< draft-ietf-ace-cbor-web-token-03.txt   draft-ietf-ace-cbor-web-token-04.txt >
ACE Working Group M. Jones ACE Working Group M. Jones
Internet-Draft Microsoft Internet-Draft Microsoft
Intended status: Standards Track E. Wahlstroem Intended status: Standards Track E. Wahlstroem
Expires: September 3, 2017 Expires: October 15, 2017
S. Erdtman S. Erdtman
Spotify AB Spotify AB
H. Tschofenig H. Tschofenig
ARM Ltd. ARM Ltd.
March 2, 2017 April 13, 2017
CBOR Web Token (CWT) CBOR Web Token (CWT)
draft-ietf-ace-cbor-web-token-03 draft-ietf-ace-cbor-web-token-04
Abstract Abstract
CBOR Web Token (CWT) is a compact means of representing claims to be CBOR Web Token (CWT) is a compact means of representing claims to be
transferred between two parties. CWT is a profile of the JSON Web transferred between two parties. CWT is a profile of the JSON Web
Token (JWT) that is optimized for constrained devices. The claims in Token (JWT) that is optimized for constrained devices. The claims in
a CWT are encoded in the Concise Binary Object Representation (CBOR) a CWT are encoded in the Concise Binary Object Representation (CBOR)
and CBOR Object Signing and Encryption (COSE) is used for added and CBOR Object Signing and Encryption (COSE) is used for added
application layer security protection. A claim is a piece of application layer security protection. A claim is a piece of
information asserted about a subject and is represented as a name/ information asserted about a subject and is represented as a name/
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 3, 2017. This Internet-Draft will expire on October 15, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Claim Names . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Claim Names . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. iss (Issuer) Claim . . . . . . . . . . . . . . . . . 4 3.1.1. iss (Issuer) Claim . . . . . . . . . . . . . . . . . 4
3.1.2. sub (Subject) Claim . . . . . . . . . . . . . . . . . 4 3.1.2. sub (Subject) Claim . . . . . . . . . . . . . . . . . 5
3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 5 3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 5
3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 5 3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 5
3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 5 3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 5
3.1.6. iat (Issued At) Claim . . . . . . . . . . . . . . . . 5 3.1.6. iat (Issued At) Claim . . . . . . . . . . . . . . . . 5
3.1.7. cti (CWT ID) Claim . . . . . . . . . . . . . . . . . 5 3.1.7. cti (CWT ID) Claim . . . . . . . . . . . . . . . . . 5
4. Summary of the values, CBOR major types and encoded claim 4. Summary of the values, CBOR major types and encoded claim
keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. CWT CBOR Tag . . . . . . . . . . . . . . . . . . . . . . . . 6 5. CBOR Tags and Claim Values . . . . . . . . . . . . . . . . . 6
6. Creating and Validating CWTs . . . . . . . . . . . . . . . . 6 6. CWT CBOR Tag . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Creating a CWT . . . . . . . . . . . . . . . . . . . . . 6 7. Creating and Validating CWTs . . . . . . . . . . . . . . . . 7
6.2. Validating a CWT . . . . . . . . . . . . . . . . . . . . 7 7.1. Creating a CWT . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7.2. Validating a CWT . . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8.1. CBOR Web Token (CWT) Claims Registry . . . . . . . . . . 9 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8.1.1. Registration Template . . . . . . . . . . . . . . . . 9 9.1. CBOR Web Token (CWT) Claims Registry . . . . . . . . . . 9
8.1.2. Initial Registry Contents . . . . . . . . . . . . . . 10 9.1.1. Registration Template . . . . . . . . . . . . . . . . 10
8.2. Media Type Registration . . . . . . . . . . . . . . . . . 11 9.1.2. Initial Registry Contents . . . . . . . . . . . . . . 10
8.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 11 9.2. Media Type Registration . . . . . . . . . . . . . . . . . 12
8.3. CoAP Content-Formats Registration . . . . . . . . . . . . 12 9.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 12
8.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 12 9.3. CoAP Content-Formats Registration . . . . . . . . . . . . 12
8.4. CBOR Tag registration . . . . . . . . . . . . . . . . . . 12 9.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 12
8.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 12 9.4. CBOR Tag registration . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14
A.1. Example CWT Claims Set . . . . . . . . . . . . . . . . . 14 A.1. Example CWT Claims Set . . . . . . . . . . . . . . . . . 14
A.2. Example keys . . . . . . . . . . . . . . . . . . . . . . 15 A.2. Example keys . . . . . . . . . . . . . . . . . . . . . . 15
A.2.1. 128-bit Symmetric Key as Hex Encoded String . . . . . 15 A.2.1. 128-bit Symmetric Key as Hex Encoded String . . . . . 15
A.2.2. 256-bit Symmetric Key as Hex Encoded String . . . . . 15 A.2.2. 256-bit Symmetric Key as Hex Encoded String . . . . . 15
A.2.3. ECDSA P-256 256-bit COSE Key . . . . . . . . . . . . 15 A.2.3. ECDSA P-256 256-bit COSE Key . . . . . . . . . . . . 15
A.3. Example Signed CWT . . . . . . . . . . . . . . . . . . . 16 A.3. Example Signed CWT . . . . . . . . . . . . . . . . . . . 16
A.4. Example MACed CWT . . . . . . . . . . . . . . . . . . . . 17 A.4. Example MACed CWT . . . . . . . . . . . . . . . . . . . . 17
A.5. Example Encrypted CWT . . . . . . . . . . . . . . . . . . 18 A.5. Example Encrypted CWT . . . . . . . . . . . . . . . . . . 17
A.6. Example Nested CWT . . . . . . . . . . . . . . . . . . . 19 A.6. Example Nested CWT . . . . . . . . . . . . . . . . . . . 18
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 20 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 19
Appendix C. Document History . . . . . . . . . . . . . . . . . . 20 Appendix C. Document History . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
The JSON Web Token (JWT) [RFC7519] is a standardized security token The JSON Web Token (JWT) [RFC7519] is a standardized security token
format that has found use in OAuth 2.0 and OpenID Connect format that has found use in OAuth 2.0 and OpenID Connect
deployments, among other applications. JWT uses JSON Web Signatures deployments, among other applications. JWT uses JSON Web Signature
(JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the (JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the
contents of the JWT, which is a set of claims represented in JSON contents of the JWT, which is a set of claims represented in JSON.
[RFC7519]. The use of JSON for encoding information is popular for The use of JSON for encoding information is popular for Web and
Web and native applications, but it is considered inefficient for native applications, but it is considered inefficient for some
some Internet of Things (IoT) systems that use low power radio Internet of Things (IoT) systems that use low power radio
technologies. technologies.
In this document an alternative encoding of claims is defined. An alternative encoding of claims is defined in this document.
