TXID
Revision as of 15:07, 9 January 2020 by AlexMackay (talk | contribs)
A Transaction ID or TXID is a double SHA256 hash of the serialised transaction. TXIDs are not part of the the transaction, as the hash cannot be generated until the transaction is complete. A TXID and VOUT index are used to reference UTXOs when they are added to a transaction as an input.
Data
Input: Previous tx: f5d8ee39a430901c91a5917b9f2dc19d6d1a0e9cea205b009ca73dd04470b9a6 Index: 0 scriptSig: 304502206e21798a42fae0e854281abd38bacd1aeed3ee3738d9e1446618c4571d10 90db022100e2ac980643b0b82c0e88ffdfec6b64e3e6ba35e7ba5fdd7d5d6cc8d25c6b241501 Output: Value: 5000000000 scriptPubKey: OP_DUP OP_HASH160 404371705fa9bd789a2fcd52d2c580b65d35549d OP_EQUALVERIFY OP_CHECKSIG
Explanation
The double SHA256 hash can be used to enable users to know that a corresponding party has a copy of the full TX by requesting the intermediate hash, which can only be generated by hashing the full transaction. This 'proof of possession' is present across Bitcoin and enables complex functionality and checking of resources when Bitcoin is being used in a fully peer to peer environment.