need nym-differentiation, perpetual motion, and FTL travel please

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Hi.  I was thinking as I stood in the lunch line talking
with  Arnaud 
that what I like about <a href=
"http://www-ugrad.cs.colorado.edu/~wilcoxb/faq/DefnOfPseudonymity">
pseudonymity </a> is the part about being free from the
threat of violence.  I _don't_ like the part about being
able to have multiple identities nearly as much.  It would
really please me if I could figure out a way to reliably
determine that Alicenym is not the same human as Bobnym
without compromising the anonymity of the human(s) behind 
Alicenym and Bobnym.  (Since if their anonymity was thus
compromisable, they would be susceptible to the threat of
violence.)


Unfortunately I can't think of a good way to have both
pseudonymity and nym-differentiation.  I think that it is
possible, however.  Can anyone suggest a mechanism?


Regards,

Bryce




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bryce@digicash.com writes:
> Unfortunately I can't think of a good way to have both
> pseudonymity and nym-differentiation.  I think that it is
> possible, however.  Can anyone suggest a mechanism?

Terminals which genetically sample their users?

Seriously, the problem, as stated, is thoroughly impossible to solve
in the real world. Anyone can pretend to be anyone in the
non-cyberspace world -- how can you stop them on the net?

.pm

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 The entity calling itself "Perry Metzger" <perry@piermont.com>
 is alleged to have written:

> bryce@digicash.com writes:
> > Unfortunately I can't think of a good way to have both
> > pseudonymity and nym-differentiation.  I think that it is
> > possible, however.  Can anyone suggest a mechanism?
> 
> Terminals which genetically sample their users?


I hate hardware solutions.  I'm a software guy.  <img alt=":-)"
src="http://www-ugrad.cs.colorado.edu/~wilcoxb/smiley.1.gif">


> Seriously, the problem, as stated, is thoroughly impossible to solve
> in the real world. Anyone can pretend to be anyone in the
> non-cyberspace world -- how can you stop them on the net?


Okay having said I couldn't think of a good way, I'll go
ahead and suggest a way.


Let's assume that it is possible to stop people from
pretending to be anyone in Real Life(tm).  (It is possible.)
Now let's collect N people and form a Dining-Cryptographers'
net.  Once the Dining-Cryptographers' net is up-and-running
let's put out a call for each of the N participants to
announce a public key which will be their nym from now on.
Assuming that you get N public keys, you can have _some_
degree of assurance that there is a one-to-one mapping
between pubkeys/nyms and humans on the DC-Net.


Voila.


It's weak and complicated, so I wouldn't call it a "good 
way", but it _is_ a way to have both pseudonymity and
nym-differentiation.



Now that I've done this part, would someone else handle the
perpetual motion, FTL travel, cold fusion and so forth?
Thanks.


Regards,

Bryce




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bryce@digicash.com writes:
> Okay having said I couldn't think of a good way, I'll go
> ahead and suggest a way.
> 
> Let's assume that it is possible to stop people from
> pretending to be anyone in Real Life(tm).  (It is possible.)

How? Identity police taking genetic samples from every person on the
planet six times a day?

Even that can't prevent me from going to a corner pay phone and
calling someone and saying I am Ignatz Ratkin.

> Now let's collect N people and form a Dining-Cryptographers'
> net.  Once the Dining-Cryptographers' net is up-and-running
> let's put out a call for each of the N participants to
> announce a public key which will be their nym from now on.
> Assuming that you get N public keys, you can have _some_
> degree of assurance that there is a one-to-one mapping
> between pubkeys/nyms and humans on the DC-Net.

And how do you catch the person who tries to send out two keys?

.pm

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 The entity calling itself "Perry Metzger"
 <perry@piermont.com> is alleged to have written:

> bryce@digicash.com writes:
> > Okay having said I couldn't think of a good way, I'll go
> > ahead and suggest a way.
> > 
> > Let's assume that it is possible to stop people from
> > pretending to be anyone in Real Life(tm).  (It is possible.)
> 
> How? Identity police taking genetic samples from every person on the
> planet six times a day?


Sure: genetic samples and biometric ID in general, collected
by identity police, by "IsAPerson" credential-distribution
organizations, and by your friends and family who hang out
with you all the time.


