Re: I'm trying to understand the exact mechanism of a UTXO spend

Quote from: warpanomaly on Today at 12:12:06 AM

Clearly I don't grasp the entire structure of a BTC transaction as indicated by the fact that I put several "IDK"s in the diagram. Can someone fill in the gaps in my knowledge?

Read this technical article: https://learnmeabitcoin.com/technical/transaction-data
It breaks-down every part of the transaction, with clickable links to explanation to that specific part and even has a diagram for you to understand how it works,
like the scriptPubKey: https://learnmeabitcoin.com/technical/scriptPubKey (hover-over to display the "IDK what goes here" part)

For the "signature of IDK", refer to this for p2pkh/p2sh: https://learnmeabitcoin.com/technical/ecdsa#signing-a-transaction
For SegWit, the message that needs to be signed is different, read BIP143.
The rest, you already figured out.