Subject: Re: Certificate / CPS issues

From: Graham Klyne <[email-masked]>
Date: Fri, 06 Jun 2003 11:50:13 +0100

At 12:12 05/06/03 -0700, Hallam-Baker, Phillip wrote:
>A spam sender could attempt to use disposable certificates in the same way
>that IP addresses and dialup accounts are considered disposable. This is
>unlikely to work for long, the spam sender can set up lots of shell
>companies at the same address but if the CA keeps authenticating to the same
>address or phone number the pattern will soon become apparent.

Hmmm... is there an economic play here?

<background>
First, briefly, my view of the spam situation.  I don't think it's 
fundamentally an Internet protocol design issue (though some design tweaks 
may help).  Essentially, I think people currently have the choice of
(1) putting filters in place and accept the loss of some non-spam mail, or
(2) accepting a deluge of spam, and not lose any mail.  In practice, I 
think this option doesn't exist, because I find that (lacking spam filters) 
I do lose a few pieces of non-spam mail because I don't recognize the 
sender or subject.  So I see a way forward to be a "passport" mechanism to 
reliably bypass automated spam filters, a kind of whitelist++.
</background>

So back to my question: is there an economic play here?

(I was offered the opinion once that a big *disadvantage* of email compared 
with fax for business transactions was that it has almost zero incremental 
cost of use.)

I'm thinking of a cert issued for a small sum of money, without any 
authentication other than the purchaser promises something like "I promise 
not to spam with this certificate".  At the earliest evidence of it being 
used for spamming, it is revoked.  The price should be small enough to be 
accessible to any reasonable person, but high enough that the bill for 
daily or hourly renewal would become significant.

Maybe crazy, just thinking aloud...

#g

-------------------
Graham Klyne
<[email-masked]>
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E

---

From: Einar Stefferud <[email-masked]>
Date: Fri, 6 Jun 2003 12:40:18 -0700

OK, so what happens when someone else uses my address, perhaps using 
my passport, captured from some mail sent by me to someone? 

I think the term of art is "being Joe Jobbed".

Every now and then,  I get a bounced report that claims something I sent 
is being returned, but it was not sent by me.  This "something" is most 
often spam sent to someone else.  Sometimes it contains a virus.
Apparently this  is a trick to get me to open it.

Anyway, I think your Passport Scheme needs some more work.

Cheers...\Stef

At 11:50 +0100 6/6/03, Graham Klyne wrote:
>First, briefly, my view of the spam situation.  I don't think it's fundamentally an Internet protocol design issue (though some design tweaks may help).  Essentially, I think people currently have the choice of
>(2) accepting a deluge of spam, and not lose any mail.  In practice, I think this option doesn't exist, because I find that (lacking spam filters) I do lose a few pieces of non-spam mail because I don't recognize the sender or subject.  So I see a way forward to be a "passport" mechanism to reliably bypass automated spam filters, a kind of whitelist++.
></background>
>
>(I was offered the opinion once that a big *disadvantage* of email compared with fax for business transactions was that it has almost zero incremental cost of use.)
>
>I'm thinking of a cert issued for a small sum of money, without any authentication other than the purchaser promises something like "I promise not to spam with this certificate".  At the earliest evidence of it being used for spamming, it is revoked.  The price should be small enough to be accessible to any reasonable person, but high enough that the bill for daily or hourly renewal would become significant.
>

---

From: Graham Klyne <[email-masked]>
Date: Fri, 06 Jun 2003 22:02:34 +0100

>Apparently this  is a trick to get me to open it.

I see a couple of differences:  re-using someone's email address is easy 
... I've had a flurry of 'bounces' recently for messages I certainly did 
not send.  But the information to send those (deceitful) messages is very 
easily obtained.

By putting some of the information behind a cryptrographic screen, it 
becomes harder for others to casually use it.

And if security is compromised, then the cert gets revoked and the genuine 
owner has to buy another one.  Hey, don't we occasionally lose theatre 
tickets?  Tough, but not disastrous -- we just have to buy another one.

>Anyway, I think your Passport Scheme needs some more work.

I'm sure it does!

#g
--

> fundamentally an Internet protocol design issue (though some design 
> tweaks may help).  Essentially, I think people currently have the choice of
> think this option doesn't exist, because I find that (lacking spam 
> filters) I do lose a few pieces of non-spam mail because I don't 
> recognize the sender or subject.  So I see a way forward to be a 
> "passport" mechanism to reliably bypass automated spam filters, a kind of 
> whitelist++.
> ></background>
> >
> >(I was offered the opinion once that a big *disadvantage* of email 
> compared with fax for business transactions was that it has almost zero 
> incremental cost of use.)
> >
> authentication other than the purchaser promises something like "I 
> promise not to spam with this certificate".  At the earliest evidence of 
> it being used for spamming, it is revoked.  The price should be small 
> enough to be accessible to any reasonable person, but high enough that 
> the bill for daily or hourly renewal would become significant.
> >

-------------------
Graham Klyne
<[email-masked]>

---

From: "Haren Visavadia" <[email-masked]>
Date: Sat, 7 Jun 2003 08:30:34 +0100

> Apparently this  is a trick to get me to open it.

The CA holds no warranty, making the certificate invalid in legal terms,
since they can not prove the certificate is yours.

---

From: [email-masked]
Date: Sat, 07 Jun 2003 19:34:21 -0400

> since they can not prove the certificate is yours.

IANAL, but you better check with a lawyer on that one.  Depending where you
live, a digital signature *could* be binding even if it's invalid... Yes,
there's some broken legislation out there...

Also, remember that a signature merely proves the signed data and the
public key were accessible to a computational device at the same time.
This is a LONG stretch from actually meaning you signed it intentionally.
See Schneier's "Secrets and Lies", there's a whole chapter on this point,
or just wait till somebody you know gets nailed with the next Sobig/Nimda/Klez
or whatever, and ask if any of the mail they sent out was intentional. ;)

---

From: "Haren Visavadia" <[email-masked]>
Date: Sun, 8 Jun 2003 11:11:28 +0100

>or whatever, and ask if any of the mail they sent out was intentional.
;)

You are telling if someone else was given a certificate in my name and
signed a virus code and distributed it. I would go to jail for it
because it was signed in my name.

I would challenge the law altogether and fill in a complaint against the
government for this.

---

From: "Haren Visavadia" <[email-masked]>
Date: Sun, 8 Jun 2003 11:34:20 +0100

> a digital signature *could* be binding even if it's invalid

If it is legal binding, when if the CA signs my certificate would also
be a legal blinding act? Since a certificate is a document that has a
digital signature.

False certification would make CA in trouble regardless of their
disclaimer.

---

From: [email-masked]
Date: Sun, 08 Jun 2003 19:27:03 -0400

> because it was signed in my name.

Check with a lawyer - and note that the spammers are *already* using things
like Jeem trojans to relay their spam.  If they've got that much of a
foothold on your machine, adding code to sign the spam with your private key
is pretty trivial, really....

> I would challenge the law altogether and fill in a complaint against the

There are any number of good political activism groups that will assist you
with that....

---

From: [email-masked]
Date: Sun, 08 Jun 2003 19:37:11 -0400

> False certification would make CA in trouble regardless of their

Verisign found that out the hard way with the bogus Microsoft certificate.

The *bigger* problem is that a very high percentage of the private keys out
there are probably stored on one particular series of operating systems that
are well known for their security flaws - and as such, attacking said machines
with malware designed to harvest keys is a high-profit attack.