draft-ietf-ace-cbor-web-token-00.txt   draft-ietf-ace-cbor-web-token-01.txt 
ACE Working Group E. Wahlstroem ACE Working Group E. Wahlstroem
Internet-Draft Nexus Technology Internet-Draft
Intended status: Informational M. Jones Intended status: Informational M. Jones
Expires: November 21, 2016 Microsoft Expires: January 8, 2017 Microsoft
H. Tschofenig H. Tschofenig
ARM Ltd. ARM Ltd.
May 20, 2016 S. Erdtman
Spotify AB
July 7, 2016
CBOR Web Token (CWT) CBOR Web Token (CWT)
draft-ietf-ace-cbor-web-token-00 draft-ietf-ace-cbor-web-token-01
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/
skipping to change at page 1, line 40 skipping to change at page 1, line 42
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This Internet-Draft will expire on November 21, 2016. This Internet-Draft will expire on January 8, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 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 . . . . . . . . . . . . . . . . . 4
3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 4 3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 4
3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 4 3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 5
3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 4 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. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Creating and Validating CWTs . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5.1. Creating a CWT . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6 5.2. Validating a CWT . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
A.1. CWT with "aud" and symmetric key . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
A.2. CWT with "aud" and EC key . . . . . . . . . . . . . . . . 8 7.1. CBOR Web Token (CWT) Claims Registry . . . . . . . . . . 8
A.3. Full CWT . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1.1. Registration Template . . . . . . . . . . . . . . . . 8
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 12 7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 9
Appendix C. Document History . . . . . . . . . . . . . . . . . . 12 7.2. CoAP Content-Format Registration . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 7.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 12
A.1. CWT with "aud" and symmetric key . . . . . . . . . . . . 12
A.2. CWT with "aud" and EC key . . . . . . . . . . . . . . . . 13
A.3. Full CWT . . . . . . . . . . . . . . . . . . . . . . . . 15
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 18
Appendix C. Document History . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
The JSON Web Token (JWT) [5] is a standardized security token format The JSON Web Token (JWT) [RFC7519] is a standardized security token
that has found use in OAuth 2.0 and OpenID Connect deployments, among format that has found use in OAuth 2.0 and OpenID Connect
other applications. JWT uses JSON Web Signatures (JWS) [3] and JSON deployments, among other applications. JWT uses JSON Web Signatures
Web Encryption (JWE) [4] to secure the contents of the JWT, which is (JWS) [RFC7515] and JSON Web Encryption (JWE) [RFC7516] to secure the
a set of claims represented in JSON [5]. The use of JSON for contents of the JWT, which is a set of claims represented in JSON
encoding information is popular for Web and native applications, but [RFC7519]. The use of JSON for encoding information is popular for
it is considered inefficient for some Internet of Things (IoT) Web and native applications, but it is considered inefficient for
systems that use low power radio technologies. some Internet of Things (IoT) systems that use low power radio
technologies.
In this document an alternative encoding of claims is defined. In this document an alternative encoding of claims is defined.
Instead of using JSON, as provided by JWTs, this specification uses Instead of using JSON, as provided by JWTs, this specification uses
CBOR [6] and calls this new structure "CBOR Web Token (CWT)", which CBOR [RFC7049] and calls this new structure "CBOR Web Token (CWT)",
is a compact means of representing secured claims to be transferred which is a compact means of representing secured claims to be
between two parties. CWT is closely related to JWT. It references transferred between two parties. CWT is closely related to JWT. It
the JWT claims and both its name and pronunciation are derived from references the JWT claims and both its name and pronunciation are
JWT. To protect the claims contained in CWTs, the CBOR Object derived from JWT. To protect the claims contained in CWTs, the CBOR
Signing and Encryption (COSE) [7] specification is used. Object Signing and Encryption (COSE) [I-D.ietf-cose-msg]
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
"cot". "cot".
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" [1]. "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
This document reuses terminology from JWT [5] and COSE [7]. This document reuses terminology from JWT [RFC7519] and COSE
[I-D.ietf-cose-msg].
Type3StringOrURI: Type3StringOrURI:
The "Type3StringOrURI" term has the same meaning, syntax, and The "Type3StringOrURI" 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 [5], except that Type3StringOrURI uses CBOR major type 3 JWT [RFC7519], except that Type3StringOrURI uses CBOR major type 3
instead of a JSON string value. instead of a JSON string value.
FIXME: Use tag 32 for URIs?
