# vUSD

{% hint style="danger" %}
**Notice: Cronos zkEVM is being sunset, please** [**bridge out your assets**](/for-developers/using-zkcro-veth-and-vusd/vusd.md#l2-greater-than-l1-withdrawing-usddai-from-usdvusd) **before the network is fully decommissioned.**
{% endhint %}

[#l2-greater-than-l1-withdrawing-usddai-from-usdvusd](#l2-greater-than-l1-withdrawing-usddai-from-usdvusd "mention")

## \[L2 -> L1] Withdrawing $DAI from $vUSD

*From Cronos zkEVM mainnet (L2) -> Ethereum mainnet (L1)*

{% hint style="info" %}
For withdrawing $vUSD (Cronos zkEVM Mainnet) and get $DAI (Ethereum Mainnet) , we would need to:

1. \[On Cronos zkEVM] Use $vUSD to redeem $ybUSD;
2. \[On Cronos zkEVM] Bridge $ybUSD to Ethereum;
3. \[On Ethereum] Redeem $ybUSD for $DAI
   {% endhint %}

To redeem $vUSD from `Cronos zkEVM mainnet -> Ethereum mainnet`, and withdraw $DAI we would need to interact with the following contracts:

* $vUSD token contract
  * Cronos zkEVM: [`0x5b91e29Ae5A71d9052620Acb813d5aC25eC7a4A2`](https://explorer.zkevm.cronos.org/address/0x5b91e29Ae5A71d9052620Acb813d5aC25eC7a4A2)
* `L2Bridge`
  * Cronos zkEVM: [0x309429DE3621992Cb0ab8982A448c9Cc5c38405b](https://explorer.zkevm.cronos.org/address/0x309429DE3621992Cb0ab8982A448c9Cc5c38405b)
* zk Chain Shared Bridge
  * Ethereum: [0xD7f9f54194C633F36CCD5F3da84ad4a1c38cB2cB](https://etherscan.io/address/0xD7f9f54194C633F36CCD5F3da84ad4a1c38cB2cB)
* $ybUSD token contract
  * Ethereum: [0xFA59075DfCE274E028b58BdDFcC3D709960F594a](https://etherscan.io/address/0xFA59075DfCE274E028b58BdDFcC3D709960F594a)
  * Cronos zkEVM: [`0xb1Ece5b548766215272BAFCfa36396B06Cd9e4C9`](https://explorer.zkevm.cronos.org/address/0xb1Ece5b548766215272BAFCfa36396B06Cd9e4C9)

### Step 1) Approving $vUSD to be spend by vUSD contract

On Cronos zkEVM, call `approve` on the $vUSD contract to approve $vUSD spend with appropriate amount.

### Step 2) Redeeming $vUSD for $ybUSD

On Cronos zkEVM, call `redeem` on the vUSD contract, to burn $vUSD and redeem $ybUSD

```
function redeem(
        address _receiver,
        uint256 _vUsdAmount
        )
```

| Parameters    | Comments                                            |
| ------------- | --------------------------------------------------- |
| `_receiver`   | Address to receive $ybUSD on Cronos zkEVM           |
| `_vUsdAmount` | Amount of vUSD that will be burned to redeem $ybUSD |

Once done, corresponding $ybUSD will be transfer to the `_reciever` address 

### Step 3) Approving $ybUSD to be spend by the L2Bridge

On Cronos zkEVM, call `approve` on the ybUSD contract, to approve L2Bridge contract to spend $ybUSD.

### Step 4) Withdrawing $ybUSD and store withdrawal hash

On Cronos zkEVM, call `withdraw` on the L2Bridge contract

```
function withdraw(
        address _l1Receiver, 
        address _l2Token, 
        uint256 _amount
        )
```

| Parameters    | Comments                                                                          |
| ------------- | --------------------------------------------------------------------------------- |
| `_l1Receiver` | Address on Ethereum to receive the token                                          |
| `_l2Token`    | The token to be withdrawn, the Cronos zkEVM contract address $ybUSD in this case. |
| `_amount`     | amount of tokens to be withdrawn, note $ybUSD has `18` decimals                   |

Keep the transaction hash for later use in Step 5. This withdraws $ybUSD from Cronos zkEVM to Ethereum. It takes 24 hours before the withdrawal can be finalized on Ethereum. Store the transaction hash from the withdrawal transaction; it will be needed to finalize the withdrawal.

### Step 5) Gathering information for $ybUSD withdrawal on L1

Extra information for the L2 -> L1 transaction is required for the next step in claiming the $ybUSD. This information can be gathered by [finalizeWithdrawalParams](https://docs.zksync.io/sdk/js/ethers/api/v5/accounts/wallet#finalizewithdrawalparams), using `zksync-ethers` package

```
finalizeWithdrawalParams(withdrawalHash)
```

This takes the L2 withdrawal hash as parameters and returns the parameters required for finalizing a withdrawal in the next step.

