> ## Documentation Index
> Fetch the complete documentation index at: https://cosmos-docs-sync-security-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Step 4: Wire the IFT Bridge

> Register IFT token contracts on each chain to enable cross-chain burn and mint

After the previous step, both light clients exist and their counterparties are registered. This step wires the IFT application layer: it tells each chain's IFT module and contract which addresses and denoms correspond across chains, and what to mint or burn when a packet arrives.

Run [`setup.sh`](https://github.com/cosmos/ibc-e2e-docs-example/blob/main/demo/cosmos-evm/setup.sh):

```bash theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
./setup.sh wire
```

## What the script does

### 1. Register the IFT bridge (Cosmos side)

The following transactions are submitted on the Cosmos chain.

First, if the tokenfactory denom does not yet exist, it is created:

```bash theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
sandboxd tx tokenfactory create-denom $subdenom
```

The denom takes the form `factory/{creator_addr}/{subdenom}`.

Then the IFT bridge is registered:

```bash theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
sandboxd tx ift register-bridge $COSMOS_IFT_DENOM $COSMOS_CLIENT_ID $IFT_CONTRACT_ADDR_CHECKSUM evm
```

Note that the IFT contract address must be EIP-55 checksummed.

This tells the Cosmos IFT module: EVM packets verified by `COSMOS_CLIENT_ID` (the attestation light client on Cosmos) that originate from `$IFT_CONTRACT_ADDR_CHECKSUM` should mint `$COSMOS_IFT_DENOM`. When tokens are sent in the other direction, the module burns them and sends a packet to that contract.

Output: `COSMOS_IFT_DENOM` in the format `factory/{creator_addr}/{subdenom}`.

### 2. Register the IFT bridge (EVM side)

The EVM side requires a constructor contract and a bridge registration on the IFT contract.

1. Compute the ICA address

The GMP module derives a Cosmos account deterministically from the source client ID, the EIP-55 checksummed sender contract address, and a salt. This is the account the GMP module uses on Cosmos to execute the embedded `MsgIFTMint` when a packet arrives from the EVM:

```bash theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
sandboxd query gmp get-address $COSMOS_CLIENT_ID $IFT_CONTRACT_ADDR_CHECKSUM ""
```

This address is baked into the `CosmosIFTSendCallConstructor` at deploy time. The sender address must be EIP-55 checksummed. Querying with a lowercase address produces a different ICA.

2. Query the Cosmos IFT module account

The `counterpartyIFTAddress` registered on the EVM side must be the Cosmos IFT module account — the sender address that appears in GMP packets originating from Cosmos. This is distinct from the ICA above:

```bash theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
sandboxd query auth module-account ift
```

3. Deploy [`CosmosIFTSendCallConstructor`](https://github.com/cosmos/solidity-ibc-eureka/blob/main/contracts/utils/CosmosIFTSendCallConstructor.sol)

This contract encodes the `MsgIFTMint` message for EVM-to-Cosmos transfers. It is initialized with:

* `bridgeReceiveTypeUrl`: `/ibc.applications.prototypes.ift.v1.MsgIFTMint`
* `denom`: `COSMOS_IFT_DENOM`
* `icaAddress`: the ICA address computed in step 1

4. Register the bridge on the IFT contract

```
IFTOwnable.registerIFTBridge(
  clientId,                  // EVM_CLIENT_ID
  counterpartyIFTAddress,    // Cosmos IFT module account (from step 2)
  iftSendCallConstructor     // CTOR_ADDR
)
```

## Applying to your own setup

### GMP account address

The GMP account address is deterministically derived from `(client_id, contract_addr, salt)`. If the client ID or IFT contract address changes, the GMP account address changes and `CosmosIFTSendCallConstructor` must be redeployed and re-registered.

## Next steps

With the IFT bridge registered, the next step is to [configure and start the attestors](/ibc/next/cosmos-evm/tutorial/walkthrough/05-attestors).