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JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                          March 12, 2012
Expires: September 13, 2012


                       JSON Web Algorithms (JWA)
                 draft-ietf-jose-json-web-algorithms-01

Abstract

   The JSON Web Algorithms (JWA) specification enumerates cryptographic
   algorithms and identifiers to be used with the JSON Web Signature
   (JWS) and JSON Web Encryption (JWE) specifications.

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.

   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 September 13, 2012.

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
   (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



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   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
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Cryptographic Algorithms for JWS . . . . . . . . . . . . . . .  3
     3.1.  Creating a JWS with HMAC SHA-256, HMAC SHA-384, or
           HMAC SHA-512 . . . . . . . . . . . . . . . . . . . . . . .  4
     3.2.  Creating a JWS with RSA SHA-256, RSA SHA-384, or RSA
           SHA-512  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  Creating a JWS with ECDSA P-256 SHA-256, ECDSA P-384
           SHA-384, or ECDSA P-521 SHA-512  . . . . . . . . . . . . .  6
     3.4.  Creating a Plaintext JWS . . . . . . . . . . . . . . . . .  7
     3.5.  Additional Digital Signature/HMAC Algorithms . . . . . . .  7
   4.  Cryptographic Algorithms for JWE . . . . . . . . . . . . . . .  8
     4.1.  Encrypting a JWE with TBD  . . . . . . . . . . . . . . . .  9
     4.2.  Additional Encryption Algorithms . . . . . . . . . . . . .  9
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  Open Issues and Things To Be Done (TBD)  . . . . . . . . . . . 10
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Digital Signature/HMAC Algorithm Identifier
                Cross-Reference . . . . . . . . . . . . . . . . . . . 13
   Appendix B.  Encryption Algorithm Identifier Cross-Reference . . . 15
   Appendix C.  Acknowledgements  . . . . . . . . . . . . . . . . . . 19
   Appendix D.  Document History  . . . . . . . . . . . . . . . . . . 19
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 19

















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1.  Introduction

   The JSON Web Algorithms (JWA) specification enumerates cryptographic
   algorithms and identifiers to be used with the JSON Web Signature
   (JWS) [JWS] and JSON Web Encryption (JWE) [JWE] specifications.
   Enumerating the algorithms and identifiers for them in this
   specification, rather than in the JWS and JWE specifications, is
   intended to allow them to remain unchanged in the face of changes in
   the set of required, recommended, optional, and deprecated algorithms
   over time.  This specification also describes the semantics and
   operations that are specific to these algorithms and algorithm
   families.


2.  Terminology

   This specification uses the terminology defined by the JSON Web
   Signature (JWS) [JWS] and JSON Web Encryption (JWE) [JWE]
   specifications.


3.  Cryptographic Algorithms for JWS

   JWS uses cryptographic algorithms to sign the contents of the JWS
   Header and the JWS Payload.  The use of the following algorithms for
   producing JWSs is defined in this section.

   The table below Table 1 is the set of "alg" (algorithm) header
   parameter values defined by this specification for use with JWS, each
   of which is explained in more detail in the following sections:

   +--------------------+----------------------------------------------+
   | Alg Parameter      | Algorithm                                    |
   | Value              |                                              |
   +--------------------+----------------------------------------------+
   | HS256              | HMAC using SHA-256 hash algorithm            |
   | HS384              | HMAC using SHA-384 hash algorithm            |
   | HS512              | HMAC using SHA-512 hash algorithm            |
   | RS256              | RSA using SHA-256 hash algorithm             |
   | RS384              | RSA using SHA-384 hash algorithm             |
   | RS512              | RSA using SHA-512 hash algorithm             |
   | ES256              | ECDSA using P-256 curve and SHA-256 hash     |
   |                    | algorithm                                    |
   | ES384              | ECDSA using P-384 curve and SHA-384 hash     |
   |                    | algorithm                                    |
   | ES512              | ECDSA using P-521 curve and SHA-512 hash     |
   |                    | algorithm                                    |




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   | none               | No digital signature or HMAC value included  |
   +--------------------+----------------------------------------------+

                Table 1: JWS Defined "alg" Parameter Values

   See Appendix A for a table cross-referencing the digital signature
   and HMAC "alg" (algorithm) values used in this specification with the
   equivalent identifiers used by other standards and software packages.

