Hongwei, > The encryption function in Kerberos is described in details in 5.3 > [RFC3961] (http://www.ietf.org/rfc/rfc3961.txt), which is referenced by > [MS-KILE]. > I can summarize as follows > > * "conf" is actually a random confounder prefix of length c ,such as > 16. > > * "pad" is for shortest padding to bring confounder and plaintext to > a length that is the multiple of message block size m, which is octet(8) for > AES encryption, as specified in section 6 [RFC 3962] > (http://www.ietf.org/rfc/rfc3962.txt) > > * Ke is an encryption key and Ki is a checksum key. > > * Plain text is the input confidential data before encryption. > > * The GSSWrapEX() is exactly the same as the GSSWrap except that it > supports ordered list of input buffers. Input buffers for which > conf_req_flag == TRUE are encrypted and returned. Buffers which sign == TRUE > are included in the signature. >
It would be extremly useful if the MS-RPCE document would explain what the exact input buffers to GssWrapEX() are and what flags are used in each of the cases (with and without header signing). Then it would be useful to know to what exactly SSPI EncryptMessage call this is mapped. And finally how each of the of the encryption types (des-*, arcfour-hmac-md5, and aes-*) are supposed to process the EncryptMessage input. It would be nice if you could use a realistic example, with explicit values. A bit like the "A.5 Test suite" section of RFC1321 - The MD5 Message-Digest Algorithm. metze > * We use the Kerberos standard's encryption and signatures. It is > very important to concatenate the correct buffers to make it work. > > > > Please let me know if further clarification is needed and I will be happy > to assist you. > > Thanks > > ---------------------------------------------------------- > Hongwei Sun - Support Escalation Engineer > DSC Protocol Team, Microsoft > [EMAIL PROTECTED] > Tel: 469-7757027 x 57027 > ----------------------------------------------------------- > > > > > > > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Andrew Bartlett > Sent: Monday, July 28, 2008 12:53 AM > To: Interoperability Documentation Help > Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: [cifs-protocol] Clarify AEAD behaviour for GSSAPI with AES > > > > I've been spending most of today staring at MS-KILE 3.4.5.4.1 and Heimdal's > implementation of GSSAPI CFX. > > > > What has me stumped is exactly what this means: > > > >> If the session key encryption type is AES128-CTS-HMAC-SHA1-96 or > >> AES256-CTS-HMAC-SHA1-96, as specified in [RFC3961], the base line is > >> [RFC4121] and the encrypted data per [RFC3961] (which [RFC4121] is based on) >> is: > >> C1 | H1[1..h] > >> Where > >> (C1, newIV) = E(Ke, conf | plaintext | pad, oldstate.ivec) > >> H1 = HMAC(Ki, conf | plaintext+encrypted-data | pad) where the > >> "plaintext+encrypted-data" is all the input data buffers supplied to > >> GSS_WrapEx() concatenated in the order provided in the ordered list, >> input_message. It would be extremly useful if the MS-RPCE document would explain what the exact input buffers are and > I see that C1 is the output of the encryption function E, and presume that Ke > is the encryption key, but what is 'conf', and is 'plaintext' > > the confidential data in plaintext, or the data over which only a signature > is computed (presumably the confidential data in plaintex, but then what is > conf)? > > > > I presume again that Ki is the signing key. > > > > Likewise, a description of how the pad fits into the HMAC function here would > be very helpful. > > > > In short, because this is a deviation from the GSSAPI spec (as the spec does > not allow data to be signed, but not sealed), I really need much more detail, > and all the inputs and outputs clearly labelled, particularly as this seems > to require a major rework of Heimdal to implement :-( > > > > Thanks, > > > > Andrew Bartlett > > -- > > Andrew Bartlett > > http://samba.org/~abartlet/ > > Authentication Developer, Samba Team http://samba.org > > Samba Developer, Red Hat Inc. > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pfif mailing list > [EMAIL PROTECTED] > http://lists.tridgell.net/cgi-bin/mailman/listinfo/pfif
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