Subject: S/MIME X.400 Transport

From: "Prasad, Nandi" <[email-masked]>
Date: Tue, 14 Aug 2001 14:59:25 +0530

Hello everybody

		I need some clarifications regarding the transport of S/MIME
in X.400 as
per the draft  "draft-ietf-smime-x400transport-03.txt". The draft says that
one should have 
a separate content to represent the CMS object. The "content-type" field of
P1 envelope 
should contain the CMS defined value:

id-data OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) 
                                                       pkcs7(7) 1 }

if the CMS object is covered by outer MIME wrapper and should contain value:

id-ct-contentInfo  OBJECT IDENTIFIER ::= { iso(1) member-body(2)  us(840)
rsadsi(113549) 
                                                          pkcs(1) pkcs-9(9)
smime(16) content-types(1) 6 }

if the CMS object is not covered by an outer MIME wrapper.

	The draft also says that, In case the S/MIME message is forwarded,
the CMS object
should be a bodypart of the "Forwarded IPM".

	X.400 recommendations define different content types with
Interpersonal Message (IPM)
and EDI to quote as some examples. Our X400 MTA/Gateway implementation uses
APIs  as
specified by Xopen Group http://www.opengroup.org/  i.e. XAPIs to build an
IPM.

	The XAPI document also defines and describes a content type called
the "General Content" 
type with binary data being its content. Since CMS object is a binary, can
we use this content type
to convey CMS objects? and can I assume that the receiving User Agent (UA)
will be 
responsible to interpret the message as secure one?

The layout of the message will be as follows:

            __________________________________
	|   P1 Envelope				|
	|   containing S/MIME oid		|
	|					|
	|-----------------------------------------------------------	|
	|    General Content Type		|
	|   					|
	|    with CMS object being the binary	|
	|    data.				|
	|					|
	|__________________________________|

Following is the dump of the message as seen in X.400:
----------------------------------------------------------------------------
---------------------------------
	XAPI dump of a General content message with CMS object
			being the content
----------------------------------------------------------------------------
---------------------------------

OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_DELIV_MESSAGE
MH_T_CONTENT [OM_S_OBJECT]: (Object)
      OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_GENERAL_CONTENT
<< The above OID indicates that it is a general content>>

      MH_T_BINARY_CONTENT [OM_S_OCTET_STRING]: Long string.
<< Binary CMS object follows here >>
30 80  6  9 2a 86 48 86 f7  d  1  7  2 a0 80 30 80  2  1  1 0...*.H.÷....
.0....
31  b 30  9  6  5 2b  e  3  2 1a  5  0 30 80  6  9 2a 86 48
1.0...+......0...*.H
86 f7  d  1  7  1 a0 80 24 80  4  c 43 6f 6e 74 65 6e 74 2d .÷....
.$...Content-
<< More data follows here ...but removed >>.
33 b2 bd ed 85 19 af 77 9d 5c 62 9d 1b b1 ab 19 bb 36 26 5c
3²½í..¯w.\b..±«.»6&\
6f  d 37 a6 99 90 82 6c  0  0  0  0  0  0  0  0  0  0  0  0
o.7¦...l............
Total Length 3394
<< Envelope starts from here >>
MH_T_ENVELOPES [OM_S_OBJECT]: (Object)
      OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_DELIVERY_ENVELOPE
      MH_T_ACTUAL_RECIPIENT_NAME [OM_S_OBJECT]: (Object)
            OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_OR_NAME
            MH_T_ADMD_NAME [OM_S_PRINTABLE_STRING]: vsnl
            MH_T_COMMON_NAME [OM_S_PRINTABLE_STRING]: test
            MH_T_COUNTRY_NAME [OM_S_PRINTABLE_STRING]: in
            MH_T_ORGANIZATION_NAME [OM_S_PRINTABLE_STRING]: idc
            MH_T_PRMD_NAME [OM_S_PRINTABLE_STRING]: digital
      MH_T_BUREAU_FAX_DELIVERY [OM_S_BOOLEAN]: OM_FALSE
      MH_T_CONTENT_TYPE [OM_S_OBJECT_IDENTIFIER_STRING]: 
ObjID: 2a 86 48 86 f7 0d 01 09 10 0106
<< The above OID is the OID for S/MIME (unwrapped) >>

      MH_T_CONVERSION_LOSS_PROHIBITED [OM_S_BOOLEAN]: OM_FALSE
      MH_T_CONVERSION_PROHIBITED [OM_S_BOOLEAN]: OM_FALSE
      MH_T_DELIVERY_TIME [OM_S_UTC_TIME_STRING]: 010809152452Z
      MH_T_FORWARDING_ADDR_REQUESTED [OM_S_BOOLEAN]: OM_FALSE
      MH_T_FORWARDING_PROHIBITED [OM_S_BOOLEAN]: OM_FALSE
      MH_T_MTS_IDENTIFIER [OM_S_OBJECT]: (Object)
            OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_MTS_IDENTIFIER
            MH_T_ADMD_NAME [OM_S_PRINTABLE_STRING]: vsnl
            MH_T_COUNTRY_NAME [OM_S_PRINTABLE_STRING]: in
            MH_T_LOCAL_IDENTIFIER [OM_S_IA5_STRING]:
9B265BAE11D58CDA00001590
            MH_T_PRMD_IDENTIFIER [OM_S_PRINTABLE_STRING]: digital
      MH_T_ORIGINATOR_NAME [OM_S_OBJECT]: (Object)
            OM_CLASS [OM_S_OBJECT_IDENTIFIER_STRING]: MH_C_OR_NAME
            MH_T_ADMD_NAME [OM_S_PRINTABLE_STRING]: vsnl
            MH_T_COMMON_NAME [OM_S_PRINTABLE_STRING]: nandi
            MH_T_COUNTRY_NAME [OM_S_PRINTABLE_STRING]: in
            MH_T_ORGANIZATION_NAME [OM_S_PRINTABLE_STRING]: idc
            MH_T_PRMD_NAME [OM_S_PRINTABLE_STRING]: digital
      MH_T_POSTAL_REPORT [OM_S_ENUMERATION]: MH_PR_UNDELIVBLE_MAIL_VIA_PDS
      MH_T_PREFERRED_DELIVERY_MODES [OM_S_ENUMERATION]: MH_DM_ANY
      MH_T_PRIORITY [OM_S_ENUMERATION]: MH_PTY_NORMAL
      MH_T_PROOF_OF_DELIV_REQUESTED [OM_S_BOOLEAN]: OM_FALSE
      MH_T_REGISTRATION [OM_S_ENUMERATION]: 0
      MH_T_RENDITION_ATTRIBUTES [OM_S_OBJECT_IDENTIFIER_STRING]:
MH_RA_BASIC_RENDITION
      MH_T_SUBMISSION_TIME [OM_S_UTC_TIME_STRING]: 010809152421Z
----------------------------------------------------------------------------
---------------------------------

	Could anybody comment on the usage of General content in the
transfer
of CMS object from MIME to X.400.

Regards
Nandi

---

From: "Housley, Russ" <[email-masked]>
Date: Tue, 14 Aug 2001 10:49:34 -0400

I am confused by this diagram.  My understanding of the content type in the 
P1 envelope tells what ASN.1 syntax is to be used to decode the 
content.  Therefore, the CMS content needs to have its own content-type 
OID.  How can the S/MIME OID in the P1 envelope of the diagram compatible 
with the general content type in the content.

Russ