Hi,
As you can see I have found my errors, corrected it and posted the updated code before you replied, sorry for wasting your time.
Topic: Recalculating the hash in python (Read 3686 times)
Looking at your code, you have some byte order issues:
First, the i2w function. I'm too tired to actually fix this, so I went ahead and used the struct module (you should look into using it, it makes life a lot easier):
Then, when assembling the header, you still need to reverse p and m:
And lastly, when printing out the result, you need to reverse it too:
First, the i2w function. I'm too tired to actually fix this, so I went ahead and used the struct module (you should look into using it, it makes life a lot easier):
Code:
def i2w(integer):
"""Convert integer to 4 byte word in a string.
Will raise exception if overflows."""
#the < stands for little endian, and I for unsigned int
return struct.pack("
Then, when assembling the header, you still need to reverse p and m:
Code:
tmp = i2w(v) + p.decode('hex')[::-1] + m.decode('hex')[::-1] + i2w(t) + i2w(b) + i2w(n)
And lastly, when printing out the result, you need to reverse it too:
Code:
print(hash_two[::-1].encode('hex'))
As promised:
Code:
#! /usr/bin/env python
# The Python Equivalent of http://pastebin.com/Ya3604J0
import hashlib
# This is the data from the 'genesis' block, see: http://blockexplorer.com/b/0
VERSION = 1
PREV_BLOCK = "0000000000000000000000000000000000000000000000000000000000000000"
MERKLE_ROOT = "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"
TIMESTAMP = 1231006505
BITS = 486604799
NONCE = 2083236893
def _hex_word_from_integer(integer):
"""Convert integer to 4 byte word in a string.
Will raise exception if overflows."""
work = bin(integer)[2::].zfill(32)
if len(work) > 32:
raise(OverflowError(integer))
tmp = list()
while len(work) > 7:
part = work[:8]
work = work[8:]
char = chr(int(part, 2))
tmp.append(char)
return(''.join(tmp).encode('hex'))
def _hex_value_byteswap(hex_string):
"Swap the byte order in a hex string."
work = hex_string[::]
temp = list()
while len(work) > 1:
# Split string up in parts of two
part = work[0:2]
work = work[2::]
temp.append(part)
temp = temp[::-1] # reverse temp
return(''.join(temp))
def main():
# Building up the header
header = list()
header.append(_hex_word_from_integer(VERSION))
header.append(PREV_BLOCK)
header.append(MERKLE_ROOT)
header.append(_hex_word_from_integer(TIMESTAMP))
header.append(_hex_word_from_integer(BITS))
header.append(_hex_word_from_integer(NONCE))
# In place byteswap the items in the header list
for index in range(len(header)):
header[index] = _hex_value_byteswap(header[index])
# Generic information
header = ''.join(header).decode('hex')
print('sizeof(block_header) = %s' % len(header))
text = "Block header (in human readable hexadecimal representation): %s"
print(text % header.encode('hex'))
# The first hashing
hash = hashlib.sha256()
hash.update(header)
text = "Useless First Pass Checksum: %s"
text = text % _hex_value_byteswap(hash.hexdigest())
print(text)
# The second hashing
next = hash.digest()
hash = hashlib.sha256()
hash.update(next)
text = "Target Second Pass Checksum: %s"
text = text % _hex_value_byteswap(hash.hexdigest())
print(text)
if __name__ == '__main__':
main()
Never mind I see already a couple of errors, I'll try to convert http://pastebin.com/Ya3604J0
And will update this here once I get something working.
And will update this here once I get something working.
Hi all,
I am trying to recalculate the hash but I think I am making somewhere a giant snafu.
I attached my code, would anyone be willing to hint me in the right direction?
Thanks
I am trying to recalculate the hash but I think I am making somewhere a giant snafu.
I attached my code, would anyone be willing to hint me in the right direction?
Thanks
import hashlib
def i2w(integer):
"""Convert integer to 4 byte word in a string.
Will raise exception if overflows."""
work = bin(integer)[2::].zfill(32)
if len(work) > 32:
raise(OverflowError(integer))
tmp = list()
while len(work) > 7:
part = work[:8]
work = work[8:]
char = chr(int(part, 2))
tmp.append(char)
return(''.join(tmp))
if __name__ == '__main__':
# Contents of genesis block: http://blockexplorer.com/b/0
#"hash":"000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f",
#"ver":1,
#"prev_block":"0000000000000000000000000000000000000000000000000000000000000000",
#"mrkl_root":"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b",
#"time":1231006505,
#"bits":486604799,
#"nonce":2083236893,
#
hash = "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"
# Try to reproduce the above hash with below data
v = 1
p = "0000000000000000000000000000000000000000000000000000000000000000"
m = "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"
t = 1231006505
b = 486604799
n = 2083236893
tmp = i2w(v) + p.decode('hex') + m.decode('hex') + i2w(t) + i2w(b) + i2w(n)
one = hashlib.sha256()
one.update(tmp)
hash_one = one.digest()
two = hashlib.sha256()
two.update(hash_one)
hash_two = two.digest()
print(hash)
print(hash_two.encode('hex'))
Jump to: