Jorge,

Why won't the attacker use asicboost too? (Please don't say because of patents)

We're assuming the ASIC optimization in my example is incompatible with ASICBoost. But if the new optimization were compatible with ASICBoost, you're right, the network would be in an equivalent situation whether ASICBoost was banned or not.

I want to point out again that overt ASICBoost can be used on the network today. My proposal is to bring ASICBoost usage out into the open vs hiding it. Banning ASICBoost via protocol changes is another issue completely.

Jimmy

 

On 9 Apr 2017 12:26 am, "Jimmy Song" <jaejoon@gmail.com> wrote:

Jorge,

Suppose someone figures out an ASIC optimization that's completely unrelated that gives X% speed boost over your non-ASICBoosted implementation. If you ban ASICBoost, someone with this optimization can get 51% of the network by adding N machines with their new optimization. If you allow ASICBoost and assuming this gets a 20% speed boost over non-ASICBoosted hardware, someone with this optimization would need 1.2N machines to get 51%. The network in that sense is 20% stronger against this attack in terms of cost.

Jimmy

On Sat, Apr 8, 2017 at 12:22 PM, Jorge Timón <jtimon@jtimon.cc> wrote:

To be more specific, why "being higher will secure the Bitcoin network
better against newer optimizations"?
Or, to be more clear, let's forget about future "optimizations", let's
just think of an attacker. Does asicboost being used by all miners
make the system more secure against an attacker? No, for the attacker
can use asicboost too.
What about the case when not all the miners are using asicboost? Then
the attacker can actually get an advantage by suing asicboost.

Sometimes people compare asicboost with the use of asics in general as
both providing more security for the network and users. But I don't
think this is accurate. The existence of sha256d asics makes an attack
with general purpose computing hardware (or even more specialized
architectures like gpgpu) much more expensive and unlikely. As an
alternative the attacker can spend additional resources investing in
asics himself (again, making many attacks more expensive and
unlikely).

But as far as I know, asicboost can be implemented with software
running on general purpose hardware that integrates with regular
sha256d asics. There is probably an advantage on having the asicboost
implementation "in the same box" as the sha256d, yet again the
attacker can invest in hardware with the competitive advantage from
having asicboost more intergrated with the sha256d asics too.

To reiterate, whether all miners use asicboost or only a subset of
them, I remain unconvinced that provides any additional security to
the network (to be more precise whether that makes "tx history harder
to rewrite"), even if it results on the hashrate charts looking "more
secure".

On Sat, Apr 8, 2017 at 6:27 PM, Jorge Timón <jtimon@jtimon.cc> wrote:
>
>
> On 8 Apr 2017 5:06 am, "Jimmy Song via bitcoin-dev"
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Praxeology Guy,
>
>> Why would the actual end users of Bitcoin (the long term and short term
>> owners of bitcoins) who run fully verifying nodes want to change Bitcoin
>> policy in order to make their money more vulnerable to 51% attack?
>
>
> Certainly, if only one company made use of the extra nonce space, they would
> have an advantage. But think of it this way, if some newer ASIC optimization
> comes up, would you rather have a non-ASICBoosted hash rate to defend with
> or an ASICBoosted hash rate? Certainly, the latter, being higher will secure
> the Bitcoin network better against newer optimizations.
>
>
> Why?