Hi Metze/Mike:
Finally, I get the AES-based schannel working with windows 2008r2
domain now, thank you for your clue and help!
The [MS-NRPC].pdf have following incorrect and misleading information:
1. The spec (section 3.3.4.2.1 step 8) did not clearly mention how to
construct the initialization vector for data encryption.
The correct ivec to use in encrypting the data is
seqNum + encrypted(confounder)
2. When AES encryption type is negotiated, the auth signature to use is
NL_AUTH_SHA2_SIGNATURE (which confounder offset=48), as mentioned in section
2.2.1.3.3
However, one have to put the confounder at offset=24, which is
same offset as NL_AUTH_SIGNATURE.
Thanks,
Yen
-----Original Message-----
From: Stefan (metze) Metzmacher [mailto:[email protected]]
Sent: Tuesday, July 05, 2011 2:37 PM
To: Moh Yen Liew
Cc: Michael B Allen; [email protected]
Subject: Re: [cifs-protocol] [MS-NRPC] Problem encrypting data when use AES
based Netlogon SChannel
Hi,
> According to MS-NRPC pg 111, bit 17 (indicated as bit R) of negotiable
> flag is actually referring to "supports the NetrServerPasswordSet2
> functionality".
> In the packet trace that attached earlier, I had successfully negotiated the
> session key (from pkt 519-523) with the DC using unprotected RPC and
> established the SChannel.
> However, when sending the encrypted message (encrypted with AES-key derived
> from the session key) over Schannel to DC, DC responded with DCE RPC fault
> with error = 0x00000721.
>
> And, I also tried to use the initialization vector constructed using the
> last block (size=8 bytes) of the encrypted Confounder field, same error code
> returned from DC.
>
> There's no problem if only integrity is negotiated.
> So, I suppose the ivec mentioned in the MS-NRPC spec to encrypt the message
> might not correct ?
Take a look at this branch, it contains working code, at least it worked
a year ago against w2k8r2.
http://gitweb.samba.org/?p=metze/samba/wip.git;a=shortlog;h=refs/heads/master3-schannel
Maybe that helps.
metze
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