JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                        November 6, 2012
Expires: May 10, 2013


                            JSON Private Key
                  draft-jones-jose-json-private-key-01

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.

Status of this Memo

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   This Internet-Draft will expire on May 10, 2013.

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   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  . . . . . . . . . . . . . . . . . . . . . . . . . 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.  "d" (Private Exponent) Parameter  . . . . . . . . . . . 4
       3.2.2.  "p" (First Prime Factor) Parameter  . . . . . . . . . . 4
       3.2.3.  "q" (Second Prime Factor) Parameter . . . . . . . . . . 4
       3.2.4.  "dp" (First Factor CRT Exponent) Parameter  . . . . . . 4
       3.2.5.  "dq" (Second Factor CRT Exponent) Parameter . . . . . . 4
       3.2.6.  "qi" (First CRT Coefficient) Parameter  . . . . . . . . 4
       3.2.7.  "oth" (Other Primes Info) Parameter . . . . . . . . . . 4
         3.2.7.1.  "r" (Prime Factor)  . . . . . . . . . . . . . . . . 5
         3.2.7.2.  "d" (Factor CRT Exponent) . . . . . . . . . . . . . 5
         3.2.7.3.  "t" (Factor CRT Coefficient)  . . . . . . . . . . . 5
   4.  Example Private Keys  . . . . . . . . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
     5.1.  JSON Web Key Parameters Registration  . . . . . . . . . . . 7
       5.1.1.  Registry Contents . . . . . . . . . . . . . . . . . . . 7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 8
   Appendix A.  Document History . . . . . . . . . . . . . . . . . . . 8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 8
























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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.  "d" (Private Exponent) Parameter

   The "d" (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.

3.2.2.  "p" (First Prime Factor) Parameter

   The "p" (first prime factor) member contains the first prime factor,
   a positive integer.  It is represented as the base64url encoding of
   the value's unsigned big endian representation as a byte array.

3.2.3.  "q" (Second Prime Factor) Parameter

   The "q" (second prime factor) member contains the second prime
   factor, a positive integer.  It is represented as the base64url
   encoding of the value's unsigned big endian representation as a byte
   array.

3.2.4.  "dp" (First Factor CRT Exponent) Parameter

   The "dp" (first factor CRT exponent) member contains the Chinese
   Remainder Theorem (CRT) exponent of the first factor, a positive
   integer.  It is represented as the base64url encoding of the value's
   unsigned big endian representation as a byte array.

3.2.5.  "dq" (Second Factor CRT Exponent) Parameter

   The "dq" (second factor CRT exponent) member contains the Chinese
   Remainder Theorem (CRT) exponent of the second factor, a positive
   integer.  It is represented as the base64url encoding of the value's
   unsigned big endian representation as a byte array.

3.2.6.  "qi" (First CRT Coefficient) Parameter

   The "dp" (first CRT coefficient) member contains the Chinese
   Remainder Theorem (CRT) coefficient of the second factor, a positive
   integer.  It is represented as the base64url encoding of the value's
   unsigned big endian representation as a byte array.

3.2.7.  "oth" (Other Primes Info) Parameter

   The "oth" (other primes info) member contains an array of information
   about any third and subsequent primes, should they exist.  When only



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   two primes have been used (the normal case), this parameter MUST be
   omitted.  When three or more primes have been used, the number of
   array elements MUST be the number of primes used minus two.  Each
   array element MUST be an object with the following members:

3.2.7.1.  "r" (Prime Factor)

   The "r" (prime factor) parameter within an "oth" array member
   represents the value of a subsequent prime factor, a positive
   integer.  It is represented as the base64url encoding of the value's
   unsigned big endian representation as a byte array.

3.2.7.2.  "d" (Factor CRT Exponent)

   The "d" (Factor CRT Exponent) parameter within an "oth" array member
   represents the CRT exponent of the corresponding prime factor, a
   positive integer.  It is represented as the base64url encoding of the
   value's unsigned big endian representation as a byte array.

3.2.7.3.  "t" (Factor CRT Coefficient)

   The "t" (factor CRT coefficient) parameter within an "oth" array
   member represents the CRT coefficient of the corresponding prime
   factor, a positive integer.  It is represented as the base64url
   encoding of the value's unsigned big endian representation as a byte
   array.


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.)
















