--- 1/draft-ietf-ace-cbor-web-token-07.txt 2017-08-16 15:13:16.989674810 -0700 +++ 2/draft-ietf-ace-cbor-web-token-08.txt 2017-08-16 15:13:17.033675871 -0700 @@ -1,23 +1,23 @@ ACE Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track E. Wahlstroem -Expires: December 31, 2017 +Expires: February 17, 2018 S. Erdtman Spotify AB H. Tschofenig ARM Ltd. - June 29, 2017 + August 16, 2017 CBOR Web Token (CWT) - draft-ietf-ace-cbor-web-token-07 + draft-ietf-ace-cbor-web-token-08 Abstract CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR) and CBOR Object Signing and Encryption (COSE) is used for added application layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token @@ -31,66 +31,66 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on December 31, 2017. + This Internet-Draft will expire on February 17, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. CBOR Related Terminology . . . . . . . . . . . . . . . . 3 - 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Registered Claims . . . . . . . . . . . . . . . . . . . . 5 3.1.1. iss (Issuer) Claim . . . . . . . . . . . . . . . . . 5 3.1.2. sub (Subject) Claim . . . . . . . . . . . . . . . . . 5 3.1.3. aud (Audience) Claim . . . . . . . . . . . . . . . . 5 3.1.4. exp (Expiration Time) Claim . . . . . . . . . . . . . 5 3.1.5. nbf (Not Before) Claim . . . . . . . . . . . . . . . 5 3.1.6. iat (Issued At) Claim . . . . . . . . . . . . . . . . 5 3.1.7. cti (CWT ID) Claim . . . . . . . . . . . . . . . . . 6 4. Summary of the claim names, keys, and value types . . . . . . 6 5. CBOR Tags and Claim Values . . . . . . . . . . . . . . . . . 6 6. CWT CBOR Tag . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Creating and Validating CWTs . . . . . . . . . . . . . . . . 7 7.1. Creating a CWT . . . . . . . . . . . . . . . . . . . . . 7 7.2. Validating a CWT . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 9.1. CBOR Web Token (CWT) Claims Registry . . . . . . . . . . 10 9.1.1. Registration Template . . . . . . . . . . . . . . . . 10 9.1.2. Initial Registry Contents . . . . . . . . . . . . . . 11 9.2. Media Type Registration . . . . . . . . . . . . . . . . . 13 9.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 13 9.3. CoAP Content-Formats Registration . . . . . . . . . . . . 13 - 9.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 14 + 9.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 13 9.4. CBOR Tag registration . . . . . . . . . . . . . . . . . . 14 9.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 14 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 14 10.2. Informative References . . . . . . . . . . . . . . . . . 15 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15 A.1. Example CWT Claims Set . . . . . . . . . . . . . . . . . 15 A.2. Example keys . . . . . . . . . . . . . . . . . . . . . . 16 A.2.1. 128-bit Symmetric Key as Hex Encoded String . . . . . 16 A.2.2. 256-bit Symmetric Key as Hex Encoded String . . . . . 16 @@ -116,43 +116,42 @@ Internet of Things (IoT) systems that use low power radio technologies. An alternative encoding of claims is defined in this document. Instead of using JSON, as provided by JWTs, this specification uses CBOR [RFC7049] and calls this new structure "CBOR Web Token (CWT)", which is a compact means of representing secured claims to be transferred between two parties. CWT is closely related to JWT. It references the JWT claims and both its name and pronunciation are derived from JWT. To protect the claims contained in CWTs, the CBOR - Object Signing and Encryption (COSE) [I-D.ietf-cose-msg] - specification is used. + Object Signing and Encryption (COSE) [RFC8152] specification is used. The suggested pronunciation of CWT is the same as the English word "cot". 1.1. CBOR Related Terminology In JSON, maps are called objects and only have one kind of map key: a string. CBOR uses strings, negative integers, and unsigned integers as map keys. The integers are used for compactness of encoding and easy comparison. The inclusion of strings allows for an additional range of short encoded values to be used. