Additional instructions in TX

Question

1. Would it be possibile to add additional information in TX?

I would like to add time of transaction in it.

2. Would hash of TX change if hostile node would change that time ?

Answer 1

You could add an extra output with a locking script that uses OP_RETURN to embed an arbitrary timestamp.

Obviously this increases the size and therefore likely increases the cost in required transaction fee to get the transaction confirmed promptly.

This would be time of transaction creation, not time of confirmation.

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Related:

• Explanation of what an OP_RETURN transaction looks like