In Bitcoin you may have totally different UTXO with totally different public keys in a single transaction.
So suppose somebody broadcasts a transaction with sending 10000 BTC. Theoretically I can copy this transaction, add my enter with 0.1 BTC and alter output to my handle. Then signal a transaction and rebroadcast it.
Some miner will obtain it, and get transaction with two inputs: from preliminary sender (10000 BTC unlocked by him) and mine (0.1 BTC unlocked with my public key); and 1 output to my handle. The entire transaction is signed with my non-public key. Public key for verifying the signature is extracted from one of many inputs. So my public key from the second enter can be utilized for this objective and the transaction will probably be legitimate. The supply of 10000 BTC is unlocked with proprietor’s non-public key, so I will simply steal the cash.
Suppose my transaction has larger payment and propagates throughout the community sooner then unique.
Is that this risk actual or not? If not then why? If sure then why is not it eradicated trough proscribing transaction inputs so all of them have the identical public key?
EDIT:
What I imply is use a transaction with 2 inputs: one is used as an precise supply of cash and is unlocked with a sound signature (as a result of it’s copied from the transaction of the one who owns the cash) and one other one is used as public key supplier (it may be 0.00001 BTC, however have to be unlocked with my public key so that’s might be retrieved throughout complete transaction signature verifying and the entire transaction can be legitimate).