> For the complete documentation index, see [llms.txt](https://tonify.gitbook.io/tonify/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tonify.gitbook.io/tonify/getting-started/how-does-tonify-work/core-functions/ethereum.md).

# Ethereum

**SWAP AND BRIDGE TRANSFER** -

SwapAndBridge() initiates the cross-chain transfer by creating a unique message hash and transferring tokens to the bridge contract. This function handles the source chain operations and token locking mechanism

```solidity
function swapAndBridge(
        uint256 sourceChainId,
        address addr,
        uint256 amount,
        address tokenAddress,
        uint256 nonce,
        uint256 destinationChainId
    ) public returns (bytes32) {
        bytes32 message = hashMessage(sourceChainId, addr, amount, tokenAddress, nonce, destinationChainId);
        messenger.sendMessage(message);

        //Before calling this function, the user must approve the contract to spend their tokens
        IERC20(tokenAddress).transferFrom(msg.sender, address(this), amount);
        return message;
    }
```

### TOKEN RECEPTION HANDLER-  

`receiveTokens()` processes incoming bridge transfers by verifying the message hash and preventing duplicate transactions. This function manages token distribution on the destination chain after validation.

```solidity
function receiveTokens(
        uint256 sourceChainId,
        address addr,
        uint256 amount,
        address tokenAddress,
        uint256 nonce,
        uint256 destinationChainId
    ) external {
        bytes32 message = hashMessage(sourceChainId, addr, amount, tokenAddress, nonce, destinationChainId);
        bool isReceived = messenger.hasMessageBeenReceived(message);

        if (!isReceived) {
            revert Bridge__MessageNotreceived();
        }

        if (processedMessages[message] != 0) {
            revert Bridge__MessageAlreadyProcess();
        }
        processedMessages[message] = 1;
        IERC20(tokenAddress).transfer(addr, amount);
    }
```

### VALIDATOR SIGNATURE VERIFICATION-

`receiveMessage()` implements multi-signature validation using primary and secondary validator signatures through ecrecover. This function ensures secure message verification before completing cross-chain transfers

```solidity
function resiveMessage(bytes32 message, uint8 v1, bytes32 r1, bytes32 s1, uint8 v2, bytes32 r2, bytes32 s2)
        external
    {
        bytes32 prefixedHash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", message));
        // bytes32 messageHash = keccak256(abi.encodePacked(message));
        address primaryValidatorRecoveredAddress = ecrecover(prefixedHash, v1, r1, s1);
        address secondaryValidatorsRecoveredAddress = ecrecover(prefixedHash, v2, r2, s2);

        if (primaryValidatorRecoveredAddress != primaryValidator) {
            revert Messenger__InvaildPrimaryValidat(primaryValidatorRecoveredAddress);
        }

        if (secondaryValidators[secondaryValidatorsRecoveredAddress] != true) {
            revert Messenger__InvaildSecondaryValidat();
        }

        receivedMessages[message] = 1;
        emit MessageReceived(message);
    }
```