Post
Topic
Board Bitcoin Discussion
Re: Would Quantum Computer Kill Bitcoin
by
squatter
on 05/10/2019, 06:09:52 UTC
Now the issue is that ECC is NOT "quantum-safe" meaning that a quantum computer could theoretically decrypt a user's private keys and forge transaction signatures.
Is this the end of Crypto?
I don't think so, but I'd love to hear your opinions too! (Especially the opinion of a cryptographer)

Here's what Bitcoin developer Pieter Wuille said a few months ago:

Quote
Any unconfirmed transaction in flight exposes public keys, so if a QC exists, at least moving coins around safely becomes impossible. Further, a massive fraction of the currency supply can be taken. Lastly, you likely have exposed your own pubkey already.
https://twitter.com/pwuille/status/1133539556936912896
Quote
If there's ever evidence of theft due to a QC, and 5M BTC are readily available for the taking to such a hypothetical machine, do you think BTC will still have any value left?
https://twitter.com/pwuille/status/1133537183854239745

It sounds pretty grim. I didn't realize that P2PKH outputs weren't really secure against hypothetical quantum computing attacks. On top of that, the pubkey problem is really bad. Anyone who has shared an xpub, used Electrum, etc. has exposed pubkeys. It's not just early P2PK outputs or reused addresses.