zhongwei/gh-tenequm-claude-plugins-solana

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Durable Transaction Nonces

This guide covers Solana's durable transaction nonces, which enable transactions to remain valid indefinitely by replacing the time-limited recent blockhash mechanism. Essential for offline signing, multi-signature coordination, and scheduled transaction execution.

Introduction

The Expiration Problem

Solana transactions normally include a recent_blockhash field that serves two purposes:

Double-spend prevention: Ensures each transaction is unique and can only be processed once
Transaction freshness: Limits transaction validity to prevent spam and stale transactions

The limitation:

Recent blockhashes expire after 150 blocks (~60-90 seconds)
Transactions with expired blockhashes are permanently rejected
Cannot be re-validated, even with identical content

Critical constraint:

Transaction must be:
1. Signed with recent blockhash
2. Submitted to network
3. Processed by validator
4. Confirmed in block

All within ~60-90 seconds!

Problems This Creates

Hardware Wallet Users:

Fetch blockhash from network
Transfer to air-gapped device
User reviews and signs (can take minutes)
Transfer back to online device
Submit to network
Risk: Blockhash expires during manual review

Multi-Signature Wallets (DAOs, Squads, Realms):

Create transaction with blockhash
Send to signer 1 for approval (hours/days)
Send to signer 2 for approval (hours/days)
Send to signer N for approval
Risk: Blockhash expires while collecting signatures

Scheduled Transactions:

Want to pre-sign transaction for future execution
E.g., vesting unlock, scheduled payment, conditional trade
Risk: Cannot pre-sign hours/days in advance

Cross-Chain Bridges:

Wait for finality on source chain (minutes/hours)
Sign transaction on destination chain
Risk: Blockhash expires during cross-chain confirmation

The Solution: Durable Nonces

Durable nonces replace recent_blockhash with a stored on-chain value that:

✅ Never expires (remains valid indefinitely)
✅ Changes with each use (prevents replay attacks)
✅ Enables offline signing without time pressure
✅ Supports multi-signature coordination
✅ Allows pre-signing transactions for future execution

Key insight: Instead of using the blockchain's recent history (blockhashes) to ensure uniqueness, durable nonces use a dedicated account that stores a nonce value and advances it after each transaction.

How Durable Nonces Work

Core Mechanism

Nonce Account: On-chain account (owned by System Program) storing a 32-byte nonce value
Transaction Structure: Use nonce value as recent_blockhash field
Nonce Advancement: First instruction MUST advance the nonce to prevent replay
Authority Control: Only nonce authority can advance nonce or authorize transactions

Transaction Flow

Normal Transaction:
1. Fetch recent blockhash (expires in 90s)
2. Build transaction with blockhash
3. Sign transaction
4. Submit (must be within 90s)
5. Process and confirm

Durable Nonce Transaction:
1. Create nonce account (one-time setup)
2. Fetch current nonce value (no expiration!)
3. Build transaction with nonce as blockhash
4. Add advance_nonce instruction (MUST be first)
5. Sign transaction (no time pressure)
6. Submit anytime (minutes, hours, days later)
7. Process: advances nonce, executes instructions

Double-Spend Prevention

Without expiration, how does it prevent double-spending?

The nonce value changes after each transaction:

// Transaction 1 with nonce value "ABC123..."
{
    recent_blockhash: "ABC123...",  // Current nonce value
    instructions: [
        advance_nonce_account(...),  // Changes nonce to "XYZ789..."
        transfer(...),
    ]
}

// If you try to submit Transaction 1 again:
// Runtime checks: Is "ABC123..." the current nonce?
// NO! It's now "XYZ789..."
// Transaction REJECTED (nonce mismatch)

Critical: The runtime always advances the nonce, even if the transaction fails after the advance instruction. This prevents replay attacks.

