JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                            May 12,                            July 6, 2012
Expires: November 13, 2012 January 7, 2013

                       JSON Web Algorithms (JWA)
                 draft-ietf-jose-json-web-algorithms-02
                 draft-ietf-jose-json-web-algorithms-03

Abstract

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

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", (JWE), and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119]. JSON Web Key (JWK)
   specifications.

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
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   This Internet-Draft will expire on November 13, 2012. January 7, 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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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Terms Incorporated from the JWS Specification  . . . . . .  4
     2.2.  Terms Incorporated from the JWE Specification  . . . . . .  5
     2.3.  Terms Incorporated from the JWK Specification  . . . . . .  6
     2.4.  Defined Terms  . . . . . . . . . . . . . . . . . . . . . .  7
   3.  Cryptographic Algorithms for JWS . . . . . . . . . . . . . . .  4  7
     3.1.  "alg" (Algorithm) Header Parameter Values for JWS  . . . .  4  7
     3.2.  MAC with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512 . . .  5  8
     3.3.  Digital Signature with RSA SHA-256, RSA SHA-384, or
           RSA SHA-512  . . . . . . . . . . . . . . . . . . . . . . .  6  9
     3.4.  Digital Signature with ECDSA P-256 SHA-256, ECDSA
           P-384 SHA-384, or ECDSA P-521 SHA-512  . . . . . . . . . .  7 10
     3.5.  Creating a Plaintext JWS .  Using the Algorithm "none" . . . . . . . . . . . . . . . .  9 11
     3.6.  Additional Digital Signature/MAC Algorithms and
           Parameters . . . . . . . . . . . . . . . . . . . . . . . .  9 12
   4.  Cryptographic Algorithms for JWE . . . . . . . . . . . . . . .  9 12
     4.1.  "alg" (Algorithm) Header Parameter Values for JWE  . . . .  9 12
     4.2.  "enc" (Encryption Method) Header Parameter Values for
           JWE  . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 13
     4.3.  "int" (Integrity Algorithm) Header Parameter Values
           for JWE  . . . . . . . . . . . . . . . . . . . . . . . . . 11 14
     4.4.  Key Encryption with RSA using RSA-PKCS1-1.5 Padding  "kdf" (Key Derivation Function) Header Parameter
           Values for JWE . . . 11 . . . . . . . . . . . . . . . . . . . 14
     4.5.  Key Encryption with RSA using Optimal Asymmetric
           Encryption Padding (OAEP) RSAES-PKCS1-V1_5 . . . . . . . . . . . 15
     4.6.  Key Encryption with RSAES OAEP . . . . . 11
     4.6. . . . . . . . . . 15
     4.7.  Key Agreement with Elliptic Curve Diffie-Hellman
           Ephemeral Static (ECDH-ES) . . . . . . . . . . . . . . . . 12
     4.7. 15
     4.8.  Key Encryption with AES Key Wrap . . . . . . . . . . . . . 12
     4.8. 15
     4.9.  Plaintext Encryption with AES Cipher Block Chaining
           (CBC) CBC Mode . . . . . . . . . . 15
     4.10. Plaintext Encryption with AES GCM  . . . . . . . . . . . . . . 12
     4.9.  Plaintext Encryption with AES Galois/Counter Mode (GCM)  . 12
     4.10. 16
     4.11. Integrity Calculation with HMAC SHA-256, HMAC SHA-384,
           or HMAC SHA-512  . . . . . . . . . . . . . . . . . . . . . 13
     4.11. Additional Encryption Algorithms 16
     4.12. Key Derivation with Concat KDF and Parameters SHA-256, SHA-384,
           or SHA-512 . . . . . 13
   5. . . . . . . . . . . . . . . . . . . . 16
     4.13. Additional Encryption Algorithms and Parameters  . . . . . 17
   5.  Cryptographic Algorithms for JWK . . . . . . . . . . . . . . . 13 18
     5.1.  "alg" (Algorithm Family) Parameter Values for JWK  . . . . 14 18
     5.2.  JWK Parameters for Elliptic Curve Keys . . . . . . . . . . 14 18
       5.2.1.  "crv" (Curve) Parameter  . . . . . . . . . . . . . . . 14 18
       5.2.2.  "x" (X Coordinate) Parameter . . . . . . . . . . . . . 14 19
       5.2.3.  "y" (Y Coordinate) Parameter . . . . . . . . . . . . . 14 19
     5.3.  JWK Parameters for RSA Keys  . . . . . . . . . . . . . . . 14 19
       5.3.1.  "mod" (Modulus) Parameter  . . . . . . . . . . . . . . 15 19
       5.3.2.  "exp" (Exponent) Parameter . . . . . . . . . . . . . . 15 19

