[ExI] You'd better sell your bitcoins

[Jason Resch]

Public keys are only exposed when money is spent. Otherwise the block chain
stores only hashes of public keys.

While quantum computers can attack public keys once they are exposed they
can't reverse cryptographic hash functions.

So when the usual convention that addresses only spend bitcoin once is
followed, stored funds are not vulnerable to quantum attacks. Instead an
attacker would have to wait until money is spent, intercept that
transaction, break the key, and try to double spend before the transaction
is accepted by other nodes.

And all this assumes there's no migration to post-quantum-secure
cryptography between now and the future where such attacks become possible.
These algorithms not only already exist, but they have been standardized
and vetted:

https://www.nist.gov/news-events/news/2024/08/nist-releases-first-3-finalized-post-quantum-encryption-standards

So I think it's only a matter of time before we see upgrades to
cryptocurrency protocols to support keys based on these algorithms, which
are invulnerable to quantum attacks.

Jason

On Mon, Nov 17, 2025, 9:49 AM John Clark via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

>
> On Sun, Nov 16, 2025 at 9:07 AM Adrian Tymes via extropy-chat <
> extropy-chat at lists.extropy.org> wrote:
>
> *> Even if all of this is true, wait until that computer actually comes
>> out.  This isn't Roko's Basilisk; this computer can't affect things before
>> it exists. *
>
>
> *Actually it can. There will come a time when quantum computers have made
> a lot of progress very rapidly but they're still not big enough to run
> Shor’s algorithm; however, an increasingly large number of people realize
> that they soon will be, and then there's going to be a wave of panic
> selling. Sure you could theoretically make a lot of money if you waited to
> sell your bitcoin's until the day before the onset of the panic, but your
> timing would need to be perfect. You'd be playing Russian roulette with
> your money.*
>
> *John K Clark*
>
>
>
>
>
>
>
>> On Sun, Nov 16, 2025 at 8:14 AM John Clark via extropy-chat
>> <extropy-chat at lists.extropy.org> wrote:
>> >
>> > Quantum computer expert Scott Aaronson has always been a vocal critic
>> of the excessive hype surrounding his subject, but just a few days ago he
>> wrote this:
>> >
>> > "I now think it’s a live possibility that we’ll have a fault-tolerant
>> quantum computer running Shor’s algorithm before the next US presidential
>> election. And I say that not only because of the possibility of the next US
>> presidential election getting cancelled, or preempted by runaway
>> superintelligence!"
>> >
>> > When we have a quantum computer big enough to run Shor's algorithm,
>> bitcoin becomes worthless. Aaronson then says this:
>> >
>> > "The two biggest known application areas for QC remain (a) quantum
>> simulation and (b) the breaking of public-key cryptography, just as they
>> were thirty years ago."
>> >
>> > Quantum Computing, too much to handle
>> >
>> > John K Clark
>> >
>> >
>>
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