[Cryptography] blockchain and trustworthy computing

[Lodewijk andré de la porte]

2015-10-01 5:22 GMT+02:00 ianG <iang at iang.org>:

> In practical terms, if I run a personal blockchain on my laptop, home
> computer, TV, android tablet, iPhone, and xWatch, have I created a
> trustworthy computing platform?  In the process, has the
> hardware-I-Don't-Trust conundrum been solved?
>

You have a platform that's as fast as it's slowest component, a power
consumption of the sum of it's components. It's trustworthiness is the sum
of half the network - if over half the nodes say such is so it is accepted
globally.

Since these processors are all from either of the two foundries, well, draw
your own conclusions.

Note that there's little rationale for a blockchain here. You need
replicated work across devices. That means: being able to input a program
to every node without corruption (signed source) and being able to
checkpoint - hash the used memory. If all the hashes are equal you're good.
If they do not all line up - well it's probably your non-ecc xWatch/tablet
goofing up.


> Or, for a more hypothetical example, if I have an EPA-tester running on
> the blockchain calculating in turn over the various cars that are providing
> the nodes, does this solve the VW problem?
>

We are supposed to be doing this with academic papers. Reproduce the result
at another university that's as different as possible (different sponsors,
affiliations, religions, researchers, nations, etc), and the
trustworthiness increases. Thing is - the VW cars fooled the procedure.
Replication does not make a difference. The procedure was faulty.

Making a trustworthier platform by replicating work across many machines
seems doable. Using homomorphic encryption or some other means of
obfuscating the computation one could probably fool whatever attacks are
present in silicon.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20151006/8abba641/attachment.html>