Instead of using JSON, as provided by JWTs, this specification uses Instead of using JSON, as provided by JWTs, this specification uses
CBOR [RFC7049] and calls this new structure "CBOR Web Token (CWT)", CBOR [RFC7049] and calls this new structure "CBOR Web Token (CWT)",
which is a compact means of representing secured claims to be which is a compact means of representing secured claims to be
transferred between two parties. CWT is closely related to JWT. It transferred between two parties. CWT is closely related to JWT. It
references the JWT claims and both its name and pronunciation are references the JWT claims and both its name and pronunciation are
derived from JWT. To protect the claims contained in CWTs, the CBOR derived from JWT. To protect the claims contained in CWTs, the CBOR
Object Signing and Encryption (COSE) [I-D.ietf-cose-msg] Object Signing and Encryption (COSE) [I-D.ietf-cose-msg]
specification is used. specification is used.
The suggested pronunciation of CWT is the same as the English word The suggested pronunciation of CWT is the same as the English word
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2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
"Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
This document reuses terminology from JWT [RFC7519] and COSE This document reuses terminology from JWT [RFC7519] and COSE
[I-D.ietf-cose-msg]. [I-D.ietf-cose-msg].
Type3StringOrURI: StringOrURI:
The "Type3StringOrURI" term has the same meaning, syntax, and The "StringOrURI" term has the same meaning, syntax, and
processing rules as the "StringOrUri" term defined in Section 2 of processing rules as the "StringOrUri" term defined in Section 2 of
JWT [RFC7519], except that Type3StringOrURI uses CBOR major type 3 JWT [RFC7519], except that a CWT StringOrURI uses CBOR major type
instead of a JSON string value. 3 (text string) instead of a JSON string value.
Type6NumericDate: NumericDate:
The "Type6NumericDate" term has the same meaning, syntax, and The "NumericDate" term has the same meaning, syntax, and
processing rules as the "NumericDate" term defined in Section 2 of processing rules as the "NumericDate" term defined in Section 2 of
JWT [RFC7519], except that Type6NumericDate uses CBOR major type JWT [RFC7519], except that a CWT NumericDate uses one of the CBOR
6, with tag value 1, instead of a numeric JSON value. numeric types (0, 1, or 7 with subtypes 25, 26, or 27), instead of
a numeric JSON value. The numeric date values that can used for a
CWT NumericDate are identical to the epoch-based date/time values
that are specified to follow the tag defined in Section 2.4.1
(Date and Time) of [RFC7049], except that the tag itself need not
be present.
CBOR encoded claim key: CBOR encoded claim key:
The key used to identify a claim value. The key used to identify a claim value.
CWT Claims Set CWT Claims Set
A CBOR map that contains the claims conveyed by the CWT. A CBOR map that contains the claims conveyed by the CWT.
3. Claims 3. Claims
The set of claims that a CWT must contain to be considered valid is The set of claims that a CWT must contain to be considered valid is
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None of the claims defined below are intended to be mandatory to use None of the claims defined below are intended to be mandatory to use
or implement. They rather provide a starting point for a set of or implement. They rather provide a starting point for a set of
useful, interoperable claims. Applications using CWTs should define useful, interoperable claims. Applications using CWTs should define
which specific claims they use and when they are required or which specific claims they use and when they are required or
optional. optional.
3.1.1. iss (Issuer) Claim 3.1.1. iss (Issuer) Claim
The "iss" (issuer) claim has the same meaning, syntax, and processing The "iss" (issuer) claim has the same meaning, syntax, and processing
rules as the "iss" claim defined in Section 4.1.1 of JWT [RFC7519], rules as the "iss" claim defined in Section 4.1.1 of JWT [RFC7519],
except that the format MUST be a Type3StringOrURI. The CBOR encoded except that the format MUST be a StringOrURI. The CBOR encoded claim
claim key 1 MUST be used to identify this claim. key 1 MUST be used to identify this claim.
3.1.2. sub (Subject) Claim 3.1.2. sub (Subject) Claim
The "sub" (subject) claim has the same meaning, syntax, and The "sub" (subject) claim has the same meaning, syntax, and
processing rules as the "sub" claim defined in Section 4.1.2 of JWT processing rules as the "sub" claim defined in Section 4.1.2 of JWT
[RFC7519], except that the format MUST be a StringOrURI. The CBOR
[RFC7519], except that the format MUST be a Type3StringOrURI. The encoded claim key 2 MUST be used to identify this claim.
CBOR encoded claim key 2 MUST be used to identify this claim.
3.1.3. aud (Audience) Claim 3.1.3. aud (Audience) Claim
The "aud" (audience) claim has the same meaning, syntax, and The "aud" (audience) claim has the same meaning, syntax, and
processing rules as the "aud" claim defined in Section 4.1.3 of JWT processing rules as the "aud" claim defined in Section 4.1.3 of JWT
[RFC7519], except that the format MUST be a Type3StringOrURI. The [RFC7519], except that the format MUST be a StringOrURI. The CBOR
CBOR encoded claim key 3 MUST be used to identify this claim. encoded claim key 3 MUST be used to identify this claim.
3.1.4. exp (Expiration Time) Claim 3.1.4. exp (Expiration Time) Claim
The "exp" (expiration time) claim has the same meaning, syntax, and The "exp" (expiration time) claim has the same meaning, syntax, and
processing rules as the "exp" claim defined in Section 4.1.4 of JWT processing rules as the "exp" claim defined in Section 4.1.4 of JWT
[RFC7519], except that the format MUST be a Type6NumericDate. The [RFC7519], except that the format MUST be a CWT NumericDate. The
CBOR encoded claim key 4 MUST be used to identify this claim. CBOR encoded claim key 4 MUST be used to identify this claim.
3.1.5. nbf (Not Before) Claim 3.1.5. nbf (Not Before) Claim
The "nbf" (not before) claim has the same meaning, syntax, and The "nbf" (not before) claim has the same meaning, syntax, and
processing rules as the "nbf" claim defined in Section 4.1.5 of JWT processing rules as the "nbf" claim defined in Section 4.1.5 of JWT
[RFC7519], except that the format MUST be a Type6NumericDate. The [RFC7519], except that the format MUST be a CWT NumericDate. The
CBOR encoded claim key 5 MUST be used to identify this claim. CBOR encoded claim key 5 MUST be used to identify this claim.
3.1.6. iat (Issued At) Claim 3.1.6. iat (Issued At) Claim
The "iat" (issued at) claim has the same meaning, syntax, and The "iat" (issued at) claim has the same meaning, syntax, and
processing rules as the "iat" claim defined in Section 4.1.6 of JWT processing rules as the "iat" claim defined in Section 4.1.6 of JWT
[RFC7519], except that the format MUST be a Type6NumericDate. The [RFC7519], except that the format MUST be a CWT NumericDate. The
CBOR encoded claim key 6 MUST be used to identify this claim. CBOR encoded claim key 6 MUST be used to identify this claim.
