Here’s an article on how to finalize a PSBT (Proof of Stake Bulletproofs) when the last signature is provided by a Hardware Wallet (HWW):

Finalizing PSBT with HWW Signature

When using device APIs for hardware wallets like Ledger or Trezor, you may encounter situations where the final signature is not yet provided. However, it’s essential to note that these devices typically provide the necessary signature upon successful initialization.

To finalize a PSBT (Proof of Stake Bulletproofs) after receiving an HWW signature, follow these steps:

Step 1: Obtain the HWW Signature

The first step is to obtain the HWW signature from your hardware wallet. This can be done using the sign_tx method provided by device APIs, as mentioned in the question.

use psbt::foreplay::*;


// Assume you have a Ledger device and a Trezor device with the same API.

let hww = LedgerDevice::new("path/to/ledger").unwrap();

hww.sign_tx(psbt::Tx::NewTransaction(

    psbt::Amount::Zero(),

    psbt::Target,

    psbt::Hash,

    psbt::ProofOfStake::Unconfirmed,

));

Step 2: Create the Finalized PSBT

Once you have the HWW signature, you can create the finalized PSBT using the finalize method provided by device APIs.

// Assume you have a Ledger device and a Trezor device with the same API.

let psbt = finalize(

    hww.hww_signature,

    psbt::Amount::Zero(),

    psbt::Target,

    psbt::Hash,

);

Step 3: Sign the Finalized PSBT (Optional)

If you want to sign the finalized PSBT using a different HWW, use the sign_tx method again.

// Assume you have another Ledger device and a Trezor device with the same API.

let hww_sign = LedgerDevice::new("path/to/other_ledger").unwrap();

let psbt_sign = finalize(

    hww.sign_tx(psbt::Amount::Zero(), psbt::Target, psbt::Hash),

    psbt::Amount::Zero(),

    psbt::Target,

    psbt::Hash,

);

Step 4: Verify the Finalized PSBT

To ensure that the finalized PSBT is correct, verify it by checking its hash and signature.

// Assume you have a Ledger device and a Trezor device with the same API.

let hww = LedgerDevice::new("path/to/ledger").unwrap();

hww.verify_finalized_psbt(&psbt::Hash, &psbt::Signature);

Sample Use Cases

Here’s an example use case that demonstrates how to finalize a PSBT using HWW signatures:

use psbt::foreplay::*;


fn main() {

    // Create a new Trezor device with the same API.

    let treasure = TreasuryDevice::new("path/to/treasure").unwrap();


    // Generate a public key and private key for your wallet.

    let pk = generate_keys().unwrap();

    let sk = generate_keys().unwrap();


    // Create a new PSBT (Proof of Stake Bulletproofs) transaction.

    let mut psbt = create_psbt(&pk, &sk);


    // Sign the PSBT with a Ledger device and another Trezor device.

    let hww_sign = LedgerDevice::new("path/to/ledger").unwrap();

    let trezor_sign = TrezorDevice::new("path/to/trezor").unwrap();


    psbt.sign_tx(hww_sign.hww_signature, &psbt);

    psbt.sign_tx(trezor_sign.hww_signature, &psbt);


    // Get the finalized PSBT.

    let finalized_psbt = finalize(&hww_sign.hww_signature, &psbt).unwrap();


    println!("Finalized PSBT Hash: {}", finalized_psbt.hash());

}

Note that this is a simplified example and you should consult your device API documentation for specific instructions on how to finalize PSBTs with HWW signatures. Additionally, keep in mind that using HWWs for key storage and signing transactions is not recommended by the Bitcoin community due to security concerns.

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