Type6NumericDate: Type6NumericDate:
The "Type6NumericDate" term has the same meaning, syntax, and The "Type6NumericDate" 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 [5], except that Type6NumericDate uses CBOR major type 6, with JWT [RFC7519], except that Type6NumericDate uses CBOR major type
tag value 1, instead of a numeric JSON value. 6, with tag value 1, instead of a numeric JSON value.
CBOR encoded claim key: CBOR encoded claim key:
The key used to identify a claim value. The key used to identify a claim value.
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
context dependent and is outside the scope of this specification. context dependent and is outside the scope of this specification.
Specific applications of CWTs will require implementations to Specific applications of CWTs will require implementations to
skipping to change at page 4, line 20 skipping to change at page 4, line 31
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 [5], except rules as the "iss" claim defined in Section 4.1.1 of JWT [RFC7519],
that the format MUST be a Type3StringOrURI. The CBOR encoded claim except that the format MUST be a Type3StringOrURI. The CBOR encoded
key 1 MUST be used to identify this claim. 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
[5], except that the format MUST be a Type3StringOrURI. 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
[5], except that the format MUST be a Type3StringOrURI. The CBOR [RFC7519], except that the format MUST be a Type3StringOrURI. The
encoded claim key 3 MUST be used to identify this claim. CBOR 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
[5], except that the format MUST be a Type6NumericDate. The CBOR [RFC7519], except that the format MUST be a Type6NumericDate. The
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
[5], except that the format MUST be a Type6NumericDate. The CBOR [RFC7519], except that the format MUST be a Type6NumericDate. The
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
[5], except that the format MUST be a Type6NumericDate. The CBOR [RFC7519], except that the format MUST be a Type6NumericDate. The
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 [5], except rules as the "jti" claim defined in Section 4.1.7 of JWT [RFC7519],
that the format MUST be of major type 3 with a case-sensitive string except that the format MUST be of major type 2, binary string. The
value. The CBOR encoded claim key 7 MUST be used to identify this CBOR encoded claim key 7 MUST be used to identify this claim.
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 | 6 tag value 1 |
| nbf | 5 | 6 tag value 1 | | nbf | 5 | 6 tag value 1 |
| iat | 6 | 6 tag value 1 | | iat | 6 | 6 tag value 1 |
| cti | 7 | 3 | | 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.
Note: Claims defined by the OpenID Foundation have not yet been 5. Creating and Validating CWTs
included in the table above.
5. Security Considerations 5.1. Creating a CWT
To create a CWT, the following steps are performed. The order of the
steps is not significant in cases where there are no dependencies
between the inputs and outputs of the steps.
1. Create a CWT Claims Set containing the desired claims.
2. Let the Message be the binary representation of the CWT Claims
Set.
3. Create a COSE Header containing the desired set of Header
Parameters. The CWT Header MUST be a valid according to the
[I-D.ietf-cose-msg] specification.
4. Depending upon whether the CWT is signed, MACed or encrypted,
there are three cases:
* If the CWT is signed, create a COSE_Sign/COSE_Sign1 object
using the Message as the COSE_Sign/COSE_Sign1 Payload; all
steps specified in [I-D.ietf-cose-msg] for creating a
COSE_Sign/COSE_Sign1 object MUST be followed.
* Else, if the CWT is MACed, create a COSE_Mac/COSE_Mac0 object
using the Message as the COSE_Mac/COSE_Mac0 Payload; all steps
specified in [I-D.ietf-cose-msg] for creating a COSE_Mac/
COSE_Mac0 object MUST be followed.
* Else, if the CWT is a COSE_Encrypt/COSE_Encrypt0 object,
create a COSE_Encrypt/COSE_Encrypt0 using the Message as the
plaintext for the COSE_Encrypt/COSE_Encrypt0 object; all steps
specified in [I-D.ietf-cose-msg] for creating a COSE_Encrypt/
COSE_Encrypt0 object MUST be followed.
5. If a nested signing, MACing or encryption operation will be
performed, let the Message be the COSE_Sign/COSE_Sign1, COSE_Mac/
COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, and return to Step 3,
using "content type" header value of "CWT" in the new COSE Header
created in that 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.
5.2. Validating a CWT
When validating a CWT, the following steps are performed. The order
of the steps is not significant in cases where there are no
dependencies between the inputs and outputs of the steps. If any of
the listed steps fail, then the CWT MUST be rejected -- that is,
treated by the application as an invalid input.
1. Verify that the CWT is a valid CBOR object.
2. Verify that the resulting COSE Header includes only parameters
and values whose syntax and semantics are both understood and
supported or that are specified as being ignored when not
understood.
3. Use the CBOR tag to determine the type the CWT, COSE_Sign/
COSE_Sign1, COSE_Mac/COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0.