3.1.7. cti (CWT ID) Claim 3.1.7. cti (CWT ID) Claim
The "cti" (CWT ID) claim has the same meaning, syntax, and processing The "cti" (CWT ID) claim has the same meaning, syntax, and processing
rules as the "jti" claim defined in Section 4.1.7 of JWT [RFC7519], rules as the "jti" claim defined in Section 4.1.7 of JWT [RFC7519],
except that the format MUST be of major type 2, binary string. The except that the format MUST be of major type 2, binary string. The
CBOR encoded claim key 7 MUST be used to identify this claim. CBOR encoded claim key 7 MUST be used to identify this claim.
4. Summary of the values, CBOR major types and encoded claim keys 4. Summary of the values, CBOR major types and encoded claim keys
/---------+------------------------+--------------------------\ /---------+------------------------+-------------------------------\
| Claim | CBOR encoded claim key | CBOR major type of value | | Claim | CBOR encoded claim key | CBOR major type of value |
|---------+------------------------+--------------------------| |---------+------------------------+-------------------------------|
| iss | 1 | 3 | | iss | 1 | 3 |
| sub | 2 | 3 | | sub | 2 | 3 |
| aud | 3 | 3 | | aud | 3 | 3 |
| exp | 4 | 6 tag value 1 | | exp | 4 | 0, 1, or 7 with float subtype |
| nbf | 5 | 6 tag value 1 | | nbf | 5 | 0, 1, or 7 with float subtype |
| iat | 6 | 6 tag value 1 | | iat | 6 | 0, 1, or 7 with float subtype |
| cti | 7 | 2 | | cti | 7 | 2 |
\---------+------------------------+--------------------------/ \---------+------------------------+-------------------------------/
Figure 1: Summary of the values, CBOR major types and encoded claim Figure 1: Summary of the values, CBOR major types and encoded claim
keys. keys.
5. CWT CBOR Tag 5. CBOR Tags and Claim Values
The use of CBOR tags to prefix any of the claim values defined in
this specification is NOT RECOMMENDED. For instance, while CBOR tag
6.1 (seconds-since-the-epoch) could logically be prefixed to values
of the "exp", "nbf", and "iat" claims, this is unnecessary, since the
representation of the claim values is already specified by the claim
definitions. Tagging claim values would only take up extra space,
without adding information. However, other claims defined by other
specifications can specify that a tag prefix the claim value, when
appropriate.
6. CWT CBOR Tag
How to determine that a CBOR data structure is a CWT is application- How to determine that a CBOR data structure is a CWT is application-
dependent. In some cases, this information is known from the dependent. In some cases, this information is known from the
application context, such as from the position of the CWT in a data application context, such as from the position of the CWT in a data
structure at which the value must be a CWT. One method of indicating structure at which the value must be a CWT. One method of indicating
that a CBOR object is a CWT is the use of the "application/cwt" that a CBOR object is a CWT is the use of the "application/cwt"
content type by a transport protocol. content type by a transport protocol.
This section defines the CWT CBOR tag as another means for This section defines the CWT CBOR tag as another means for
applications to declare that a CBOR data structure is a CWT. Its use applications to declare that a CBOR data structure is a CWT. Its use
is optional, and is intended for use in cases in which this is optional, and is intended for use in cases in which this
information would not otherwise be known. information would not otherwise be known.
The CWT tag MUST prefix a tagged object using one of the COSE CBOR If present, the CWT tag MUST prefix a tagged object using one of the
tags. In this example, the COSE_Mac0 tag is used. The actual COSE CBOR tags. In this example, the COSE_Mac0 tag is used. The
COSE_Mac0 object has been excluded from this example. actual COSE_Mac0 object has been excluded from this example.
/ CWT CBOR tag / 61( / CWT CBOR tag / 61(
/ COSE_Mac0 CBOR tag / 17( / COSE_Mac0 CBOR tag / 17(
/ COSE_Mac0 object / / COSE_Mac0 object /
) )
) )
Figure 2: Example of a CWT tag usage Figure 2: Example of a CWT tag usage
6. Creating and Validating CWTs 7. Creating and Validating CWTs
6.1. Creating a CWT 7.1. Creating a CWT
To create a CWT, the following steps are performed. The order of the To create a CWT, the following steps are performed. The order of the
steps is not significant in cases where there are no dependencies steps is not significant in cases where there are no dependencies
between the inputs and outputs of the steps. between the inputs and outputs of the steps.
1. Create a CWT Claims Set containing the desired claims. 1. Create a CWT Claims Set containing the desired claims.
2. Let the Message be the binary representation of the CWT Claims 2. Let the Message be the binary representation of the CWT Claims
Set. Set.
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plaintext for the COSE_Encrypt/COSE_Encrypt0 object; all steps plaintext for the COSE_Encrypt/COSE_Encrypt0 object; all steps
specified in [I-D.ietf-cose-msg] for creating a COSE_Encrypt/ specified in [I-D.ietf-cose-msg] for creating a COSE_Encrypt/
COSE_Encrypt0 object MUST be followed. COSE_Encrypt0 object MUST be followed.
5. If a nested signing, MACing or encryption operation will be 5. If a nested signing, MACing or encryption operation will be
performed, let the Message be the COSE_Sign/COSE_Sign1, COSE_Mac/ performed, let the Message be the COSE_Sign/COSE_Sign1, COSE_Mac/
COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, and return to Step 3, COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, and return to Step 3,
using a "content type" header value corresponding to the media using a "content type" header value corresponding to the media
type "application/cwt" in the new COSE Header created in that type "application/cwt" in the new COSE Header created in that
step. step.
Note: If integrity (signing/MACing) and confidentiality
(encryption) protection are needed, it is recommended to use an
authenticated encryption algorithm to save space and processing.
6. If needed by the application, add the appropriate COSE CBOR tag 6. If needed by the application, add the appropriate COSE CBOR tag
to the COSE object to indicate type of COSE object. If also to the COSE object to indicate type of COSE object. If also
needed by the application, add the CWT CBOR tag to indicate that needed by the application, add the CWT CBOR tag to indicate that
the COSE object is a CWT. the COSE object is a CWT.
6.2. Validating a CWT 7.2. Validating a CWT
When validating a CWT, the following steps are performed. The order When validating a CWT, the following steps are performed. The order
of the steps is not significant in cases where there are no of the steps is not significant in cases where there are no
dependencies between the inputs and outputs of the steps. If any of dependencies between the inputs and outputs of the steps. If any of
the listed steps fail, then the CWT MUST be rejected -- that is, the listed steps fail, then the CWT MUST be rejected -- that is,
treated by the application as an invalid input. treated by the application as invalid input.