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. This document reuses terminology from JWT [RFC7519] and COSE - [I-D.ietf-cose-msg]. + [RFC8152]. StringOrURI The "StringOrURI" term has the same meaning, syntax, and processing rules as the "StringOrUri" term defined in Section 2 of JWT [RFC7519], except that it uses a CBOR text string instead of a JSON string value. NumericDate The "NumericDate" term has the same meaning, syntax, and processing rules as the "NumericDate" term defined in Section 2 of @@ -305,40 +304,40 @@ 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 COSE Header MUST be valid per the - [I-D.ietf-cose-msg] specification. + Parameters. The COSE Header MUST be valid per the [RFC8152] + 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. + steps specified in [RFC8152] 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. + specified in [RFC8152] 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/ + specified in [RFC8152] 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, add the matching COSE CBOR tag, and return to Step 3. 6. If needed by the application, add the appropriate COSE CBOR tag to the COSE object to indicate the type of the COSE object. If needed by the application, add the CWT CBOR tag to indicate that @@ -365,34 +364,33 @@ 4. 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. 5. Depending upon whether the CWT is a signed, MACed, or encrypted, 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. + specified in [RFC8152] 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. + specified in [RFC8152] 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. + follow the steps specified in [RFC8152] Section 5 (Encryption + Objects) for validating a COSE_Encrypt/COSE_Encrypt0 object. + Let the Message be the resulting plaintext. 6. If the Message begins with a COSE CBOR tag, then the Message is a CWT that was the subject of nested signing, MACing, or encryption operations. In this case, return to Step 1, using the Message as the CWT. 7. Verify that the Message is a valid CBOR map; let the CWT Claims Set be this CBOR map. 8. Security Considerations @@ -627,24 +624,20 @@ o Data Item: CBOR Web Token (CWT) o Semantics: CBOR Web Token (CWT), as defined in [[ this specification ]] o Reference: [[ this specification ]] o Point of Contact: Michael B. Jones, mbj@microsoft.com 10. References 10.1. Normative References - [I-D.ietf-cose-msg] - Schaad, J., "CBOR Object Signing and Encryption (COSE)", - draft-ietf-cose-msg-24 (work in progress), November 2016. - [IANA.CBOR.Tags] IANA, "Concise Binary Object Representation (CBOR) Tags", . [IANA.CoAP.Content-Formats] IANA, "CoAP Content-Formats", . @@ -658,20 +651,24 @@ . [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, October 2013, . [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, . + [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", + RFC 8152, DOI 10.17487/RFC8152, July 2017, + . + 10.2. Informative References [IANA.JWT.Claims] IANA, "JSON Web Token Claims", . [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, DOI 10.17487/RFC5226, May 2008, . @@ -691,20 +688,25 @@ Appendix A. Examples This appendix includes a set of CWT examples that show how the CWT Claims Set can be protected. There are examples that are signed, MACed, encrypted, and that use nested signing and encryption. To make the examples easier to read, they are presented both as hex strings and in the extended CBOR diagnostic notation described in Section 6 of [RFC7049]. + Where a byte string is to carry an embedded CBOR-encoded item, the + diagnostic notation for this CBOR data item can be enclosed in '<<' + and '>>' to notate the byte string resulting from encoding the data + item, e.g., h'63666F6F' translates to <<"foo">>. + A.1. Example CWT Claims Set The CWT Claims Set used for the different examples displays usage of all the defined claims. For signed and MACed examples, the CWT Claims Set is the CBOR encoding as a binary string. a70175636f61703a2f2f61732e6578616d706c652e636f6d02656572696b7703 7818636f61703a2f2f6c696768742e6578616d706c652e636f6d041a5612aeb0 051a5610d9f0061a5610d9f007420b71 @@ -771,36 +773,33 @@ d28443a10126a05850a70175636f61703a2f2f61732e6578616d706c652e636f6 d02656572696b77037818636f61703a2f2f6c696768742e6578616d706c652e63 6f6d041a5612aeb0051a5610d9f0061a5610d9f007420b7158405427c1ff28d23 fbad1f29c4c7c6a555e601d6fa29f9179bc3d7438bacaca5acd08c8d4d4f96131 680c429a01f85951ecee743a52b9b63632c57209120e1c9e30 Figure 7: Signed CWT as hex string 18( [ - / protected / h'a10126' / { + / protected / << { / alg / 1: -7 / ECDSA 256 / - } / , + } >>, / unprotected / {}, - / payload / h'a70175636f61703a2f2f61732e6578616d706c652e63 - 6f6d02656572696b77037818636f61703a2f2f6c6967 - 68742e6578616d706c652e636f6d041a5612aeb0051a - 5610d9f0061a5610d9f007420b71' / { + / payload / << { / 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' - } / , + } >>, / signature / h'5427c1ff28d23fbad1f29c4c7c6a555e601d6fa29f 9179bc3d7438bacaca5acd08c8d4d4f96131680c42 9a01f85951ecee743a52b9b63632c57209120e1c9e 30' ] ) Figure 8: Signed CWT in CBOR diagnostic notation A.4. Example MACed CWT @@ -815,36 +814,33 @@ d83dd18443a10104a05850a70175636f61703a2f2f61732e6578616d706c652e 636f6d02656572696b77037818636f61703a2f2f6c696768742e6578616d706c 652e636f6d041a5612aeb0051a5610d9f0061a5610d9f007420b7148093101ef 6d789200 Figure 9: MACed CWT with CWT tag as hex string 61( 17( [ - / protected / h'a10104' / { - / alg / 1: 4 / HMAC 256/64 / - } / , + / protected / << { + / alg / 1: 4 / HMAC-256-64 / + } >>, / unprotected / {}, - / payload / h'a70175636f61703a2f2f61732e6578616d706c652e636f - 6d02656572696b77037818636f61703a2f2f6c69676874 - 2e6578616d706c652e636f6d041a5612aeb0051a5610d9 - f0061a5610d9f007420b71' / { + / payload / << { / 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 with CWT tag in CBOR diagnostic notation A.5. Example Encrypted CWT This section shows an encrypted CWT with a single recipient and a @@ -856,23 +852,23 @@ d08343a1010aa1054d99a0d7846e762c49ffe8a63e0b5858b918a11fd81e438b 7f973d9e2e119bcb22424ba0f38a80f27562f400ee1d0d6c0fdb559c02421fd3 84fc2ebe22d7071378b0ea7428fff157444d45f7e6afcda1aae5f6495830c586 27087fc5b4974f319a8707a635dd643b Figure 11: Encrypted CWT as hex string 16( [ - / protected / h'a1010a' / { + / protected / << { / alg / 1: 10 / AES-CCM-16-64-128 / - } /, + } >>, / unprotected / { / iv / 5: h'99a0d7846e762c49ffe8a63e0b' }, / ciphertext / h'b918a11fd81e438b7f973d9e2e119bcb22424ba0f38 a80f27562f400ee1d0d6c0fdb559c02421fd384fc2e be22d7071378b0ea7428fff157444d45f7e6afcda1a ae5f6495830c58627087fc5b4974f319a8707a635dd 643b' ] ) @@ -900,23 +896,23 @@ 601ebfb29454050a3c99fd13b27216d084556496c7355c4bb462510f8e0e8479 dbe08722d620e96bcb7764d75140d96220f062679b46b897e7abe0c325dc2c96 d8bb2c8334e3b92a42c0078983e753c054e647ad5387ed149f802f52b5a95ebf 5f153c4fd64854ab7531e082b7f22721f939d257c94f8bc248e1d9cf04f9dd4e 5de7ab62df37842fabec230a657d4abf7162bc786345ebb8eb3af0 Figure 13: Signed and Encrypted CWT as hex string 16( [ - / protected / h'a203183d010a' / { + / protected / << { / alg / 1: 10 / AES-CCM-16-64-128 / - } / , + } >>, / unprotected / { / iv / 5: h'86bbd41cc32604396324b7f380' }, / ciphertext / h'72439fbff538aa7b601ebfb29454050a3c99fd13b27 216d084556496c7355c4bb462510f8e0e8479dbe087 22d620e96bcb7764d75140d96220f062679b46b897e 7abe0c325dc2c96d8bb2c8334e3b92a42c0078983e7 53c054e647ad5387ed149f802f52b5a95ebf5f153c4 fd64854ab7531e082b7f22721f939d257c94f8bc248 e1d9cf04f9dd4e5de7ab62df37842fabec230a657d4 @@ -934,45 +930,50 @@ 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 purposes only. d18443a10104a04ba106fb41d584367c20000048b8816f34c0542892 Figure 15: MACed CWT with a floating-point value as hex string 17( [ - / protected / h'a10104' / { - / alg / 1: 4 / HMAC 256/64 / - } / , + / protected / << { + / alg / 1: 4 / HMAC-256-64 / + } >>, / unprotected / {}, - / payload / h'a106fb41d584367c200000' / { + / payload / << { / iat / 6: 1443944944.5 - } / , + } >>, / tag / h'b8816f34c0542892' ] ) Figure 16: MACed CWT with a floating-point value in CBOR diagnostic notation Appendix B. Acknowledgements This specification is based on JSON Web Token (JWT) [RFC7519], the authors of which also include Nat Sakimura and John Bradley. It also incorporates suggestions made by many people, notably Carsten Bormann, Jim Schaad, Ludwig Seitz, and Goeran Selander. Appendix C. Document History [[ to be removed by the RFC Editor before publication as an RFC ]] + -08 + + o Updated the diagnostic notation for embedded objects in the + examples, addressing feedback by Carsten Bormann. + -07 o Updated examples for signing and encryption. Signatures are now deterministic as recommended by COSE specification. -06 o Addressed review comments by Carsten Bormann and Jim Schaad. All changes were editorial in nature.