4. Depending upon whether the CWT is a COSE_Sign/COSE_Sign1,
COSE_Mac/COSE_Mac0 or COSE_Encrypt/COSE_Encrypt0, there are three
cases:
* If the CWT is a COSE_Sign/COSE_Sign1, follow the steps
specified in [I-D.ietf-cose-msg] Section 4 (Signing Objects)
for validating a COSE_Sign/COSE_Sign1 object. Let the Message
be the COSE_Sign/COSE_Sign1 payload.
* Else, if the CWT is a COSE_Mac/COSE_Mac0, follow the steps
specified in [I-D.ietf-cose-msg] Section 6 (MAC Objects) for
validating a COSE_Mac/COSE_Mac0 object. Let the Message be
the COSE_Mac/COSE_Mac0 payload.
* Else, if the CWT is a COSE_Encrypt/COSE_Encrypt0 object,
follow the steps specified in [I-D.ietf-cose-msg] Section 5
(Encryption Objects) for validating a COSE_Encrypt/
COSE_Encrypt0 object. Let the Message be the resulting
plaintext.
5. If the JOSE Header contains a "content type" value of "CWT", then
the Message is a CWT that was the subject of nested signing or
encryption operations. In this case, return to Step 1, using the
Message as the CWT.
6. Verify that the Message is a valid CBOR object; let the CWT
Claims Set be this CBOR object.
6. Security Considerations
The security of the CWT is dependent on the protection offered by The security of the CWT is dependent on the protection offered by
COSE. Without protecting the claims contained in a CWT an adversary COSE. Without protecting the claims contained in a CWT an adversary
is able to modify, add or remove claims. Since the claims conveyed is able to modify, add or remove claims. Since the claims conveyed
in a CWT are used to make authorization decisions it is not only in a CWT are used to make authorization decisions it is not only
important to protect the CWT in transit but also to ensure that the important to protect the CWT in transit but also to ensure that the
recipient is able to authenticate the party that collected the claims recipient is able to authenticate the party that collected the claims
and created the CWT. Without trust of the recipient in the party and created the CWT. Without trust of the recipient in the party
that created the CWT no sensible authorization decision can be made. that created the CWT no sensible authorization decision can be made.
Furthermore, the creator of the CWT needs to carefully evaluate each Furthermore, the creator of the CWT needs to carefully evaluate each
claim value prior to including it in the CWT so that the recipient claim value prior to including it in the CWT so that the recipient
can be assured about the correctness of the provided information. can be assured about the correctness of the provided information.
6. IANA Considerations 7. IANA Considerations
This section will create a registry for CWT claims, possibly relating 7.1. CBOR Web Token (CWT) Claims Registry
them to the JWT Claims Registry.
7. Normative References This section establishes the IANA "CBOR Web Token (CWT) Claims"
registry.
[1] Bradner, S., "Key words for use in RFCs to Indicate Values are registered on a Specification Required [RFC5226] basis, on
the advice of one or more Designated Experts. However, to allow for
the allocation of values prior to publication, the Designated Experts
may approve registration once they are satisfied that such a
specification will be published.
Criteria that should be applied by the Designated Experts includes
determining whether the proposed registration duplicates existing
functionality, whether it is likely to be of general applicability or
whether it is useful only for a single application, and whether the
registration description is clear.
7.1.1. Registration Template
Claim Name:
The human-readable name requested (e.g., "iss").
Claim Description:
Brief description of the claim (e.g., "Issuer").
JWT Claim Name:
Claim Name of the equivalent JWT claim as registered in
[IANA.JWT.Claims]. CWT claims should normally have a
corresponding JWT claim. If a corresponding JWT claim would not
make sense, the Designated Experts can choose to accept
registrations for which the JWT Claim Name is listed as "N/A".
CBOR Key Value:
Key value for the claim. The key value MUST be an integer in the
range of 1 to 65536.
CBOR Major Type:
CBOR Major type and optional tag for the claim.
Change Controller:
For Standards Track RFCs, list the "IESG". For others, give the
name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included.
Specification Document(s):
Reference to the document or documents that specify the parameter,
preferably including URIs that can be used to retrieve copies of
the documents. An indication of the relevant sections may also be
included but is not required.
