Subject: Short Summary - KRB-WG London meeting

From: "Douglas E. Engert" <[email-masked]>
Date: Thu, 09 Aug 2001 08:23:37 -0500

[Comments from the attendees as to the correctness of these minutes are
    welcome. But PEASE do NOT respond to this note with comments as to the merit 
    of any of these statements, till after I get the official minutes out. But feel 
    free to discuss the merits as seperate threads. i.e. Don't respond
    to this note unless you where an attendee, and are comenting on the correctness
    of the minutes.]
 
The fourth meeting of the Kerberos WG was held 8/8/2001 in London, with about 45
attendees. Since the last meeting we have had two WG last calls, on the Password 
change protocol and IAKERB. The Password change draft has been sent to the IESG.
The IAKERB will be shortly. 

The bulk of the meeting was concerned with the Kerberos Revisions. 

Cliff Neuman described a number of changes most of which where suggested at the 
last meeting. Compatibility with existing implementations, and reuse of code
was highly desirable. A list of how the client, server and KDC could know if 
it was OK to use the new format was listed.   

Ken talked on Section 6, the encryption framework. There was consensus that the
list of required encryption types will be listed in an appendix. What that list is 
is still undecided, as timing is an issue as a strong method is required, all agree 
the if AES if available it should be required, but if AES is not available then
either 3des or rc4. There are two camps on which should be required.  

Tom talked on Section 5, messages. A new approach for compatibility is now included
which uses new Application Tags for new format messages, which are the same as old
format messages, but have additional fields, or optional fields thus allowing the 
same parser to pares both old and new format messages. 

Sam talked on some of the other new features which will be included. These include 
ticket extensions, and a way of using a new address type to avoid the problems 
with addresses introduced by NAT and VPNs.     

Jeff discussed authenticated error messages, and there was consensus that if possible
messages should be authenticated, as long as this does not help expose the users key,
as described below in the AS_REP concerns. 

The main unresolved issue is the (mis)use of GeneralString and UTF8. All agreed that 
this has to be addressed at some time. Harald Alvestrand [email-masked] gave us the 
IESG's view on internationalization. (The next day we also meet with Patrik Faltstrom 
[email-masked] Application's Area director who went into greater detail on the problems 
dealing with internationalization. He is willing to work with us on this. It also looks 
like we have a migration path for this, allowing us to state in the revisions the use 
of GeneralString really only applies to ASCII, and that we are working on a solution.) 
So it might be possible to have this as a separate draft, and to proceed with the 
revisions with a warning about the misuse of GeneralString for other then ASCII. 

So it looks like the Revisions are finally starting to fall into place. There was also 
consensus that if there are older sections of RFC 1510 such as DES, we could reference
RFC 1510, rather then rewriting in new revisions.  

John presented some concerns with the security of the AP_REP. An attack might be possible
if enough separate responses could be collected. Possible solutions include SSL,
SRP, EKE, or PDM.       

John then described the revised referral informational draft. There are still issues
with cache efficiency, GSSAPI canonicalization, (John will try and talk to Martin),
and the use of the KRB_ERR.  

Ken described the AES draft, and there was consensus that the 192 could be dropped
but keep 128 and 256. There are still issues with the string-to-key functions. 

Brian has a new version of the PKINIT which addresses some concerns. 

Matt described a new draft which allows a user to use unmodified telnet
along with a hardware token to have a modified telnetd obtain a ticket
for the user without exposing the Kerberos password.    

[Comments from the attendees as to the correctness of these minutes are
welcome. But please do not respond to this note with comments as to the merit 
of any of these comments, till after I get the official minutes out. But feel 
free to discuss the merits, but do NOT use this thread. I.e. Don't respond
to this note unless you where an attendee.]

-- 

 Douglas E. Engert  <[email-masked]>
 Argonne National Laboratory
 9700 South Cass Avenue
 Argonne, Illinois  60439 
 (630) 252-5444