I am making an attempt to calculate the hash of transactions in bitcoin blocks, however I am not getting the fitting solutions.
For instance, the genesis block has a single transaction.
This is how I am trying to calculate its hash…
Transactions are encoded as:
- a 32 bit ‘nVersion’
- an inventory of enter transactions, vin
- an inventory of output transactions, vout
- a 32 bit ‘nLockTime’
For the transaction within the genesis block, these are:
- nVersion:
01000000
- inputs
- depend:
01
- 1st enter:
- prevout_hash:
0000000000000000000000000000000000000000000000000000000000000000
- prevout_n:
ffffffff
- scriptSig:
4d
:04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73
- sequence: ffffffff
- prevout_hash:
- depend:
- outputs
- depend:
01
- 1st output:
- worth:
00f2052a01000000
(hex(50*10^8) is 0000012a05f200, and bitcoin places the bytes in reverse order) - scriptPubKey:
43
:4104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac
- worth:
- depend:
- nLockTime:
00000000
If I string all these collectively finish to finish, I get 204 bytes: 01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff4d04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73ffffffff0100f2052a01000000434104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac00000000
Taking the sha256 hash of this offers 27362e66e032c731c1c8519f43063fe0e5d070db1c0c3552bb04afa18a31c6bf
.
Taking the sha256 hash of that hash offers 3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a
.
However the true transaction hash in accordance with blockexplorer.com is 4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b
.
What am I doing fallacious? How can I get to the right transaction hash?
This is my working in Python:
>>> import Crypto.Hash.SHA256 as hash, binascii
>>> tx = '01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff4d04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73ffffffff0100f2052a01000000434104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac00000000'
>>> len(binascii.unhexlify(tx))
204
>>> hash.new(binascii.unhexlify(tx)).digest().encode('hex_codec')
'27362e66e032c731c1c8519f43063fe0e5d070db1c0c3552bb04afa18a31c6bf'
>>> hash.new(hash.new(binascii.unhexlify(tx)).digest()).digest().encode('hex_codec')
'3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a'