[cifs-protocol] RE: Regarding [MS-KILE] Three-Leg DCE-Style Mutual Authentication

Andrew Bartlett abartlet at samba.org
Wed Aug 20 00:25:18 GMT 2008

On Fri, 2008-08-08 at 11:07 -0700, John Dunning wrote:
> Hello Andrew,
>    I've received feedback from the Product team and they are
> requesting additional clarification. To start with I would like to
> insure we understand the issue.
> We understand the problem to be the following, please let me know if
> this is not correct.
> The behavior SAMBA is seeing is Client authenticates to Server using
> KILE and the following occurs:
> 1. Client sends RFC std AP_REQ to server
> 2. Server sends RFC std AP_REP to client
>    in this message the sequence number is n
> 3. Client sends AP_Rep to server
>    in this message the sequence number is n in XP and n+1 in Vista
> only when AES is used
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> Please clarify what GSSAPI you are using. From the Product team's
> investigation they don't see a difference in behavior with AES. They
> are also requesting possible repro steps and Kerberos logs.
> Please let me know if you have any questions regarding this
> information request.

The issue is that AES triggers the new SPNEGO, which requires that an
additional GetMIC call is made over the mechanism list that the client
sends the server in SPEGNO.

Windows 2008 and Vista introduce the new SPENGO.  The challenge is that
because AES is negotiated, checking the signature on that SPENGO blob
becomes mandatory.

Andrew Bartlett

Andrew Bartlett
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Red Hat Inc.
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