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Can anyone provide a clear example on how to calculate a previous transaction hash?
Say I want to create a new transaction, I get that the hash is calculated by doubling sha256 a message m, but I'm having a hard time understanding the structure of m.
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You do not need to calculate previous transaction hash, because it is already known. To spend the previous output you just have to know
plus you should choose
then create some byte data and sign it with appropriate private key
Good manual you can find here: How to redeem a basic Tx?
0
You hash the header. Format is here: https://en.bitcoin.it/wiki/Block_hashing_algorithm The body contains the transactions. Here's the Bitcoin transaction format: https://en.bitcoin.it/wiki/Transactions
