Re: holographic remailing & the scientologists (fwd)

A number of secret-sharing/splitting programs for Unix are available
at idea.sec.dsi.unimi.it/pub/crypt/code, ftp.dsi.unimi.it's new location

For instance, check idea.sec.dsi.unimi.it/pub/crypt/code/secshar.tar.gz

Ciao,
David

> Forwarded by Robert Hettinga
> 
> -----------------------------------------------------------------------
> Date: Sun, 26 May 1996 15:20:32 -0700 (PDT)
>  From: Wei Dai <weidai@eskimo.com>
>  To: "Vladimir Z. Nuri" <vznuri@netcom.com>
>  cc: cypherpunks@toad.com
>  Subject: Re: holographic remailing & the scientologists
>  MIME-Version: 1.0
>  Sender: owner-cypherpunks@toad.com
>  Precedence: bulk
> 
> 
> On Sat, 25 May 1996, Vladimir Z. Nuri wrote:
>  
>  > frankly, I think this was a great idea that we could explore
>  > some more. in a sense, it stores data "holographically" over
>  > all kinds of different people's messages. imagine a system in which
>  > the scientology documents are stored in people's signatures,
>  > and someone writes software to go and recombine the documents
>  > based on finding signatures "out there".
>  
>  This software already exists.  Take a look at Disperse/Collect at
>  http://www.eskimo.com/~weidai.  Disperse splits a file into n base64
>  encoded pieces where any k of them can be used to reconstruct the
>  original.  Collect will search through arbitrary collection of files (for
>  example the entire news spool) for these pieces and automatically
>  reconstruct everything that it finds.
>  
>  Wei Dai
>  
> 
> 
> --------------------------------------------------
> The e$ lists are brought to you by:
> 
> Take Your Business Online with Intertrader Ltd, Edinburgh, U.K.
> Visit http://www.intertrader.com or email info@intertrader.com
> 
> Making Commerce Convenient (tm) - Oki Advanced Products - Marlboro, MA
> Value-Checker(tm) smart card reader= http://www.oki.com/products/vc.html
> 
> Where people, networks and money come together: Consult Hyperion
> http://www.hyperion.co.uk                    info@hyperion.co.uk
> 
> See your name here. Be a charter sponsor for e$pam, e$, and Ne$ws!
> See http://thumper.vmeng.com/pub/rah/ or e-mail rah@shipwright.com
> for details...
> -------------------------------------------------
>

On Tue, 28 May 1996, David Vincenzetti wrote:

> A number of secret-sharing/splitting programs for Unix are available
> at idea.sec.dsi.unimi.it/pub/crypt/code, ftp.dsi.unimi.it's new location
> 
> For instance, check idea.sec.dsi.unimi.it/pub/crypt/code/secshar.tar.gz

Disperse/Collect is a information dispersal program rather than a secret
sharing program.  They are similiar have different purposes.  Here we
want to improve accessibility and reliability without regard to secrecy.
That is, for information dispersal we don't care if information about the
original file is leaked with with each share, whereas secret sharing has
to guarantee that an attacker can find out nothing about the original
secret unless he has at least k shares.

That aside, Disperse/Collect might be better suited for what Vladimir had
in mind because it was explicitly designed for broadcasting files through
Usenet.  The secret sharing programs you mention would not work well
because each share would be as big as the original secret.  (There are
secret sharing schemes with short shares, but I don't think any of those
programs implement the more efficient schemes.)

Wei Dai