Subject: Re: [Asrg] Email Certification Path Proposal

From: "Jacqui Caren" <[email-masked]>
Date: Tue, 11 Mar 2003 08:16:04

On Tue, 11 Mar 2003 02:05:45 -0500, [email-masked] wrote:

> 2) a Verisign/X.509 model where somebody runs a central set of servers.
> Nobody is going to do one of these that scales to Internet size for free
> either (hint - what percent of domains have their own CA that can sign
> certs for their users?)

[thinking aloud] 
Hmm - If we followed a hierachical (heterachic would probably be better)
model of CA's then someone would run a secure central responsitory for
certifying CA's who would then certify the rest of the world.

The technology is not expensive or complex - and apart from security issues
(which are not too be sneezed at) the technical resource implications are
very similar to running an mid range ISP news or web server pool.

If we could find some sucker^Wkind-person who would host the initial
central CA for free and we could then find say a few dozen companies
who would offer free public CA's we could have an infrastructure in place
with little or no cost to the public.

Seriously...

Yes, the internet is very commercial these days however it should be
remembered that what we are talking about is a way to save ISP's 
significant sums of money by being able to more effectively block spam/UCE
in some manner. The projected savings should be enough to convince many
of the larger ISPs that a small investment in becoming a public CA
will result in savings beyond the original cost. After all if what we
propose does not save more than it costs why are we doing it anyway?
- at least thats the view many businesses will have to take...

In the same way that ISps block external access to news servers we will
have a number of ISps that ill want to offer CA services to thier own
customer base only. How we avoid this happening is a question I have no
answer to...

Demon internet tried the large private new pool + small slow public news
pool and this model failed for some reason - the public pool was withdrawn
after a few years with no stated reasons etc.

I suppose contracts could force CAs to remain public however we all know
force does not work... :-)

My last coment is that no matter what solution or technology is selected
we should aim for incremental implementation - "big bang" solutions
almost always fail (IMHO).

Anyway back to lurking ;-)

Jacqui

Jacqui Caren, Ingram Group Ltd. [email-masked]
ph: +44 (0) 1483 8628xx main=00 fax=01 ddi=65
http://www.ig.co.uk/ http://www.sitedirector.org/
http://www.perl.co.uk/

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From: [email-masked]
Date: Tue, 11 Mar 2003 03:50:07 -0500

> with little or no cost to the public.

And said certificates would be worth what they cost. Little to nothing.

Running a CA is easy.  Certifying that the users are who they say they
are is *HARD*.

Let's say the actual server, software, install, bandwidth, etc, costs $20K.
Let's say we've also decided to charge $5 per certificate.

Now you need an office where 4,000 people can come in and show ID to prove
they are themselves so you can create a certificate for them.

Now you have to pay for office rent and a clerical worker to do that work,
so your break-even point just went to 10K people.  Hopefully you're in a
city, so you don't have to open multiple offices all over the place...

Work out the business model for 500K certificates.  Remember to include
in the price tag the private investigator doing background checks on the
people who run the CA's to make sure they don't have any ties to spammers
or organized crime....

If you don't think the background check isn't needed, you need to think
about it some more....

Here's what happens when it isn't done right:

http://www.cert.org/advisories/CA-2001-04.html

---

From: Vernon Schryver <[email-masked]>
Date: Tue, 11 Mar 2003 08:30:51 -0700 (MST)

> From: [email-masked]

> ...
> ...

Say you do all of that.  What keeps Ralsky from hiring people off the
street to go into the office, get a certificate, and give it to Ralsky
who uses it for the next 20 spews of spam?

Authentication is not authorization.  The only thing that certs, keys,
and so forth can do is reduce genuine forgery of sender information.

If I'm right that the reason that almost all spam with what some claim
is "forged" sender information involves free mail provider domains
from a few 100 domains instead the other 50,000,000 domains is that
it is not really "forged," then all of the cert-ing in the universe
will have no effect on spam.  When you sign up for a Yahoo mailbox,
you'll simply get a cert in addition to a username and a password.