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     {"keys":
       [
         {"alg":"EC",
          "crv":"P-256",
          "x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4",
          "y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM",
          "d":"870MB6gfuTJ4HtUnUvYMyJpr5eUZNP4Bk43bVdj3eAE",
          "use":"enc",
          "kid":"1"},

         {"alg":"RSA",
          "n":"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4
     cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMst
     n64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2Q
     vzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbIS
     D08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw
     0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
          "e":"AQAB",
          "d":"X4cTteJY_gn4FYPsXB8rdXix5vwsg1FLN5E3EaG6RJoVH-HLLKD9
     M7dx5oo7GURknchnrRweUkC7hT5fJLM0WbFAKNLWY2vv7B6NqXSzUvxT0_YSfqij
     wp3RTzlBaCxWp4doFk5N2o8Gy_nHNKroADIkJ46pRUohsXywbReAdYaMwFs9tv8d
     _cPVY3i07a3t8MN6TNwm0dSawm9v47UiCl3Sk5ZiG7xojPLu4sbg1U2jx4IBTNBz
     nbJSzFHK66jT8bgkuqsk0GjskDJk19Z4qwjwbsnn4j2WBii3RL-Us2lGVkY8fkFz
     me1z0HbIkfz0Y6mqnOYtqc0X4jfcKoAC8Q",
          "p":"83i-7IvMGXoMXCskv73TKr8637FiO7Z27zv8oj6pbWUQyLPQBQxtPV
     nwD20R-60eTDmD2ujnMt5PoqMrm8RfmNhVWDtjjMmCMjOpSXicFHj7XOuVIYQyqV
     WlWEh6dN36GVZYk93N8Bc9vY41xy8B9RzzOGVQzXvNEvn7O0nVbfs",
          "q":"3dfOR9cuYq-0S-mkFLzgItgMEfFzB2q3hWehMuG0oCuqnb3vobLyum
     qjVZQO1dIrdwgTnCdpYzBcOfW5r370AFXjiWft_NGEiovonizhKpo9VVS78TzFgx
     kIdrecRezsZ-1kYd_s1qDbxtkDEgfAITAG9LUnADun4vIcb6yelxk",
          "dp":"G4sPXkc6Ya9y8oJW9_ILj4xuppu0lzi_H7VTkS8xj5SdX3coE0oim
     YwxIi2emTAue0UOa5dpgFGyBJ4c8tQ2VF402XRugKDTP8akYhFo5tAA77Qe_Nmtu
     YZc3C3m3I24G2GvR5sSDxUyAN2zq8Lfn9EUms6rY3Ob8YeiKkTiBj0",
          "dq":"s9lAH9fggBsoFR8Oac2R_E2gw282rT2kGOAhvIllETE1efrA6huUU
     vMfBcMpn8lqeW6vzznYY5SSQF7pMdC_agI3nG8Ibp1BUb0JUiraRNqUfLhcQb_d9
     GF4Dh7e74WbRsobRonujTYN1xCaP6TO61jvWrX-L18txXw494Q_cgk",
          "qi":"GyM_p6JrXySiz1toFgKbWV-JdI3jQ4ypu9rbMWx3rQJBfmt0FoYzg
     UIZEVFEcOqwemRN81zoDAaa-Bk0KWNGDjJHZDdDmFhW3AN7lI-puxk_mHZGJ11rx
     yR8O55XLSe3SPmRfKwZI6yU24ZxvQKFYItdldUKGzO6Ia6zTKhAVRU",
          "kid":"2011-04-29"}
       ]
     }


5.  IANA Considerations






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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: "d"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.1 of [[ this document ]]

   o  Parameter Name: "p"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.2 of [[ this document ]]

   o  Parameter Name: "q"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.3 of [[ this document ]]

   o  Parameter Name: "dp"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.4 of [[ this document ]]

   o  Parameter Name: "dq"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.5 of [[ this document ]]

   o  Parameter Name: "qi"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.6 of [[ this document ]]

   o  Parameter Name: "oth"
   o  Change Controller: IETF
   o  Specification Document(s): Section 3.2.7 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.




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7.  Normative References

   [JWA]      Jones, M., "JSON Web Algorithms (JWA)", November 2012.

   [JWK]      Jones, M., "JSON Web Key (JWK)", November 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 ]]

   -01

   o  Changed the names of the RSA key parameters so that the
      identifiers are the same as those used in RFC 3447.

   o  Added the RSA private key fields enabling Chinese Remainder
      Theorem (CRT) calculations, based upon their use in RFC 3447.

   -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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