1. Verify that the CWT is a valid CBOR object. 1. Verify that the CWT is a valid CBOR object.
2. If the object begins with the CWT CBOR tag, remove it and verify 2. If the object begins with the CWT CBOR tag, remove it and verify
that one of the COSE CBOR tags follows it. that one of the COSE CBOR tags follows it.
3. If the object is tagged with one of the COSE CBOR tags, remove it 3. If the object is tagged with one of the COSE CBOR tags, remove it
and verify that it corresponds to the structure of the following and verify that it corresponds to the structure of the following
COSE object. COSE object.
skipping to change at page 9, line 5 skipping to change at page 9, line 17
7. If the COSE Header contains a "content type" header value 7. If the COSE Header contains a "content type" header value
corresponding to the media type "application/cwt", then the corresponding to the media type "application/cwt", then the
Message is a CWT that was the subject of nested signing or Message is a CWT that was the subject of nested signing or
encryption operations. In this case, return to Step 1, using the encryption operations. In this case, return to Step 1, using the
Message as the CWT. Message as the CWT.
8. Verify that the Message is a valid CBOR object; let the CWT 8. Verify that the Message is a valid CBOR object; let the CWT
Claims Set be this CBOR object. Claims Set be this CBOR object.
7. Security Considerations 8. Security Considerations
The security of the CWT is dependent on the protections offered by The security of the CWT is dependent on the protections offered by
COSE. Unless the claims in a CWT are protected, an adversary can COSE. Unless the claims in a CWT are protected, an adversary can
modify, add, or remove claims. Since the claims conveyed in a CWT modify, add, or remove claims. Since the claims conveyed in a CWT
may be used to make authorization decisions, it is not only important may be used to make authorization decisions, it is not only important
to protect the CWT in transit but also to ensure that the recipient to protect the CWT in transit but also to ensure that the recipient
can authenticate the party that assembled the claims and created the can authenticate the party that assembled the claims and created the
CWT. Without trust of the recipient in the party that created the CWT. Without trust of the recipient in the party that created the
CWT, no sensible authorization decision can be made. Furthermore, CWT, no sensible authorization decision can be made. Furthermore,
the creator of the CWT needs to carefully evaluate each claim value the creator of the CWT needs to carefully evaluate each claim value
prior to including it in the CWT so that the recipient can be assured prior to including it in the CWT so that the recipient can be assured
of the validity of the information provided. of the validity of the information provided.
8. IANA Considerations 9. IANA Considerations
8.1. CBOR Web Token (CWT) Claims Registry 9.1. CBOR Web Token (CWT) Claims Registry
This section establishes the IANA "CBOR Web Token (CWT) Claims" This section establishes the IANA "CBOR Web Token (CWT) Claims"
registry. registry.
Values are registered on a Specification Required [RFC5226] basis, on Values are registered on a Specification Required [RFC5226] basis, on
the advice of one or more Designated Experts. However, to allow for the advice of one or more Designated Experts. However, to allow for
the allocation of values prior to publication, the Designated Experts the allocation of values prior to publication, the Designated Experts
may approve registration once they are satisfied that such a may approve registration once they are satisfied that such a
specification will be published. specification will be published.
Criteria that should be applied by the Designated Experts includes Criteria that should be applied by the Designated Experts includes
determining whether the proposed registration duplicates existing determining whether the proposed registration duplicates existing
functionality, whether it is likely to be of general applicability or functionality, whether it is likely to be of general applicability or
whether it is useful only for a single application, and whether the whether it is useful only for a single application, and whether the
registration description is clear. registration description is clear.
8.1.1. Registration Template 9.1.1. Registration Template
Claim Name: Claim Name:
The human-readable name requested (e.g., "iss"). The human-readable name requested (e.g., "iss").
Claim Description: Claim Description:
Brief description of the claim (e.g., "Issuer"). Brief description of the claim (e.g., "Issuer").
JWT Claim Name: JWT Claim Name:
Claim Name of the equivalent JWT claim as registered in Claim Name of the equivalent JWT claim, as registered in
[IANA.JWT.Claims]. CWT claims should normally have a [IANA.JWT.Claims]. CWT claims should normally have a
corresponding JWT claim. If a corresponding JWT claim would not corresponding JWT claim. If a corresponding JWT claim would not
make sense, the Designated Experts can choose to accept make sense, the Designated Experts can choose to accept
registrations for which the JWT Claim Name is listed as "N/A". registrations for which the JWT Claim Name is listed as "N/A".
CBOR Key Value: CBOR Key Value:
Key value for the claim. The key value MUST be an integer in the Key value for the claim. The key value MUST be an integer in the
range of 1 to 65536. range of 1 to 65536.
CBOR Major Type: CBOR Major Type:
skipping to change at page 10, line 23 skipping to change at page 10, line 38
For Standards Track RFCs, list the "IESG". For others, give the For Standards Track RFCs, list the "IESG". For others, give the
name of the responsible party. Other details (e.g., postal name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included. address, email address, home page URI) may also be included.
Specification Document(s): Specification Document(s):
Reference to the document or documents that specify the parameter, Reference to the document or documents that specify the parameter,
preferably including URIs that can be used to retrieve copies of preferably including URIs that can be used to retrieve copies of
the documents. An indication of the relevant sections may also be the documents. An indication of the relevant sections may also be
included but is not required. included but is not required.
