> For the complete documentation index, see [llms.txt](https://bitfi-2.gitbook.io/bitfi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bitfi-2.gitbook.io/bitfi/developer/using-contract/unstake-bfbtc.md). # Unstake bfBTC > **Warning:** We currently support RedStone Oracle for price feeds. BitFi plans to integrate more underlying asset oracles in the future. *** ## Introduction This document provides a technical guide for developers on how to interact with the bfBTC smart contract to unstake (withdraw) bfBTC tokens and receive the underlying BTC assets. The unstaking process is a multi-step procedure involving a request, an administrative approval, and a final claim. ## 1. Previewing a Withdrawal Before initiating a withdrawal, it's recommended to use this view function to estimate the amount of the underlying asset you will receive and the associated fees. **`previewWithdraw`** ``` function previewWithdraw(uint256 share, bool native) public view returns (uint256 underlyingAmount, uint256 fee) ``` * Description: This function previews the amount of underlying asset (e.g., BTC, BTCB) you will receive when unstaking a specific amount of bfBTC, and it also calculates the total fee. * Parameters: * `share`: The amount of bfBTC you intend to withdraw (8 decimals). * `native`: A boolean indicating the withdrawal destination. * `true` for the native Bitcoin network; * `false` for an EVM network. * On the Bitlayer contract, this parameter is currently unused. * Returns: * `underlyingAmount`: The estimated net amount of the underlying asset you will receive after fees. * `fee`: The total withdrawal fee, combining both percentage and fixed fees. Fee is calculated as bfBTC. * Notes: If the calculated fee is greater than or equal to the withdrawal amount, the function will return an `underlyingAmount` of 0. The final received amount may vary slightly due to ratio changes between the preview and the actual claim. *** ## 2. Requesting a Withdrawal The first step in the unstaking process is to submit a withdrawal request. This locks your bfBTC in the contract and creates a pending request. **`requestWithdraw` (for EVM chains)** This function initiates a withdrawal to the user's address on the same EVM chain. ``` function requestWithdraw(uint256 amount) external ``` * Description: Initiates a withdrawal request for bfBTC, locking the tokens in the contract while awaiting approval. * Parameters: * `amount`: The amount of bfBTC to be withdrawn. * Notes: The specified amount must be greater than the `minWithdrawBfbtcAmount`. The request's initial status is set to `PENDING`. **`requestWithdrawNative` (for native Bitcoin withdrawal)** This function initiates a withdrawal directly to a Bitcoin network address. ``` function requestWithdrawNative(uint256 amount, uint8 btcAddressType, bytes32 btcAddress) external ``` * Description: Initiates a withdrawal request where the final underlying asset will be sent to a specified native Bitcoin address. * Parameters: * `amount`: The amount of bfBTC to be withdrawn. * `btcAddressType`: An integer representing the BTC address type (1 for P2TR, 2 for P2WPKH, 3 for P2SH\_P2WPKH, 4 for P2PKH). * `btcAddress`: The user's native Bitcoin address, formatted as `bytes32`. *** ## 3. Administrative Approval After a request is submitted, it must be approved by an authorized multisig manager. This is an administrative, off-chain process. **`approveWithdraw` (for EVM claims)** This function is called by the multisig manager to approve requests that will be claimed on an EVM chain. ``` function approveWithdraw(uint256 epoch, uint256[] calldata withdrawIds) external ``` * Description: An administrator-only function to approve multiple pending withdrawal requests. Approved requests have their status updated to `CLAIMABLE`. * Parameters: * `epoch`: A historical epoch number used for the exchange rate calculation. This must be less than the current epoch and satisfy the cooldown period. * `withdrawIds`: An array of withdrawal request IDs to approve. **`nativeWithdraw` (for native Bitcoin claims)** This function is called by the multisig manager after the BTC has been sent on the Bitcoin network. ``` function nativeWithdraw(uint256 epoch, uint256[] calldata withdrawIds, bytes32[] calldata nativeTxs) external ``` * Description: An administrator-only function to finalize native Bitcoin withdrawals. It records the Bitcoin transaction hash and updates the status to `SENT_ON_NATIVE`, effectively burning the corresponding bfBTC shares. * Parameters: * `epoch`: The historical epoch for rate calculation. * `withdrawIds`: An array of withdrawal request IDs. * `nativeTxs`: An array of corresponding Bitcoin transaction hashes. *** ## 4. Claiming the Withdrawal Once a request has been approved and its status is `CLAIMABLE`, the user can execute the final step to receive their underlying assets. **`claim`** ``` function claim(uint256[] calldata withdrawIds) external ``` * Description: Allows a user to claim their approved withdrawals and receive the underlying asset in their wallet. * Parameters: * `withdrawIds`: An array of the user's approved withdrawal request IDs to claim. * Notes: * This function can only be called by the user who originally made the request. * The request status must be `CLAIMABLE`. * After a successful claim, the status is updated to `CLAIMED`. * The final amount received is calculated based on the exchange ratio of the `settleEpoch` recorded during approval. You can check the final claimable amount using the `claimable(withdrawId)` view function. *** ## Withdrawal Process Summary * Step 1: Request: User calls `requestWithdraw` or `requestWithdrawNative` to lock bfBTC. Status becomes `PENDING`. * Step 2: Approve: The multisig manager calls `approveWithdraw` (for EVM) or `nativeWithdraw` (for Native BTC) after a cooldown period (typically 1 epoch). * Step 3: Claim (EVM only): If approved via `approveWithdraw`, the user calls `claim` to receive the underlying ERC20 asset. Status becomes `CLAIMED`. *** ## **Important Notes** * Stakes and Unstakes must be made while the contract is not paused. * Unstake require a cooldown period. (1 epoch) * The actual amount of BTC received depends on the current epoch's ratio and price. * The displayed receive amount may differ. * Unstake approval time may vary depending on Ceffu's processing speed. BitFi aims to process unstake request within 5 epochs.