Print Page - wif to integer - problem checksum

Title: wif to integer - problem checksum
Post by: ecdsa123 on January 01, 2023, 07:25:34 PM

I got problem - and I do not know where is problem. I got problem with checksum
any help?

Code:

import hashlib

def wif_to_int_private_key(wif: str) -> int:
    # Decode the WIF string to a bytes object
    
    wif_bytes = wif.encode()
    print(f"wif_bytes: {wif_bytes}")
    
    # The last four bytes of the WIF string represent the checksum
    
    checksum = wif_bytes[-4:]
    print(f"checksum: {checksum}")
    # The private key is the bytes preceding the checksum
    private_key_bytes = wif_bytes[1:-4]
    print(f"private_key_bytes: {private_key_bytes}")
    # Calculate the checksum of the private key bytes
    calculated_checksum = hashlib.sha256(private_key_bytes).digest()[:4]
    print(f"calculated_checksum: {calculated_checksum}")
    # Verify that the calculated checksum matches the one in the WIF string
    if calculated_checksum != checksum:
        raise ValueError("Invalid WIF checksum")
    # Check if the WIF string is compressed or uncompressed
    if wif_bytes[0] == 0x80:
        # Uncompressed WIF
        # Convert the private key bytes to an integer
        private_key = int.from_bytes(private_key_bytes, "big")
    elif wif_bytes[0] == 0xef:
        # Compressed WIF
        # Convert the private key bytes to an integer
        private_key = int.from_bytes(private_key_bytes[:-1], "big")
    else:
        raise ValueError("Invalid WIF format")
    return private_key

Code:

WIF="KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn"
private_key = wif_to_int_private_key(WIF)
print(private_key)

Title: Re: wif to integer - problem checksum
Post by: BlackHatCoiner on January 01, 2023, 07:38:25 PM

Printing is the friend of debugging. What does it print for checksum? It should be 0x4671fc3f for compressed private key = 1. Also, what's the error it shows to you? You can't expect everyone who sees this, to run it on their local machine. Explain better.

Quote from: ecdsa123 on January 01, 2023, 07:25:34 PM

and I do not know where is problem. I got problem with checksum

You don't know where the problem is, but you know that it has to do with checksum? Again, what's the error?

Title: Re: wif to integer - problem checksum
Post by: ecdsa123 on January 01, 2023, 08:18:39 PM

error is : Invalid WIF checksum

Title: Re: wif to integer - problem checksum
Post by: brainless on January 01, 2023, 08:19:02 PM

https://github.com/matja/bitcoin-tool

use these tools, for all side converters

Title: Re: wif to integer - problem checksum
Post by: witcher_sense on January 01, 2023, 09:09:51 PM

Code:

import base58

from sha256 import sha256


def wif_to_hex(wif: str) -> str:
    uncompressed = True if wif.startswith('5') else False
    private_key = base58.b58decode(wif).hex(
    )[2:-8] if uncompressed else base58.b58decode(wif).hex()[2:-10]
    return private_key                                                                                         

def is_checksum_valid(wif: str) -> bool:
    wif_bytes = base58.b58decode(wif).hex()
    wif_key, checksum = wif_bytes[:-8], wif_bytes[-8:]
    checksum_temp = sha256(sha256(bytes.fromhex(wif_key))).hex()[:8]
    return checksum_temp == checksum


print(wif_to_hex('5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreVqkVkk8'))
print(is_checksum_valid('5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreVqkVkk8'))

Title: Re: wif to integer - problem checksum
Post by: pooya87 on January 02, 2023, 04:08:15 AM

Quote from: ecdsa123 on January 01, 2023, 07:25:34 PM

# Decode the WIF string to a bytes object

wif_bytes = wif.encode()

You want to "decode" then you call "encode" method?! Doesn't that return a string instead of bytes? If so, the rest of your code is also wrong since it is not using the decoded base58 but a converted string.

Title: Re: wif to integer - problem checksum
Post by: odolvlobo on January 02, 2023, 04:36:53 AM

Quote from: ecdsa123 on January 01, 2023, 07:25:34 PM

Code:

    # The last four bytes of the WIF string represent the checksum

The last four bytes of the decoded WIF is the checksum, and the the last four characters in the string.

https://en.bitcoin.it/wiki/Wallet_import_format

Title: Re: wif to integer - problem checksum
Post by: witcher_sense on January 02, 2023, 05:02:39 AM

Have you consulted https://en.bitcoin.it/wiki/Wallet_import_format page before writing your code?

