Signature Verification in a P2WPKH Transaction: A Step-by-Step Guide

Cryptocurrencies like Bitcoin have gained immense popularity over the years, and one of the most significant security features that contribute to its reliability is the process of verifying signature transactions. In this article, we will dive deeper into how to verify signatures in a P2WPKH (private transaction) transaction in Bitcoin.

Standard P2PKH Signature Verification Process

For standard P2PKH transactions, the signature verification process involves the following steps:

• New Transaction: The transaction is created and includes the sender address, receiver address, amount, and other relevant details.

• Settle TxOuts: Transaction outputs are settled (i.e., their balances are updated) to ensure that there are sufficient funds for the transaction.

• Set all TxIn scripts to blank: All transaction inputs are set to an empty script hash, indicating that no funds or assets will be transferred from the sender’s wallet to the recipient’s address.

• Enter previous block information: The transaction includes a “Previous block” field, which contains the previous block script (e.g. the sender’s public key) and any associated data.

Generating a signature digest

To verify the signature on a P2WPKH transaction, we need to generate the signature digest. Here’s how:

• Create a new Transaction object

  : A new NewTransaction object is created, including all the necessary details.

• Tune TxOuts: The outputs are adjusted according to the specified rules.

• Set all TxIn scripts to empty: All transaction inputs are set to an empty script hash.

• Insert information from previous block: The data from the previous block is inserted into the transaction.

Signature digest generation

The signature digest is generated using a cryptographic hash function (e.g. SHA-256). The resulting hexadecimal string is used to verify the signature in subsequent transactions.

Here is an example of how to generate the signature digest:

import hashlib
tx_outs = {"quantity": 10.0, "scriptPubKey": "q1..."}
tx_in_scripts = {}
previous_locking = {"public_key": "sender_public_key"}
new_transaction = NewTransaction(tx_outs=tx_outs,
tx_in_scripts=tx_in_scripts,
previous_locking=previous_locking)

Generate signature digest using SHA-256
signature_digest = hashlib.sha256(new_transaction.signature).hexdigest()

Verifying the signature in a P2WPKH transaction

To verify the signature in a transaction P2WPKH, you need to follow these steps:

• Get Signed Data: The recipient of the transaction must get the signed data, which includes the transaction ID and other relevant information.

• Create a new Transaction object: A new NewTransaction object is created, including all the necessary details.

• Tune TxOuts: The outputs are adjusted according to the specified rules.

• Set all TxIn scripts to empty: All transaction inputs are set to an empty script hash.

• Insert Previous Block Information: The data from the previous block is inserted into the transaction.

Verifying the signature in a P2WPKH transaction

Here’s how to verify the signature in a P2WPKH transaction:

“`Python

import hashlib

signed_data = …

tx_outs = {“amount”: 10.0, “scriptPubKey”: signed_data}

tx_in_scripts = {}

previous_block = {}

new_transaction = NewTransaction(tx_outs=tx_outs,

tx_in_scripts=tx_in_scripts,

previous_block=previous_block)

Generate signature digest using SHA-256

signature_digest = hashlib.sha256(new_transaction.signature).