> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fluton.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Smart Contracts

> Explanations for Smart Contracts of the protocol

Our smart contracts utilize Zama and Fhenix's coprocessors to perform FHE operations on encrypted data. On each chain supported by Fluton, there is a corresponding Bridge and IntentPool contract. While bridging logic could technically be embedded into the IntentPool contract, bridging represents one of the most common and performance-critical intent types. For this reason, we separated it into a dedicated Bridge contract to reduce gas costs, simplify execution paths, and allow more targeted optimization.

## Bridge Contract

The bridge contract is used for submitting bridging intents. The contract accepts both encrypted and non-encrypted intents. The main entrypoint of this contract is the `bridge` function.

### Bridge Function (Public)

```solidity theme={null}
function bridge(
  address sender,
  address receiver,
  address relayer,
  address inputToken,
  address outputToken,
  uint256 inputAmount,
  uint256 outputAmount,
  uint32 destinationChainId
) external payable
```

* `sender`
  * The original owner of the input funds. This address authorizes locking of tokens into escrow.
* `receiver`
  * The address that will receive assets on the destination chain once the solver executes the intent.
* `relayer`
  * The solver selected by the user. Only this address will be eligible to claim repayment after fulfillment.
* `inputToken`
  * The token being locked on the source chain.
* `outputToken`
  * The token expected on the destination chain.
* `inputAmount`
  * The quantity of tokens transferred into escrow.
* `outputAmount`
  * The amount the solver has committed to deliver on the destination chain.
* `destinationChainId`
  * The identifier of the chain where execution will occur.

### Bridge Function (Private)

```solidity theme={null}
function bridge(
  address sender,
  address receiver,
  address relayer,
  address inputToken,
  eaddress outputToken,
  euint256 inputAmount,
  euint256 outputAmount,
  euint32 destinationChainId
) external payable
```

The private version of the `bridge` function differs from the public variant by supporting encrypted data types. These types do not store plaintext values directly on-chain. Rather, they act as references (handles) to encrypted data that is maintained and processed through a fully homomorphic encryption (FHE) system.