Correct antiFeeSniping data for Cake Wallet, BitBoxApp, and Trezor Suite in wallet guide

[4rkad]

Source code verification reveals that 3 wallets currently listed with antiFeeSniping: true in src/data/guide/wallets.ts do not implement anti-fee-sniping based on their source code.

Findings

Cake Wallet — antiFeeSniping should be false

File: cw_bitcoin/lib/psbt/transaction_builder.dart

The PSBT transaction builder sets nVersion = 2 and nSequence = 0xFFFFFFFD (RBF) or 0xFFFFFFFF, but never sets nLocktime. No reference to block height, anti-fee-sniping, or locktime exists anywhere in the cw_bitcoin transaction construction code. The PSBT default is 0.

psbt.setGlobalTxVersion(2);
psbt.setInputSequence(i, enableRBF ? 0xfffffffd : 0xffffffff);
// No setGlobalLocktime() call anywhere

BitBoxApp — antiFeeSniping should be false

File: backend/coins/btc/maketx/maketx.go

Explicitly sets LockTime: 0 with a comment explaining the decision:

// Locktime is also enabled by this, but we keep
// the locktime at 0, which has no effect.
txIn.Sequence = wire.MaxTxInSequenceNum - 2

unsignedTransaction := &wire.MsgTx{
    Version:  wire.TxVersion,
    TxIn:     inputs,
    TxOut:    outputs,
    LockTime: 0,
}

Trezor Suite — antiFeeSniping likely false, needs confirmation

File: common/protob/messages-bitcoin.proto

The protobuf definition defaults lock_time to 0:

optional uint32 lock_time = 5 [default = 0];

Trezor Suite (sendFormBitcoinThunks.ts) only sets locktime when the user manually configures bitcoinLocktimeBlockHeight or bitcoinLocktimeDatetime. There is no automatic anti-fee-sniping logic that sets locktime to current block height. The enhanceSignTx function was not found to add it either.

Wallets correctly listed

For reference, the following wallets were verified to implement anti-fee-sniping:

• Bitcoin Core — src/wallet/spend.cpp → DiscourageFeeSniping(): sets nLocktime = block_height, 10% chance of subtracting random(0-99) blocks
• Electrum — electrum/wallet.py → get_locktime_for_new_transaction(): same algorithm as Core
• Blockstream Green (GDK) — src/ga_tx.cpp → set_anti_snipe_locktime(): same algorithm as Core

Suggested change

In src/data/guide/wallets.ts:

  // Cake Wallet
- antiFeeSniping: true,
+ antiFeeSniping: false,

  // BitBoxApp
- antiFeeSniping: true,
+ antiFeeSniping: false,

  // Trezor Suite (pending further confirmation)
- antiFeeSniping: true,
+ antiFeeSniping: false,

[4rkad]

Additional finding: BlueWallet also lacks anti-fee-sniping

BlueWallet — antiFeeSniping should be false

File: class/wallets/abstract-hd-electrum-wallet.ts

The createTransaction() method creates a new bitcoin.Psbt() without setting locktime. All "locktime" references in the file are for parsing existing transactions (tx.blocktime), not for construction. The bitcoinjs-lib Psbt default is nLocktime = 0.

Updated suggested change

  // BlueWallet
- antiFeeSniping: true,
+ antiFeeSniping: false,

Summary of all verified wallets

Wallet	antiFeeSniping (current)	Verified value	Source
Bitcoin Core	true	✅ true	src/wallet/spend.cpp → DiscourageFeeSniping()
Electrum	true	✅ true	electrum/wallet.py → get_locktime_for_new_transaction()
Blockstream Green	true	✅ true	GDK src/ga_tx.cpp → set_anti_snipe_locktime()
Ashigaru	true	✅ true	Verified in real transactions
Sparrow	true	✅ true	Verified in real transactions
Cake Wallet	true	❌ false	cw_bitcoin/lib/psbt/transaction_builder.dart
BitBoxApp	true	❌ false	backend/coins/btc/maketx/maketx.go
Trezor Suite	true	❌ false	messages-bitcoin.proto + sendFormBitcoinThunks.ts
Wasabi	false	✅ false (confirmed)	TransactionFactory.cs → LockTime.Zero
BlueWallet	true	❌ false	abstract-hd-electrum-wallet.ts
Bull Bitcoin	true	⚠️ unverified	Uses BDK
Nunchuk	true	⚠️ unverified	Uses Bitcoin Core RPC

4 wallets need correction: Cake Wallet, BitBoxApp, Trezor Suite, BlueWallet.

