RE: Keyservers and Spam

2003-06-15 Thread David Honig
At 03:41 PM 6/13/03 -0700, Bill Frantz wrote:

The HighFire project at Cryptorights
http://www.cryptorights.org/research/highfire/ is planning on building a
web of trust rooted in the NGOs who will be using the system.  Each NGO
will have a signing key.  A NGO will sign the keys of the people working
for it.  In this manner, we have way of saying, The John Jones who works
for Amnesty International.  A NGO may decide to sign another NGO's signing
key.  Now we have a way to say to someone in Amnesty, Send a message to
Steve Smith in Médecins Sans Frontières.  The plan is to show the trust
relationship in the UI as a path of keys.

I would appreciate your comments.

Threat model: NGO_Alice is compromised and signs GESTAPO key, leading
to NGO_Bob's demise.

Possible counters: 

NGO_Alice's NGO key is a split key, so 1 person needs
be rubber hosed.  I don't know if PGP supports this, I don't think so.

Short key expirations, in the limit trusted for just 1 day.  Already
possible, just document this.



Also, how do you counter the GESTAPO from seeing queries to the 
key servers?   It might be enough to jail anyone making such an
inquiry.  Possible solutions would include having the keyserver
perform some innocuous function, and use SSL for all connections
to it.  Also SSL proxying and stego of course.









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RE: Keyservers and Spam

2003-06-13 Thread Pat Farrell
At 11:56 AM 6/13/2003 -0400, John Kelsey wrote:
At 10:27 AM 6/11/03 -0700, bear wrote:
That is the theory.  In practice, as long as the PGP web of trust
The thing that strikes me is that the PGP web of trust idea is appropriate 
for very close-knit communities, where reputations matter and people 
mostly know one another.  A key signed by Carl Ellison or Jon Callas 
actually means something to me, because I know those people.  But 
transitive trust is just always a slippery and unsatisfactory sort of thing--
I may have missed it, but I thought that the web-o-trust model of PGP has
generally been dismissed by the crypto community
precisely because trust is not transitive.
Similarly, the tree structured, hierarchical trust model has failed,
we currently have a one level, not very trusted model with Verisign
or Thawte or yourself at the top.
I know from discussions with some of the SPKI folks that encouraging
self defined trust trees was one of the goals.
Of course, if the size of the tree is small enough, you can just
use shared secrets.
Pat

Pat Farrell [EMAIL PROTECTED]
http://www.pfarrell.com
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RE: Keyservers and Spam

2003-06-13 Thread Bill Frantz
At 2:35 PM -0700 6/13/03, Pat Farrell wrote:
At 11:56 AM 6/13/2003 -0400, John Kelsey wrote:
At 10:27 AM 6/11/03 -0700, bear wrote:
That is the theory.  In practice, as long as the PGP web of trust

The thing that strikes me is that the PGP web of trust idea is appropriate
for very close-knit communities, where reputations matter and people
mostly know one another.  A key signed by Carl Ellison or Jon Callas
actually means something to me, because I know those people.  But
transitive trust is just always a slippery and unsatisfactory sort of thing--

I may have missed it, but I thought that the web-o-trust model of PGP has
generally been dismissed by the crypto community
precisely because trust is not transitive.

Similarly, the tree structured, hierarchical trust model has failed,
we currently have a one level, not very trusted model with Verisign
or Thawte or yourself at the top.

I know from discussions with some of the SPKI folks that encouraging
self defined trust trees was one of the goals.

Of course, if the size of the tree is small enough, you can just
use shared secrets.

The HighFire project at Cryptorights
http://www.cryptorights.org/research/highfire/ is planning on building a
web of trust rooted in the NGOs who will be using the system.  Each NGO
will have a signing key.  A NGO will sign the keys of the people working
for it.  In this manner, we have way of saying, The John Jones who works
for Amnesty International.  A NGO may decide to sign another NGO's signing
key.  Now we have a way to say to someone in Amnesty, Send a message to
Steve Smith in Médecins Sans Frontières.  The plan is to show the trust
relationship in the UI as a path of keys.

I would appreciate your comments.

Cheers - Bill


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RE: Keyservers and Spam

2003-06-13 Thread Anne Lynn Wheeler
At 11:56 AM 6/13/2003 -0400, John Kelsey wrote:
The thing that strikes me is that the PGP web of trust idea is appropriate 
for very close-knit communities, where reputations matter and people 
mostly know one another.  A key signed by Carl Ellison or Jon Callas 
actually means something to me, because I know those people.  But 
transitive trust is just always a slippery and unsatisfactory sort of 
thing--the fact that Jon Callas trusts Fred Smith trusts John Jones to 
sign a key doesn' t really tell me whether or not I should trust him--by 
the time we're about three hops away, you'd have to be God to know enough 
to have your signature mean anything.
PGP  or other similar account-based mechanisms provide trust between 
parties that have established relationship  on a purely pair-wise, 
bilaterial basis.  It does allow some direct trust operations to diffuse 
out to other parties. It isn't so much a close-knit community  it is 
how far every specific entities's trust operation diffuse out across other 
individuals.

If the entity is called a certification authority  and it provides an 
online service ... then the diffusing of specific trust operation might 
propogate out to a wide community. The issue of course is what trust 
attributes are propagating/diffusing and the diligence that the entity used 
in establishing the information to be trusted.