     5.4.  Additional Key Algorithm Families and Parameters . . . . . 15 19
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15 20
     6.1.  JSON Web Signature and Encryption Header Parameters Algorithms Registry  . . 20
       6.1.1.  Registration Template  . . . . . . . . . . . . . . . . 21
       6.1.2.  Initial Registry Contents  . . . . . . . 15 . . . . . . . 21
     6.2.  JSON Web Signature and Encryption Algorithms Key Algorithm Families Registry . . 15
     6.3.  JSON Web Signature and Encryption "typ" Values Registry . 16
     6.4.  JSON Web Key Parameters . . . . . . 26
       6.2.1.  Registration Template  . . . . . . . . . . . . . . . . 26
       6.2.2.  Initial Registry Contents  . . . . . . . . . . . . . 16
     6.5. . 27
     6.3.  JSON Web Key Algorithm Families Parameters Registration . . . . . . . . . . . 27
       6.3.1.  Registry Contents  . . . . . . . . . 16 . . . . . . . . . 27
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16 28
   8.  Open Issues and Things To Be Done (TBD)  . . . . . . . . . . . 17 . . . . . . . . . . . . . . 29
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 29
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 17 29
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 18 31
   Appendix A.  Digital Signature/MAC Algorithm Identifier
                Cross-Reference . . . . . . . . . . . . . . . . . . . 19 32
   Appendix B.  Encryption Algorithm Identifier Cross-Reference . . . 21 34
   Appendix C.  Acknowledgements  . . . . . . . . . . . . . . . . . . 25 36
   Appendix D.  Document History  . . . . . . . . . . . . . . . . . . 25 36
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 26 39

1.  Introduction

   The JSON Web Algorithms (JWA) specification enumerates cryptographic
   algorithms and identifiers to be used with the JSON Web Signature
   (JWS) [JWS] and [JWS], JSON Web Encryption (JWE) [JWE] [JWE], and JSON Web Key (JWK)
   [JWK] specifications.  This specification also describes the
   semantics and operations that are specific to these algorithms and
   algorithm families.

   Enumerating the algorithms and identifiers for them in this
   specification, rather than in the JWS JWS, JWE, and JWE JWK 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

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
   operations that "OPTIONAL" in this
   document are specific to these algorithms and algorithm
   families. be interpreted as described in Key words for use in
   RFCs to Indicate Requirement Levels [RFC2119].

2.  Terminology

   This specification uses

2.1.  Terms Incorporated from the terminology JWS Specification

   These terms defined by the JSON Web Signature (JWS) [JWS] and
   specification are incorporated into this specification:

   JSON Web Encryption (JWE) [JWE]
   specifications.

3.  Cryptographic Algorithms for Signature (JWS)  A data structure cryptographically securing
      a JWS Header and a JWS uses cryptographic algorithms to digitally sign Payload with a JWS Signature value.

   JWS Header  A string representing a JavaScript Object Notation (JSON)
      [RFC4627] object that describes the digital signature or MAC
      operation applied to create the JWS Signature value.

   JWS Payload  The bytes to be secured - a.k.a., the message.  The
      payload can contain an arbitrary sequence of bytes.

   JWS Signature  A byte array containing the cryptographic material
      that secures the contents of the JWS Header and the JWS Payload.  The use

   Encoded JWS Header  Base64url encoding of the
   following algorithms for producing JWSs is defined in this section.

3.1.  "alg" (Algorithm) Header Parameter Values for bytes of the UTF-8
      [RFC3629] representation of the JWS Header.

   Encoded JWS Payload  Base64url encoding of the JWS Payload.

   Encoded JWS Signature  Base64url encoding of the JWS Signature.

   JWS Secured Input  The table below is concatenation of the set Encoded JWS Header, a
      period ('.') character, and the Encoded JWS Payload.

   Base64url Encoding  For the purposes of "alg" (algorithm) header parameter
   values defined by this specification for use specification, this term
      always refers to the URL- and filename-safe Base64 encoding
      described in RFC 4648 [RFC4648], Section 5, with JWS, each the (non URL-
      safe) '=' padding characters omitted, as permitted by Section 3.2.
      (See Appendix C of which
   is explained in more detail [JWS] for notes on implementing base64url
      encoding without padding.)