   Of these algorithms, only HMAC SHA-256 and "none" MUST be implemented
   by conforming JWS implementations.  It is RECOMMENDED that
   implementations also support the RSA SHA-256 and ECDSA P-256 SHA-256
   algorithms.  Support for other algorithms and key sizes is OPTIONAL.

3.1.  Creating a JWS with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512

   Hash based Message Authentication Codes (HMACs) enable one to use a
   secret plus a cryptographic hash function to generate a Message
   Authentication Code (MAC).  This can be used to demonstrate that the
   MAC matches the hashed content, in this case the JWS Secured Input,
   which therefore demonstrates that whoever generated the MAC was in
   possession of the secret.  The means of exchanging the shared key is
   outside the scope of this specification.

   The algorithm for implementing and validating HMACs is provided in
   RFC 2104 [RFC2104].  This section defines the use of the HMAC SHA-
   256, HMAC SHA-384, and HMAC SHA-512 cryptographic hash functions as
   defined in FIPS 180-3 [FIPS.180-3].  The "alg" (algorithm) header
   parameter values "HS256", "HS384", and "HS512" are used in the JWS
   Header to indicate that the Encoded JWS Signature contains a
   base64url encoded HMAC value using the respective hash function.

   The HMAC SHA-256 MAC is generated as follows:

   1.  Apply the HMAC SHA-256 algorithm to the UTF-8 representation of
       the JWS Secured Input using the shared key to produce an HMAC
       value.

   2.  Base64url encode the resulting HMAC value.

   The output is the Encoded JWS Signature for that JWS.

   The HMAC SHA-256 MAC for a JWS is validated as follows:

   1.  Apply the HMAC SHA-256 algorithm to the UTF-8 representation of
       the JWS Secured Input of the JWS using the shared key.





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   2.  Base64url encode the resulting HMAC value.

   3.  If the Encoded JWS Signature and the base64url encoded HMAC value
       exactly match, then one has confirmation that the shared key was
       used to generate the HMAC on the JWS and that the contents of the
       JWS have not be tampered with.

   4.  If the validation fails, the JWS MUST be rejected.

   Alternatively, the Encoded JWS Signature MAY be base64url decoded to
   produce the JWS Signature and this value can be compared with the
   computed HMAC value, as this comparison produces the same result as
   comparing the encoded values.

   Securing content with the HMAC SHA-384 and HMAC SHA-512 algorithms is
   performed identically to the procedure for HMAC SHA-256 - just with
   correspondingly longer minimum key sizes and result values.

3.2.  Creating a JWS with RSA SHA-256, RSA SHA-384, or RSA SHA-512

   This section defines the use of the RSASSA-PKCS1-v1_5 digital
   signature algorithm as defined in RFC 3447 [RFC3447], Section 8.2
   (commonly known as PKCS#1), using SHA-256, SHA-384, or SHA-512 as the
   hash function.  The RSASSA-PKCS1-v1_5 algorithm is described in FIPS
   186-3 [FIPS.186-3], Section 5.5, and the SHA-256, SHA-384, and SHA-
   512 cryptographic hash functions are defined in FIPS 180-3
   [FIPS.180-3].  The "alg" (algorithm) header parameter values "RS256",
   "RS384", and "RS512" are used in the JWS Header to indicate that the
   Encoded JWS Signature contains a base64url encoded RSA digital
   signature using the respective hash function.

   A 2048-bit or longer key length MUST be used with this algorithm.

   The RSA SHA-256 digital signature is generated as follows:

   1.  Generate a digital signature of the UTF-8 representation of the
       JWS Secured Input using RSASSA-PKCS1-V1_5-SIGN and the SHA-256
       hash function with the desired private key.  The output will be a
       byte array.

   2.  Base64url encode the resulting byte array.

   The output is the Encoded JWS Signature for that JWS.

   The RSA SHA-256 digital signature for a JWS is validated as follows:

   1.  Take the Encoded JWS Signature and base64url decode it into a
       byte array.  If decoding fails, the JWS MUST be rejected.



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   2.  Submit the UTF-8 representation of the JWS Secured Input and the
       public key corresponding to the private key used by the signer to
       the RSASSA-PKCS1-V1_5-VERIFY algorithm using SHA-256 as the hash
       function.

