2. Deriving the private key(s) from the public key(s)
3. Creating and broadcasting its own transaction using the stolen keypairs before the original transaction confirms (presumably with a higher fee to win the confirmation race).
Please correct me if I'm wrong.
EDIT: correction: every transaction completely spends any selected UTXO of an associated keypair, not all of the "source keypairs' funds". Thus the attack vector also includes being able to steal from any keypair that has ever made a transaction and also has UTXOs.
The newest transaction mechanism (taproot; P2TR) exposes the public key of the receiver as part of the transaction. If it becomes more commonly used, the supply of bitcoins with exposed public keys would start going up again. See figure 5 of https://arxiv.org/pdf/2603.28846#page=14 .
Slightly off-topic, but I wish more OSS projects and maintainers would advertise cryptocurrency donation addresses. It's probably the easiest way for end users to donate.
I have done that for years, and so far have received the equivalent of $25 (through three mBTC transactions) on my Bitcoin address, and maybe $90 through whatever the token is Brave uses (BAT?).
I still get random donations through an old PayPal email address that's listed on the same page as my bitcoin address, and that totals more like $100 (a year, not over the lifetime).
That's what is suggested here but according to the Giant Impact Hypothesis the impact happened about 4.5 billion years ago and formed the Moon from debris, and it likely vaporized much of any existing water on proto-Earth rather than delivering it...
More investigations needed ...
And every transaction completely spends the source keypairs' funds.
So the only attack vector a quantum computer could use is:
1. Observing newly broadcast/unconfirmed transactions
2. Deriving the private key(s) from the public key(s)
3. Creating and broadcasting its own transaction using the stolen keypairs before the original transaction confirms (presumably with a higher fee to win the confirmation race).
Please correct me if I'm wrong.
EDIT: correction: every transaction completely spends any selected UTXO of an associated keypair, not all of the "source keypairs' funds". Thus the attack vector also includes being able to steal from any keypair that has ever made a transaction and also has UTXOs.
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