Nonce Account Structure

Account Layout

Nonce accounts are owned by the System Program and have this structure:

pub struct NonceState {
    pub version: NonceVersion,
}

pub enum NonceVersion {
    Legacy(Box<NonceData>),
    Current(Box<NonceData>),
}

pub struct NonceData {
    pub authority: Pubkey,         // Who can authorize nonce operations
    pub durable_nonce: Hash,       // The actual nonce value (32 bytes)
    pub fee_calculator: FeeCalculator,  // Historic fee data
}

Account requirements:

Owner: System Program (11111111111111111111111111111111)
Size: 80 bytes
Rent exemption: Required (minimum ~0.00144768 SOL)
Authority: Can be any pubkey (keypair or PDA)

Nonce Authority

The authority pubkey controls the nonce account:

Can: Advance nonce, withdraw funds, authorize nonce transactions, change authority
Cannot: Execute other instructions without nonce advancement (runtime enforces this)

Authority options:

Keypair: Direct control (hot wallet, cold wallet)
PDA: Program-controlled nonces (advanced use case)
Multisig: Multiple signers required (DAO wallets)

Creating Nonce Accounts

Using Native Rust

use solana_sdk::{
    instruction::Instruction,
    pubkey::Pubkey,
    signature::{Keypair, Signer},
    system_instruction,
    sysvar::rent::Rent,
    transaction::Transaction,
};
use solana_client::rpc_client::RpcClient;

fn create_nonce_account(
    rpc_client: &RpcClient,
    payer: &Keypair,
    nonce_account: &Keypair,
    authority: &Pubkey,
) -> Result<(), Box<dyn std::error::Error>> {
    // Calculate rent-exempt balance for nonce account
    let rent = rpc_client.get_minimum_balance_for_rent_exemption(80)?;

    // Create account instruction
    let create_account_ix = system_instruction::create_account(
        &payer.pubkey(),
        &nonce_account.pubkey(),
        rent,                     // Lamports (rent-exempt minimum)
        80,                       // Space (nonce account size)
        &solana_program::system_program::id(),  // Owner (System Program)
    );

    // Initialize nonce instruction
    let initialize_nonce_ix = system_instruction::initialize_nonce_account(
        &nonce_account.pubkey(),
        authority,                // Nonce authority
    );

    // Build transaction
    let recent_blockhash = rpc_client.get_latest_blockhash()?;
    let transaction = Transaction::new_signed_with_payer(
        &[create_account_ix, initialize_nonce_ix],
        Some(&payer.pubkey()),
        &[payer, nonce_account],  // Both payer and nonce account must sign
        recent_blockhash,
    );

    // Send transaction
    let signature = rpc_client.send_and_confirm_transaction(&transaction)?;
    println!("Created nonce account: {}", signature);

    Ok(())
}

Single-Step Creation

There's also a convenience function that combines both steps:

let instruction = system_instruction::create_nonce_account(
    &payer.pubkey(),
    &nonce_account.pubkey(),
    authority,
    rent_lamports,
);

// This creates a single instruction that:
// 1. Creates the account
// 2. Initializes it as a nonce account

Using CLI

# Generate keypair for nonce account
solana-keygen new -o nonce-account.json

# Create nonce account
solana create-nonce-account nonce-account.json 0.0015

# Verify creation
solana nonce nonce-account.json
# Output: Current nonce value (32-byte hash)

Querying Nonce Accounts

Fetching Nonce Value

use solana_sdk::account::Account;
use solana_program::system_program;

fn get_nonce_value(
    rpc_client: &RpcClient,
    nonce_pubkey: &Pubkey,
) -> Result<Hash, Box<dyn std::error::Error>> {
    // Fetch account data
    let account = rpc_client.get_account(nonce_pubkey)?;

    // Verify it's a nonce account
    if account.owner != system_program::id() {
        return Err("Account is not owned by System Program".into());
    }

    // Deserialize nonce data
    let nonce_data = bincode::deserialize::<NonceState>(&account.data)?;

    match nonce_data {
        NonceState::Current(data) => Ok(data.durable_nonce),
        NonceState::Legacy(data) => Ok(data.durable_nonce),
    }
}

Parsing Nonce Account

use solana_program::nonce::state::{Data, State};

fn parse_nonce_account(account_data: &[u8]) -> Result<Data, Box<dyn std::error::Error>> {
    let state: State = bincode::deserialize(account_data)?;

    match state {
        State::Initialized(data) => Ok(data),
        State::Uninitialized => Err("Nonce account not initialized".into()),
    }
}

// Access nonce components
fn display_nonce_info(nonce_data: &Data) {
    println!("Authority: {}", nonce_data.authority);
    println!("Nonce value: {}", nonce_data.blockhash);
    println!("Fee calculator: {:?}", nonce_data.fee_calculator);
}

Building Transactions with Durable Nonces

Transaction Structure

Critical requirements:

