What is prevTxHash?

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I have some questions regarding transactions, prevTxHash in Inputs of a Transaction, does this carry the hash of previous transaction in block or hash of the prev transaction by the same private key.

Hamza Tahir

Posted 2017-07-24T21:10:37.553

Reputation: 3

Welcome to the site. It is best to use a descriptive title that explains what your post is about; titles that just say "please help" don't draw the attention of the relevant experts. I made an edit; if you prefer something else you may also use the edit button.Nate Eldredge 2017-07-25T00:59:37.250

Answers

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I have some questions regarding transactions, prevTxHash in Inputs of a Transaction, does this carry the hash of previous transaction in block or hash of the prev transaction by the same private key.

No, it's the hash of the transaction whose output you are currently spending. Suppose I wanted to spend this transaction. I would include 961763d1c918e654c0ec922eb0aeb7f7e951e9bfae5398ec52e93fa0576c1f74 as the previous transaction hash in order to identify which output I am spending.

Nick ODell

Posted 2017-07-24T21:10:37.553

Reputation: 26 536

Thanx for the reply it helped me a lot, hopefully you have heard about SEGWIT soft fork, i just wanted to know that f signatures are not included in transaction how can they verify the transaction without it?Hamza Tahir 2017-07-31T03:28:04.690

They're not hashed in the transaction ID. However, signatures are kept alongside the transaction when relayed or in blocks. The wtxid in the block commits to the signature.Nick ODell 2017-07-31T03:31:49.253

thanx, but this arise a confusion in my mind, So as in segwit soft fork witnesses are kept in an extension block, so the software that is not updated it yet still accept the blockchain, so how can it understand and validate the transactions as it doesn't know the new rule that witnesses are in extension block not with the transaction?Hamza Tahir 2017-07-31T03:47:34.650

@HamzaTahir Segwit outputs appear as anyone-can-spend outputs to nodes that do not understand segwit. Non-segwit clients do no meaningful validation of segwit outputs.Nick ODell 2017-07-31T06:54:31.837