JOSE Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track August 15, 2012
Expires: February 16, 2013
JSON Private Key
draft-jones-jose-json-private-key-00
Abstract
The JSON Private Key specification extends the JSON Web Key (JWK) and
JSON Web Algorithms (JWA) specifications to define a JavaScript
Object Notation (JSON) representation of private keys.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. JWK Parameters for Private Keys . . . . . . . . . . . . . . . . 3
3.1. JWK Parameters for Elliptic Curve Private Keys . . . . . . 3
3.1.1. "d" (ECC Private Key) Parameter . . . . . . . . . . . . 3
3.2. JWK Parameters for RSA Private Keys . . . . . . . . . . . . 3
3.2.1. "pri" (Private Exponent) Parameter . . . . . . . . . . 4
4. Example Private Keys . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5.1. JSON Web Key Parameters Registration . . . . . . . . . . . 5
5.1.1. Registry Contents . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Document History . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The JSON Private Key specification extends the JSON Web Key (JWK)
[JWK] and JSON Web Algorithms (JWA) [JWA] specifications to define a
JavaScript Object Notation (JSON) [RFC4627] representation of private
keys.
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 Key
(JWK) [JWK] and JSON Web Algorithms (JWA) [JWA] specifications.
3. JWK Parameters for Private Keys
This section defines additional JSON Web Key parameters that enable
JWKs to represent private keys.
3.1. JWK Parameters for Elliptic Curve Private Keys
When the JWK "alg" member value is "EC", the following member MAY be
used to represent an Elliptic Curve private key:
3.1.1. "d" (ECC Private Key) Parameter
The "d" (ECC private key) member contains the Elliptic Curve private
key value. It is represented as the base64url encoding of the
value's unsigned big endian representation as a byte array. The
array representation MUST not be shortened to omit any leading zero
bytes. For instance, when representing 521 bit integers, the byte
array to be base64url encoded MUST contain 66 bytes, including any
leading zero bytes.
3.2. JWK Parameters for RSA Private Keys
When the JWK "alg" member value is "RSA", the following member MAY be
used to represent an RSA private key:
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3.2.1. "pri" (Private Exponent) Parameter
The "pri" (private exponent) member contains the private exponent
value for the RSA private key. It is represented as the base64url
encoding of the value's unsigned big endian representation as a byte
array. The array representation MUST not be shortened to omit any
leading zero bytes. For instance, when representing 2048 bit
integers, the byte array to be base64url encoded MUST contain 256
bytes, including any leading zero bytes.
4. Example Private Keys
The following example JWK Set contains two keys represented as JWKs
containing both public and private key values: one using an Elliptic
Curve algorithm and a second one using an RSA algorithm. This
example extends the example in Section 3 of [JWK], adding private key
values. (Line breaks are for display purposes only.)
{"keys":
[
{"alg":"EC",
"crv":"P-256",
"x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4",
"y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM",
"d":"870MB6gfuTJ4HtUnUvYMyJpr5eUZNP4Bk43bVdj3eAE",
"use":"enc",
"kid":"1"},
{"alg":"RSA",
"mod":"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4
cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMst
n64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2Q
vzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbIS
D08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw
0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
"exp":"AQAB",
"pri":"X4cTteJY_gn4FYPsXB8rdXix5vwsg1FLN5E3EaG6RJoVH-HLLKD9
M7dx5oo7GURknchnrRweUkC7hT5fJLM0WbFAKNLWY2vv7B6NqXSzUvxT0_YSfqij
wp3RTzlBaCxWp4doFk5N2o8Gy_nHNKroADIkJ46pRUohsXywbReAdYaMwFs9tv8d
_cPVY3i07a3t8MN6TNwm0dSawm9v47UiCl3Sk5ZiG7xojPLu4sbg1U2jx4IBTNBz
nbJSzFHK66jT8bgkuqsk0GjskDJk19Z4qwjwbsnn4j2WBii3RL-Us2lGVkY8fkFz
me1z0HbIkfz0Y6mqnOYtqc0X4jfcKoAC8Q",
"kid":"2011-04-29"}
]
}
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5. IANA Considerations
5.1. JSON Web Key Parameters Registration
This specification registers the parameter names defined in
Section 3.1 and Section 3.2 in the IANA JSON Web Key Parameters
registry [JWK].
5.1.1. Registry Contents
o Parameter Name: "d"
o Change Controller: IETF
o Specification Document(s): Section 3.1.1 of [[ this document ]]
o Parameter Name: "pri"
o Change Controller: IETF
o Specification Document(s): Section 3.2.1 of [[ this document ]]
6. Security Considerations
The security considerations for this specification are the same as
those for the JSON Web Key (JWK) [JWK] specification and the portion
of the JSON Web Algorithms (JWA) [JWA] specification that pertains to
key representations.
7. Normative References
[JWA] Jones, M., "JSON Web Algorithms (JWA)", July 2012.
[JWK] Jones, M., "JSON Web Key (JWK)", July 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.
Appendix A. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
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-00
o Created draft-jones-jose-json-private-key to facilitate discussion
of the question from the W3C WebCrypto WG to the IETF JOSE WG of
whether JOSE plans to support a format for representing private
keys.
Author's Address
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
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