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  • Kaveh Goudarzi thinks this is interesting:

A transaction ID is not authoritative until a transaction has been confirmed. Absence of a transaction hash in the blockchain does not mean the transaction was not processed. This is known as “transaction malleability,” because transaction hashes can be modified prior to confirmation in a block. After confirmation, the txid is immutable and authoritative.

From

Cover of Mastering Bitcoin, 2nd Edition

Note

who generates the txid before confirmation and why would it be modified?