8.1.2. Initial Registry Contents 9.1.2. Initial Registry Contents
o Claim Name: "iss" o Claim Name: "iss"
o Claim Description: Issuer o Claim Description: Issuer
o JWT Claim Name: "iss" o JWT Claim Name: "iss"
o CBOR Key Value: 1 o CBOR Key Value: 1
o CBOR Major Type: 3 o CBOR Major Type: 3
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.1 of [[ this specification o Specification Document(s): Section 3.1.1 of [[ this specification
]] ]]
skipping to change at page 11, line 7 skipping to change at page 11, line 22
o CBOR Key Value: 3 o CBOR Key Value: 3
o CBOR Major Type: 3 o CBOR Major Type: 3
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.3 of [[ this specification o Specification Document(s): Section 3.1.3 of [[ this specification
]] ]]
o Claim Name: "exp" o Claim Name: "exp"
o Claim Description: Expiration Time o Claim Description: Expiration Time
o JWT Claim Name: "exp" o JWT Claim Name: "exp"
o CBOR Key Value: 4 o CBOR Key Value: 4
o CBOR Major Type: 6, tag value 1 o CBOR Major Type: 0, 1, or 7 with subtypes 25, 26, or 27
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.4 of [[ this specification o Specification Document(s): Section 3.1.4 of [[ this specification
]] ]]
o Claim Name: "nbf" o Claim Name: "nbf"
o Claim Description: Not Before o Claim Description: Not Before
o JWT Claim Name: "nbf" o JWT Claim Name: "nbf"
o CBOR Key Value: 5 o CBOR Key Value: 5
o CBOR Major Type: 6, tag value 1 o CBOR Major Type: 0, 1, or 7 with subtypes 25, 26, or 27
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.5 of [[ this specification o Specification Document(s): Section 3.1.5 of [[ this specification
]] ]]
o Claim Name: "iat" o Claim Name: "iat"
o Claim Description: Issued At o Claim Description: Issued At
o JWT Claim Name: "iat" o JWT Claim Name: "iat"
o CBOR Key Value: 6 o CBOR Key Value: 6
o CBOR Major Type: 6, tag value 1 o CBOR Major Type: 0, 1, or 7 with subtypes 25, 26, or 27
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.6 of [[ this specification o Specification Document(s): Section 3.1.6 of [[ this specification
]] ]]
o Claim Name: "cti" o Claim Name: "cti"
o Claim Description: CWT ID o Claim Description: CWT ID
o JWT Claim Name: "jti" o JWT Claim Name: "jti"
o CBOR Key Value: 7 o CBOR Key Value: 7
o CBOR Major Type: 2 o CBOR Major Type: 2
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1.7 of [[ this specification o Specification Document(s): Section 3.1.7 of [[ this specification
]] ]]
8.2. Media Type Registration 9.2. Media Type Registration
This section registers the "application/cwt" media type [RFC2046] in This section registers the "application/cwt" media type in the "Media
the "Media Types" registry [IANA.MediaTypes] in the manner described Types" registry [IANA.MediaTypes] in the manner described in RFC 6838
in RFC 6838 [RFC6838], which can be used to indicate that the content [RFC6838], which can be used to indicate that the content is a CWT.
is a CWT.
8.2.1. Registry Contents 9.2.1. Registry Contents
o Type name: application o Type name: application
o Subtype name: cwt o Subtype name: cwt
o Required parameters: N/A o Required parameters: N/A
o Optional parameters: N/A o Optional parameters: N/A
o Encoding considerations: binary o Encoding considerations: binary
o Security considerations: See the Security Considerations section o Security considerations: See the Security Considerations section
of [[ this specification ]] of [[ this specification ]]
o Interoperability considerations: N/A o Interoperability considerations: N/A
o Published specification: [[ this specification ]] o Published specification: [[ this specification ]]
skipping to change at page 12, line 26 skipping to change at page 12, line 41
Macintosh file type code(s): N/A Macintosh file type code(s): N/A
o Person & email address to contact for further information: o Person & email address to contact for further information:
IESG, iesg@ietf.org IESG, iesg@ietf.org
o Intended usage: COMMON o Intended usage: COMMON
o Restrictions on usage: none o Restrictions on usage: none
o Author: Michael B. Jones, mbj@microsoft.com o Author: Michael B. Jones, mbj@microsoft.com
o Change controller: IESG o Change controller: IESG
o Provisional registration? No o Provisional registration? No
8.3. CoAP Content-Formats Registration 9.3. CoAP Content-Formats Registration
This section registers the CoAP Content-Format ID for the This section registers the CoAP Content-Format ID for the
"application/cwt" media type in the "CoAP Content-Formats" registry "application/cwt" media type in the "CoAP Content-Formats" registry
[IANA.CoAP.Content-Formats] established by [RFC7252]. [IANA.CoAP.Content-Formats].
8.3.1. Registry Contents 9.3.1. Registry Contents
o Media Type: application/cwt o Media Type: application/cwt
o Encoding: - o Encoding: -
o Id: TBD (maybe 61) o Id: TBD (maybe 61)
o Reference: [[ this specification ]] o Reference: [[ this specification ]]
8.4. CBOR Tag registration 9.4. CBOR Tag registration
This section registers the CWT CBOR tag in the "CBOR Tags" registry This section registers the CWT CBOR tag in the "CBOR Tags" registry
[IANA.CBOR.Tags] established by [RFC7049]. [IANA.CBOR.Tags].
8.4.1. Registry Contents 9.4.1. Registry Contents
o CBOR Tag: TBD (maybe 61 to use the same value as the Content- o CBOR Tag: TBD (maybe 61 to use the same value as the Content-
Format) Format)
o Data Item: CBOR Web Token (CWT) o Data Item: CBOR Web Token (CWT)
o Semantics: CBOR Web Token (CWT), as defined in [[ this o Semantics: CBOR Web Token (CWT), as defined in [[ this
specification ]] specification ]]
o Reference: [[ this specification ]] o Reference: [[ this specification ]]
o Point of Contact: Michael B. Jones, mbj@microsoft.com o Point of Contact: Michael B. Jones, mbj@microsoft.com
9. References 10. References
9.1. Normative References 10.1. Normative References
[I-D.ietf-cose-msg] [I-D.ietf-cose-msg]
Schaad, J., "CBOR Object Signing and Encryption (COSE)", Schaad, J., "CBOR Object Signing and Encryption (COSE)",
draft-ietf-cose-msg-24 (work in progress), November 2016. draft-ietf-cose-msg-24 (work in progress), November 2016.
[IANA.CBOR.Tags] [IANA.CBOR.Tags]
IANA, "Concise Binary Object Representation (CBOR) Tags", IANA, "Concise Binary Object Representation (CBOR) Tags",
<http://www.iana.org/assignments/cbor-tags/ <http://www.iana.org/assignments/cbor-tags/
cbor-tags.xhtml>. cbor-tags.xhtml>.
[IANA.CoAP.Content-Formats] [IANA.CoAP.Content-Formats]
IANA, "CoAP Content-Formats", IANA, "CoAP Content-Formats",
<http://www.iana.org/assignments/core-parameters/ <http://www.iana.org/assignments/core-parameters/
core-parameters.xhtml#content-formats>. core-parameters.xhtml#content-formats>.
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>.
[IANA.MediaTypes] [IANA.MediaTypes]
IANA, "Media Types", IANA, "Media Types",
<http://www.iana.org/assignments/media-types>. <http://www.iana.org/assignments/media-types>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<http://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
10.2. Informative References
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>. <http://www.rfc-editor.org/info/rfc6838>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<http://www.rfc-editor.org/info/rfc7252>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <http://www.rfc-editor.org/info/rfc7515>. 2015, <http://www.rfc-editor.org/info/rfc7515>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015, RFC 7516, DOI 10.17487/RFC7516, May 2015,
<http://www.rfc-editor.org/info/rfc7516>. <http://www.rfc-editor.org/info/rfc7516>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
9.2. Informative References
[I-D.greevenbosch-appsawg-cbor-cddl]
Vigano, C. and H. Birkholz, "CBOR data definition language
(CDDL): a notational convention to express CBOR data
structures", draft-greevenbosch-appsawg-cbor-cddl-09 (work
in progress), September 2016.
