Bitcoin hash block algorithm

整体如图所示：

Block_Header:

Field	Purpose	Updated when...	Size (Bytes)
Version	Block version number	You upgrade the software and it specifies a new version	4
hashPrevBlock	256-bit hash of the previous block header	A new block comes in	32
hashMerkleRoot	256-bit hash based on all of the transactions in the block	A transaction is accepted	32
Time	Current timestamp as seconds since 1970-01-01T00:00 UTC	Every few seconds	4
Bits	Current target in compact format	The difficulty is adjusted	4
Nonce	32-bit number (starts at 0)	A hash is tried (increments)	4

 Hash = SHA256(SHA256(Block_Header))

以Block 125552为例：

import hashlib
import struct
import time


def calculate_block_hash(version, hash_prev_block, hash_merkle_root, timestamp, bits, nonce):
	version = struct.pack("<I", version)
	hash_prev_block = bytes.fromhex(hash_prev_block)[::-1]
	hash_merkle_root = bytes.fromhex(hash_merkle_root)[::-1]
	timestamp = struct.pack("<I", int(time.mktime(time.strptime(timestamp, "%Y-%m-%d %H:%M:%S"))))
	bits = struct.pack("<I", bits)
	nonce = struct.pack("<I", nonce)
	block_header = version + hash_prev_block +  hash_merkle_root + timestamp + bits + nonce
	return ''.join( [ "%02x" % x for x in __calculate_block_hash(block_header) ] ).strip()
	
 
def __calculate_block_hash(block_header):
	return hashlib.sha256(hashlib.sha256(block_header).digest()).digest()[::-1]


if __name__ == '__main__':
	# https://www.blockchain.com/btc/block/125552
	version = 0x1
	hash_prev_block = "00000000000008a3a41b85b8b29ad444def299fee21793cd8b9e567eab02cd81"
	hash_merkle_root = "2b12fcf1b09288fcaff797d71e950e71ae42b91e8bdb2304758dfcffc2b620e3"
	timestamp = "2011-05-22 01:26:31" # But in BlockChain Explorer front-end(https://www.blockchain.com/), we can not see the 'second' part.
	bits = 440711666
	nonce = 2504433986
	
	block_hash = calculate_block_hash(version, hash_prev_block, hash_merkle_root, timestamp, bits, nonce)
	print(block_hash)