[4rkad]

Nunchuk — antiFeeSniping should be false

Source code verification confirms that Nunchuk does not enable anti-fee-sniping by default.

libnunchuk (C++ backend)

File: include/nunchuk.h

The CreateTransaction API defaults anti_fee_sniping to false:

bool anti_fee_sniping = false,

File: src/nunchukimpl.cpp

The locktime is only set to current block height when anti_fee_sniping is explicitly true:

uint32_t locktime = 0, sequence = 0;
if (wallet.get_wallet_type() == WalletType::MINISCRIPT && use_script_path) {
    // ... handles miniscript timelocks ...
} else if (anti_fee_sniping) {
    locktime = GetChainTip();           // only if anti_fee_sniping == true
    sequence = MAX_BIP125_RBF_SEQUENCE;
}
// If anti_fee_sniping == false → locktime stays at 0

Nunchuk Android app

File: nunchuk-core/.../NcDataStore.kt

The preference defaults to false:

val antiFeeSnipingFlow: Flow<Boolean>
    get() = context.dataStore.data.map {
        it[antiFeeSniping] == true  // default: false
    }

File: nunchuk-settings/.../FeeSettingsViewModel.kt

val antiFeeSniping: Boolean = false,

The UI in Settings → Fee Settings shows a toggle labeled "Enable Anti-Fee Sniping" / "Adds the latest block height to the PSBT to prevent fee sniping attacks" — it's opt-in, disabled by default.

Even internal operations like SATSCARD sweep hardcode it to false:

antiFeeSniping = false,

---

Bull Bitcoin — antiFeeSniping is correctly true

Bull Bitcoin uses BDK (bdk_wallet) as its transaction engine. BDK implements anti-fee-sniping by default — the same algorithm as Bitcoin Core's DiscourageFeeSniping().

BDK wallet engine (Rust)

File: src/wallet/mod.rs

When no explicit nLockTime is set by the caller, BDK automatically sets it to the current block height:

let current_height = match params.current_height {
    // If they didn't tell us the current height, we assume it's the latest sync height.
    None => {
        let tip_height = self.chain.tip().height();
        absolute::LockTime::from_height(tip_height).expect("invalid height")
    }
    Some(h) => h,
};

let lock_time = match params.locktime {
    // When no nLockTime is specified, we try to prevent fee sniping, if possible.
    None => {
        // Fee sniping can be partially prevented by setting the timelock
        // to current_height.
        let fee_sniping_height = current_height;

        match requirements.timelock {
            // No requirement, just use the fee_sniping_height.
            None => fee_sniping_height,
            Some(value @ absolute::LockTime::Blocks(_)) if value < fee_sniping_height => {
                fee_sniping_height
            }
            Some(value) => value,
        }
    }
    // Specific nLockTime required and compatible with constraints
    Some(x) if requirements.timelock.is_none() => x,
    // ...
};

File: src/wallet/tx_builder.rs

The TxBuilder doc confirms the intent:

/// Set the current blockchain height.
///
/// This will be used to:
/// 1. Set the nLockTime for preventing fee sniping.
/// ...
/// In both cases, if you don't provide a current height, we use the last sync height.

Bull Bitcoin app (Flutter/Dart)

File: lib/core/wallet/data/datasources/bdk_wallet_datasource.dart

The app creates transactions using BDK's TxBuilder without overriding the locktime, so BDK's default anti-fee-sniping behavior applies:

bdk.TxBuilder txBuilder;

if (drain == true) {
    txBuilder = bdk.TxBuilder().drainWallet().drainTo(script);
} else {
    txBuilder = bdk.TxBuilder().addRecipient(script, BigInt.from(amountSat));
}

if (replaceByFee) txBuilder.enableRbf();
// ... fee rate, coin selection ...
// No .nlocktime() call — BDK default applies

final (psbt, _) = await txBuilder.finish(bdkWallet);

No call to .nlocktime() anywhere in the transaction building code → BDK sets nLockTime = current_height automatically.

---

Suggested changes

  // Nunchuk
- antiFeeSniping: true,
+ antiFeeSniping: false,

Bull Bitcoin's antiFeeSniping: true is correct — no change needed.