Metze,
The SharedSecret used for AES session key computation, as described in
3.1.4.3 MS-NRPC , should be the NTOWF (MD4(UNICODE(Passwd))) of the plaintext
password. The section 3.1.1 of MS-NRPC explains what a SharedSecret is used
for session key calculation in Windows implementations. The SharedSecret is
stored in UnicodePwd AD attribute. Please see section 3.1.1 and Windows
Behavior notes <66>,<67> of MS-NRPC for details.
I will continue working on all questions related to AES encryption.
Thanks!
--------------------------------------------------------------------
Hongwei Sun - Sr. Support Escalation Engineer
DSC Protocol Team, Microsoft
[email protected]<mailto:[email protected]>
Tel: 469-7757027 x 57027
---------------------------------------------------------------------
-----Original Message-----
From: Stefan (metze) Metzmacher [mailto:[email protected]]
Sent: Tuesday, August 25, 2009 11:13 AM
To: Interoperability Documentation Help
Cc: [email protected]; [email protected]
Subject: MS-NRPC: AES Schannel problems
Hi,
I'm currently trying to implement the AES based Netlogon Secure Channel in
Samba.
But the documentation is not really clear about the used algorithms.
I have started with the implementation here:
http://gitweb.samba.org/?p=metze/samba/wip.git;a=shortlog;h=refs/heads/master4-schannel
And here's the actual commit that tries to add aes support:
http://gitweb.samba.org/?p=metze/samba/wip.git;a=commitdiff;h=50dca9ce0f051c863f00cc949db2c19bf247887b
In Section "3.1.4.3 Session-Key Computation" the hmac-sha256 base computation
of the session-key seems to use the plain SharedSecret and not the NT-HASH of
it (MD4(UNICODE(ShareSecret))), is that correct?
I thought the plain text is never stored in AD by default...
Where should the netlogon server get the plain text from?
I just tried the NT-HASH see my netlogon_creds_init_hmac_sha256() function.
In Section "3.1.4.4 Netlogon Credential Computation" there's a AesEncrypt
function used. Can you please document the exact algorithm that's used there.
You say AES128 is used in CFB mode without initialization vector.
http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation
says that all modes except ECB require an IV.
It would also be nice if you could add some more example values in secion 4.2
Cryptographic Values for Session Key Validation.
metze
_______________________________________________
cifs-protocol mailing list
[email protected]
https://lists.samba.org/mailman/listinfo/cifs-protocol