   3.  If the validation fails, the JWS MUST be rejected.

   Signing with the RSA SHA-384 and RSA SHA-512 algorithms is performed
   identically to the procedure for RSA SHA-256 - just with
   correspondingly longer minimum key sizes and result values.

3.3.  Creating a JWS with ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or
      ECDSA P-521 SHA-512

   The Elliptic Curve Digital Signature Algorithm (ECDSA) is defined by
   FIPS 186-3 [FIPS.186-3].  ECDSA provides for the use of Elliptic
   Curve cryptography, which is able to provide equivalent security to
   RSA cryptography but using shorter key lengths and with greater
   processing speed.  This means that ECDSA digital signatures will be
   substantially smaller in terms of length than equivalently strong RSA
   digital signatures.

   This specification defines the use of ECDSA with the P-256 curve and
   the SHA-256 cryptographic hash function, ECDSA with the P-384 curve
   and the SHA-384 hash function, and ECDSA with the P-521 curve and the
   SHA-512 hash function.  The P-256, P-384, and P-521 curves are also
   defined in FIPS 186-3.  The "alg" (algorithm) header parameter values
   "ES256", "ES384", and "ES512" are used in the JWS Header to indicate
   that the Encoded JWS Signature contains a base64url encoded ECDSA
   P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA P-521 SHA-512 digital
   signature, respectively.

   The ECDSA P-256 SHA-256 digital signature is generated as follows:

   1.  Generate a digital signature of the UTF-8 representation of the
       JWS Secured Input using ECDSA P-256 SHA-256 with the desired
       private key.  The output will be the EC point (R, S), where R and
       S are unsigned integers.

   2.  Turn R and S into byte arrays in big endian order.  Each array
       will be 32 bytes long.

   3.  Concatenate the two byte arrays in the order R and then S.

   4.  Base64url encode the resulting 64 byte array.

   The output is the Encoded JWS Signature for the JWS.




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   The ECDSA P-256 SHA-256 digital signature for a JWS is validated as
   follows:

   1.  Take the Encoded JWS Signature and base64url decode it into a
       byte array.  If decoding fails, the JWS MUST be rejected.

   2.  The output of the base64url decoding MUST be a 64 byte array.

   3.  Split the 64 byte array into two 32 byte arrays.  The first array
       will be R and the second S. Remember that the byte arrays are in
       big endian byte order; please check the ECDSA validator in use to
       see what byte order it requires.

   4.  Submit the UTF-8 representation of the JWS Secured Input, R, S
       and the public key (x, y) to the ECDSA P-256 SHA-256 validator.

   5.  If the validation fails, the JWS MUST be rejected.

   The ECDSA validator will then determine if the digital signature is
   valid, given the inputs.  Note that ECDSA digital signature contains
   a value referred to as K, which is a random number generated for each
   digital signature instance.  This means that two ECDSA digital
   signatures using exactly the same input parameters will output
   different signature values because their K values will be different.
   The consequence of this is that one must validate an ECDSA digital
   signature by submitting the previously specified inputs to an ECDSA
   validator.

   Signing with the ECDSA P-384 SHA-384 and ECDSA P-521 SHA-512
   algorithms is performed identically to the procedure for ECDSA P-256
   SHA-256 - just with correspondingly longer minimum key sizes and
   result values.

3.4.  Creating a Plaintext JWS

   To support use cases where the content is secured by a means other
   than a digital signature or HMAC value, JWSs MAY also be created
   without them.  These are called "Plaintext JWSs".  Plaintext JWSs
   MUST use the "alg" value "none", and are formatted identically to
   other JWSs, but with an empty JWS Signature value.

3.5.  Additional Digital Signature/HMAC Algorithms

   Additional algorithms MAY be used to protect JWSs with corresponding
   "alg" (algorithm) header parameter values being defined to refer to
   them.  New "alg" header parameter values SHOULD either be defined in
   the IANA JSON Web Signature Algorithms registry or be a URI that
   contains a collision resistant namespace.  In particular, it is



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   permissible to use the algorithm identifiers defined in XML DSIG
   [RFC3275] and related specifications as "alg" values.