First instruction MUST be advance_nonce_account
Use nonce value as recent_blockhash
Sign with nonce authority (in addition to other required signers)

use solana_sdk::{
    hash::Hash,
    instruction::Instruction,
    message::Message,
    signature::{Keypair, Signer},
    system_instruction,
    transaction::Transaction,
};

fn build_nonce_transaction(
    nonce_pubkey: &Pubkey,
    nonce_authority: &Keypair,
    nonce_value: Hash,
    instructions: Vec<Instruction>,
    payer: &Keypair,
) -> Transaction {
    // 1. Create advance_nonce instruction (MUST BE FIRST)
    let advance_nonce_ix = system_instruction::advance_nonce_account(
        nonce_pubkey,
        &nonce_authority.pubkey(),
    );

    // 2. Combine with your instructions
    let mut all_instructions = vec![advance_nonce_ix];
    all_instructions.extend(instructions);

    // 3. Build message with nonce as blockhash
    let message = Message::new_with_blockhash(
        &all_instructions,
        Some(&payer.pubkey()),
        &nonce_value,  // Use nonce value instead of recent blockhash!
    );

    // 4. Sign with both payer and nonce authority
    let mut signers = vec![payer];
    if nonce_authority.pubkey() != payer.pubkey() {
        signers.push(nonce_authority);
    }

    Transaction::new(&signers, message, nonce_value)
}

Complete Example: Transfer with Durable Nonce

fn transfer_with_nonce(
    rpc_client: &RpcClient,
    nonce_account: &Pubkey,
    nonce_authority: &Keypair,
    payer: &Keypair,
    recipient: &Pubkey,
    amount: u64,
) -> Result<(), Box<dyn std::error::Error>> {
    // 1. Fetch current nonce value
    let nonce_value = get_nonce_value(rpc_client, nonce_account)?;

    // 2. Create transfer instruction
    let transfer_ix = system_instruction::transfer(
        &payer.pubkey(),
        recipient,
        amount,
    );

    // 3. Build transaction with nonce
    let transaction = build_nonce_transaction(
        nonce_account,
        nonce_authority,
        nonce_value,
        vec![transfer_ix],
        payer,
    );

    // 4. Can now submit immediately or store for later
    // No expiration pressure!
    let signature = rpc_client.send_and_confirm_transaction(&transaction)?;
    println!("Transfer completed: {}", signature);

    Ok(())
}

Serializing for Offline Signing

use base58::ToBase58;

fn serialize_for_offline_signing(transaction: &Transaction) -> String {
    // Serialize transaction to bytes
    let serialized = bincode::serialize(transaction).unwrap();

    // Encode as base58 for transport
    serialized.to_base58()
}

fn deserialize_signed_transaction(base58_tx: &str) -> Transaction {
    use base58::FromBase58;

    let bytes = base58_tx.from_base58().unwrap();
    bincode::deserialize(&bytes).unwrap()
}

Managing Nonce Accounts

Advancing Nonce

Automatic advancement: When you submit a transaction with a durable nonce, the runtime automatically advances the nonce as part of processing the advance_nonce_account instruction.

Manual advancement (without submitting transaction):

fn advance_nonce_manually(
    rpc_client: &RpcClient,
    nonce_account: &Pubkey,
    nonce_authority: &Keypair,
    payer: &Keypair,
) -> Result<(), Box<dyn std::error::Error>> {
    let advance_ix = system_instruction::advance_nonce_account(
        nonce_account,
        &nonce_authority.pubkey(),
    );

    let recent_blockhash = rpc_client.get_latest_blockhash()?;
    let transaction = Transaction::new_signed_with_payer(
        &[advance_ix],
        Some(&payer.pubkey()),
        &[payer, nonce_authority],
        recent_blockhash,
    );

    rpc_client.send_and_confirm_transaction(&transaction)?;
    Ok(())
}

When to manually advance:

Before reusing nonce for a new transaction
To invalidate a previously signed transaction
Regular rotation for security

Withdrawing from Nonce Account

fn withdraw_from_nonce(
    rpc_client: &RpcClient,
    nonce_account: &Pubkey,
    nonce_authority: &Keypair,
    recipient: &Pubkey,
    amount: u64,
    payer: &Keypair,
) -> Result<(), Box<dyn std::error::Error>> {
    let withdraw_ix = system_instruction::withdraw_nonce_account(
        nonce_account,
        &nonce_authority.pubkey(),
        recipient,
        amount,
    );

    let recent_blockhash = rpc_client.get_latest_blockhash()?;
    let transaction = Transaction::new_signed_with_payer(
        &[withdraw_ix],
        Some(&payer.pubkey()),
        &[payer, nonce_authority],
        recent_blockhash,
    );

    rpc_client.send_and_confirm_transaction(&transaction)?;
    Ok(())
}

Important: Must maintain rent-exempt minimum balance. Can only withdraw to zero if closing the account.