7.1.2. Initial Registry Contents
o Claim Name: "iss"
o Claim Description: Issuer
o JWT Claim Name: "iss"
o CBOR Key Value: 1
o CBOR Major Type: 3
o Change Controller: IESG
o Specification Document(s): Section 3.1.1 of [[ this specification
]]
o Claim Name: "sub"
o Claim Description: Subject
o JWT Claim Name: "sub"
o CBOR Key Value: 2
o CBOR Major Type: 3
o Change Controller: IESG
o Specification Document(s): Section 3.1.2 of [[ this specification
]]
o Claim Name: "aud"
o Claim Description: Audience
o JWT Claim Name: "aud"
o CBOR Key Value: 3
o CBOR Major Type: 3
o Change Controller: IESG
o Specification Document(s): Section 3.1.3 of [[ this specification
]]
o Claim Name: "exp"
o Claim Description: Expiration Time
o JWT Claim Name: "exp"
o CBOR Key Value: 4
o CBOR Major Type: 6, tag value 1
o Change Controller: IESG
o Specification Document(s): Section 3.1.4 of [[ this specification
]]
o Claim Name: "nbf"
o Claim Description: Not Before
o JWT Claim Name: "nbf"
o CBOR Key Value: 5
o CBOR Major Type: 6, tag value 1
o Change Controller: IESG
o Specification Document(s): Section 3.1.5 of [[ this specification
]]
o Claim Name: "iat"
o Claim Description: Issued At
o JWT Claim Name: "iat"
o CBOR Key Value: 6
o CBOR Major Type: 6, tag value 1
o Change Controller: IESG
o Specification Document(s): Section 3.1.6 of [[ this specification
]]
o Claim Name: "cti"
o Claim Description: CWT ID
o JWT Claim Name: "jti"
o CBOR Key Value: 7
o CBOR Major Type: 2
o Change Controller: IESG
o Specification Document(s): Section 3.1.7 of [[ this specification
]]
7.2. CoAP Content-Format Registration
This section registers the "application/cwt" CoAP Content-Format ID
in the "CoRE Parameters" sub-registry "CoAP Content-Format" in the
manner described in [RFC7252].
7.2.1. Registry Contents
o Media Type: application/cwt
o Encoding: -
o Id: TBD (maybe 61)
o Reference: [[ this specification ]]
8. References
8.1. Normative References
[I-D.ietf-cose-msg]
Schaad, J., "CBOR Object Signing and Encryption (COSE)",
draft-ietf-cose-msg-14 (work in progress), June 2016.
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>.
[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>.
[2] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[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 Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>. 2014, <http://www.rfc-editor.org/info/rfc7159>.
[3] Jones, M., Bradley, J., and N. Sakimura, "JSON Web [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
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>.
[4] 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>.
[5] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>. <http://www.rfc-editor.org/info/rfc7519>.
[6] Bormann, C. and P. Hoffman, "Concise Binary Object 8.2. Informative References
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[7] Schaad, J., "CBOR Encoded Message Syntax", draft-ietf-
cose-msg-12 (work in progress), May 2016.
[8] Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and [I-D.seitz-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authorization for the Internet of Things H. Tschofenig, "Authorization for the Internet of Things
using OAuth 2.0", draft-seitz-ace-oauth-authz-00 (work in using OAuth 2.0", draft-seitz-ace-oauth-authz-00 (work in
progress), October 2015. progress), October 2015.
Appendix A. Examples Appendix A. Examples
Three examples of CWTs follow. Three examples of CWTs follow.
A.1. CWT with "aud" and symmetric key A.1. CWT with "aud" and symmetric key
skipping to change at page 7, line 25 skipping to change at page 12, line 37
[ // COSE_Key is a CBOR map with an array of keys [ // COSE_Key is a CBOR map with an array of keys
{ {
"kty":4, // symmetric key is indicated using kty 4 "kty":4, // symmetric key is indicated using kty 4
"k": "loremipsum" // the symmetric key "k": "loremipsum" // the symmetric key
} }
] ]
} }
Figure 2: "aud" claim and symmetric key in non-normative JSON Figure 2: "aud" claim and symmetric key in non-normative JSON
Using the CBOR encoded claim keys according to Section 4 and COSE [7] Using the CBOR encoded claim keys according to Section 4 and COSE
makes a CWT with "aud" and a symmetric key look like this in CBOR [I-D.ietf-cose-msg] makes a CWT with "aud" and a symmetric key look
diagnostic notation: like this in CBOR diagnostic notation:
{ {
3: "coap://light.example.com", 3: "coap://light.example.com",
8: 8:
