hash checker for Bitcoin

hash_check.py

#!/usr/bin/env python3
''' python3.10 hash_check.py -f inp.json '''

from binascii import unhexlify
from hashlib import sha256
import json
import sys
import urllib.request

# Convert into little endian format
def little_endian(string):
    splited = [str(string)[i:i + 2] for i in range(0, len(str(string)), 2)]
    splited.reverse()
    return "".join(splited)

help_message = 'Please give arguments to read the block data\nTo read the block as a json file\n-f <fileName>\nTo read the block from a url as a json body\n-i <url>\n'

if len(sys.argv) < 3:
    print(help_message)
    sys.exit()
elif sys.argv[1] == '-f':
    with open(sys.argv[2], 'r') as file:
        response = json.load(file)
elif sys.argv[1] == '-i':
    with urllib.request.urlopen(sys.argv[2]) as url:
        response = json.loads(url.read().decode())

version = '01000000'
little_endian_previous_hash = little_endian(response['prev_block'])
little_endian_merkle_root = little_endian(response['mrkl_root'])
little_endian_time = little_endian(hex(response['time'])[2:])
little_endian_difficulty_bits = little_endian(hex(response['bits'])[2:])
little_endian_nonce = little_endian(hex(response['nonce'])[2:])

# Append
header = version + little_endian_previous_hash + little_endian_merkle_root + little_endian_time + little_endian_difficulty_bits + little_endian_nonce

header = unhexlify(header)
# Sent hash by the miner
response_hash = little_endian(response['hash'])
# Calculated hash
calculated_hash = sha256(sha256(header).digest()).hexdigest()

# Verify the hash is smaller than the target
solved = 'Hash is smaller than the target' if response_hash <= little_endian_difficulty_bits else 'Hash is larger than the target'
print(solved)
# Equality of the calculated and received hashes
state = 'Hash of the block is acceptable.' if response_hash == calculated_hash else 'Hash of the block is not acceptable.'
print(state)