Changing Nonce Authority

fn change_nonce_authority(
    rpc_client: &RpcClient,
    nonce_account: &Pubkey,
    current_authority: &Keypair,
    new_authority: &Pubkey,
    payer: &Keypair,
) -> Result<(), Box<dyn std::error::Error>> {
    let authorize_ix = system_instruction::authorize_nonce_account(
        nonce_account,
        &current_authority.pubkey(),
        new_authority,
    );

    let recent_blockhash = rpc_client.get_latest_blockhash()?;
    let transaction = Transaction::new_signed_with_payer(
        &[authorize_ix],
        Some(&payer.pubkey()),
        &[payer, current_authority],
        recent_blockhash,
    );

    rpc_client.send_and_confirm_transaction(&transaction)?;
    Ok(())
}

Use cases:

Transfer control to PDA for program-managed nonces
Rotate keys for security
Transfer to multisig for DAO control

Offline Signing Workflows

Hardware Wallet Flow

Setup (online device):

// 1. Create nonce account (one-time)
create_nonce_account(&rpc_client, &payer, &nonce_account, &hw_wallet_pubkey)?;

// 2. Fetch nonce value
let nonce_value = get_nonce_value(&rpc_client, &nonce_account.pubkey())?;

// 3. Build unsigned transaction
let unsigned_tx = build_nonce_transaction(
    &nonce_account.pubkey(),
    &hw_wallet_keypair,  // Will be replaced with actual signature
    nonce_value,
    vec![transfer_ix],
    &payer,
);

// 4. Serialize for hardware wallet
let serialized = serialize_for_offline_signing(&unsigned_tx);

// 5. Transfer to hardware wallet (USB, QR code, etc.)

Signing (air-gapped hardware wallet):

// 1. Receive serialized transaction
let tx = deserialize_signed_transaction(&serialized);

// 2. Display to user for review (no time pressure!)
// User reviews: recipient, amount, etc.

// 3. Sign with hardware wallet private key
// (Hardware wallet handles this internally)

// 4. Export signed transaction
let signed_serialized = serialize_for_offline_signing(&signed_tx);

// 5. Transfer back to online device

Submission (online device):

// 1. Receive signed transaction
let signed_tx = deserialize_signed_transaction(&signed_serialized);

// 2. Submit to network (can be hours/days after signing!)
let signature = rpc_client.send_and_confirm_transaction(&signed_tx)?;

Multi-Signature Coordination

DAO Proposal Execution Flow:

// 1. Proposer creates transaction with nonce
let nonce_value = get_nonce_value(&rpc_client, &dao_nonce_account)?;
let proposal_tx = build_nonce_transaction(
    &dao_nonce_account,
    &dao_authority,  // PDA controlled by governance
    nonce_value,
    vec![execute_proposal_ix],
    &proposer,
);

// 2. Serialize and store in DAO state
let tx_data = bincode::serialize(&proposal_tx)?;
// Store tx_data in proposal account

// 3. Members vote over time (hours/days)
// Each vote increments approval count

// 4. When threshold reached, anyone can execute
let stored_tx: Transaction = bincode::deserialize(&proposal.tx_data)?;

// 5. Submit (nonce ensures it's still valid!)
rpc_client.send_and_confirm_transaction(&stored_tx)?;

CLI Multi-Sig Example

First co-signer (offline):

solana transfer \
  --from sender.json \
  --sign-only \
  --nonce nonce-account.json \
  --nonce-authority nonce-authority.json \
  --blockhash <NONCE_VALUE> \
  --fee-payer co-sender.json \
  receiver.json 0.1

# Output:
# Pubkey=Signature
# 5nZ8nY5...=4SBv7Xp...

Second co-signer (online, hours/days later):

solana transfer \
  --from sender.json \
  --nonce nonce-account.json \
  --nonce-authority nonce-authority.json \
  --blockhash <NONCE_VALUE> \
  --fee-payer sender.json \
  --signer 5nZ8nY5...=4SBv7Xp... \
  receiver.json 0.1