4.  Cryptographic Algorithms for JWE

   JWE uses cryptographic algorithms to encrypt the Content Encryption
   Key (CEK) and the Plaintext.  This section specifies a set of
   specific algorithms for these purposes.

   The table below Table 2 is the set of "alg" (algorithm) header
   parameter values that are defined by this specification for use with
   JWE.  These algorithms are used to encrypt the CEK, which produces
   the JWE Encrypted Key.

   +-----------+-------------------------------------------------------+
   | alg       | Encryption Algorithm                                  |
   | Parameter |                                                       |
   | Value     |                                                       |
   +-----------+-------------------------------------------------------+
   | RSA1_5    | RSA using RSA-PKCS1-1.5 padding, as defined in RFC    |
   |           | 3447 [RFC3447]                                        |
   | RSA-OAEP  | RSA using Optimal Asymmetric Encryption Padding       |
   |           | (OAEP), as defined in RFC 3447 [RFC3447]              |
   | ECDH-ES   | Elliptic Curve Diffie-Hellman Ephemeral Static, as    |
   |           | defined in RFC 6090 [RFC6090], and using the Concat   |
   |           | KDF, as defined in [NIST-800-56A], where the Digest   |
   |           | Method is SHA-256 and all OtherInfo parameters are    |
   |           | the empty bit string                                  |
   | A128KW    | Advanced Encryption Standard (AES) Key Wrap Algorithm |
   |           | using 128 bit keys, as defined in RFC 3394 [RFC3394]  |
   | A256KW    | Advanced Encryption Standard (AES) Key Wrap Algorithm |
   |           | using 256 bit keys, as defined in RFC 3394 [RFC3394]  |
   | A512KW    | Advanced Encryption Standard (AES) Key Wrap Algorithm |
   |           | using 512 bit keys, as defined in RFC 3394 [RFC3394]  |
   | A128GCM   | Advanced Encryption Standard (AES) using 128 bit keys |
   |           | in Galois/Counter Mode, as defined in [FIPS-197] and  |
   |           | [NIST-800-38D]                                        |
   | A256GCM   | Advanced Encryption Standard (AES) using 256 bit keys |
   |           | in Galois/Counter Mode, as defined in [FIPS-197] and  |
   |           | [NIST-800-38D]                                        |
   +-----------+-------------------------------------------------------+

                Table 2: JWE Defined "alg" Parameter Values

   The table below Table 3 is the set of "enc" (encryption method)
   header parameter values that are defined by this specification for
   use with JWE.  These algorithms are used to encrypt the Plaintext,



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   which produces the Ciphertext.

   +-----------+-------------------------------------------------------+
   | enc       | Symmetric Encryption Algorithm                        |
   | Parameter |                                                       |
   | Value     |                                                       |
   +-----------+-------------------------------------------------------+
   | A128CBC   | Advanced Encryption Standard (AES) using 128 bit keys |
   |           | in Cipher Block Chaining mode, as defined in          |
   |           | [FIPS-197] and [NIST-800-38A]                         |
   | A256CBC   | Advanced Encryption Standard (AES) using 256 bit keys |
   |           | in Cipher Block Chaining mode, as defined in          |
   |           | [FIPS-197] and [NIST-800-38A]                         |
   | A128GCM   | Advanced Encryption Standard (AES) using 128 bit keys |
   |           | in Galois/Counter Mode, as defined in [FIPS-197] and  |
   |           | [NIST-800-38D]                                        |
   | A256GCM   | Advanced Encryption Standard (AES) using 256 bit keys |
   |           | in Galois/Counter Mode, as defined in [FIPS-197] and  |
   |           | [NIST-800-38D]                                        |
   +-----------+-------------------------------------------------------+

                Table 3: JWE Defined "enc" Parameter Values

   See Appendix B for a table cross-referencing the encryption "alg"
   (algorithm) and "enc" (encryption method) values used in this
   specification with the equivalent identifiers used by other standards
   and software packages.

   Of these algorithms, only RSA-PKCS1-1.5 with 2048 bit keys, AES-128-
   CBC, and AES-256-CBC MUST be implemented by conforming JWE
   implementations.  It is RECOMMENDED that implementations also support
   ECDH-ES with 256 bit keys, AES-128-GCM, and AES-256-GCM.  Support for
   other algorithms and key sizes is OPTIONAL.

