Subject: dissemination of public encryption certificates

From: [email-masked] (Julien Pierre)
Date: Fri, 8 Aug 2003 19:07:24 -0700

Hi,

Since this is my first posting to this mailing list, let me introduce 
myself :

I'm a software engineer in AOL / Netscape and one of my responsibilities 
for several years has been to maintain the open source Netscape Security 
Services (NSS) library, which is used in the Mozilla browsers, many 
Netscape and Sun servers, and other internal products. The NSS library 
contains an implementation of S/MIME v3.

I was wondering what thoughts you may have on the following problem :

If I have a keypair and e-mail certificate, and I want to send encrypted 
e-mail to somebody knowing his e-mail address, what's a systematic way 
to obtain the recipient's encryption certificate ?

Traditionally today, signed e-mail messages typically contain the 
signer's public encryption certificate. However that means one party 
needs to first send a signed unencrypted, e-mail message to transmit the 
public encryption certificate before both parties can exchange encrypted 
messages.

There are also ways to find recipient certificates today using corporate 
directory servers, but users must know about them and manually configure 
them in their applications, and they are typically not widely available 
on the Internet.

I'm envisioning some standardized scheme where, by starting with the 
recipient's email address, it would be possible to locate a public 
directory server, then find the recipient's certificate by looking it up 
in that directory server.

My main question is : has any similar scheme been proposed ? I would 
rather work with something that exists, but if there is nothing that 
fits, I'm open to writing an RFC.

Also, what are the other ways that people locate recipient S/MIME e-mail 
encryption certificates ?

Thanks.

---

From: "Blake Ramsdell" <[email-masked]>
Date: Fri, 8 Aug 2003 19:41:12 -0700

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Julien Pierre
> Sent: Friday, August 08, 2003 7:07 PM
> To: [email-masked]
> Subject: dissemination of public encryption certificates
> 

Systematic is an interesting choice of words ;).

I have seen LDAP work (if properly configured).  For the most part, the
most reliable way I've seen is for an intended recipient to send a
signed message containing their encrypting certificate (which you are
about to point out ;)).

> public encryption certificate before both parties can 

Yup.

> them in their applications, and they are typically not widely 

Yup.

> in that directory server.

I believe that at least one proposal exists for this in the PKIX working
group -- look at the operational protocols for certificate store access.

> fits, I'm open to writing an RFC.

Check out PKIX.  They're not taking new drafts, but there may be
something useful for you there.  Any work along these lines would most
likely be handled by that working group.

Blake

---

From: "Alberto Cozer" <[email-masked]>
Date: Tue, 12 Aug 2003 18:19:00 -0300

Julien,

I have seen this idea in the past, but so far no RFC nor any agency 
officialy documented it. We should have an hierarchical structure for 
public directories, similar to the DNS hierarchy. Maybe the DNS hierarchy 
itself could be used for that. We could have a new DNS record type (DRY, 
from Directory, for instance). Then, as mail servers and clients consult 
MX record to deliver a message they could check for the DRY record to 
deliver S/MIME messages. Without this DRY record set in the DNS zone file, 
must be possible to deliver a signed message but impossible to deliver an 
encrypted one. 

In my oppinion it is really hard to solve the public keys problem without 
changing the way people send e-mails. With minor changes in the DNS and 
E-MAIL RFC's would be possible to have people sending and receiving 
encrypted mail transparently in a couple of years. 

Best regards,

Alberto Cozer
Security Outsource Director, Future Technologies Digital Security
IBM Certified AIX System Specialist
Checkpoint Certified Security Expert, CCSE NG
[email-masked]
http://www.fti.com.br
Tel / Fax: 55 (21) 2522-5362

[email-masked] (Julien Pierre)
Sent by: [email-masked]
08/08/2003 23:07
 
        To:     [email-masked]
        cc: 

Hi,

Thanks.

---

From: Simon Josefsson <[email-masked]>
Date: Tue, 12 Aug 2003 13:26:15 +0200

Julien, Alberto,

There is a DNS RR for X.509 certificates (and CRLs), see RFC 2538.

Unfortunately it doesn't include useful RR owner name guidelines to
make it work in practice.  I have made some clarifications for this in

http://josefsson.org/draft-josefsson-pkix-dns.txt

which also includes recommended owner names for S/MIME certificates.

The document has expired on the IETF servers, but if there is interest
in picking up this, let me know.

(The idea has been implemented in experimental environments.  Similar
solutions for OpenPGP are freely available.  I did my master's thesis
on distributing certificate via DNS, to allow for "opportunistic email
encryption".)

Regards,
Simon

---

From: [email-masked] (Julien Pierre)
Date: Wed, 13 Aug 2003 15:51:44 -0700

Blake,

Sorry for the long delay in response - workload goes in spikes...

 > likely be handled by that working group.

Thanks. I joined the PKIX list and will keep an eye on the related drafts.

-- 
I am the dog in dogfood

---

From: [email-masked] (Julien Pierre)
Date: Wed, 13 Aug 2003 16:23:47 -0700

Simon,

 > which also includes recommended owner names for S/MIME certificates.

Thanks. This is very useful and I will look into it.

-- 
I am the dog in dogfood