Security Considerations

The Neodyme Vulnerability (2020)

Historic issue: Before Solana v1.3, there was a critical vulnerability in how durable nonce transactions were processed:

The bug:

Transaction with durable nonce starts processing
Runtime advances nonce (changes state)
Later instruction in transaction fails
Runtime rolls back ALL state changes
BUG: Nonce advancement was rolled back too!
Attacker could replay the transaction

The exploit:

// Malicious transaction:
{
    instructions: [
        advance_nonce(...),        // Advances nonce
        write_arbitrary_data(...), // Attacker's payload
        fail_intentionally(...),   // Forces transaction to fail
    ]
}

// After rollback:
// - Nonce reverted to original value
// - Arbitrary data write WAS NOT rolled back
// - Can replay transaction infinitely!

Impact: Could write arbitrary data to any account by replaying failed transactions.

Fix (Solana v1.3+): Nonce advancement is now permanent even on transaction failure. The runtime explicitly handles nonce accounts separately from normal rollback logic.

Lesson: This demonstrates why nonce advancement MUST happen regardless of transaction success/failure.

Best Practices

1. Never reuse nonce without advancing

// BAD: Reusing nonce value
let nonce = get_nonce_value(&rpc, &nonce_account)?;
let tx1 = build_nonce_transaction(&nonce_account, &auth, nonce, vec![ix1], &payer);
let tx2 = build_nonce_transaction(&nonce_account, &auth, nonce, vec![ix2], &payer);
// If tx1 fails, tx2 might also fail with "nonce mismatch"

// GOOD: Advance between uses
let nonce1 = get_nonce_value(&rpc, &nonce_account)?;
let tx1 = build_nonce_transaction(&nonce_account, &auth, nonce1, vec![ix1], &payer);
rpc.send_and_confirm_transaction(&tx1)?;

// Fetch fresh nonce (it was advanced)
let nonce2 = get_nonce_value(&rpc, &nonce_account)?;
let tx2 = build_nonce_transaction(&nonce_account, &auth, nonce2, vec![ix2], &payer);

2. Protect nonce authority

// Use cold storage for nonce authority
// OR use PDA with program logic to restrict usage
let authority_pda = Pubkey::find_program_address(
    &[b"nonce_authority", dao.key().as_ref()],
    program_id,
);

3. Maintain rent exemption

// Check before withdrawal
let nonce_account = rpc.get_account(&nonce_pubkey)?;
let rent = rpc.get_minimum_balance_for_rent_exemption(80)?;

if nonce_account.lamports - withdraw_amount < rent {
    return Err("Would violate rent exemption".into());
}

4. Verify nonce advancement in transaction

// In your program that uses nonce transactions:
pub fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    // First account should be nonce account
    let nonce_account = &accounts[0];

    // Verify it's a valid nonce account
    if nonce_account.owner != &system_program::id() {
        return Err(ProgramError::InvalidAccountData);
    }

    // Verify advance_nonce was called
    // (Runtime enforces this, but you can add checks)

    Ok(())
}

5. Monitor nonce account balance

// Periodic check (e.g., daily job)
fn check_nonce_health(rpc: &RpcClient, nonce: &Pubkey) -> Result<(), String> {
    let account = rpc.get_account(nonce)
        .map_err(|_| "Nonce account not found")?;

    let rent = rpc.get_minimum_balance_for_rent_exemption(80)
        .map_err(|_| "Failed to fetch rent")?;

    if account.lamports < rent {
        return Err(format!(
            "Nonce account below rent exemption: {} < {}",
            account.lamports, rent
        ));
    }

    Ok(())
}

Use Cases

1. Scheduled Payments (Vesting)

// Pre-sign monthly vesting releases
fn create_vesting_schedule(
    rpc: &RpcClient,
    nonce_account: &Pubkey,
    nonce_authority: &Keypair,
    recipient: &Pubkey,
    amount_per_month: u64,
    months: usize,
) -> Result<Vec<Transaction>, Box<dyn std::error::Error>> {
    let mut transactions = Vec::new();

    for month in 0..months {
        // Fetch current nonce
        let nonce = get_nonce_value(rpc, nonce_account)?;

        // Create transfer
        let transfer_ix = system_instruction::transfer(
            &nonce_authority.pubkey(),
            recipient,
            amount_per_month,
        );