Appendix A. Examples Appendix A. Examples
This appendix includes a set of CWT examples that show how the CWT This appendix includes a set of CWT examples that show how the CWT
Claims Set can be protected. There are examples that are signed, Claims Set can be protected. There are examples that are signed,
MACed, encrypted, and that use nested signing and encryption. To MACed, encrypted, and that use nested signing and encryption. To
make the examples easier to read, they are presented both as hex make the examples easier to read, they are presented both as hex
strings and in the extended CBOR diagnostic notation strings and in the extended CBOR diagnostic notation described in
[I-D.greevenbosch-appsawg-cbor-cddl]. Section 6 of [RFC7049].
A.1. Example CWT Claims Set A.1. Example CWT Claims Set
The CWT Claims Set used for the different examples displays usage of The CWT Claims Set used for the different examples displays usage of
all the defined claims. For signed and MACed examples, the CWT all the defined claims. For signed and MACed examples, the CWT
Claims Set is the CBOR encoding as a binary string. Claims Set is the CBOR encoding as a binary string.
a702656572696b77037818636f61703a2f2f6c696768742e6578616d706c652e a70175636f61703a2f2f61732e6578616d706c652e636f6d02656572696b7703
636f6d041a5612aeb0051a5610d9f0061a5610d9f00175636f61703a2f2f6173 7818636f61703a2f2f6c696768742e6578616d706c652e636f6d041a5612aeb0
2e6578616d706c652e636f6d07420b71 051a5610d9f0061a5610d9f007420b71
Figure 3: Example CWT Claims Set as hex string Figure 3: Example CWT Claims Set as hex string
{ {
/ iss / 1: "coap://as.example.com", / iss / 1: "coap://as.example.com",
/ sub / 2: "erikw", / sub / 2: "erikw",
/ aud / 3: "coap://light.example.com", / aud / 3: "coap://light.example.com",
/ exp / 4: 1444064944, / exp / 4: 1444064944,
/ nbf / 5: 1443944944, / nbf / 5: 1443944944,
/ iat / 6: 1443944944, / iat / 6: 1443944944,
skipping to change at page 15, line 31 skipping to change at page 15, line 25
Figure 4: Example CWT Claims Set in CBOR diagnostic notation Figure 4: Example CWT Claims Set in CBOR diagnostic notation
A.2. Example keys A.2. Example keys
This section contains the keys used to sign, MAC, and encrypt the This section contains the keys used to sign, MAC, and encrypt the
messages in this appendix. Line breaks are for display purposes messages in this appendix. Line breaks are for display purposes
only. only.
A.2.1. 128-bit Symmetric Key as Hex Encoded String A.2.1. 128-bit Symmetric Key as Hex Encoded String
9e4f3e65cc1a558b39ce97b3db469b04 8e82e68e61654ecb5a369fe8be7572dd
A.2.2. 256-bit Symmetric Key as Hex Encoded String A.2.2. 256-bit Symmetric Key as Hex Encoded String
e60198ac1650ec9210d7f4f5b27aeae2ada8f4adada555909edca75ce2ae506e 403697de87af64611c1d32a05dab0fe1fcb715a86ab435f1ec99192d79569388
A.2.3. ECDSA P-256 256-bit COSE Key A.2.3. ECDSA P-256 256-bit COSE Key
a6225820feb11ca73b028a10cf77d58a2dfdf2a11eab8ffeeeaaeeb03097ffee a622582060f7f1a780d8a783bfb7a2dd6b2796e8128dbbcef9d3d168db952997
9f3ef2fc2358200657fada2568959c49a404583fe237290ebeb1956f3ad3d966 1a36e7b92358206c1382765aec5358f117733d281c1c7bdc39884d04a45a1e6c
ea09e33369d7b103260102215820c4f9160fc22682991c59c4d96e8accc2da3c 67c858bc206c1903260102215820143329cce7868e416927599cf65a34f3ce2f
c7b7a9bc197c7c1e1bc6d0c1dc612001 fda55a7eca69ed8919a394d42f0f2001
Figure 5: ECDSA 256-bit COSE Key as hex string Figure 5: ECDSA 256-bit COSE Key as hex string
{ {
/ d / -4: h'0657fada2568959c49a404583fe237290ebeb1956f3ad3d966 / d / -4: h'6c1382765aec5358f117733d281c1c7bdc39884d04a45a1e
ea09e33369d7b1', 6c67c858bc206c19',
/ y / -3: h'feb11ca73b028a10cf77d58a2dfdf2a11eab8ffeeeaaeeb030 / y / -3: h'60f7f1a780d8a783bfb7a2dd6b2796e8128dbbcef9d3d168
97ffee9f3ef2fc', db9529971a36e7b9',
/ x / -2: h'c4f9160fc22682991c59c4d96e8accc2da3cc7b7a9bc197c7c / x / -2: h'143329cce7868e416927599cf65a34f3ce2ffda55a7eca69
1e1bc6d0c1dc61', ed8919a394d42f0f',
/ crv / -1: 1 / P-256 / / crv / -1: 1 / P-256 / ,
/ kty / 1: 2 / EC2 /, / kty / 1: 2 / EC2 / ,
/ alg / 3: -7, \ ECDSA 256 \ / alg / 3: -7 / ECDSA 256 /
} }
Figure 6: ECDSA 256-bit COSE Key in CBOR diagnostic notation Figure 6: ECDSA 256-bit COSE Key in CBOR diagnostic notation
A.3. Example Signed CWT A.3. Example Signed CWT
This section shows a signed CWT with a single recipient and a full This section shows a signed CWT with a single recipient and a full
CWT Claims Set. CWT Claims Set.
The signature is generated using the private ECDSA key from The signature is generated using the private key listed in
Appendix A.2.3 and it can be validated using the public part of the Appendix A.2.3 and it can be validated using the public key from
ECDSA key from Appendix A.2.3. Line breaks are for display purposes Appendix A.2.3. Line breaks are for display purposes only.
only.
