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bluesky - dealing with the lack of ecash (Re: User Anonymity)

bluesky AT lists.ibiblio.org

Subject: Global-Scale Distributed Storage Systems

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  • From: Adam Back <adam AT cypherspace.org>
  • To: weidai AT eskimo.com
  • Cc: bluesky AT franklin.oit.unc.edu
  • Subject: dealing with the lack of ecash (Re: User Anonymity)
  • Date: Fri, 16 Feb 2001 00:57:37 -0500



Man this is a nice list, discussions on my favorite topic, cool
people, active discussion etc. Like cypherpunks from maybe 5 or more
years ago. Some of the same people too. I'd like to thank Ted and
Wei for taking the initiative. There was for a brief time some
interesting discussion on eternity list about USENET eternity and
Anderson's eternity, and distributed file systems in general, but it
died out after a while.

Wei writes:
> I think censorship resistance will ultimately depend on market
> mechanisms. Suppose each storage server charges money to deliver
> requested data. As a data object is supressed and becomes rarer, its
> price goes up and more servers will enter the market to serve
> it. What the equlibrium price turns out to be depends on what
> penalties the servers face and the probability of getting caught.

Economic pressures with real money do help a lot of problems, because
arguments like "so use the profits to buy more bandwidth" or "put your
price up because demand is too high" are robust answers to DoS and
resource allocation.

I discussed a bit in the past the idea of using hashcash (or perhaps
Wei's b-money, though that I think is a little harder to deploy) as a
substitute for cash as no one seems able to deploy ecash.

I also proposed a kind of amortizable hashcash for distributed file
systems specifically. The idea is basically that you use hashcash,
except that each server keeps and generally forwards around the
largest collision it has seen for each file it serves. The collision
is computed on the filename. (Hashcash will give you a collision
longer than you asked for 50% of the time). The "amortization"
function for these tokens is just max(x,y), so it's a very crude
estimate.

There were a few other tricks like protecting against overspending
where someone would try to artificially inflate the value of the
collision by computing larger collisions in a light-weight security
setting presuming you trust servers a little more than users.

Anyway the amortizable hashcash idea was to have a lightweight
security distributed document popularity metering system which might
be one way to arbitrate which documents deserve to be mirrored, which
could combat or add resistance against some of the DoS attacks you
tend to be able to do against systems that allow free publishing.

Also hashcash is kind of pointing out that there is actually some
network currency: CPU power, and bandwidth. (Bandwidth is involved
because the inference is that in paying with a hashcash token a client
has consumed both CPU and network bandwidth to download the content).

So while it's not exactly paying because you're just proving what
resources you've consumed, so the recipient can't use it directly, he
may be able to use it indirectly if he also obtains hashcash voting
that his server is a contributor of bandwidth. And so you have this
kind of closed system where people are having to contribute to
participate a bit like MojoNation's payment system. Perhaps even
you'd end up with after markets trading unused server reptuation
tokens to allow access. With paypal and other peer-to-peer (not
anonymous, but fairly unstoppable and anyway indirect) payment systems
after markets are now easier than they were in the days of the
DigiCash beta-bucks trial.

Adam

Personal comments, of course.



  • dealing with the lack of ecash (Re: User Anonymity), Adam Back, 02/16/2001

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