For example (as pooya87 has already noted):

Code:

# Decode the WIF string to a bytes object
wif_bytes = wif.encode()

Wrong. You should be using b58decode function from base58 module or something similar to convert encoded string to bytes.

Therefore, the following two lines are also wrong because you are dealing with improperly decoded string.
And yes, when you calculate a checksum you don't disregard a first byte (you add it instead).

Code:

# The last four bytes of the WIF string represent the checksum

checksum = wif_bytes[-4:]
  
# The private key is the bytes preceding the checksum
private_key_bytes = wif_bytes[1:-4]

Checksum is a double hash of a byte string, so your calculated checksum is wrong by definition:

Code:

calculated_checksum = hashlib.sha256(private_key_bytes).digest()[:4]

Lines like

Code:

if wif_bytes[0] == 0x80:

will never work because you didn't specify encoding (bytes[0].hex() == '80' or b.hex() == f'{0x80:x}' if you like)

Code:

wif_bytes[0] == 0xef:
# Compressed WIF

Wrong, it is not compressed WIF, 0xef byte is for testnet keys. In order to determine whether a private key is compressed or uncompressed, you should be checking for 0x01 byte at the end of a private key. However, the more accurate way would be to check against length in bytes. Uncompressed private keys will be 1 byte shorter than compressed.

Something like the following should work:

Code:

def wif_to_int_private_key(wif: str) -> int:
    import base58
    from sha256 import sha256

    # https://en.bitcoin.it/wiki/Wallet_import_format
    wif_bytes = base58.b58decode(wif)
    private_key_bytes, checksum = wif_bytes[:-4], wif_bytes[-4:]
    calculated_checksum = sha256(sha256(private_key_bytes))[:4]

    if calculated_checksum != checksum:
        raise ValueError("Invalid WIF checksum")
    private_key = int.from_bytes(private_key_bytes[1:-1]) if len(
        private_key_bytes) == 34 else int.from_bytes(private_key_bytes[1:])
    return private_key

Title: Re: wif to integer - problem checksum
Post by: mash23 on January 02, 2023, 07:14:08 AM

if wif_bytes[0] == 0x80:
will never work because you didn't specify encoding (bytes[0].hex() == '80' or b.hex() == f'{0x80:x}' if you like)

Title: Re: wif to integer - problem checksum
Post by: witcher_sense on January 02, 2023, 07:54:44 AM

Quote from: mash23 on January 02, 2023, 07:14:08 AM

if wif_bytes[0] == 0x80:
will never work because you didn't specify encoding (bytes[0].hex() == '80' or b.hex() == f'{0x80:x}' if you like)

You can also convert a hex representation of bytes to integer with base 16 and compare it with a given hexadecimal value.
You can't compare them directly because bytes can represent different things (not only integers).

You can also use this method to compare bytes as integers:

Quote from: https://stackoverflow.com/questions/24842764/comparison-of-byte-literals-in-python?rq=1

If you want to interpret these sequences explicitly as integer literals, then use ast.literal_eval() to interpret decoded text values; always normalise first before comparison:

Code:

>>> import ast
>>> ast.literal_eval(b'0b11111111'.decode('utf8'))
255
>>> ast.literal_eval(b'0xff'.decode('utf8'))
255

Here is a complete script to convert wif to an integer:

Code:

import base58

from sha256 import sha256


def wif_to_bytes(wif: str) -> tuple[bytes, ...]:
    private_key = base58.b58decode(wif)
    return private_key[:1], private_key[1:-4], private_key[-4:]


def is_checksum_valid(version: bytes, private_key: bytes, checksum: bytes) -> bool:
    return sha256(sha256(version + private_key))[:4] == checksum


def wif_to_int_private_key(wif: str) -> int:
    # https://en.bitcoin.it/wiki/Wallet_import_format
    version, private_key, checksum = wif_to_bytes(wif)
    if not is_checksum_valid(version, private_key, checksum):
        raise ValueError("Invalid WIF checksum")
    private_key_int = int.from_bytes(private_key[:-1], 'big') if len(
        private_key) == 33 else int.from_bytes(private_key, 'big')
    return private_key_int

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Bitcoin => Development & Technical Discussion => Topic started by: ecdsa123 on January 01, 2023, 07:25:34 PM