d28446a203183d0126a05850a702656572696b77037818636f61703a2f2f6c69 d28443a10126a05850a70175636f61703a2f2f61732e6578616d706c652e636f6
6768742e6578616d706c652e636f6d041a5612aeb0051a5610d9f0061a5610d9 d02656572696b77037818636f61703a2f2f6c696768742e6578616d706c652e63
f00175636f61703a2f2f61732e6578616d706c652e636f6d07420b7158407eef 6f6d041a5612aeb0051a5610d9f0061a5610d9f007420b7158401fe410abce650
29abe962ac185e5a372d95d69ce1b5683c5c25efb69a81710dc5173254f5179a effed497f05d7f9462de67d571384097de0d96f1e2514d284cdd85634f269af6c
639827694c22828819704eb026676ca78aaf8da76672a6b5537fb90e710d 36c64f22e7691abb464bed2ff23176cdba9fd9e213f637d082
Figure 7: Signed CWT as hex string Figure 7: Signed CWT as hex string
18( 18(
[ [
/ protected / h'a203183d0126' / { / protected / h'a10126' / {
/ content type / 3: 61, / CWT /
/ alg / 1: -7 / ECDSA 256 / / alg / 1: -7 / ECDSA 256 /
} / , } / ,
/ unprotected / {}, / unprotected / {},
/ payload / h'a702656572696b77037818636f61703a2f2f6c69676874 / payload / h'a70175636f61703a2f2f61732e6578616d706c652e63
2e6578616d706c652e636f6d041a5612aeb0051a5610d9 6f6d02656572696b77037818636f61703a2f2f6c6967
f0061a5610d9f00175636f61703a2f2f61732e6578616d 68742e6578616d706c652e636f6d041a5612aeb0051a
706c652e636f6d07420b71' / { 5610d9f0061a5610d9f007420b71' / {
/ iss / 1: "coap://as.example.com", / iss / 1: "coap://as.example.com",
/ sub / 2: "erikw", / sub / 2: "erikw",
/ aud / 3: "coap://light.example.com", / aud / 3: "coap://light.example.com",
/ exp / 4: 1444064944, / exp / 4: 1444064944,
/ nbf / 5: 1443944944, / nbf / 5: 1443944944,
/ iat / 6: 1443944944, / iat / 6: 1443944944,
/ cti / 7: h'0b71' / cti / 7: h'0b71'
} / , } / ,
/ signature / h'7eef29abe962ac185e5a372d95d69ce1b5683c5c25ef / signature / h'1fe410abce650effed497f05d7f9462de67d571384
b69a81710dc5173254f5179a639827694c2282881970 097de0d96f1e2514d284cdd85634f269af6c36c64f
4eb026676ca78aaf8da76672a6b5537fb90e710d' 22e7691abb464bed2ff23176cdba9fd9e213f637d0
82'
] ]
) )
Figure 8: Signed CWT in CBOR diagnostic notation Figure 8: Signed CWT in CBOR diagnostic notation
A.4. Example MACed CWT A.4. Example MACed CWT
This section shows a MACed CWT with a single recipient and a full CWT This section shows a MACed CWT with a single recipient and a full CWT
Claims Set. Claims Set.
The MAC is generated using the 256-bit symmetric key from The MAC is generated using the 256-bit symmetric key from
Appendix A.2.2 with a 64-bit truncation. Line breaks are for display Appendix A.2.2 with a 64-bit truncation. Line breaks are for display
purposes only. purposes only.
d18446a203183d0104a05850a702656572696b77037818636f61703a2f2f6c69 d83dd18443a10104a05850a70175636f61703a2f2f61732e6578616d706c652e
6768742e6578616d706c652e636f6d041a5612aeb0051a5610d9f0061a5610d9 636f6d02656572696b77037818636f61703a2f2f6c696768742e6578616d706c
f00175636f61703a2f2f61732e6578616d706c652e636f6d07420b7148b59884 652e636f6d041a5612aeb0051a5610d9f0061a5610d9f007420b7148093101ef
6f1ce93f9d 6d789200
Figure 9: MACed CWT as hex string Figure 9: MACed CWT with CWT tag as hex string
17( 61(
[ 17(
/ protected / h'a203183d0104' / { [
/ content type / 3: 61, / CWT / / protected / h'a10104' / {
/ alg / 1: 4 / HMAC 256/64 / / alg / 1: 4 / HMAC 256/64 /
} / ,
/ unprotected / {},
/ payload / h'a702656572696b77037818636f61703a2f2f6c69676874
2e6578616d706c652e636f6d041a5612aeb0051a5610d9
f0061a5610d9f00175636f61703a2f2f61732e6578616d
706c652e636f6d07420b71' / {
/ iss / 1: "coap://as.example.com",
/ sub / 2: "erikw",
/ aud / 3: "coap://light.example.com",
/ exp / 4: 1444064944,
/ nbf / 5: 1443944944,
/ iat / 6: 1443944944,
/ cti / 7: h'0b71'
} / , } / ,
/ tag / h'b598846f1ce93f9d' / unprotected / {},
] / payload / h'a70175636f61703a2f2f61732e6578616d706c652e636f
6d02656572696b77037818636f61703a2f2f6c69676874
2e6578616d706c652e636f6d041a5612aeb0051a5610d9
f0061a5610d9f007420b71' / {
/ iss / 1: "coap://as.example.com",
/ sub / 2: "erikw",
/ aud / 3: "coap://light.example.com",
/ exp / 4: 1444064944,
/ nbf / 5: 1443944944,
/ iat / 6: 1443944944,
/ cti / 7: h'0b71'
} / ,
/ tag / h'093101ef6d789200'
]
)
) )
Figure 10: MACed CWT in CBOR diagnostic notation Figure 10: MACed CWT with CWT tag in CBOR diagnostic notation
A.5. Example Encrypted CWT A.5. Example Encrypted CWT
This section shows an encrypted CWT with a single recipient and a This section shows an encrypted CWT with a single recipient and a
full CWT Claims Set. full CWT Claims Set.
The encryption is done with AES-CCM mode using the 128-bit symmetric The encryption is done with AES-CCM mode using the 128-bit symmetric
key from Appendix A.2.1 with a 64-bit tag and 13-byte nonce, i.e., key from Appendix A.2.1 with a 64-bit tag and 13-byte nonce, i.e.,
COSE AES-CCM-16-64-128. Line breaks are for display purposes only. COSE AES-CCM-16-64-128. Line breaks are for display purposes only.
d08346a203183d010aa1054dadbe290e8c9c23067a558b15795858f7a8ec3e32 d08343a1010aa1054d3a869e378e72b77d077c29be025858d275ad9cd7df1b10
3bb6e006e8aec087666f6fc0d65d7aa272f5f1dde1dfb52fd3a5e1ace97e5bfc ba8cde785c74b1e1e6ada287e2baf1451b06862529b784d230b0111773b6c369
8f05a146fd8a9feab7bb9e722254e2660612f956041264c06ea3b95afb0d8ce3 1319aec4dcc379fe47115a5d62632727c05f4567fc84dd79554db86676a14978
138bc80baf2511565d3dad63ea7534699fa449 42de805d8be93180af4d6ff3043886a0
Figure 11: Encrypted CWT as hex string Figure 11: Encrypted CWT as hex string
16( 16(
[ [
/ protected / h'a203183d010a' / { / protected / h'a1010a' / {
/ content type / 3: 61, / CWT /
/ alg / 1: 10 / AES-CCM-16-64-128 / / alg / 1: 10 / AES-CCM-16-64-128 /
} /, } /,
/ unprotected / { / unprotected / {
/ iv / 5: h'adbe290e8c9c23067a558b1579' / iv / 5: h'3a869e378e72b77d077c29be02'
}, },
/ ciphertext / h'f7a8ec3e323bb6e006e8aec087666f6fc0d65d7aa27 / ciphertext / h'd275ad9cd7df1b10ba8cde785c74b1e1e6ada287e2b
2f5f1dde1dfb52fd3a5e1ace97e5bfc8f05a146fd8a af1451b06862529b784d230b0111773b6c3691319ae
9feab7bb9e722254e2660612f956041264c06ea3b95 c4dcc379fe47115a5d62632727c05f4567fc84dd795
afb0d8ce3138bc80baf2511565d3dad63ea7534699f 54db86676a1497842de805d8be93180af4d6ff30438
a449' 86a0'
] ]
) )
Figure 12: Encrypted CWT in CBOR diagnostic notation Figure 12: Encrypted CWT in CBOR diagnostic notation
A.6. Example Nested CWT A.6. Example Nested CWT
This section shows a Nested CWT, signed and then encrypted, with a This section shows a Nested CWT, signed and then encrypted, with a
single recipient and a full CWT Claims Set. single recipient and a full CWT Claims Set.
