SMB3.0 alternate channel

Arnab Bakshi arnab.bakshi at
Thu Feb 14 05:42:05 MST 2013


  Was going through the smb2_key_derivation() function which generates the
session->signingKey from the session->sessionKey. As per the MS_SMB2 spec
section- page 130 the algorithm should be as specified
in [SP800-108] section 5.1 i.e KDF in counter mode with PRF as HMAC-256.
Also the [MS-SMB2] spec specifies a *'r'* value of 32 and 'L' value of 128.

In the Samba-4.0.3  implementation that I downloaded I could see the
*'L'*value being defined but did not find the
*'r*' value anywhere which is supposed to be the size of binary string
representing the counter *'i'*.

    Can anybody please throw some light on this?..Also do you have any
example values of session->sessionKey and session->signingKey using which
this function was validated..

Thanks in advance

On Thu, Feb 14, 2013 at 1:50 PM, Arnab Bakshi <arnab.bakshi at>wrote:

> Thanks Stefan...Will check...
> On Thu, Feb 14, 2013 at 1:16 PM, Stefan (metze) Metzmacher <
> metze at> wrote:
>> Hi Arnab,
>> >       I am mainly talking about smbclient tool.
>> >       I was browsing the code and in the folder libcli/smb/ there is a
>> file
>> > smb2_signing.c where I found some code to support signing for alternate
>> > channel Session-Setup ....
>> > Does this code work or is it part of ongoing development of
>> multichannel .
>> > Regards
>> > Arnab
>> We have tests for multichannel.
>> See the SMB2-MULTI-CHANNEL test in smbtorture3.
>> run_smb2_multi_channel() in source3/torture/test_smb2.c
>> metze

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