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User Flows

There are two main user flows for interacting with hashi, deposits and withdrawals.

Deposit Flow

In order for a user to leverage their BTC on Sui (e.g. as collateral for a loan), they’ll need to deposit the BTC they want to leverage to a hashi mpc controlled bitcoin address.

---
title: Deposit Flow
config:
  sequence:
    diagramMarginX: 0
---
sequenceDiagram
    autonumber

    participant User
    participant Hashi as Sui / Hashi
    participant Bitcoin

    User    ->>     Bitcoin:    Deposit native BTC
    User    ->>     Hashi:      Notify hashi of deposit
    Hashi   ->>     Bitcoin:    Query for deposit
    Hashi   ->>     Hashi:      Quorum agreement on deposit
    Hashi   ->>     User:       hBTC sent to User

BTC deposit address

Every Sui address has its own unique Hashi Bitcoin deposit address. See address scheme for the full derivation details.

Deposit

Once a user’s deposit address has been determined, they can initiate a deposit to hashi.

  1. Broadcast a Bitcoin transaction depositing BTC into the user’s unique deposit address.
  2. Notify hashi of the deposit by submitting a transaction to Sui including the deposit transaction id.
  3. Hashi nodes will query Bitcoin and watch for confirmation of the deposit transaction.
  4. Hashi nodes communicate, waiting till a quorum has confirmed the deposit (after X block confirmations).
  5. Hashi confirms the deposit on chain, minting the equivalent amount of hBTC and transferring it to the user’s Sui address. The user can then immediately use the hBTC to interact with a defi protocol to, for example, leverage the hBTC as collateral for a loan in USDC.

For a detailed breakdown of each phase, see deposit.

Withdraw Flow

Once a user has decided they want their BTC back on Bitcoin (e.g. they’ve paid off their loan) they can initiate a withdrawal.

---
title: Withdraw Flow
config:
  sequence:
    diagramMarginX: 0
---
sequenceDiagram
    autonumber

    participant User
    participant Hashi as Sui / Hashi
    participant Bitcoin

    User    ->>     Hashi:   Request withdrawal
    Hashi   ->>     Hashi:   Craft and sign Bitcoin transaction using MPC
    Hashi   ->>     Bitcoin: Broadcast transaction

Withdraw

  1. User sends a transaction to Sui with the amount of hBTC they would like to withdraw and the Bitcoin address they want to withdraw to.
  2. Hashi will pick up the withdrawal request and will craft a bitcoin transaction that sends the requested BTC (minus fees) to the provided Bitcoin address and uses MPC to sign the transaction.
  3. The transaction is broadcast to the Bitcoin network.

For a detailed breakdown of each phase, see withdraw.