If the entity is called a certification authority, and it manufactures 
certificates (basically stale, static copies of some CA internal account 
record) then those certificates will presumably contains some information 
that is bound to the public key ... where there is some degree of 
confidence (aka trust) with regard to the binding between the information 
and the public key.

One issue is what meaning is there between having absolute certainty 
between something like an email address and a public key. Let's say it is 
an email address. Typically, email addresses at random are meaningless to 
me unless they are part of some specific context  like somebody I have 
an established relationship with. However, if I have an established 
relationship with the entity, then it is back to the PGP scenario.  In a 
broad context, businesses run on established relationships; aka financial 
institutions.  The whole existing payment infrastructure effectively has 
the PGP scenario without needing certificates, and not exactly being 
considered a very close-knit community.

The primary difference between a financial institution actiing as an entity 
in a PGP web-of-trust paradigm (say payment cards, credit, debit, etc) and 
individual  is the typical scope of the reputation of the financial 
institution is larger than an individual, and therefor the 
propagation/diffusing of trust is likely to have a much further reach. To a 
larger degree ... the trust radius of an entity is somewhat independent of 
whether it is operating in the PGP manner w/o certificates or in 
certificate paradigm.

The primary difference in the certificate paradigm is not the scope of the 
entity's trust  it is the design point of delivering the trust. The 
certificate paradigm of trust delivery was targeted at an offline 
environment for relying parties that had no previous relationship (and had 
no online and/or direct recourse to the trust entity.

The payment card industry established a certificateless nearly world-wide 
scope of trust, in part by providing an extensive online network.

The certificate-based design point was to be able to provide an 
infrastructure for propogating trust between relying parties that had no 
previous relationship, were unlikely to need future relationship, and had 
no online or direct recourse to the trust enttity.
--
Anne  Lynn Wheelerhttp://www.garlic.com/~lynn/
Internet trivia 20th anv http://www.garlic.com/~lynn/rfcietff.htm
 

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RE: Keyservers and Spam

2003-06-12 Thread David Honig
At 05:47 PM 6/11/03 -0700, Bill Frantz wrote:
To try to reflect some of David's points with a real-world situation.  I
was at work, with a brand new installation of PGP.  I wanted to send some
confidential data home so I could work with it.  However I didn't have my
home key at work, so I didn't have a secure way to send either the data, or
the work key.  I didn't even have the fingerprint of the home key.

My solution was to pull Carl Ellison's business card out of my pocket.  It
had his key fingerprint on it, and I remember getting it directly from him,
so I could trust the fingerprint.  Now Carl had signed my key, so when I
downloaded it from the key server, I could verify that it was indeed mine
(to the extent I trusted Carl).  Carl's signature, and the key server
allowed me to bootstrap trust into my own key.


But with a key server, I didn't have to bother Carl to send me my key.  Or
depend on him being online when I needed it.

True, although: 
1. you could have had your own key-fingerprint on your own bizcard
and done the same.  

2. you needn't have had your valid email address there (going back
to the spam-thread), perhaps just your regular name.  In fact you
could have your key on your home server, not in a public 
server which serves as spambait.  Your home server could be
unlisted by using an alternate port.  (I do this to get around
ISP blocking, but then I'm not trying to publish papers on my
home server.)  Or use CGI, or a password mechanism, to deter spam-spiders.

The point with spam and publishing your email address
is that its like having a public
physical storefront: anyone can pay the price of a cigarette 
to a stream of homeless people to
clog your physical store.  Or form a huge line if you have bouncers
at the door.  That's what having a public interface means.

3. I think you also trusted that Carl has not been compromised
and re-signed a bogus key *after* he first signed it.  (Not picking
on Carl here :-)





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RE: Keyservers and Spam

2003-06-11 Thread Bill Frantz
To try to reflect some of David's points with a real-world situation.  I
was at work, with a brand new installation of PGP.  I wanted to send some
confidential data home so I could work with it.  However I didn't have my
home key at work, so I didn't have a secure way to send either the data, or
the work key.  I didn't even have the fingerprint of the home key.

My solution was to pull Carl Ellison's business card out of my pocket.  It
had his key fingerprint on it, and I remember getting it directly from him,
so I could trust the fingerprint.  Now Carl had signed my key, so when I
downloaded it from the key server, I could verify that it was indeed mine
(to the extent I trusted Carl).  Carl's signature, and the key server
allowed me to bootstrap trust into my own key.

At 3:53 PM -0700 6/10/03, David Honig wrote:
At 04:54 PM 6/10/03 +0100, [EMAIL PROTECTED] wrote:
I don't know you.  Why should I trust your signing of someone else's key?

If I know a mutual aquaintence, no need for web of trust.
...
If we allow this, then the entire web-of-trust disintegrates.

There *is no web of trust* unless you know the signers.  In which
case you may as well have them forward keys manually.

But with a key server, I didn't have to bother Carl to send me my key.  Or
depend on him being online when I needed it.

Cheers - Bill


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[EMAIL PROTECTED] | American way.  | Los Gatos, CA 95032, USA



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RE: Keyservers and Spam

2003-06-10 Thread David Honig
At 12:43 PM 6/10/03 -0400, Jeffrey Kay wrote:
number (which I now use Call Intercept to avoid telephone solicitors).

But for privacy reasons, some folks will not automatically forward
their phone number.  You either deny them access or require them 
to jump through extra hoops (redial w/ special control codes 
that send their ID).  Analogy w/ email  PGP left as an exercise..







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