# Self-Custody

BlockATM uses decentralized self-custody model, your assets are completely under your control.

## Core Principle

### Traditional Payment

```mermaid
graph LR
    User[User] -->|Payment| Central[Payment Institution]
    Central -->|Settlement| Merchant[Merchant]

    style Central fill:#ffe1e1
```

**Problems**:

* Funds custodied by payment institution
* Withdrawal restrictions (amount, time)
* Need to trust institution

### BlockATM

```mermaid
graph LR
    User[User] -->|Payment| Contract[Smart Contract]
    Contract -->|Self-custody| Merchant[Merchant]

    style Contract fill:#e1f5ff
```

**Advantages**:

* Funds stored in smart contract
* Contract rules public and transparent
* Only you can control funds

## Fund Control

### Contract Permissions

| Role            | Can Do                           | Cannot Do                   |
| --------------- | -------------------------------- | --------------------------- |
| **You (Owner)** | Manage contract configuration    | Use contract funds          |
| **Signer**      | Withdraw funds to preset address | Transfer to other addresses |
| **BlockATM**    | ❌ Nothing                        | ❌ Use funds                 |

{% hint style="danger" %}
**BlockATM cannot access your funds**: Even if we wanted to, we cannot use tokens in your contract.
{% endhint %}

## Security Guarantee

### Technical Guarantee

| Safeguard              | Description                                         |
| ---------------------- | --------------------------------------------------- |
| Smart Contract         | Deployed on blockchain, code public and transparent |
| Signature Verification | All operations require valid signature              |
| Whitelist              | Funds can only be transferred to preset addresses   |

### Operational Guarantee

| Operation            | Requirement                   |
| -------------------- | ----------------------------- |
| Create contract      | You control Owner address     |
| Withdraw funds       | You control Signer signature  |
| Modify configuration | You control Owner private key |

## Self-custody Responsibilities

{% hint style="warning" %}
**Important**: Self-custody means you bear full responsibility for fund security. Please be sure to:

1. **Securely store keys**: Owner and Signer private keys/recovery phrases must be securely stored
2. **Do not disclose**: Do not reveal your keys to anyone
3. **Backup**: Make backup of keys to prevent loss
4. **Be cautious with operations**: Contract configuration once set usually cannot be modified
   {% endhint %}

## Comparison Summary

| Comparison         | Traditional Payment    | BlockATM                      |
| ------------------ | ---------------------- | ----------------------------- |
| Fund Custody       | Institution custodied  | Smart contract self-custody   |
| Withdrawal Control | Institution controlled | Completely under your control |
| Withdrawal Limits  | Amount/time limits     | No limits                     |
| Fund Risk          | Institution risk       | Your own responsibility       |
| Transparency       | Not transparent        | Completely transparent        |


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