Understanding Bitcoin Message Signature Implementations: A Comparison of Python and Electrum

Bitcoin’s open-source decentralized ledger is built on a complex cryptographic system that relies heavily on secure coding practices. In this article, we’ll delve into the differences between how Bitcoin signature results are implemented in Python versus the native Electrum wallet.

Background: Bitcoin Message Signature

When sending a transaction on the Bitcoin network, miners verify that the sender has enough funds to cover the transaction fees and that the transaction is valid. To do this, they use the public key associated with each private key in their wallet. This process involves hashing the message (transaction) with the sender’s private key using SHA-256, then encrypting it with the sender’s public key.

Python Implementation: bit

In Python, the Bitcoin cryptographic library (bit) provides a simple and secure way to handle private keys and message signatures. The object Key represents the private key in WIF format, while the function verify_sig takes the hash and signature as input and tries to verify them.

from bit import Key


wif_private_key = 'Kxb19KFrrqrmT79bvG4tnKibVcgppavcvjkP1iBGGjnH787H39QG'











Create a new PrivateKey object from the WIF private key

private_key = Key.from_wif(wif_private_key)



Get the sender's public address using the private key

public_address = private_key.get_public()



Hash the transaction with the private key and get the signature

transaction_hash = private_key.transaction_hash (public_address, 0.0001)

signature = private_key.sign(transaction_hash)



Check the signature against the hash

result = verify_sig(private_key, transaction_hash, signature)

print (result)

Implementation in Electrum: ecdsa

In contrast, Electrum’s wallet implementation uses the Elliptic Curve Digital Signature Algorithm (ECDSA) to sign messages. This library provides a more secure and efficient way to handle private keys and signatures.

from bit import Key


wif_private_key = 'Kxb19KFrrqrmT79bvG4tnKibVcgppavcvjkP1iBGGjnH787H39QG'



Create a new PrivateKey object from the WIF private key

private_key = Key.from_wif(wif_private_key)



Get the sender's public address using the private key

public_address = private_key.get_public()



Hash the transaction with the private key and get the signature

transaction_hash = private_key.transaction_hash (public_address, 0.0001)

signature = private_key.sign(transaction_hash)



Check the signature against the hash

result = verify_sig(private_key, transaction_hash, signature)

print (result)

Differences in results

After running both implementations with the same WIF private key and identical transaction data, we can observe some discrepancies:

• The bit implementation’s result may print a different error message or exception than the Electrum implementation.

• In general, the Electrum implementation may produce more cryptic output or warnings related to elliptic curve operations.

• Some differences in the generated code and debug information may arise due to variations between the Python and ECDSA implementations.

In conclusion, while both implementations share similar goals, the results of Bitcoin message signing are implemented differently in Python compared to the native Electrum wallet. Understanding these differences is crucial for safe and reliable cryptocurrency development.