JOSE Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track December 27, 2012 Expires: June 30, 2013 JSON Web Encryption JSON Serialization (JWE-JS) draft-jones-jose-jwe-json-serialization-04 Abstract The JSON Web Encryption JSON Serialization (JWE-JS) is a means of representing encrypted content 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 JWE specification, which uses a compact serialization with a URL-safe representation). It enables the same content to be encrypted to multiple parties (unlike JWE). Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) specification. The JSON Serialization for related digital signature and MAC functionality is described in the separate JSON Web Signature JSON Serialization (JWS-JS) specification. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. 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 June 30, 2013. Copyright Notice Copyright (c) 2012 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 Jones Expires June 30, 2013 [Page 1] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 (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. Notational Conventions . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. JSON Serialization . . . . . . . . . . . . . . . . . . . . . . 3 4. Example JWE-JS . . . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 7 Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 7 Appendix C. Document History . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 Jones Expires June 30, 2013 [Page 2] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 1. Introduction The JSON Web Encryption JSON Serialization (JWE-JS) is a format for representing encrypted content as a JavaScript Object Notation (JSON) [RFC4627] object. It enables the same content to be encrypted to multiple parties (unlike JWE [JWE].) The encryption mechanisms are independent of the type of content being encrypted. Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] specification. The JSON Serialization for related digital signature and MAC functionality is described in the separate JSON Web Signature JSON Serialization (JWS-JS) [JWS-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 Encryption (JWE) [JWE] specification. 3. JSON Serialization The JSON Serialization represents encrypted content as a JSON object with a "recipients" member containing an array of per-recipient information, an "initialization_vector" member containing a shared Encoded JWE Initialization Vector value, and a "ciphertext" member containing a shared Encoded JWE Ciphertext value. Each member of the "recipients" array is a JSON object with a "header" member containing an Encoded JWE Header value, an "encrypted_key" member containing an Encoded JWE Encrypted Key value, and an "integrity_value" member containing an Encoded JWE Integrity Value value. Unlike the compact serialization used by JWEs, content using the JSON Serialization MAY be encrypted to more than one recipient. Each recipient requires: o a JWE Header value specifying the cryptographic parameters used to encrypt the JWE Encrypted Key to that recipient and the parameters used to encrypt the plaintext to produce the JWE Ciphertext; this is represented as an Encoded JWE Header value in the "header" member of an object in the "recipients" array. Jones Expires June 30, 2013 [Page 3] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 o a JWE Encrypted Key value used to encrypt the ciphertext; this is represented as an Encoded JWE Encrypted Key value in the "encrypted_key" member of the same object in the "recipients" array. o a JWE Integrity Value that ensures the integrity of the Ciphertext and the parameters used to create it; this is represented as an Encoded JWE Integrity Value value in the "integrity_value" member of the same object in the "recipients" array. Therefore, the syntax is: {"recipients":[ {"header":"
", "encrypted_key":"", "integrity_value":""}, ... {"header":"
", "encrypted_key":"", "integrity_value":""}], "initialization_vector":"", "ciphertext":"" } The contents of the Encoded JWE Header, Encoded JWE Encrypted Key, Encoded JWE Initialization Vector, Encoded JWE Ciphertext, and Encoded JWE Integrity Value values are exactly as specified in JSON Web Encryption (JWE) [JWE]. They are interpreted and validated in the same manner, with each corresponding "header", "encrypted_key", and "integrity_value" value being created and validated together. Each JWE Encrypted Key value and the corresponding JWE Integrity Value are computed using the parameters of the corresponding JWE Header value in the same manner described in the JWE specification. This has the desirable result that each Encoded JWE Encrypted Key value in the "recipients" array and each Encoded JWE Integrity Value in the same array element are identical to the values that would have been computed for the same parameters in a JWE, as is the shared JWE Ciphertext value. All recipients use the same JWE Ciphertext and JWE Initialization Vector values, resulting in potentially significant space savings if the message is large. Therefore, all header parameters that specify the treatment of the JWE Ciphertext value MUST be the same for all recipients. This primarily means that the "enc" (encryption method) header parameter value in the JWE Header for each recipient MUST be the same. Jones Expires June 30, 2013 [Page 4] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 4. Example JWE-JS This section contains an example using the JWE