re using [IBC hooks (iirc)](https://github.com/osmosis-labs/osmosis/tree/main/x/ibc-hooks#wasm-hooks) to trigger wasm contracts, it will derive the sender for the wasm call itself (rather than just the plain IBC sender). In this instance as well you can require the contract to expect this specific derived sender address. 
+
+