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<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Metze,<o:p></o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>
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. <o:p></o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>
I will continue working on all questions related to AES encryption.<o:p></o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Thanks!<o:p></o:p></span></p>
<p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal>--------------------------------------------------------------------<o:p></o:p></p>
<p class=MsoNormal>Hongwei Sun - Sr. Support Escalation Engineer<o:p></o:p></p>
<p class=MsoNormal>DSC Protocol Team, Microsoft<o:p></o:p></p>
<p class=MsoNormal><a href="mailto:hongweis@microsoft.com"><span
style='color:blue'>hongweis@microsoft.com</span></a><o:p></o:p></p>
<p class=MsoNormal>Tel: 469-7757027 x 57027<o:p></o:p></p>
<p class=MsoNormal>---------------------------------------------------------------------<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p>
<p class=MsoPlainText>-----Original Message-----<o:p></o:p></p>
<p class=MsoPlainText>From: Stefan (metze) Metzmacher [mailto:metze@samba.org] <o:p></o:p></p>
<p class=MsoPlainText>Sent: Tuesday, August 25, 2009 11:13 AM<o:p></o:p></p>
<p class=MsoPlainText>To: Interoperability Documentation Help<o:p></o:p></p>
<p class=MsoPlainText>Cc: pfif@tridgell.net; cifs-protocol@samba.org<o:p></o:p></p>
<p class=MsoPlainText>Subject: MS-NRPC: AES Schannel problems<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Hi,<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I'm currently trying to implement the AES based Netlogon
Secure Channel in Samba.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>But the documentation is not really clear about the used
algorithms.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I have started with the implementation here:<o:p></o:p></p>
<p class=MsoPlainText>http://gitweb.samba.org/?p=metze/samba/wip.git;a=shortlog;h=refs/heads/master4-schannel<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>And here's the actual commit that tries to add aes support:<o:p></o:p></p>
<p class=MsoPlainText>http://gitweb.samba.org/?p=metze/samba/wip.git;a=commitdiff;h=50dca9ce0f051c863f00cc949db2c19bf247887b<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>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?<o:p></o:p></p>
<p class=MsoPlainText>I thought the plain text is never stored in AD by
default...<o:p></o:p></p>
<p class=MsoPlainText>Where should the netlogon server get the plain text from?<o:p></o:p></p>
<p class=MsoPlainText>I just tried the NT-HASH see my
netlogon_creds_init_hmac_sha256() function.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>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.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation<o:p></o:p></p>
<p class=MsoPlainText>says that all modes except ECB require an IV.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>It would also be nice if you could add some more example
values in secion 4.2 Cryptographic Values for Session Key Validation.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>metze<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
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