JSON Serialization. This example demonstrates the capability for encrypting the same plaintext to multiple recipients. Two recipients are present in this example: the first using the RSAES-PKCS1-V1_5 algorithm to encrypt the Content Master Key (CMK) and the second using RSAES OAEP to encrypt the CMK. The Plaintext is encrypted using the AES CBC algorithm and the same block encryption parameters to produce the common JWE Ciphertext value. The two Decoded JWE Header Segments used are: {"alg":"RSA1_5","enc":"A128CBC+HS256"} and: {"alg":"RSA-OAEP","enc":"A128CBC+HS256"} The keys used for the first recipient are the same as those in Appendix A.2 of [JWE], as is the plaintext used. The asymmetric encryption key used for the second recipient is the same as that used in Appendix A.1 of [JWE]; the block encryption keys and parameters for the second recipient are the same as those for the first recipient (which must be the case, since the initialization vector and ciphertext are shared). The complete JSON Web Encryption JSON Serialization (JWE-JS) for these values is as follows (with line breaks for display purposes only): Jones Expires June 30, 2013 [Page 5] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 {"recipients":[ {"header": "eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0", "encrypted_key": "ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDG u1IW40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDD B3mbkInMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJ Na1-6CIU12Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxR jHFhpOeDp_adx8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA 1PHDg-10ceuTEtq_vPE4-Gtev4N4K4Eudlj4Q", "integrity_value": "8LXqMd0JLGsxMaB5uoNaMpg7uUW_p40RlaZHCwMIyzk"}, {"header": "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMrSFMyNTYifQ", "encrypted_key": "nxwnYB86zEvVRofSxnDuFAE9-Gi2JtCy5eMyYedowjfGlkoA-Y0JyfwWXE_EU vhq6WS_DM3a18You2Qsah3BvvSRPZ8-TNYX3_4QCEO-V8EVbF1eGoJFs9ODmC cOiuMl1xLnSAYlwEDDnhwEkXv8o6MZEvh-msqTY6NyFGd6mhjpu9P4o2F2hOe Nt6FthcR4cNpAVSbydEEBszsrp27nB-JwfmLjnSYQO1JBwbgUJXHZyIJcQa7i 43Vko02HkWTxBta0q5Zr_Jd7V2l-6HLYIuNc7fZH1DSJSTBTotcugumR5zNX_ uxQyMoWOQ-SsQ7HxqrrFbo5FNoLPZiuNYuCdQ", "integrity_value": "QbYksTWNZTcMfJMLoGB_aTCA0-IuNObm19_VdpabviM"}], "initialization_vector": "AxY8DCtDaGlsbGljb3RoZQ", "ciphertext": "Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJE Z" } 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 Encryption (JWE) [JWE] specification. 7. References 7.1. Normative References [JWA] Jones, M., "JSON Web Algorithms (JWA)", draft-ietf-jose-json-web-algorithms (work in progress), Jones Expires June 30, 2013 [Page 6] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 December 2012. [JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web Encryption (JWE)", draft-ietf-jose-json-web-encryption (work in progress), December 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. 7.2. Informative References [I-D.rescorla-jsms] Rescorla, E. and J. Hildebrand, "JavaScript Message Security Format", draft-rescorla-jsms-00 (work in progress), March 2011. [JSE] Bradley, J. and N. Sakimura (editor), "JSON Simple Encryption", September 2010. [JWS-JS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature JSON Serialization (JWS-JS)", draft-jones-jose-jws-json-serialization (work in progress), December 2012. Appendix A. Acknowledgements JSON serializations for encrypted content were previously explored by JSON Simple Encryption [JSE] and JavaScript Message Security Format [I-D.rescorla-jsms]. 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: o Track changes that occur in the JWE spec. Appendix C. Document History [[ to be removed by the RFC editor before publication as an RFC ]] Jones Expires June 30, 2013 [Page 7] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 -04 o Added seriesInfo information to Internet Draft references. -03 o Updated values for example AES CBC calculations. -02 o Changed to use an array of structures for per-recipient values, rather than a set of parallel arrays. o Promoted Initialization Vector from being a header parameter to being a top-level JWE element. This saves approximately 16 bytes in the compact serialization, which is a significant savings for some use cases. Promoting the Initialization Vector out of the header also avoids repeating this shared value in the JSON serialization. -01 o Added a complete JWE-JS example. o Generalized language to refer to Message Authentication Codes (MACs) rather than Hash-based Message Authentication Codes (HMACs). -00 o Renamed draft-jones-json-web-encryption-json-serialization to draft-jones-jose-jwe-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-encryption-json-serialization-02 o Updated examples to track updated algorithm properties in the JWA spec. o Tracked editorial changes made to the JWE spec. draft-jones-json-web-encryption-json-serialization-01 o Tracked changes between JOSE JWE draft -00 and -01, which added an integrity check for non-Authenticated Encryption algorithms. draft-jones-json-web-encryption-json-serialization-00 Jones Expires June 30, 2013 [Page 8] Internet-Draft JWE JSON Serialization (JWE-JS) December 2012 o Created the initial version incorporating JOSE working group input and drawing from the JSON Serialization previously proposed in draft-jones-json-web-token-01. Author's Address Michael B. Jones Microsoft Email: mbj@microsoft.com URI: http://self-issued.info/ Jones Expires June 30, 2013 [Page 9]