Re: [bitcoin-dev] summarising security assumptions (re cost metrics)

From: Jeremy <jlrubin@mit•edu>
To: Eric Voskuil <eric@voskuil•org>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] summarising security assumptions (re cost metrics)
Date: Thu, 5 Nov 2015 20:56:49 -0500	[thread overview]
Message-ID: <CAD5xwhj3Ys+kFaoFAqM4e_mec--02pij72ze6NoJ6+AaQdL0tA@mail.gmail.com> (raw)
In-Reply-To: <563BE746.5030406@voskuil.org>

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I'd also like to see some more formal analysis of the notion that "$10 in
the hand of 10 people is more than $50 in the hand of two, or $100 in the
hand of one". I think this encapsulates the security assumption on why we
want decentralization at all.

This is a very critical property bitcoin exploits for being able to
transact large amounts, among other things. (Closely related is the notion
that defecting will destroy all the value...)

--
@JeremyRubin <https://twitter.com/JeremyRubin>
<https://twitter.com/JeremyRubin>

On Thu, Nov 5, 2015 at 6:33 PM, Eric Voskuil via bitcoin-dev <
bitcoin-dev@lists•linuxfoundation.org> wrote:

> On 11/05/2015 03:03 PM, Adam Back via bitcoin-dev wrote:
> > ...
> > Validators: Economically dependent full nodes are an important part of
> > Bitcoin's security model because they assure Bitcoin security by
> > enforcing consensus rules.  While full nodes do not have orphan
> > risk, we also dont want maliciously crafted blocks with pathological
> > validation cost to erode security by knocking reasonable spec full
> > nodes off the network on CPU (or bandwidth grounds).
> > ...
> > Validators vs Miner decentralisation balance:
> >
> > There is a tradeoff where we can tolerate weak miner decentralisation
> > if we can rely on good validator decentralisation or vice versa.  But
> > both being weak is risky.  Currently given mining centralisation
> > itself is weak, that makes validator decentralisation a critical
> > remaining defence - ie security depends more on validator
> > decentralisation than it would if mining decentralisation was in a
> > better shape.
>
> This side of the security model seems underappreciated, if not poorly
> understood. Weakening is not just occurring because of the proliferation
> of non-validating wallet software and centralized (web) wallets, but
> also centralized Bitcoin APIs.
>
> Over time developers tend to settle on a couple of API providers for a
> given problem. Bing and Google for search and mapping, for example. All
> applications and users of them, depending on an API service, reduce to a
> single validator. Imagine most Bitcoin applications built on the
> equivalent of Bing and Google.
>
> e
>
>
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>

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