        // Build nonce transaction
        let tx = build_nonce_transaction(
            nonce_account,
            nonce_authority,
            nonce,
            vec![transfer_ix],
            nonce_authority,
        );

        transactions.push(tx);

        // Advance nonce for next month's transaction
        advance_nonce_manually(rpc, nonce_account, nonce_authority, nonce_authority)?;
    }

    Ok(transactions)
}

// Executor submits each month
fn execute_vesting_payment(
    rpc: &RpcClient,
    pre_signed_tx: &Transaction,
) -> Result<(), Box<dyn std::error::Error>> {
    // No time pressure - can submit anytime!
    rpc.send_and_confirm_transaction(pre_signed_tx)?;
    Ok(())
}

2. Conditional Trades (Limit Orders)

// Pre-sign trade execution at specific price
fn create_limit_order(
    nonce: &Pubkey,
    authority: &Keypair,
    swap_instruction: Instruction,  // Execute when price reached
) -> Transaction {
    let nonce_value = /* fetch nonce */;

    build_nonce_transaction(
        nonce,
        authority,
        nonce_value,
        vec![swap_instruction],
        authority,
    )
}

// Bot monitors price and submits when condition met
fn execute_limit_order(rpc: &RpcClient, current_price: f64, limit_tx: &Transaction) {
    if current_price >= target_price {
        rpc.send_transaction(limit_tx).ok();  // Submit pre-signed transaction
    }
}

3. Cross-Chain Bridges

// Sign Solana transaction while waiting for Ethereum finality
async fn bridge_from_ethereum_to_solana(
    eth_tx_hash: H256,
    solana_mint_ix: Instruction,
    nonce_account: &Pubkey,
    nonce_authority: &Keypair,
) -> Result<(), Box<dyn std::error::Error>> {
    // 1. Pre-sign Solana mint transaction
    let nonce = get_nonce_value(&solana_rpc, nonce_account)?;
    let mint_tx = build_nonce_transaction(
        nonce_account,
        nonce_authority,
        nonce,
        vec![solana_mint_ix],
        nonce_authority,
    );

    // 2. Wait for Ethereum finality (12+ minutes)
    wait_for_ethereum_finality(eth_tx_hash).await?;

    // 3. Submit Solana transaction (still valid!)
    solana_rpc.send_and_confirm_transaction(&mint_tx)?;

    Ok(())
}

4. DAO Governance Execution

Already covered in multi-sig example above - proposals can be voted on over days/weeks, then executed with pre-signed transaction.

CLI Reference

Create nonce account:

solana create-nonce-account <KEYPAIR_PATH> <AMOUNT>

Get current nonce:

solana nonce <NONCE_ACCOUNT>

Manually advance nonce:

solana new-nonce <NONCE_ACCOUNT>

Get nonce account info:

solana nonce-account <NONCE_ACCOUNT>

Withdraw from nonce:

solana withdraw-from-nonce-account <NONCE_ACCOUNT> <DESTINATION> <AMOUNT>

Change nonce authority:

solana authorize-nonce-account <NONCE_ACCOUNT> <NEW_AUTHORITY>

Sign transaction offline:

solana <COMMAND> \
  --sign-only \
  --nonce <NONCE_ACCOUNT> \
  --nonce-authority <AUTHORITY_KEYPAIR> \
  --blockhash <NONCE_VALUE>

Submit pre-signed transaction:

solana <COMMAND> \
  --nonce <NONCE_ACCOUNT> \
  --nonce-authority <AUTHORITY_KEYPAIR> \
  --blockhash <NONCE_VALUE> \
  --signer <PUBKEY=SIGNATURE>

Limitations and Considerations

Transaction size:

Adding advance_nonce_account instruction adds ~40 bytes
May push transaction over size limit if already near maximum

Extra signature requirement:

Nonce authority must sign (if different from fee payer)
Increases transaction complexity

Rent cost:

Each nonce account requires ~0.0015 SOL rent-exempt minimum
For many scheduled transactions, can become expensive

Nonce advancement overhead:

Compute units to advance nonce (~few hundred CU)
Minimal but worth considering for CU-constrained transactions

Cannot mix recent blockhashes and nonces:

Transaction uses either recent blockhash OR durable nonce
Cannot use both in the same transaction

Resources

Official Documentation

Code Examples

Security Analysis

Neodyme: Nonce Upon a Time - Historic vulnerability analysis

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