skipping to change at page 19, line 41 skipping to change at page 19, line 5
from Appendix A.2.3. The encryption is done with AES-CCM mode using from Appendix A.2.3. The encryption is done with AES-CCM mode using
the 128-bit symmetric key from Appendix A.2.1 with a 64-bit tag and the 128-bit symmetric key from Appendix A.2.1 with a 64-bit tag and
13-byte nonce, i.e., COSE AES-CCM-16-64-128. The content type is set 13-byte nonce, i.e., COSE AES-CCM-16-64-128. The content type is set
to CWT to indicate that there are multiple layers of COSE protection to CWT to indicate that there are multiple layers of COSE protection
before finding the CWT Claims Set. The decrypted ciphertext will be a before finding the CWT Claims Set. The decrypted ciphertext will be a
COSE_sign1 structure. In this example, it is the same one as in COSE_sign1 structure. In this example, it is the same one as in
Appendix A.3, i.e., a Signed CWT Claims Set. Note that there is no Appendix A.3, i.e., a Signed CWT Claims Set. Note that there is no
limitation to the number of layers; this is an example with two limitation to the number of layers; this is an example with two
layers. Line breaks are for display purposes only. layers. Line breaks are for display purposes only.
d08346a203183d010aa1054d2653469d58937647a6a1bb023458a65da538206c33 d08346a203183d010aa1054d9120e5dc42c9f9aec05ebe8a4858a538be026c02
cf941df7ea933ba7b93c60322017f9db9c904608fce2688b51028b5b912f9010 4a40b19d6dbea3ddb18b31021f874a097a05ff3cdaa4665bafc8e46a3d7f37ad
ae72802bf65778593c7270b20683b1587824eb4074e03323ccf0541b495a3757 f002fe57eee267f8f62a9c1621af75e1ecd742a3d801c2cc82358cf104a8d902
f353a8424b6ceeaaec1898964d8a03e04e514a5b0ca143b57689a2a9f1c6c84d 4d38a599ea6027d482dc2948a88fe83f9734804299c832401029e2d32a984789
535d1966adf900dfaf0dd045d2325c40150a07d602b65c60e62894c870ad5fc2 c8e9563e8d2a751323bb7e4462b549e0fa89ef93f78bf6425635fba76b4aa804
cb709e4d17d381806797b6cf118608e18c3facd0a0ac09d88ea73d4ed7e3b57c 7908e89b3b7c3d59d8a80e22f70a1b6ee8c162c564341c2f15cec252d3da038c
Figure 13: Signed and Encrypted CWT as hex string Figure 13: Signed and Encrypted CWT as hex string
16( 16(
[ [
/ protected / h'a203183d010a' / { / protected / h'a203183d010a' / {
/ content type / 3: 61, / CWT / / content type / 3: 61, / CWT /
/ alg / 1: 10 / AES-CCM-16-64-128 / / alg / 1: 10 / AES-CCM-16-64-128 /
} / , } / ,
/ unprotected / { / unprotected / {
/ iv / 5: h'2653469d58937647a6a1bb0234' / iv / 5: h'9120e5dc42c9f9aec05ebe8a48'
}, },
/ ciphertext / h'5da538206c33cf941df7ea933ba7b93c60322017f9d / ciphertext / h'38be026c024a40b19d6dbea3ddb18b31021f874a097
b9c904608fce2688b51028b5b912f9010ae72802bf6 a05ff3cdaa4665bafc8e46a3d7f37adf002fe57eee2
5778593c7270b20683b1587824eb4074e03323ccf05 67f8f62a9c1621af75e1ecd742a3d801c2cc82358cf
41b495a3757f353a8424b6ceeaaec1898964d8a03e0 104a8d9024d38a599ea6027d482dc2948a88fe83f97
4e514a5b0ca143b57689a2a9f1c6c84d535d1966adf 34804299c832401029e2d32a984789c8e9563e8d2a7
900dfaf0dd045d2325c40150a07d602b65c60e62894 51323bb7e4462b549e0fa89ef93f78bf6425635fba7
c870ad5fc2cb709e4d17d381806797b6cf118608e18 6b4aa8047908e89b3b7c3d59d8a80e22f70a1b6ee8c
c3facd0a0ac09d88ea73d4ed7e3b57c' 162c564341c2f15cec252d3da038c'
] ]
) )
Figure 14: Signed and Encrypted CWT in CBOR diagnostic notation Figure 14: Signed and Encrypted CWT in CBOR diagnostic notation
Appendix B. Acknowledgements Appendix B. Acknowledgements
This specification is based on JSON Web Token (JWT) [RFC7519], the This specification is based on JSON Web Token (JWT) [RFC7519], the
authors of which also include Nat Sakimura and John Bradley. Ludwig authors of which also include Nat Sakimura and John Bradley. Ludwig
Seitz and Goeran Selander have made contributions the specification. Seitz and Goeran Selander have made contributions the specification.
Appendix C. Document History Appendix C. Document History
[[ to be removed by the RFC Editor before publication as an RFC ]] [[ to be removed by the RFC Editor before publication as an RFC ]]
-03 -04
o Specified that the use of CBOR tags to prefix any of the claim
values defined in this specification is NOT RECOMMENDED.
-03
o Reworked the examples to include signed, MACed, encrypted, and o Reworked the examples to include signed, MACed, encrypted, and
nested CWTs. nested CWTs.
o Defined the CWT CBOR tag and explained its usage. o Defined the CWT CBOR tag and explained its usage.
-02 -02
o Added IANA registration for the application/cwt media type. o Added IANA registration for the application/cwt media type.
o Clarified the nested CWT language. o Clarified the nested CWT language.
o Corrected nits identified by Ludwig Seitz. o Corrected nits identified by Ludwig Seitz.
 End of changes. 78 change blocks. 
223 lines changed or deleted 219 lines changed or added

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