[ExI] Sell your Bitcoins!

[John Clark]

On Fri, May 22, 2026 at 4:02 AM Kelly Anderson via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

*>Bitcoin is JUST money. Nothing special about it*


*Nothing special about bitcoin except that it needs colossal amounts of
energy to operate, and even 17 years after its introduction you still can't
actually buy anything with it except for illegal drugs and other forms of
money that you can actually use to buy stuff with.  *


* >>  in addition to quantum computers that is ANOTHER huge problem bitcoin
>> is going to need to solve in the immediate future. Today about 96% of a
>> minor's income comes from block subsidies (the award of a newly minted
>> bitcoin) and only 4% from transaction fees; but that ratio is going to need
>> to be completely inverted. And that won't be easy.*
>
>
> * > I think you're forgetting something basic here. Moore's Law
> will continue to operate.*



*If the cost of computation falls because of Moore's Law that improvement
will be available to both honest miners and 51% attackers. The ratio of
attacker hash power to honest hash power will remain the same and the
network will find a new security equilibrium at the same security level.
However things are very different if the speed up is caused by the
availability of large fault tolerant quantum computers not Moore's Law.*

*For a classical computer attacking 258 bit elliptic curve cryptography,
the one that bitcoin uses, the difficulty of breaking it grows
exponentially with the key size, O(2^n/2) , but for a quantum computer
using Shors's Factoring Algorithm the difficulty increase would only be
polynomial, O(n^3) . So it would take a conventional computer 2^128
 operations to break bitcoins elliptic encryption, and that would be
completely unfeasible. However a quantum computer running Shors's algorithm
would only need 256^3 operations, about 16 million, and that would be
trivially easy to achieve. And a quantum computer doesn't just threaten
bitcoin's elliptic encryption, if a quantum computer used Grover's Search
Algorithm it could accelerate the hash function computation used in mining,
although the acceleration would not be as dramatic as that seen in
Shors's Algorithm.*

*With a conventional computer the difficulty in breaking a hash function
like SHA-256 which bitcoin uses increases exponentially according to the
Hatch size,  with a quantum computer using Grover's Algorithm the increase
would still be exponential but the exponent would be half as much, in other
words the square root. A classical computer would require about 10^256
operations to break SHA-256, a ridiculously huge number, a quantum computer
would require  2^128 operations, still a huge  number but a much much
smaller one; but defeating 128-bit security is still computationally
infeasible. *

*So a quantum computer couldn't completely break SHA-256, but Grover's
Algorithm could allow somebody with a quantum computer to win more block
rewards than somebody without a quantum computer because bitcoin mining
isn't about breaking SHA-256, it's about finding an input that produces an
output below a certain target value. Grover's Algorithm would give somebody
the power to break existing wallet signatures and steal coins, mine blocks
at significantly faster rates than classical competitors, and instigate a
51% attack much more economically than would be possible with a classical
computer.*

 * > the last person to mine a bitcoin will have spent a lot of cycles to
> get it.*


*I don't think anybody will mine the last existing bitcoin, but somebody
might get the second to the last coin. *

*John K Clark*
...









> > But there is a problem, the cost of a 51% attack is proportional to the
> hash rate and that
> is proportional to how profitable mining is. So as block subsidies
> decline mining becomes
> less profitable and that causes the hash rate to drop and that causes
> the cost of a 51%
> attack to become economically viable and that causes one individual to
> be able to engage
> in double spending and that causes the complete destruction of any
> trust the general public
> had in bitcoin.
> >
>
> This might be an issue. I'll really have to think about this one.
>


>
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