Internet DRAFT - draft-schaad-cbor-content
draft-schaad-cbor-content
Network Working Group J. Schaad
Internet-Draft August Cellars
Intended status: Informational 4 December 2019
Expires: 6 June 2020
Cryptographic Message System (CMS) Content Types for Concise Binary
Object Representation (CBOR)
draft-schaad-cbor-content-02
Abstract
Concise Binary Object Representation (CBOR) is becoming a widely used
method of doing content encoding. Cryptographic Message System (CMS)
is still a widely used method of doing message-based security. This
document defines a set of content types for CMS that hold CBOR
content.
Status of This Memo
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This Internet-Draft will expire on 6 June 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. CBOR Content Type . . . . . . . . . . . . . . . . . . . . . . 2
3. CBOR Sequence Content Type . . . . . . . . . . . . . . . . . 3
4. ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Concise Binary Object Representation (CBOR) [CBOR] is a compact self-
describing binary encoding formation that is starting to be used in
many different applications. One of the primary uses of CBOR is in
the Internet of Things where the constrained nature means that having
minimal size of encodings becomes very important. The use of the
Cryptographic Message System (CMS) [CMS] is still one of the most
common method for providing message-based security, although in many
cases the CBOR Object Signing and Encryption (COSE) [COSE] message-
based security system is starting to be used. Given that CBOR is
going to be transported using CMS, it makes sense to define CMS
content types for the purpose of denoting that the embedded content
is CBOR. This document defines two new content types: CBOR Content
Type and CBOR Sequence Content Type [CBOR-SEQ].
2. CBOR Content Type
[CBOR] defines an encoded CBOR item. This section defines a new
content type for wrapping an encoded CBOR item in a CMS object.
The following object identifier identifies the CBOR content type:
id-ct-cbor OBJECT IDENTIFIER ::= { iso(1) member-body(2) usa(840)
rsadsi(113549) pkcs(1) pkcs9(9) smime(16) ct(1) TBD1 }
The CBOR content type is intended to refer to a single object encoded
using the CBOR encoding format [CBOR]. Nothing is stated about the
specific CBOR object that is included. CBOR can always be decoded to
a tree as the encoding is self descriptive.
The CBOR content type is intended to be encapsulated in the signed
data and auth-enveloped data, but can be included in any CMS wrapper.
It cannot be predicted if the compressed CMS encapsulation will
provide compression as the content may be binary rather than text.
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[RFC7193] defined an optional parameter "innerContent" to allow for
identification of what the inner content is for an application/cms
media type. This document defines the string "cbor" as a new value
that can be placed here when a CBOR content type is used.
3. CBOR Sequence Content Type
[CBOR-SEQ] defines a CBOR Sequence as a concatenation of zero or more
CBOR objects. This section defines a new content type for wrapping a
CBOR Sequence in a CMS object.
The following object identifier identifies the CBOR Sequence content
type:
id-ct-cborSequence OBJECT IDENTIFIER ::= { iso(1) member-body(2)
usa(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) ct(1)
TBD2 }
The CBOR Sequence content type is intended to refer to a sequence of
objects encoded using the CBOR encoding format. The objects are
concatenated without any markers delimiting the individual CBOR
objects. Nothing is stated about the specific CBOR objects that are
included. CBOR can always be decoded to a tree as the encoding is
self descriptive.
The CBOR Sequence content type is intended to be encapsulated in the
signed data and auth-enveloped data, but can be included in any CMS
wrapper. It cannot be predicted if the compressed CMS encapsulation
will provide compression as the content may be binary rather than
text.
[RFC7193] defined an optional parameter "innerContent" to allow for
identification of what the inner content is for an application/cms
media type. This document defines the string "cborSequence" as a new
value that can be placed here when a CBOR Sequence content type is
used.
4. ASN.1 Module
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CborContentTypes { iso(1) member-body(2) usa(840)
rsadsi(113549) pkcs(1) pkcs9(9) smime(16) modules(0)
id-mod-cbor-2019(TBD3) }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
IMPORTS
CONTENT-TYPE
FROM CryptographicMessageSyntax-2010
{ iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0) id-mod-cms-2009(58) }
;
id-ct-cbor OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) ct(1)
TBD1 }
id-ct-cborSequence OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) ct(1)
TBD2 }
-- Content is encoded directly and does not have any ASN.1
-- structure
ct-Cbor CONTENT-TYPE ::= { IDENTIFIED BY id-ct-cbor }
-- Content is encoded directly and does not have any ASN.1
-- structure
ct-CborSequence CONTENT-TYPE ::= {
IDENTIFIED BY id-ct-cborSequence
}
END
5. IANA Considerations
In the "SMI Security for S/MIME Module Identifier" registry, create a
new entry to point to this document.
+---------+------------------+-------------------+
| Decimal | Description | References |
+=========+==================+===================+
| TBD3 | id-mod-cbor-2019 | [[This Document]] |
+---------+------------------+-------------------+
Table 1
In the "SMI Security for S/MIME Content Types" registry, add two new
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entries for id-ct-cbor and id-ct-cborSequence that point to this
document.
+---------+--------------------+-------------------+
| Decimal | Description | References |
+=========+====================+===================+
| TBD1 | id-ct-cbor | [[This Document]] |
+---------+--------------------+-------------------+
| TBD2 | id-ct-cborSequence | [[This Document]] |
+---------+--------------------+-------------------+
Table 2
In the table "CMS Inner Content Types" add two new entries:
+--------------+------------------------------+-------------------+
| Name | Object Identifier | Reference |
+==============+==============================+===================+
| cbor | 1.2.840.113549.1.9.16.1.TBD1 | [[This Document]] |
+--------------+------------------------------+-------------------+
| cborSequence | 1.2.840.113549.1.9.16.1.TBD2 | [[This Document]] |
+--------------+------------------------------+-------------------+
Table 3
6. Security Considerations
This document only provides identification for content types, it does
not introduce any new security issues by itself. The new content
types mean that id-data does not need to be used to identify these
content types and thus can reduce confusion.
7. Normative References
[CMS] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<https://www.rfc-editor.org/info/rfc5652>.
[CBOR] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[COSE] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC7193] Turner, S., Housley, R., and J. Schaad, "The application/
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cms Media Type", RFC 7193, DOI 10.17487/RFC7193, April
2014, <https://www.rfc-editor.org/info/rfc7193>.
[CBOR-SEQ] Bormann, C., "Concise Binary Object Representation (CBOR)
Sequences", Work in Progress, Internet-Draft, draft-ietf-
cbor-sequence-02, 25 September 2019,
<https://tools.ietf.org/html/draft-ietf-cbor-sequence-02>.
Author's Address
Jim Schaad
August Cellars
Email: ietf@augustcellars.com
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