[117904] in Cypherpunks
Re: request for information/virtual private network asparallel
daemon@ATHENA.MIT.EDU (Robert Lemmen)
Tue Sep 14 18:08:51 1999
Message-ID: <37DEC1CD.DFB2DDC4@cube.net>
Date: Tue, 14 Sep 1999 23:44:45 +0200
From: Robert Lemmen <robertle@cube.net>
MIME-Version: 1.0
To: holist <holist@elender.hu>
CC: "Michael J. Fromberger" <Fromberger@Clothing.Dartmouth.EDU>,
cypherpunks@toad.com
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Reply-To: Robert Lemmen <robertle@cube.net>
if you take some encrypted data, lets say N blocks of a given size, and
you need the whole bunch to decrypt it (what is given with most cyphers
working in CBC or better CBS mode), then you can devide that data among
M "nodes" giving each one a random set of O blocks. If you control
enough nodes to get all data blocks, you will be able to able to decrypt
it, but you don't need all nodes. How many nodes you need to control is
statistical (if you use the random set) and depends on M, N and O. But I
am pretty sure that you could figure out an algorithm that makes sure
that you need X, and exacly X nodes out of the M.
Or did i make a mistake??
regards
robert
holist wrote:
>
> At 10:07 1999. 09. 14. -0400, Michael J. Fromberger wrote:
> >quoth holist:
> >> I wonder if it is possible to create a virtual private network which,
> >> operating as a parallel architecture composed of its nodes, implements a
> >> database that is accessible from each of the nodes in such a way that the
> >> information contained in any one or few of the nodes does not permit
> >> reconstruction of the database and in which the database would be "doing
> >> sommersaults" all the time so that only simultaneous interception of the
> >> data content of the majority of nodes would allow the database to be
> >> reconstructed?
> >
> >It seems like you're basically describing a software RAID, where the
> >data are mirrored, but instead of mirroring literal copies, you mirror
> >shares of the data constructed using some secret-sharing scheme.
> >Would some variation of Shamir's linear-algebraic scheme work for this
> >purpose?
>
> No, while I don't pretend to be acquainted with the linear-algebraic
> scheme, I don't think mirroring is the word for what I am looking for - the
> reason is clear from your next paragraph:
>
> >Of course, you'd have the problem that if one of your nodes bit the
> >dust, you'd be screwed, but then that's the point of encryption.
>
> No, that's not the point - it would have to have graceful degradation as
> well - so that I could loose a fair-few of the nodes before the system
> breaks down. I am not a hands on programmer, the only programming
> experience I have is in programming the heads of other programmers in plain
> english - but I think in terms of a massively parallel architecture which
> implements a serial architecture such as a database with appropriate
> handling tools - given Turing's theorem, this is certainly theoretically
> possible, but I wonder if it is anywhere near implementable, or perhaps
> implemented already. The notion is basically that of developing a
> "members-only" virtual space that relies on public infrastructure but which
> is maximally robust against crackery.
>
> thanks for the response,
> holist
>
> >-M
> >