4.1.  Encrypting a JWE with TBD

   TBD: Descriptions of the particulars of using each specified
   encryption algorithm go here.

4.2.  Additional Encryption Algorithms

   Additional algorithms MAY be used to protect JWEs with corresponding
   "alg" (algorithm) and "enc" (encryption method) header parameter
   values being defined to refer to them.  New "alg" and "enc" header
   parameter values SHOULD either be defined in the IANA JSON Web
   Encryption Algorithms registry or be a URI that contains a collision
   resistant namespace.  In particular, it is permissible to use the
   algorithm identifiers defined in XML Encryption



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   [W3C.REC-xmlenc-core-20021210], XML Encryption 1.1
   [W3C.CR-xmlenc-core1-20110303], and related specifications as "alg"
   and "enc" values.


5.  IANA Considerations

   This specification calls for:

   o  A new IANA registry entitled "JSON Web Signature Algorithms" for
      values of the JWS "alg" (algorithm) header parameter is defined in
      Section 3.5.  Inclusion in the registry is RFC Required in the RFC
      5226 [RFC5226] sense.  The registry will just record the "alg"
      value and a pointer to the RFC that defines it.  This
      specification defines inclusion of the algorithm values defined in
      Table 1.

   o  A new IANA registry entitled "JSON Web Encryption Algorithms" for
      values used with the JWE "alg" (algorithm) and "enc" (encryption
      method) header parameters is defined in Section 4.2.  Inclusion in
      the registry is RFC Required in the RFC 5226 [RFC5226] sense.  The
      registry will record the "alg" or "enc" value and a pointer to the
      RFC that defines it.  This specification defines inclusion of the
      algorithm values defined in Table 2 and Table 3.


6.  Security Considerations

   TBD


7.  Open Issues and Things To Be Done (TBD)

   The following items remain to be done in this draft:

   o  Specify minimum required key sizes for all algorithms.

   o  Specify which algorithms require Initialization Vectors (IVs) and
      minimum required lengths for those IVs.

   o  Since RFC 3447 Section 8 explicitly calls for people NOT to adopt
      RSASSA-PKCS1 for new applications and instead requests that people
      transition to RSASSA-PSS, we probably need some Security
      Considerations text explaining why RSASSA-PKCS1 is being used
      (it's what's commonly implemented) and what the potential
      consequences are.





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   o  Should we define the use of RFC 5649 key wrapping functions, which
      allow arbitrary key sizes, in addition to the current use of RFC
      3394 key wrapping functions, which require that keys be multiples
      of 64 bits?  Is this needed in practice?

   o  Decide whether to move the JWK algorithm family definitions "EC"
      and "RSA" here.  This would likely result in all the family-
      specific parameter definitions also moving here ("crv", "x", "y",
      "mod", "exp"), leaving very little normative text in the JWK spec
      itself.  This seems like it would reduce spec readability and so
      was not done.

   o  It would be good to say somewhere, in normative language, that
      eventually the algorithms and/or key sizes currently specified
      will no longer be considered sufficiently secure and will be
      removed.  Therefore, implementers MUST be prepared for this
      eventuality.

   o  Write the Security Considerations section.


8.  References

8.1.  Normative References

   [FIPS-197]
              National Institute of Standards and Technology (NIST),
              "Advanced Encryption Standard (AES)", FIPS PUB 197,
              November 2001.

   [FIPS.180-3]
              National Institute of Standards and Technology, "Secure
              Hash Standard (SHS)", FIPS PUB 180-3, October 2008.

   [FIPS.186-3]
              National Institute of Standards and Technology, "Digital
              Signature Standard (DSS)", FIPS PUB 186-3, June 2009.

   [JWE]      Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
              Encryption (JWE)", March 2012.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", March 2012.

   [NIST-800-38A]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Block Cipher Modes of Operation",
              NIST PUB 800-38A, December 2001.



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   [NIST-800-38D]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Block Cipher Modes of Operation:
              Galois/Counter Mode (GCM) and GMAC", NIST PUB 800-38D,
              December 2001.

   [NIST-800-56A]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Pair-Wise Key Establishment Schemes
              Using Discrete Logarithm Cryptography (Revised)", NIST PUB
              800-56A, March 2007.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard
              (AES) Key Wrap Algorithm", RFC 3394, September 2002.

