Aleo 正在讨论中的ARC-20标准旨在为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。

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;

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

• Aleo Discord

• Aleo Website

• Aleo Github