JSON Web Signature JSON Serialization (JWS-JS)
draft-jones-jose-jws-json-serialization-04

Abstract

The JSON Web Signature JSON Serialization (JWS-JS) is a means of representing content secured with digital signatures or Message Authentication Codes (MACs) using JavaScript Object Notation (JSON) data structures. This specification describes a means of representing secured content as a JSON data object (as opposed to the JWS specification, which uses a compact serialization with a URL-safe representation). It enables multiple digital signatures and/or MACs to be applied to the same content (unlike JWS). Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) specification. The JSON Serialization for related encryption functionality is described in the separate JSON Web Encryption JSON Serialization (JWE-JS) specification.

Status of This Memo

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This Internet-Draft will expire on July 01, 2013.

Copyright Notice

Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 1.1. Notational Conventions
• 2. Terminology
• 3. JSON Serialization
• 4. Example JWS-JS
• 5. IANA Considerations
• 6. Security Considerations
• 7. References
• 7.1. Normative References
• 7.2. Informative References
• Appendix A. Acknowledgements
• Appendix B. Open Issues
• Appendix C. Document History
• Authors' Addresses

1. Introduction

The JSON Web Signature JSON Serialization (JWS-JS) is a format for representing content secured with digital signatures or Message Authentication Codes (MACs) as a JavaScript Object Notation (JSON) [RFC4627] object. It enables multiple digital signatures and/or MACs to be applied to the same content (unlike JWS [JWS]). The digital signature and MAC mechanisms used are independent of the type of content being secured, allowing arbitrary content to be secured. Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] specification. The JSON Serialization for related encryption functionality is described in the separate JSON Web Encryption JSON Serialization (JWE-JS) [JWE-JS] specification.

1.1. Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD 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].

2. Terminology

This specification uses the same terminology as the JSON Web Signature (JWS) [JWS] specification.

3. JSON Serialization

The JSON Serialization represents secured content as a JSON object with a recipients member containing an array of per-recipient information and a payload member containing a shared Encoded JWS Payload value. Each member of the recipients array is a JSON object with a header member containing an Encoded JWS Header value and a signature member containing an Encoded JWS Signature value.

Unlike the compact serialization used by JWSs, content using the JSON Serialization MAY be secured with more than one digital signature and/or MAC value. Each is represented as an Encoded JWS Signature value in the signature member of an object in the recipients array. For each, there is an Encoded JWS Encoded Header value in the header member of the same object in the recipients array. This specifies the digital signature or MAC applied to the Encoded JWS Header value and the shared Encoded JWS Payload value to create the JWS Signature value. Therefore, the syntax is:

  {"recipients":[
    {"header":"<header 1 contents>",
     "signature":"<signature 1 contents>"},
    ...
    {"header":"<header N contents>",
     "signature":"<signature N contents>"}],
   "payload":"<payload contents>"
  }

The contents of the Encoded JWS Header, Encoded JWS Payload, and Encoded JWS Signature values are exactly as specified in JSON Web Signature (JWS) [JWS]. They are interpreted and validated in the same manner, with each corresponding header and signature value being created and validated together.

Each JWS Signature value is computed on the JWS Secured Input corresponding to the concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload in the same manner described in the JWS specification. This has the desirable result that each Encoded JWS signature value in the recipients array is identical to the value that would be used for the same parameters in a JWS.

4. Example JWS-JS

This section contains an example using the JWS JSON Serialization. This example demonstrates the capability for conveying multiple digital signatures and/or MACs for the same payload.

The Encoded JWS Payload used in this example is the same as used in the examples in Appendix A of JWS (with line breaks for display purposes only):

  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

Two digital signatures are used in this example: an RSA SHA-256 signature, for which the header and signature values are the same as in Appendix A.2 of JWS, and an ECDSA P-256 SHA-256 signature, for which the header and signature values are the same as in Appendix A.3 of JWS. The two Decoded JWS Header Segments used are:

  {"alg":"RS256"}

and:

  {"alg":"ES256"}

Since the computations of the JWS Header and JWS Signature values are the same as in Appendix A.2 and Appendix A.3 of JWS, they are not repeated here.

The complete JSON Web Signature JSON Serialization (JWS-JS) for these values is as follows (with line breaks for display purposes only):

  {"recipients":[
    {"header":"eyJhbGciOiJSUzI1NiJ9",
     "signature":
      "cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZ
       mh7AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjb
       KBYNX4BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHl
       b1L07Qe7K0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZES
       c6BfI7noOPqvhJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AX
       LIhWkWywlVmtVrBp0igcN_IoypGlUPQGe77Rw"},
    {"header":"eyJhbGciOiJFUzI1NiJ9",
     "signature":
      "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
       lSApmWQxfKTUJqPP3-Kg6NU1Q"}],
   "payload":
    "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
     tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ"
  }

5. IANA Considerations

This specification makes no requests of IANA.

6. Security Considerations

The security considerations for this specification are the same as those for the JSON Web Signature (JWS) [JWS] specification.

7. References

7.1. Normative References

7.2. Informative References

Appendix A. Acknowledgements

JSON serializations for secured content were previously explored by Magic Signatures [MagicSignatures] and JSON Simple Sign [JSS].

Appendix B. Open Issues

[[ to be removed by the RFC editor before publication as an RFC ]]

The following items remain to be considered or done in this draft:

• Track changes that occur in the JWS spec.

Appendix C. Document History

[[ to be removed by the RFC editor before publication as an RFC ]]

-04

• Added seriesInfo information to Internet Draft references.

-03

• Updated references.

-02

• Changed to use an array of structures for per-recipient values, rather than a set of parallel arrays.

-01

• Generalized language to refer to Message Authentication Codes (MACs) rather than Hash-based Message Authentication Codes (HMACs).

-00

• Renamed draft-jones-json-web-signature-json-serialization to draft-jones-jose-jws-json-serialization to have "jose" be in the document name so it can be included in the Related Documents list at http://datatracker.ietf.org/wg/jose/. No normative changes.

draft-jones-json-web-signature-json-serialization-02

• Tracked editorial changes made to the JWS spec.

draft-jones-json-web-signature-json-serialization-01

• Corrected the Magic Signatures reference.

draft-jones-json-web-signature-json-serialization-00

• Created the initial version incorporating JOSE working group input and drawing from the JSON Serialization previously proposed in draft-jones-json-web-token-01.

Authors' Addresses