   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, February 2003.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6090]  McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
              Curve Cryptography Algorithms", RFC 6090, February 2011.

8.2.  Informative References

   [CanvasApp]
              Facebook, "Canvas Applications", 2010.

   [I-D.rescorla-jsms]
              Rescorla, E. and J. Hildebrand, "JavaScript Message
              Security Format", draft-rescorla-jsms-00 (work in
              progress), March 2011.

   [JCA]      Oracle, "Java Cryptography Architecture", 2011.

   [JSE]      Bradley, J. and N. Sakimura (editor), "JSON Simple
              Encryption", September 2010.




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   [JSS]      Bradley, J. and N. Sakimura (editor), "JSON Simple Sign",
              September 2010.

   [MagicSignatures]
              Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic
              Signatures", January 2011.

   [RFC3275]  Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup
              Language) XML-Signature Syntax and Processing", RFC 3275,
              March 2002.

   [W3C.CR-xmlenc-core1-20110303]
              Hirsch, F., Roessler, T., Reagle, J., and D. Eastlake,
              "XML Encryption Syntax and Processing Version 1.1", World
              Wide Web Consortium CR CR-xmlenc-core1-20110303,
              March 2011,
              <http://www.w3.org/TR/2011/CR-xmlenc-core1-20110303>.

   [W3C.REC-xmlenc-core-20021210]
              Eastlake, D. and J. Reagle, "XML Encryption Syntax and
              Processing", World Wide Web Consortium Recommendation REC-
              xmlenc-core-20021210, December 2002,
              <http://www.w3.org/TR/2002/REC-xmlenc-core-20021210>.


Appendix A.  Digital Signature/HMAC Algorithm Identifier Cross-Reference

   This appendix contains a table cross-referencing the digital
   signature and HMAC "alg" (algorithm) values used in this
   specification with the equivalent identifiers used by other standards
   and software packages.  See XML DSIG [RFC3275] and Java Cryptography
   Architecture [JCA] for more information about the names defined by
   those documents.


















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   +-------+-----+----------------------------+----------+-------------+
   | Algor | JWS | XML DSIG                   | JCA      | OID         |
   | ithm  |     |                            |          |             |
   +-------+-----+----------------------------+----------+-------------+
   | HMAC  | HS2 | http://www.w3.org/2001/04/ | HmacSHA2 | 1.2.840.113 |
   | using | 56  | xmldsig-more#hmac-sha256   | 56       | 549.2.9     |
   | SHA-2 |     |                            |          |             |
   | 56    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | HMAC  | HS3 | http://www.w3.org/2001/04/ | HmacSHA3 | 1.2.840.113 |
   | using | 84  | xmldsig-more#hmac-sha384   | 84       | 549.2.10    |
   | SHA-3 |     |                            |          |             |
   | 84    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | HMAC  | HS5 | http://www.w3.org/2001/04/ | HmacSHA5 | 1.2.840.113 |
   | using | 12  | xmldsig-more#hmac-sha512   | 12       | 549.2.11    |
   | SHA-5 |     |                            |          |             |
   | 12    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | RSA   | RS2 | http://www.w3.org/2001/04/ | SHA256wi | 1.2.840.113 |
   | using | 56  | xmldsig-more#rsa-sha256    | thRSA    | 549.1.1.11  |
   | SHA-2 |     |                            |          |             |
   | 56    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | RSA   | RS3 | http://www.w3.org/2001/04/ | SHA384wi | 1.2.840.113 |
   | using | 84  | xmldsig-more#rsa-sha384    | thRSA    | 549.1.1.12  |
   | SHA-3 |     |                            |          |             |
   | 84    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | RSA   | RS5 | http://www.w3.org/2001/04/ | SHA512wi | 1.2.840.113 |
   | using | 12  | xmldsig-more#rsa-sha512    | thRSA    | 549.1.1.13  |
   | SHA-5 |     |                            |          |             |
   | 12    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |





