A coinbase transaction follows the same format as a normal transaction, except:
It has exactly one txin
- This txin's prevout hash is
0000...0000. - This txin's prevout index is
0xFFFFFFFF - The txin's prevout script is an arbitrary byte array (it doesn't have to be a valid script, though this is commonly done anyway) of 2 to 100 bytes. It has to start with a correct push of the block height (see BIP34).
The sum of the txout's values cannot exceed the subsidy (25 BTC for now, halves every 210000 blocks) plus the fees of the non-coinbase transactions in the same block.
About the scriptSig being an arbitrary byte array, there is one caveat: the checksig operations in it are counted towards the block sigop limit (20000), so you probably don't want to accidentally trigger this. Making it a list of just push operations (including of the extranonce) avoids that.
1000000 .............................. Version
01 .................................... Number of inputs
| 00000000000000000000000000000000
| 00000000000000000000000000000000 ... Previous outpoint TXID
| ffffffff ............................ Previous outpoint index
|
| 29 .................................. Bytes in coinbase
| |
| | 03 ................................ Bytes in height
| | | 4e0105 .......................... Height: 328014
| |
| | 062f503253482f0472d35454085fffed
| | f2400000f90f54696d65202620486561
| | 6c74682021 ........................ Arbitrary data
| 00000000 ............................ Sequence
01 .................................... Output count
| 2c37449500000000 .................... Satoshis (25.04275756 BTC)
| 1976a914a09be8040cbf399926aeb1f4
| 70c37d1341f3b46588ac ................ P2PKH script
| 00000000 ............................ Locktime
参考:
https://bitcoin.stackexchange.com/questions/3374/how-to-redeem-a-basic-tx
https://en.bitcoin.it/wiki/Transaction
https://21.co/learn/parsing-blockchain-data-structures/#coinbase-transactions
https://bitcoin.stackexchange.com/questions/20721/what-is-the-format-of-the-coinbase-transaction
https://bitcoin.stackexchange.com/questions/13122/scriptsig-coinbase-structure-of-the-genesis-block
