创建 Token Mint

如何创建带有机密转账扩展的 mint

机密转账扩展通过向 mint account 添加额外状态来实现私密代币转账。本节介绍如何创建启用了此扩展的 token mint。

下图展示了创建带有机密转账扩展的 mint 所涉及的步骤：

Create Mint with Confidential Transfer Extension

机密转账 Mint 状态

该扩展将 ConfidentialTransferMint 状态添加到 mint account：

Confidential Mint State

#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Pod, Zeroable)]
pub struct ConfidentialTransferMint {
    /// Authority to modify the `ConfidentialTransferMint` configuration and to
    /// approve new accounts (if `auto_approve_new_accounts` is true)
    ///
    /// The legacy Token Multisig account is not supported as the authority
    pub authority: OptionalNonZeroPubkey,

    /// Indicate if newly configured accounts must be approved by the
    /// `authority` before they may be used by the user.
    ///
    /// * If `true`, no approval is required and new accounts may be used
    ///   immediately
    /// * If `false`, the authority must approve newly configured accounts (see
    ///   `ConfidentialTransferInstruction::ConfigureAccount`)
    pub auto_approve_new_accounts: PodBool,

    /// Authority to decode any transfer amount in a confidential transfer.
    pub auditor_elgamal_pubkey: OptionalNonZeroElGamalPubkey,
}

ConfidentialTransferMint 包含三个配置字段：

authority：有权更改 mint 的机密转账设置，并在未启用自动审批时批准新机密账户的账户。
auto_approve_new_accounts：设置为 true 时，用户可以默认创建启用机密转账的 token account。设置为 false 时，authority 必须在每个新 token account 用于机密转账之前对其进行审批。
auditor_elgamal_pubkey：一个可选的审计方，能够解密机密交易中的转账金额，在保护公众隐私的同时提供合规机制。

所需指令

创建启用了机密转账的 mint 需要在单笔交易中包含三条指令：

创建 Mint Account：调用 System Program 的 CreateAccount 指令以创建 mint account。
初始化机密转账扩展：调用 Token Extensions Program 的 ConfidentialTransferInstruction::InitializeMint 指令，为 mint 配置 ConfidentialTransferMint 状态。
初始化 Mint：调用 Token Extensions Program 的 Instruction::InitializeMint 指令以初始化标准 mint 状态。

虽然您可以手动编写这些指令，但 spl_token_client crate 提供了 create_mint 方法，可在单次函数调用中构建并发送包含全部三条指令的交易，如下方示例所示。

示例代码

以下代码演示了如何使用机密转账扩展创建铸币。

机密转账依赖于 ZK ElGamal 证明程序，该程序已在主网和开发网上启用。标准的 solana-test-validator 不会启用它，但主网分叉本地 validator（例如 Surfpool）会启用。请使用已充值的付款账户在上述环境之一中运行示例（代码默认使用开发网），并将占位符铸币地址和账户地址替换为您自己的地址。

Rust



fn main() -> Result<()> {
    let rpc_client = RpcClient::new_with_commitment(
        String::from("https://api.devnet.solana.com"),
        CommitmentConfig::confirmed(),
    );

    let payer = load_keypair()?;
    let mint = Keypair::new();
    let decimals: u8 = 2;

    // Allocate space for a mint that carries the ConfidentialTransferMint
    // extension, then fund it for rent exemption.
    let space =
        ExtensionType::try_calculate_account_len::<Mint>(&[ExtensionType::ConfidentialTransferMint])?;
    let rent = rpc_client.get_minimum_balance_for_rent_exemption(space)?;

    // The auditor ElGamal key lets the issuer decrypt transfer amounts for
    // compliance. Persist this key. Pass `None` to create a mint with no auditor.
    let auditor = ElGamalKeypair::new_rand();
    let auditor_pubkey: PodElGamalPubkey = (*auditor.pubkey()).into();

    let create_account_ix = system_instruction::create_account(
        &payer.pubkey(),
        &mint.pubkey(),
        rent,
        space as u64,
        &spl_token_2022::id(),
    );

    // The confidential-transfer extension must be initialized before the base
    // mint and cannot be added later.
    let init_confidential_ix = initialize_confidential_transfer_mint(
        &spl_token_2022::id(),
        &mint.pubkey(),
        Some(payer.pubkey()), // authority that can update confidential settings
        true,                 // auto-approve new accounts
        Some(auditor_pubkey),
    )?;

    let init_mint_ix = initialize_mint_base(
        &spl_token_2022::id(),
        &mint.pubkey(),
        &payer.pubkey(), // mint authority
        None,            // freeze authority
        decimals,
    )?;

    let blockhash = rpc_client.get_latest_blockhash()?;
    let transaction = Transaction::new_signed_with_payer(
        &[create_account_ix, init_confidential_ix, init_mint_ix],
        Some(&payer.pubkey()),
        &[&payer, &mint],
        blockhash,
    );
    let signature = rpc_client.send_and_confirm_transaction(&transaction)?;
    println!("Created confidential mint {}: {signature}", mint.pubkey());
    Ok(())
}

fn load_keypair() -> Result<Keypair> {
    let keypair_path = dirs::home_dir()
        .context("could not find home directory")?
        .join(".config/solana/id.json");
    let bytes: Vec<u8> = serde_json::from_reader(std::fs::File::open(keypair_path)?)?;
    let mut secret = [0u8; 32];
    secret.copy_from_slice(&bytes[0..32]);
    Ok(Keypair::new_from_array(secret))
}

Typescript



const client = await createClient()
  .use(signerFromFile(join(homedir(), ".config/solana/id.json")))
  .use(
    solanaRpc({
      rpcUrl: "https://api.devnet.solana.com"
    })
  );
const payer = client.payer;

const mint = await generateKeyPairSigner();

// The auditor ElGamal key lets the issuer decrypt transfer amounts for
// compliance. Persist it; omit `auditorElgamalPubkey` to create a mint with no
// auditor.
const auditor = await deriveElGamalKeypairForOwnerMint({
  signer: payer,
  owner: payer.address,
  mint: mint.address
});

const plan = getCreateMintInstructionPlan({
  payer,
  newMint: mint,
  decimals: 2,
  mintAuthority: payer,
  extensions: [
    {
      __kind: "ConfidentialTransferMint",
      authority: some(payer.address),
      autoApproveNewAccounts: true,
      auditorElgamalPubkey: some(auditor.elgamalPubkey)
    }
  ]
});

const result = await client.sendTransaction(plan);

console.log(
  `Created confidential mint ${mint.address}: ${result.context.signature}`
);