Example outputs

```
{
  l1BatchNumber: 18,
  l2MessageIndex: 59,
  l2TxNumberInBlock: 2919,
  message: '0x6c0960f935f448644c86dbda241ecb57f18a15c80f35a066000000000000000000000000000000000000000000000a2a15d09519be000000',
  sender: '0x000000000000000000000000000000000000800a',
  proof: [
    '0x23ff0fb003a6a6e111f87cff02afc8680944c711abbe792f07ab4206e9efb9a3',
    '0x09fece9c46307f2a0976a3a9b57873e453cf0f4773c2377dcd19f054166aef22',
    '0x33c106ae5601983b53c751129d1921c17e40b69aa3fdbfaf07b7a0e0750d35e4',
    '0x952ffa5de22d99815d9513dd7454949edb2a1cbcf86008f6fa8b169ffe9b4aee',
    '0x8f10560a0b5412ca2e0578fb9266f55411f357d52c8fc3b2cad43b9877a559a6',
    '0x8e70b93d3c90798df26473a3ad32a86170e8d52023a4044cf1d4c2d645471b14',
    '0xdfaacb39891bbbf4509af408239b97a6f5ef715a5c299ba1f3625c20aec4ef8f',
    '0xb04e5ee349086985f74b73971ce9dfe76bbed95c84906c5dffd96504e1e5396c',
    '0xac506ecb5465659b3a927143f6d724f91d8d9c4bdb2463aee111d9aa869874db',
    '0x124b05ec272cecd7538fdafe53b6628d31188ffb6f345139aac3c3c1fd2e470f',
    '0xc3be9cbd19304d84cca3d045e06b8db3acd68c304fc9cd4cbffe6d18036cb13f',
    '0xfef7bd9f889811e59e4076a0174087135f080177302763019adaf531257e3a87',
    '0xa707d1c62d8be699d34cb74804fdd7b4c568b6c1a821066f126c680d4b83e00b',
    '0xf6e093070e0389d2e529d60fadb855fdded54976ec50ac709e3a36ceaa64c291'
  ]
}
```

### Step 6) Claiming the $ybUSD on L1

Once the transaction in Step 4 has been finalized, we can claim the withdrawn $ybUSD from the  L2Bridge contract by calling its `finalizeWithdrawal` function. The inputs can be found in Step 5,

```
    function finalizeWithdrawal(
            uint256   _chainId,
            uint256   _l2BatchNumber,
            uint256   _l2MessageIndex,
            uint16    _l2TxNumberInBatch,
            bytes calldata _message,
            bytes32 calldata _merkleProof
        )
```

| Parameters           | Comments                                                                                                 |
| -------------------- | -------------------------------------------------------------------------------------------------------- |
| `_chainId`           | Chain id for Cronos zkEVM, which is `388`                                                                |
| `_l2BatchNumber`     | The L2 batch number where the withdrawal was processed, obtained in Step 5.                              |
| `_l2MessageIndex`    | The position in the L2 logs Merkle tree of the l2Log that was sent with the message, obtained in Step 5. |
| `_l2TxNumberInBatch` | The L2 transaction number in the batch, in which the log was sent, obtained in Step 5.                   |
| `_message`           | The L2 withdraw data, stored in an L2 -> L1 message, obtained in Step 5.                                 |
| `_merkleProof`       | The Merkle Proof, obtained in Step 5.                                                                    |

Once `finalizeWithdrawal` is completed, the withdrawn amount of $ybUSD will go into the receiver's wallet on Ethereum.

We can use `zksync-ethers` package  [`isWithdrawalFinalized`](https://docs.zksync.io/sdk/js/ethers/api/v5/accounts/wallet#iswithdrawalfinalized) call to whether the withdrawal transaction is finalized on the L1 network.

```
isWithdrawalFinalized(withdrawalHash)
```

| Parameters       | Comments                                                                                   |
| ---------------- | ------------------------------------------------------------------------------------------ |
| `withdrawalHash` | The transaction hash of the L2 transaction includes the withdrawal transaction from Step 4 |

### Step 7) Approving $ybUSD to be spend by ybUSD contract

On Ethereum, call `approve` on the $ybUSD contract, to approve the contract to spend $ybUSD

### Step 8) Redeem $ybUSD for $DAI

On Ethereum, call `redeem` on the the $ybUSD contract

```
function redeem(
        uint256 _amount
        )
```

| Parameters | Comments                                       |
| ---------- | ---------------------------------------------- |
| `_amount`  | The amount of $ybUSD tokens to redeem for $DAI |

Once `redeem` is completed, the withdrawn amount of $DAI will go into the receiver's wallet on Ethereum.


---

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