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   | ECDSA | ES2 | http://www.w3.org/2001/04/ | SHA256wi | 1.2.840.100 |
   | using | 56  | xmldsig-more#ecdsa-sha256  | thECDSA  | 45.4.3.2    |
   | P-256 |     |                            |          |             |
   | curve |     |                            |          |             |
   | and   |     |                            |          |             |
   | SHA-2 |     |                            |          |             |
   | 56    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | ECDSA | ES3 | http://www.w3.org/2001/04/ | SHA384wi | 1.2.840.100 |
   | using | 84  | xmldsig-more#ecdsa-sha384  | thECDSA  | 45.4.3.3    |
   | P-384 |     |                            |          |             |
   | curve |     |                            |          |             |
   | and   |     |                            |          |             |
   | SHA-3 |     |                            |          |             |
   | 84    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | ECDSA | ES5 | http://www.w3.org/2001/04/ | SHA512wi | 1.2.840.100 |
   | using | 12  | xmldsig-more#ecdsa-sha512  | thECDSA  | 45.4.3.4    |
   | P-521 |     |                            |          |             |
   | curve |     |                            |          |             |
   | and   |     |                            |          |             |
   | SHA-5 |     |                            |          |             |
   | 12    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   +-------+-----+----------------------------+----------+-------------+

   Table 4: Digital Signature/HMAC Algorithm Identifier Cross-Reference


Appendix B.  Encryption Algorithm Identifier Cross-Reference

   This appendix contains a table cross-referencing the "alg"
   (algorithm) and "enc" (encryption method) values used in this
   specification with the equivalent identifiers used by other standards
   and software packages.  See XML Encryption
   [W3C.REC-xmlenc-core-20021210], XML Encryption 1.1
   [W3C.CR-xmlenc-core1-20110303], and Java Cryptography Architecture
   [JCA] for more information about the names defined by those
   documents.






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   +---------+-------+---------------------------+---------------------+
   | Algorit | JWE   | XML ENC                   | JCA                 |
   | hm      |       |                           |                     |
   +---------+-------+---------------------------+---------------------+
   | RSA     | RSA1_ | http://www.w3.org/2001/04 | RSA/ECB/PKCS1Paddin |
   | using   | 5     | /xmlenc#rsa-1_5           | g                   |
   | RSA-PKC |       |                           |                     |
   | S1-1.5  |       |                           |                     |
   |  paddin |       |                           |                     |
   | g       |       |                           |                     |
   | RSA     | RSA-O | http://www.w3.org/2001/04 | RSA/ECB/OAEPWithSHA |
   | using   | AEP   | /xmlenc#rsa-oaep-mgf1p    | -1AndMGF1Padding    |
   | Optimal |       |                           |                     |
   | Asymmet |       |                           |                     |
   | ric     |       |                           |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Paddi |       |                           |                     |
   | ng(OAEP |       |                           |                     |
   | )       |       |                           |                     |
   | Ellipti | ECDH- | http://www.w3.org/2009/xm | TBD                 |
   | cCurve  | ES    | lenc11#ECDH-ES            |                     |
   |  Diffie |       |                           |                     |
   | -Hellma |       |                           |                     |
   | n Ephem |       |                           |                     |
   | eral    |       |                           |                     |
   |    Stat |       |                           |                     |
   | ic      |       |                           |                     |
   | Advance | A128K | http://www.w3.org/2001/04 | TBD                 |
   | d       | W     | /xmlenc#kw-aes128         |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  Key  |       |                           |                     |
   |    Wrap |       |                           |                     |
   |    Algo |       |                           |                     |
   | rithm R |       |                           |                     |
   | FC  339 |       |                           |                     |
   | 4   [RF |       |                           |                     |
   | C3394]  |       |                           |                     |
   | using12 |       |                           |                     |
   | 8 bitke |       |                           |                     |
   | ys      |       |                           |                     |







