# ARC-20: 同质化代币标准

By [Yaakov](https://paragraph.com/@yaakov) · 2024-06-24

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Aleo 正在讨论中的[ARC-20标准](https://aleo.up.railway.app/p/2bf1586d-b8de-419d-afac-f94f48a5de34)旨在为Aleo区块链提供代币互操作性和用户授权功能，类似于ERC-20。它允许代币轻松转账，并允许用户授权程序管理这些代币，特别适用于自动化金融应用。ARC-20标准的独特之处在于整合了Aleo的隐私特性，例如私有记录，提供用户在数字交易中的隐私和匿名性。这里我们将分别介绍这些方法。

### 规范

**程序结构**

    program token.aleo;
    
    mapping account:
        key as address.public;
        value as u64.public;
    
    record token:
        owner as address.private;
        amount as u64.private;
    
    struct approval:
        approver as address;
        spender as address;
    
    struct metadata:
        name as u128; // 16 bytes -> 16 characters with ASCII encoding
        symbol as u64; // 8 bytes -> 8 characters with ASCII encoding
        decimals as u8;
        total_supply as u64;
    
    mapping approvals:
        key as field.public;
        value as u64.public;
    

### 核心功能介绍

**1\. 获取元数据**

    function get_metadata:
        cast [name] [symbol] [decimals] [total_supply] into r0 as metadata;
        output r0 as metadata.public;
    

此函数返回代币的元数据，包括名称、符号、小数位和总供应量。这些信息有助于钱包和dApp正确显示代币信息。

**2\. 授权公共代币使用**

    function approve_public:
        input r0 as address.public; // 授权的地址
        input r1 as u64.public; // 授权的代币数量
    
        cast self.caller r0 into r2 as approval;
        hash.bhp256 r2 into r3 as field;
    
        async approve_public r3 r1 into r4;
        output r4 as token.aleo/approve_public.future;
    
    finalize approve_public:
        input r0 as field.public;
        input r1 as u64.public; // 增加授权的代币数量
    
        get.or_use approvals[r0] 0u64 into r2;
        add r1 r2 into r3;
        set r3 into approvals[r0];
    

此函数允许代币持有者授权某个地址使用一定数量的代币。这个功能对于允许智能合约代表用户执行代币操作至关重要。

**3\. 取消授权**

    function unapprove_public:
        input r0 as address.public; // 被取消授权的地址
        input r1 as u64.public; // 取消的代币数量
    
        cast self.caller r0 into r2 as approval;
        hash.bhp256 r2 into r3 as field;
    
        async unapprove_public r3 r1 into r4;
        output r4 as token.aleo/unapprove_public.future;
    
    finalize unapprove_public:
        input r0 as field.public;
        input r1 as u64.public; // 减少授权的代币数量
    
        get approvals[r0] into r2;
        sub r2 r1 into r3;
        set r3 into approvals[r0];
    

此函数撤销之前授权的代币数量，用于减少或完全撤销对某个地址的授权。

**4\. 从公共账户转账**

    function transfer_from_public:
        input r0 as address.public; // 授权者
        input r1 as address.public; // 接收者
        input r2 as u64.public; // 转账数量
    
        cast r0 self.caller into r3 as approval;
        hash.bhp256 r3 into r4 as field;
    
        async transfer_from_public r4 r0 r1 r2 into r5;
        output r5 as token.aleo/transfer_from_public.future;
    
    finalize transfer_from_public:
        input r0 as field.public;
        input r1 as address.public;
        input r2 as address.public;
        input r3 as u64.public;
    
        get approvals[r0] into r4;
        sub r4 r3 into r5;
        set r5 into approvals[r0];
        get account[r1] into r6;
        sub r6 r3 into r7;
        set r7 into account[r1];
        get.or_use account[r2] 0u64 into r8;
        add r8 r3 into r9;
        set r9 into account[r2];
    

此函数实现从授权者账户向接收者账户的代币转账，用于实现代币的自动化管理和支付。

**5\. 公共代币转账**

    function transfer_public:
        input r0 as address.public; // 接收者地址
        input r1 as u64.public; // 转账数量
    
        async transfer_public self.caller r0 r1 into r2;
        output r2 as token.aleo/transfer_public.future;
    
    finalize transfer_public:
        input r0 as address.public;
        input r1 as address.public;
        input r2 as u64.public;
    
        get.or_use account[r0] 0u64 into r3;
        sub r3 r2 into r4;
        set r4 into account[r0];
        get.or_use account[r1] 0u64 into r5;
        add r5 r2 into r6;
        set r6 into account[r1];
    

此函数将代币从调用者账户转移到指定的公共账户，实现简单的代币转账。

**6\. 私有代币转账**

    function transfer_private:
        input r0 as token.record; // 代币记录
        input r1 as address.private; // 接收者地址
        input r2 as u64.private; // 转账数量
    
        sub r0.amount r2 into r3;
        cast r0.owner r3 into r4 as token.record;
        cast r1 r2 into r5 as token.record;
        output r4 as token.record;
        output r5 as token.record;
    

此函数实现私有代币的转账，用于在保持交易隐私的情况下进行代币转移。

**7\. 私有代币转公共代币**

    function transfer_private_to_public:
        input r0 as token.record; // 私有代币记录
        input r1 as address.public; // 公共接收者地址
        input r2 as u64.public; // 转账数量
    
        sub r0.amount r2 into r3;
        cast r0.owner r3 into r4 as token.record;
        async transfer_private_to_public r1 r2 into r5;
        output r4 as token.record;
        output r5 as token.aleo/transfer_private_to_public.future;
    
    finalize transfer_private_to_public:
        input r0 as address.public;
        input r1 as u64.public;
    
        get.or_use account[r0] 0u64 into r2;
        add r2 r1 into r3;
        set r3 into account[r0];
    

此函数将私有代币转换为公共代币，允许在公共账户中持有之前私有的代币。

**8\. 公共代币转私有代币**

    function transfer_public_to_private:
        input r0 as address.public; // 公共账户地址
        input r1 as u64.public; // 转账数量
    
        cast r0 r1 into r2 as token.record;
        async transfer_public_to_private self.caller r1 into r3;
        output r2 as token.record;
        output r3 as token.aleo/transfer_public_to_private.future;
    
    finalize transfer_public_to_private:
        input r0 as address.public;
        input r1 as u64.public;
    
        get.or_use account[r0] 0u64 into r2;
        sub r2 r1 into r3;
        set r3 into account[r0];
    

此函数将公共代币转换为私有代币，以确保交易隐私和安全。

通过这些规范和示例代码，ARC-20标准在Aleo区块链上实现了兼容且安全的同质化代币管理。

**Aleo 官方链接：**

> *   _Aleo_ [_Twitter_](https://twitter.com/aleohq)
>     
> *   _Aleo_ [_Discord_](https://discord.gg/aleo)
>     
> *   _Aleo_ [_Website_](https://www.aleo.org/)
>     
> *   Aleo [Github](https://github.com/ProvableHQ)
>

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*Originally published on [Yaakov](https://paragraph.com/@yaakov/arc-20)*