[cifs-protocol] [MS-SAMR] AEAD-AES-256-CBC-HMAC-SHA512 - TrackingID#2206210040006850

Obaid Farooqi obaidf at microsoft.com
Tue Jun 21 16:08:06 UTC 2022

Hi Andreas:
Thanks for contacting Microsoft. I have created a case to track this issue. A member of the open specifications team will be in touch soon.

Obaid Farooqi
Escalation Engineer | Microsoft

-----Original Message-----
From: Andreas Schneider <asn at samba.org> 
Sent: Tuesday, June 21, 2022 8:00 AM
To: Interoperability Documentation Help <dochelp at microsoft.com>
Cc: cifs-protocol at lists.samba.org

Hello Dochelp,

I'm trying to implement support for AEAD-AES-256-CBC-HMAC-SHA512 from [MS- SAMR] AES Cipher Usage.

This is not really easy as there are some details unclear. I would love to write a unit test for AEAD-AES-256-CBC-HMAC-SHA512.

Could you please provide hexdump of the buffers used in encryption from a
SamrSetInformationUser2 level 31 from a test platform.

When it performs the following:

Let enc_key ::= HMAC-SHA-512(CEK, SAM_AES256_ENC_KEY_STRING) Let mac_key ::= HMAC-SHA-512(CEK, SAM_AES256_MAC_KEY_STRING) Let Cipher ::= AES-CBC(enc_key, IV, secret_plaintext) Let AuthData ::= HMAC-SHA-512(mac_key, versionbyte + IV + Cipher +

I would like to have hexdumps of the following buffers:

* cek (16byte sesssion key)
* enc_key
* mac_key
* IV
* secret_plaintext
* cipher
* authdata

The RFC implementation provides something like that, see:

This would allow me to write a unit test and figure out the details what in my 
implementation something goes wrong. I can then provide feedback to improve 
the documentation.

Thank you very much!

Best regards

	Andreas Schneider

Andreas Schneider                      asn at samba.org
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