This prevents, for example, me from pretending to be Arnaud
Sahuguet when I'm talking to Berry Schoenmakers, since
Berry has gathered a lot of biometric information about
Arnaud and about me, such as how we look, sound and (?)
smell.


That kind of impersonation-prevention within a given set of
people is all I need to bootstrap my cool nyms-without-
doublenyms system described below.


(As an aside Berry can also differentiate Arnaud from me by
non-biometric information like the fact that Arnaud speaks
better French than I do.  On the net, however, it is easier
to pretend to speak French.)


> > Now let's collect N people and form a Dining-Cryptographers'
> > net.  Once the Dining-Cryptographers' net is up-and-running
> > let's put out a call for each of the N participants to
> > announce a public key which will be their nym from now on.
> > Assuming that you get N public keys, you can have _some_
> > degree of assurance that there is a one-to-one mapping
> > between pubkeys/nyms and humans on the DC-Net.
> 
> And how do you catch the person who tries to send out two keys?


Simple as pie, because of some of the properties of DC-Nets.
If someone sends out the wrong number of pubkeys, then
everyone will know, right?  So when that happens everyone
just reveals their shared-secret data from the DC-Net
session.  This makes everything that happened during that
session public.  The disruptor is kicked out of the nym club
and we back up a step and generate new pubkeys for
ourselves.


I'm getting rather interested in DC-Nets.  I don't suppose
anyone has gone ahead and invented a protocol for DC-Net
conversations?  It is a _really_ interesting problem,
because of the strange requirements of DC-Nets (such as
having denial-of-service prevention in the networking
layer, and the fact that it is shared-media even up at
the network layer) and because of their efficiency 
(/scaleability) problems.


Regards,

Bryce




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bryce@digicash.com writes:
> > How? Identity police taking genetic samples from every person on the
> > planet six times a day?
> 
> Sure: genetic samples and biometric ID in general, collected
> by identity police,

I doubt that will work even were it implemented. Every phone on the
planet and terminal would need to constantly do biometric analysis of
every user, and even then people could program their terminals to lie.

> > > Now let's collect N people and form a Dining-Cryptographers'
> > > net.  Once the Dining-Cryptographers' net is up-and-running
> > > let's put out a call for each of the N participants to
> > > announce a public key which will be their nym from now on.
> > > Assuming that you get N public keys, you can have _some_
> > > degree of assurance that there is a one-to-one mapping
> > > between pubkeys/nyms and humans on the DC-Net.
> > 
> > And how do you catch the person who tries to send out two keys?
> 
> Simple as pie, because of some of the properties of DC-Nets.
> If someone sends out the wrong number of pubkeys, then
> everyone will know, right?  So when that happens everyone
> just reveals their shared-secret data from the DC-Net
> session.

And if several people lie about their shared secrets?

Really, you aren't thinking nearly deviously enough.

Perry

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 The entity calling itself "Perry Metzger" <perry@piermont.com> is alleged to
 have written:
(> Bryce wrote:)

> > Simple as pie, because of some of the properties of DC-Nets.
> > If someone sends out the wrong number of pubkeys, then
> > everyone will know, right?  So when that happens everyone
> > just reveals their shared-secret data from the DC-Net
> > session.
> 
> And if several people lie about their shared secrets?


If some of your N participants are going to collude to share
their nyms then it is manifestly impossible to stop them.
But that doesn't bother me.  The purpose of this scheme is
to create N nyms for N people and be sure that each of then 
N people who wanted a nym got one.  If you are sure that 
each of the N people wanted a nym, then you can be sure you 
have a one-to-one mapping between people and nyms, but
unconditional untraceability from nyms to people.


But perhaps what you were talking about was a
denial-of-service attack on the DC-Net's network layer.
That has been addressed extensively in Chaum's original
"Dining Cryptographers" paper.  Chaum's method for dealing
with denial-of-service attacks is typically brilliant, but
even so it is an unwieldly and expensive (in terms of
computation and bandwidth) proposition.  I recommend "Dining
Cryptographers" to everyone, and I hope that someone who
reads it will come up with a better solution.


Regards,

Bryce




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This is one of the features in the forthcoming release of Comparichino, 
the worlds first java compatible internet-secure biometric device. nyms 
are generated by xoring your key fingerprint with your index 
fingerprint. 

Simon 

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