[bitcoin-dev] hashcash-newhash

[Karl]

Hi ZmnSCPxj,

Thanks for your reply.  I'm on mobile so please excuse me for top-posting.

I'd like to sort these various points out.  Maybe we won't finish the whole
discussion, but maybe at least we can update wiki articles like
https://en.bitcoin.it/wiki/Hashcash#Cryptanalytic_Risks with more points or
a link to conversations like this.

Everything is possible but some things take a lot of work.

You mention ASICs becoming commoditized.  I'd remind you that eventually
there will be a public mathematical breaking of the algorithm, at which
point all ASICs will become obsolete regardless.  Would you agree it would
be better to prepare for this by planning algorithm change?

You mention many coordinated hardforks.  Would you agree that if we came up
with a way of programmatically cycling the algorithm, that only one
hardfork work be needed?  For example one could ask nodes to consent to new
algorithm code written in a simple scripting language, and reject old ones
slowly enough to provide for new research.

You mention the cost of power as the major factor influencing decentralized
mining.  Would you agree that access to hardware that can do the mining is
an equally large factor?  Even without ASICs you would need the physical
cycles.  Including this factor helps us discuss the same set of expected
situations.

You describe improving electricity availability in expensive areas as a way
to improve decentralization.  Honestly this sounds out of place to me and
I'm sorry if I've upset you by rehashing this old topic.  I believe this
list is for discussing the design of software, not international energy
infrastructure: what is the relation?  There is a lot of power to influence
behavior here but I thought the tools present are software design.

On Sat, May 23, 2020, 9:12 PM ZmnSCPxj <ZmnSCPxj at protonmail.com> wrote:

> Good morning Karl,
>
> > Hi,
> >
> > I'd like to revisit the discussion of the digest algorithm used in
> hashcash.
> >
> > I believe migrating to new hashing algorithms as a policy would
> significantly increase decentralization and hence security.
>
> Why do you believe so?
>
> My understanding is that there are effectively two strategies for ensuring
> decentralization based on hash algorithm:
>
> * Keep changing the hash algorithm to prevent development of ASICs and
> ensure commodity generic computation devices (GPUs) are the only practical
> target.
> * Do not change the algorithm, to ensure that knowledge of how best to
> implement an ASIC for the algorithm becomes spread out (through corporate
> espionage, ASIC reverse-engineering, patent expiry, and sheer engineering
> effort) and ASICs for the algorithm are as commoditized as GPUs.
>
> The former strategy has the following practical disadvantages:
>
> * Developing new hash algorithms is not cheap.
>   The changes to the hashcash algorithm may need to occur faster than the
> speed at which we can practically develop new, cryptographically-secure
> hash algorithms.
> * It requires coordinated hardforks over the entire network at an
> alarmingly high rate.
> * It arguably puts too much power to the developers of the code.
>
> On the other hand, the latter strategy requires us only to survive an
> intermediate period where ASICs are developed, but not yet commoditized;
> and during this intermediate period, the centralization pressure of ASICs
> might not be more powerful than other centralization pressures
>
> --
>
> Which brings us to another point.
>
> Non-ASIC-resistance is, by my understanding, a non-issue.
>
> Regardless of whether the most efficient available computing substrate for
> the hashcash algorithm is CPU, GPU, or ASIC, ultimately miner earnings are
> determined by cost of power supply.
>
> Even if you imagine that changing the hashcash algorithm would make CPUs
> practical again, you will still not run it on the CPU of a mobile, because
> a mobile runs on battery, and charging a battery takes more power than what
> you can extract from the battery afterwards, because thermodynamics.
>
> Similarly, geographic locations with significant costs of electrical power
> will still not be practical places to start a mine, regardless if the mine
> is composed of commodity server racks, commodity video cards, or commodity
> ASICs.
>
> If you want to solve the issue of miner centralization, the real solution
> is improving the efficiency of energy transfer to increase the areas where
> cheap energy is available, not stopgap change-the-algorithm-every-6-months.
>
>
> Regards,
> ZmnSCPxj
>
>
> >
> > I believe the impact on existing miners could be made pleasant by
> gradually moving the block reward from the previous hash to the next (such
> that both are accepted with different rewards).  An appropriate rate could
> possibly be calculated from the difficulty.
> >
> > You could develop the frequency of introduction of new hashes such that
> once present-day ASICs are effectively obsolete anyway due to competition,
> new ones do not have time to develop.
> >
> > I'm interested in hearing thoughts and concerns.
> >
> > Karl Semich
>
>
>
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