[ [
{ {
1: 4, 1: 4,
-1: "loremipsum" -1: "loremipsum"
} }
] ]
skipping to change at page 8, line 44 skipping to change at page 14, line 21
"kid": "11", "kid": "11",
"crv": 1, // using P-384 "crv": 1, // using P-384
"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff', "x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e' "y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'
} }
] ]
} }
Figure 5: "aud" claim and EC key in non-normative JSON Figure 5: "aud" claim and EC key in non-normative JSON
Using the CBOR encoded claim keys according to Section 4 and COSE [7] Using the CBOR encoded claim keys according to Section 4 and COSE
makes a CWT with "aud" and an EC key look like this in CBOR [I-D.ietf-cose-msg] makes a CWT with "aud" and an EC key look like
diagnostic notation: this in CBOR diagnostic notation:
{ {
3: "coap://light.example.com", 3: "coap://light.example.com",
8: 8:
[ [
{ {
1: 2, 1: 2,
2: "11", 2: "11",
-1: 1, -1: 1,
-2: h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff', -2: h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
skipping to change at page 10, line 33 skipping to change at page 16, line 28
"crv": 1, // using P-384 "crv": 1, // using P-384
"x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff', "x": h'bac5b11cad8f99f9c72b05cf4b9e26d244dc189f745228255a219a86d6a09eff',
"y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e' "y": h'20138bf82dc1b6d562be0fa54ab7804a3a64b6d72ccfed6b6fb6ed28bbfc117e'
} }
], ],
"aif": [["/s/light", 1], ["/a/led", 5], ["/dtls", 2]] "aif": [["/s/light", 1], ["/a/led", 5], ["/dtls", 2]]
} }
Figure 8: All claims, "aif" and EC key in non-normative JSON Figure 8: All claims, "aif" and EC key in non-normative JSON
Using the CBOR encoded claim keys according to Section 4 and COSE [7] Using the CBOR encoded claim keys according to Section 4 and COSE
makes a full CWT look like this in CBOR diagnostic notation: [I-D.ietf-cose-msg] makes a full CWT look like this in CBOR
diagnostic notation:
{ {
1: "coap://as.example.com", 1: "coap://as.example.com",
3: "coap://light.example.com", 3: "coap://light.example.com",
2: "erikw", 2: "erikw",
4: 1(1444064944), 4: 1(1444064944),
5: 1(1443944944), 5: 1(1443944944),
6: 1(1443944944), 6: 1(1443944944),
7: 2929, 7: 2929,
8: [ 8: [
skipping to change at page 12, line 41 skipping to change at page 18, line 41
2f64746c73 # "/dtls" 2f64746c73 # "/dtls"
02 # unsigned(2) 02 # unsigned(2)
Figure 10: Full CWT with EC in CBOR Figure 10: Full CWT with EC in CBOR
Size of the CWT with an EC key is 194 bytes. This is then packaged Size of the CWT with an EC key is 194 bytes. This is then packaged
signed and encrypted using COSE. signed and encrypted using COSE.
Appendix B. Acknowledgements Appendix B. Acknowledgements
A straw man proposal of CWT was written in the draft "Authorization This specification is based on JSON Web Token (JWT) [RFC7519], the
for the Internet of Things using OAuth 2.0" [8] with the help of authors of which also include Nat Sakimura and John Bradley. A straw
Ludwig Seitz, Goeran Selander, and Samuel Erdtman. man proposal of CWT was written in the draft "Authorization for the
Internet of Things using OAuth 2.0" [I-D.seitz-ace-oauth-authz] with
the help of Ludwig Seitz and Goeran Selander.
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 ]]
-01
o Added IANA registration for CWT Claims.
o Added IANA registration for the application/cwt CoAP content-
format type.
o Added Samuel Erdtman as an editor.
o Changed Erik's e-mail address.
-00 -00
o Created the initial working group version based on draft- o Created the initial working group version based on draft-
wahlstroem-ace-cbor-web-token-00. wahlstroem-ace-cbor-web-token-00.
Authors' Addresses Authors' Addresses
Erik Wahlstroem Erik Wahlstroem
Nexus Technology
Sweden Sweden
Email: erik.wahlstrom@nexusgroup.com Email: erik@wahlstromstekniska.se
URI: https://www.nexusgroup.com
Michael B. Jones Michael B. Jones
Microsoft Microsoft
Email: mbj@microsoft.com Email: mbj@microsoft.com
URI: http://self-issued.info/ URI: http://self-issued.info/
Hannes Tschofenig Hannes Tschofenig
ARM Ltd. ARM Ltd.
Hall in Tirol 6060 Hall in Tirol 6060
Austria Austria
Email: Hannes.Tschofenig@arm.com Email: Hannes.Tschofenig@arm.com
Samuel Erdtman
Spotify AB
Birger Jarlsgatan 61, 4tr
Stockholm 113 56
Sweden
Phone: +46702691499
Email: erdtman@spotify.com
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