[Cryptography] Fun and games with international transaction settlement (was Re: IBM looking at adopting bitcoin technology for major currencies)

Ben Laurie ben at links.org
Wed Apr 15 22:15:23 EDT 2015

On 14 April 2015 at 21:58, Ray Dillinger <bear at sonic.net> wrote:

> On 04/14/2015 08:50 AM, Ben Laurie wrote:
> > On 14 March 2015 at 20:18, Robert Hettinga <hettinga at gmail.com> wrote:
> >
> >> Bitcoin, which amounts to registered unforgeable certificates with a
> >> distributed, and also unforgeable, certificate registry.
> >
> >
> > It really doesn't. 51% (more properly, 34%) attacks show that it doesn't.
> How does the 34% attack work, exactly?

I'm on holiday on an astonishingly crap 'net connection so I can't find it
for you, but the relevant paper is referenced in Bonneau et al's excellent
survey paper on Bitcoin, which I'm sure you can find.

> > If it were done properly, i.e. with verifiable append only logs run by a
> > known set of entities, then it would. It would also be many orders of
> > magnitude cheaper. Stupidly cheap, in fact, instead of eye-wateringly
> > expensive.
> The problem is figuring out what known set of entities in a way
> that diverse people can trust and are satisfied with.  So far
> every attempt at digital cash which relied on a central authority
> or central registrar or verifier or someone running a server at a
> particular network location etc, has failed - some due to lack of
> trust in that entity, some due to lack of trustworthiness or
> reliability by that entity, and  some for other reasons.

We haven't seen any other kind of attempt (and don't claim
Bitcoin-as-implemented is, because it isn't - and seems likely to fail in
any case). Note, BTW, that 51/34% attacks work on
Bitcoin-as-originally-envisaged, not Bitcoin-as-implemented (because of the
central authority that prevents forks).

> In an era where an actor responding to a lawful order under
> threat of imprisonment is indistinguishable from an actor
> performing a breach of trust, there is no authority or group
> whom the people interested in cryptocurrencies trust enough
> to allow that authority, or that set of authorities, a
> privileged or pivotal role with respect to securing their
> assets.

Weird that they allow exactly that, then.

> The fact that demands for private information, which demands
> may or may not be legal in the first place, now come with gag
> orders to prevent anyone from talking about getting such a
> demand on threat of prosecution, undermines everyone's ability
> to trust *ANYBODY* *EVER*.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20150416/b94cc840/attachment.html>

More information about the cryptography mailing list