JOSE Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track March 5, 2012
Expires: September 6, 2012
JSON Web Encryption JSON Serialization (JWE-JS)
draft-jones-json-web-encryption-json-serialization-00
Abstract
The JSON Web Encryption JSON Serialization (JWE-JS) is a means of
representing encrypted content using 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 enumerated in the separate JSON Web Algorithms (JWA)
specification. The JSON Serialization for related digital signature
and HMAC functionality is described in the separate JSON Web
Signature JSON Serialization (JWS-JS) specification.
Requirements Language
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 RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 6, 2012.
Copyright Notice
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Copyright (c) 2012 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. JSON Serialization . . . . . . . . . . . . . . . . . . . . . . 3
4. Example JWE-JS . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. Open Issues and Things To Be Done (TBD) . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 6
Appendix B. Document History . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The JSON Web Encryption JSON Serialization (JWE-JS) is a format for
representing encrypted content as a JSON RFC 4627 [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 enumerated in the
separate JSON Web Algorithms (JWA) [JWA] specification. The JSON
Serialization for related digital signature and HMAC functionality is
described in the separate JSON Web Signature JSON Serialization
(JWS-JS) [JWS-JS] specification.
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 members for each of three constituent parts: a "headers" member
whose value is a non-empty array of Encoded JWE Header values, a
"encrypted_keys" member whose value is a non-empty array of Encoded
JWE Encrypted Key values, where the number of elements in both arrays
is the same, and a "ciphertext" member whose value is an Encoded JWE
Ciphertext value.
Unlike the compact serialization used by JWEs, content using the JSON
Serialization MAY be encrypted to more than one recipient. Each
recipient requires 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; these values are represented as Encoded JWE Header values
that are elements of the non-empty array contained in the "headers"
member. Each recipient also requires a JWE Encrypted Key value;
these values are represented as Encoded JWE Encrypted Key values that
are corresponding elements of the non-empty array contained in the
"encrypted_keys" member. Therefore, the syntax is:
{"headers":["<header 1 contents>",...,"<header N contents>"],
"encrypted_keys":["<key 1 contents>",...,"<key N contents>"],
"ciphertext":"<ciphertext contents>"
}
The contents of the Encoded JWE Header, Encoded JWE Encrypted Key,
and Encoded JWE Ciphertext values are exactly as specified in JSON
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Web Encryption (JWE) [JWE]. They are interpreted and validated in
the same manner, with each corresponding "headers" and
"encrypted_keys" value being created or validated together. The
arrays MUST have the same number of elements.
The i'th JWE Encrypted Key value is computed using the parameters of
i'th 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 "encrypted_keys" array is identical to the
value that would have been computed for the same header and payload
in a JWE, as is the JWE Ciphertext value.
All recipients use the same JWE Ciphertext value, 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. In
particular, this means that the "enc" (encryption method) header
parameter value in the JWE Header for each recipient MUST be the
same, as MUST be the "iv" (initialization vector) value (when
required for the algorithm).
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: both using the RSA-
PKCS1_1.5 algorithm to produce the JWE Encrypted Key (but with using
different public keys). The Plaintext is encrypted using the AES-
256-GCM algorithm to produce the JWE Ciphertext. The two Decoded JWE
Header Segments used are:
{"alg":"RSA1_5",
"enc":"A256GCM",
"iv":"__79_Pv6-fg",
"x5t":"7noOPq-hJ1_hCnvWh6IeYI2w9Q0"}
and:
{"alg":"RSA1_5",
"enc":"A256GCM",
"iv":"__79_Pv6-fg",
"jku":"https://example.com/public_key.jwk"}
The complete JSON Web Encryption JSON Serialization (JWE-JS) for
these values is as follows (with line breaks for display purposes
only):
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{"headers":[
"eyJhbGciOiJSU0ExXzUiLA0KICJlbmMiOiJBMjU2R0NNIiwNCiAiaXYiOiJfX
zc5X1B2Ni1mZyIsDQogIng1dCI6Ijdub09QcS1oSjFfaENudldoNkllWUkydzlRM
CJ9",
"eyJhbGciOiJSU0ExXzUiLA0KICJlbmMiOiJBMjU2R0NNIiwNCiAiaXYiOiJfX
zc5X1B2Ni1mZyIsDQogImprdSI6Imh0dHBzOi8vZXhhbXBsZS5jb20vcHVibGljX
2tleS5qd2sifQ"],
"encrypted_keys":[
"TBD_key_1_value_TBD",
"TBD_key_2_value_TBD"],
"ciphertext":"TBD_ciphertext_value_TBD"
}
TBD: Finish this example.
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. Open Issues and Things To Be Done (TBD)
The following items remain to be done in this draft:
o Complete the example.
o Track changes that occur in the JWE spec, including the
introduction of integrity protection for non AEAD operations.
8. References
8.1. Normative References
[JWA] Jones, M., "JSON Web Algorithms (JWA)", January 2012.
[JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
Encryption (JWE)", January 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
8.2. 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)", March 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. Document History
-00
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/
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