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   | Advance | A256K | http://www.w3.org/2001/04 | TBD                 |
   | d       | W     | /xmlenc#kw-aes256         |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  Key  |       |                           |                     |
   |    Wrap |       |                           |                     |
   |    Algo |       |                           |                     |
   | rithm R |       |                           |                     |
   | FC  339 |       |                           |                     |
   | 4   [RF |       |                           |                     |
   | C3394]  |       |                           |                     |
   | using25 |       |                           |                     |
   | 6 bitke |       |                           |                     |
   | ys      |       |                           |                     |
   | Advance | A512K | http://www.w3.org/2001/04 | TBD                 |
   | d       | W     | /xmlenc#kw-aes512         |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  Key  |       |                           |                     |
   |    Wrap |       |                           |                     |
   |    Algo |       |                           |                     |
   | rithm R |       |                           |                     |
   | FC  339 |       |                           |                     |
   | 4   [RF |       |                           |                     |
   | C3394]  |       |                           |                     |
   | using51 |       |                           |                     |
   | 2 bitke |       |                           |                     |
   | ys      |       |                           |                     |
   | Advance | A128C | http://www.w3.org/2001/04 | AES/CBC/PKCS5Paddin |
   | d       | BC    | /xmlenc#aes128-cbc        | g                   |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  usin |       |                           |                     |
   | g  128  |       |                           |                     |
   | bitkeys |       |                           |                     |
   |  inCiph |       |                           |                     |
   | er Bloc |       |                           |                     |
   | k  Chai |       |                           |                     |
   | ningmod |       |                           |                     |
   | e       |       |                           |                     |





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   | Advance | A256C | http://www.w3.org/2001/04 | AES/CBC/PKCS5Paddin |
   | d       | BC    | /xmlenc#aes256-cbc        | g                   |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  usin |       |                           |                     |
   | g  256  |       |                           |                     |
   | bitkeys |       |                           |                     |
   |  inCiph |       |                           |                     |
   | er Bloc |       |                           |                     |
   | k  Chai |       |                           |                     |
   | ningmod |       |                           |                     |
   | e       |       |                           |                     |
   | Advance | A128G | http://www.w3.org/2009/xm | AES/GCM/NoPadding   |
   | d       | CM    | lenc11#aes128-gcm         |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  usin |       |                           |                     |
   | g  128  |       |                           |                     |
   | bitkeys |       |                           |                     |
   |  inGalo |       |                           |                     |
   | is/Coun |       |                           |                     |
   | ter Mod |       |                           |                     |
   | e       |       |                           |                     |
   | Advance | A256G | http://www.w3.org/2009/xm | AES/GCM/NoPadding   |
   | d       | CM    | lenc11#aes256-gcm         |                     |
   |  Encryp |       |                           |                     |
   | tion    |       |                           |                     |
   |   Stand |       |                           |                     |
   | ard(AES |       |                           |                     |
   | )  usin |       |                           |                     |
   | g  256  |       |                           |                     |
   | bitkeys |       |                           |                     |
   |  inGalo |       |                           |                     |
   | is/Coun |       |                           |                     |
   | ter Mod |       |                           |                     |
   | e       |       |                           |                     |
   +---------+-------+---------------------------+---------------------+

         Table 5: Encryption Algorithm Identifier Cross-Reference








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Appendix C.  Acknowledgements

   Solutions for signing and encrypting JSON content were previously
   explored by Magic Signatures [MagicSignatures], JSON Simple Sign
   [JSS], Canvas Applications [CanvasApp], JSON Simple Encryption [JSE],
   and JavaScript Message Security Format [I-D.rescorla-jsms], all of
   which influenced this draft.  Dirk Balfanz, John Bradley, Yaron Y.
   Goland, John Panzer, Nat Sakimura, and Paul Tarjan all made
   significant contributions to the design of this specification and its
   related specifications.


Appendix D.  Document History

   -01

   o  Moved definition of "alg":"none" for JWSs here from the JWT
      specification since this functionality is likely to be useful in
      more contexts that just for JWTs.

   o  Added Advanced Encryption Standard (AES) Key Wrap Algorithm using
      512 bit keys ("A512KW").

   o  Added text "Alternatively, the Encoded JWS Signature MAY be
      base64url decoded to produce the JWS Signature and this value can
      be compared with the computed HMAC value, as this comparison
      produces the same result as comparing the encoded values".

   o  Corrected the Magic Signatures reference.

   o  Made other editorial improvements suggested by JOSE working group
      participants.

   -00

   o  Created the initial IETF draft based upon
      draft-jones-json-web-signature-04 and
      draft-jones-json-web-encryption-02 with no normative changes.

   o  Changed terminology to no longer call both digital signatures and
      HMACs "signatures".










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Author's Address

   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com
   URI:   http://self-issued.info/












































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