Vernon Schryver    [email-masked]
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---

From: Jack Nerad <[email-masked]>
Date: Tue, 11 Mar 2003 19:26:12 -0500

>who uses it for the next 20 spews of spam?
Trust.  Valdis mentioned the problems with a "web of trust" idea to be 
significant bootstrapping.  PKI alone doesn't do it, agreed.  But with a 
way to identify where the messages come from, it becomes possible to 
trust the sources.  With trust, all of a sudden you know which sources 
are reliable.  The ones you don't know are reliable can be dealt with as 
you wish.

I have no idea how a trust system would be implemented with email.  What 
other arguments are there against the web of trust?

>and so forth can do is reduce genuine forgery of sender information.
True. certs, keys and so forth can only reduce genuine forgery, but they 
create a unique identity that can then be trusted by the community at 
large or not.  Even a spamhaus generated fifty million unique certs, 
they still would not be trusted right off the bat.  I'm not really sure 
about the mathematics of networks of trust, but it seems reasonable to 
assume that the spamhaus could create networks of trust that were 
local.  Making the trust stick to the network at large would be much 
more difficult.

--
Jack Nerad

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From: Vernon Schryver <[email-masked]>
Date: Tue, 11 Mar 2003 19:07:16 -0700 (MST)

> From: Jack Nerad <[email-masked]>

> large or not. 

Why can't the identities "[email-masked]" or "bellsouth.net" be
trusted by the community at large today?  I think the answer is that
"[email-masked]" can be trusted, but "bellsouth.net" has too
much of the wrong kind of history.  One might also worry that a spammer
could forge "[email-masked]."

>                Even a spamhaus generated fifty million unique certs, 
> they still would not be trusted right off the bat. ...

Are you thinking of a system other than simply whitelisting senders
that you have determined to be trustworthy, not by their crypto certs,
but because they have good reputions, and with cryptography only
preventing forgery?

If that's the idea, then as has been suggested, you could tell your
correspondents to use PGP or SMIME and put their public keys on their
web pages so you could copy keys to your whitelist.  No changes in
protocols, no new headers, no new or old public key infrastructure (PKI),
or much of anything else would be needed.  At most you might want a
better user interface software such as MUAs to make signing easier
and perhaps integration of signature checking in MTAs to discard or
reject unread all unsigned mail.

This doesn't help the transition problem, unless you don't need to
receive mail from strangers not on your whitelist. 

It would be good if those who think the transition problem is
insignificant for their favorite solutions should say how the transition
for their solution differs from the transition for other solutions.
Consider:
 http://habeas.com/      started about August, 2002 or 6 months ago
 http://www.camram.org/     ditto
 http://www.bondedsender.com/  ditto judging from NetworkWorldFusion article

 1. What is your estimate for the percent of Internet mail that is
  now covered by those three solutions?  My guess is that there are
  between 2,000,000,000 and 10,000,000,000 msgs/day on the net, with
  5 Bmsg/day being as nice round number.  Do you think any of those
  solutions have reached 1,000,000 msgs/day or 0.02% in the 6 months
  they've been around?  (I don't, with the possible exception of Habeas
  and Topica, but which rumors make sound like something better forgotten.)

 2. What percent of email do they need to cover before many people
  would refuse unread any mail not covered by them and so have their
  individual spam loads reduced?  What fractions of the people with
  mailboxes in the U.S., Western Hemisphere, and the world must refuse
  all mail not covered by a solution before it affects spam in the
  mailboxes of people using them?

 3. Given how much mail they're covering after 0.5 years, how long until
   they reach necessary recipient participation?

If you have a spam solution, what are the answers to those questions
for it, and why is does its answer #3 differ from the apparent answers
for those solutions of about 1000 years?