Create a Token Mint

How to create a mint with Confidential Transfer extension

The Confidential Transfer extension enables private token transfers by adding extra state to the mint account. This section explains how to create a token mint with this extension enabled.

The following diagram shows the steps involved in creating a mint with the Confidential Transfer extension:

Create Mint with Confidential Transfer Extension

Confidential Transfer Mint State

The extension adds the ConfidentialTransferMint state to the 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,
}

The ConfidentialTransferMint contains three configuration fields:

authority: The account that has permission to change confidential transfer settings for the mint and approve new confidential accounts if auto-approval is disabled.
auto_approve_new_accounts: When set to true, users can create token accounts with confidential transfers enabled by default. When false, the authority must approve each new token account before it can be used for confidential transfers.
auditor_elgamal_pubkey: An optional auditor that can decrypt transfer amounts in confidential transactions, providing a compliance mechanism while maintaining privacy from the general public.

Required Instructions

Creating a mint with Confidential Transfer enabled requires three instructions in a single transaction:

Create the Mint Account: Invoke the System Program's CreateAccount instruction to create the mint account.
Initialize Confidential Transfer Extension: Invoke the Token Extension Program's ConfidentialTransferInstruction::InitializeMint instruction to configure the ConfidentialTransferMint state for the mint.
Initialize Mint: Invoke the Token Extension Program's Instruction::InitializeMint instruction to initialize the standard mint state.

While you could write these instructions manually, the spl_token_client crate provides a create_mint method that builds and sends a transaction with all three instructions in a single function call, as demonstrated in the example below.

Example Code

The following code demonstrates how to create a mint with the Confidential Transfer extension.

To run the example, start a local validator with the Token Extension Program cloned from mainnet using the following command. You must have the Solana CLI installed to start the local validator.

Terminal

$ solana-test-validator --clone-upgradeable-program TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb --url https://api.mainnet-beta.solana.com -r

At the time of writing, the Confidential Transfers isn't enabled on the default local validator. You must clone the mainnet Token Extension Program to run the example code.

use anyhow::{Context, Result};
use solana_client::nonblocking::rpc_client::RpcClient;
use solana_sdk::{
    commitment_config::CommitmentConfig,
    signature::{Keypair, Signer},
};
use spl_token_client::{
    client::{ProgramRpcClient, ProgramRpcClientSendTransaction},
    spl_token_2022::id as token_2022_program_id,
    token::{ExtensionInitializationParams, Token},
};
use std::sync::Arc;

#[tokio::main]
async fn main() -> Result<()> {
    // Create connection to local test validator
    let rpc_client = RpcClient::new_with_commitment(
        String::from("http://localhost:8899"),
        CommitmentConfig::confirmed(),
    );

    // Load the default Solana CLI keypair to use as the fee payer
    // This will be the wallet paying for the transaction fees
    // Use Arc to prevent multiple clones of the keypair
    let payer = Arc::new(load_keypair()?);
    println!("Using payer: {}", payer.pubkey());

    // Generate a new keypair to use as the address of the token mint
    let mint = Keypair::new();
    println!("Mint keypair generated: {}", mint.pubkey());

    // Set up program client for Token client
    let program_client =
        ProgramRpcClient::new(Arc::new(rpc_client), ProgramRpcClientSendTransaction);

    // Number of decimals for the mint
    let decimals = 9;

    // Create a token client for the Token-2022 program
    // This provides high-level methods for token operations
    let token = Token::new(
        Arc::new(program_client),
        &token_2022_program_id(), // Use the Token-2022 program (newer version with extensions)
        &mint.pubkey(),           // Address of the new token mint
        Some(decimals),           // Number of decimal places
        payer.clone(),            // Fee payer for transactions (cloning Arc, not keypair)
    );

    // Create extension initialization parameters
    // The ConfidentialTransferMint extension enables confidential (private) transfers of tokens
    let extension_initialization_params =
        vec![ExtensionInitializationParams::ConfidentialTransferMint {
            authority: Some(payer.pubkey()), // Authority that can modify confidential transfer settings
            auto_approve_new_accounts: true, // Automatically approve new confidential accounts
            auditor_elgamal_pubkey: None,    // Optional auditor ElGamal public key
        }];

    // Create and initialize the mint with the ConfidentialTransferMint extension
    // This sends a transaction to create the new token mint
    let transaction_signature = token
        .create_mint(
            &payer.pubkey(),                 // Mint authority - can mint new tokens
            Some(&payer.pubkey()),           // Freeze authority - can freeze token accounts
            extension_initialization_params, // Add the ConfidentialTransferMint extension
            &[&mint],                        // Mint keypair needed as signer
        )
        .await?;

    // Print results for user verification
    println!("Mint Address: {}", mint.pubkey());
    println!("Transaction Signature: {}", transaction_signature);

    Ok(())
}

// Load the keypair from the default Solana CLI keypair path (~/.config/solana/id.json)
// This enables using the same wallet as the Solana CLI tools
fn load_keypair() -> Result<Keypair> {
    // Get the default keypair path
    let keypair_path = dirs::home_dir()
        .context("Could not find home directory")?
        .join(".config/solana/id.json");

    // Read the keypair file directly into bytes using serde_json
    // The keypair file is a JSON array of bytes
    let file = std::fs::File::open(&keypair_path)?;
    let keypair_bytes: Vec<u8> = serde_json::from_reader(file)?;

    // Create keypair from the loaded bytes
    // This converts the byte array into a keypair
    let keypair = Keypair::from_bytes(&keypair_bytes)?;

    Ok(keypair)
}

Create a Token Mint

How to create a mint with Confidential Transfer extension

Confidential Transfer Mint State

Required Instructions

Example Code

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