Windows Live vs Kerberos

Anne & Lynn Wheeler lynn at
Sun Oct 7 09:00:02 EDT 2007

royend <royend at> writes:
> Can someone tell me differences between Windows Live and Kerberos?
> Is it possible for instance to sat that Windows Live uses as its basis
> the Needham-Schroeder protocol, the same way as Kerberos does?
> I believe that Kerberos is a more general protocol which is used in
> network authentication, as Windows Live is a special service for web
> sites, gathering all users at a single sign on (SSO).

how 'bout ...

for a little drift ... original kerberos was done with shared
secret/password for user authentication. once that is done,
then kerberos tickets can be passed around between a lot of
applications as a sso mechanism.

m'soft contracted with an outside corporation to do a kerberos
impelementation for windows ... making it the basis for windows
authentication. about the same time that was going on there was a
ietf/internet draft written called pk-init for kerberos. 

in the original pk-init, the registration of password was replaced with
the registration of public keys ... and in place of entering a password,
the user generated a digital signature (with their corresponding private
key). this was not a PKI implementation which requires something called
digital certificates ... which were nominally invented to provide some
trusted information about total strangers during first time
communication ... aka in the original PKI design point, a total
stranger, that is otherwise not known to the organization and/or for
which there has never been any prior contact ... can present a digital
certificate and be granted access to systems (purely based on the
information contained in the digital certificate). in that sense,
digital certificates can be considered sort of a very long lived
"tickets" ... where all the authorization information is visible/public
and targeted at being used by strangers in first time communication (the
letters of credit/introducation scenario from sailing ship days, where
relying parties had no other recourse to information for first time
interaction with total strangers)

There was then some amount of lobbying that the pk-init drift should
support both digital signature based authentication involving known
individuals (i.e. the original public key registration scenario) as well
as the PKI-scenario with digital certificates (supposedly to allow total
strangers with no prior contact and/or authorization, access to

misc. past posts mentioning kerberos and/or pk-init

in the early 80s, we were periodically involved dropping by project
athena and reviewing various projects, including kerberos. we happened
to be there a week when the original cross-domain kerberos process was
being worked out. more recently, we sat thru a vendors description of
their SAML implementation for cross-domain authentication. While the
format of SAML messages and kerberos tickets are different, the
description of the flows were identical.

corresponding kerberos wiki page

from my rfc index

and click on "Term (term->RFC#)" in the "RFCs listed by" section

and then scroll down to kerberos, i.e.

 see also authentication , generic security service , security
 5021 4757 4752 4559 4557 4556 4537 4430 4402 4121 4120 3962 3961 3244
 3129 2942 2712 2623 1964 1510 1411

clicking on the RFC numbers, brings up the corresponding summary
in the lower frame, for instance:

4757 I
 The RC4-HMAC Kerberos Encryption Types Used by Microsoft Windows,
 Brezak J., Jaganathan K., Zhu L., 2006/12/11 (18pp) (.txt=36562) (Refs
 1320, 1321, 1964, 2104, 3961, 3962, 4120, 4537)

clicking on the ".txt=nnnn" field, fetches the actual RFC

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