   Collision Resistant Namespace  A namespace that allows names to be
      allocated in a manner such that they are highly unlikely to
      collide with other names.  For instance, collision resistance can
      be achieved through administrative delegation of portions of the following sections:

   +--------------------+----------------------------------------------+
   | alg Parameter      | Digital Signature
      namespace or MAC Algorithm           |
   | Value              |                                              |
   +--------------------+----------------------------------------------+
   | HS256              | HMAC using SHA-256 hash algorithm            |
   | HS384              | HMAC using SHA-384 hash algorithm            |
   | HS512              | HMAC through use of collision-resistant name allocation
      functions.  Examples of Collision Resistant Namespaces include:
      Domain Names, Object Identifiers (OIDs) as defined in the ITU-T
      X.660 and X.670 Recommendation series, and Universally Unique
      IDentifiers (UUIDs) [RFC4122].  When 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                                    |
   | none               | No digital signature or MAC value included   |
   +--------------------+----------------------------------------------+

   See Appendix A for a table cross-referencing an administratively
      delegated namespace, the digital signature
   and MAC "alg" (algorithm) values used definer of a name needs to take
      reasonable precautions to ensure they are in this specification with control of 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
      portion of the RSA SHA-256 and ECDSA P-256 SHA-256
   algorithms.  Support for other algorithms and key sizes is OPTIONAL.

3.2.  MAC with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512

   Hash-based Message Authentication Codes (HMACs) enable one to namespace they 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 define the hashed content, in this case name.

2.2.  Terms Incorporated from the JWS Secured Input,
   which therefore demonstrates that whoever generated JWE Specification

   These terms defined by the MAC was in
   possession JSON Web Encryption (JWE) [JWE]
   specification are incorporated into this specification:

   JSON Web Encryption (JWE)  A data structure representing an encrypted
      version of the secret. a Plaintext.  The means structure consists of exchanging four parts: the shared key is
   outside
      JWE Header, the scope of this specification.

   The algorithm for implementing and validating HMACs is provided in
   RFC 2104 [RFC2104].  This section defines the use of JWE Encrypted Key, 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", JWE Ciphertext, and "HS512" are used in the JWS
   Header JWE
      Integrity Value.

   Plaintext  The bytes to indicate that be encrypted - a.k.a., the Encoded JWS Signature contains a
   base64url encoded HMAC value using message.  The
      plaintext can contain an arbitrary sequence of bytes.

   Ciphertext  The encrypted version of the respective hash function. Plaintext.

   Content Encryption Key (CEK)  A symmetric key of the same size as used to encrypt the hash output (for instance, 256 bits
      Plaintext for
   "HS256") or larger MUST be the recipient to produce the Ciphertext.

   Content Integrity Key (CIK)  A key used with this algorithm.

   The HMAC SHA-256 a MAC is generated as follows:

   1.  Apply the HMAC SHA-256 algorithm function to ensure
      the bytes of the UTF-8
       representation integrity of the JWS Secured Input (which is the same as the
       ASCII representation) using Ciphertext and the shared key parameters used to produce an HMAC
       value.

   2.  Base64url encode create
      it.

   Content Master Key (CMK)  A key from which the resulting HMAC value.

   The output is CEK and CIK are
      derived.  When key wrapping or key encryption are employed, the Encoded JWS Signature for that JWS.

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

   1.  Apply the HMAC SHA-256 algorithm randomly generated and encrypted to the bytes of the UTF-8
       representation of recipient as the JWS Secured Input (which
      JWE Encrypted Key. When key agreement is employed, the same as CMK is the
       ASCII representation)
      result of the JWS using key agreement algorithm.

   JWE Header  A string representing a JSON object that describes the shared key.

   2.  Base64url encode
      encryption operations applied to create the resulting HMAC value.

   3.  If JWE Encrypted Key, the Encoded JWS Signature
      JWE Ciphertext, and the base64url encoded HMAC value
       exactly match, then one has confirmation that the shared JWE Integrity Value.

   JWE Encrypted Key  When key was
       used to generate wrapping or key encryption are employed,
      the HMAC on Content Master Key (CMK) is encrypted with the JWS intended
      recipient's key and that the contents of the
       JWS have not be tampered with.

   4.  If resulting encrypted content is recorded as
      a byte array, which is referred to as the validation fails, JWE Encrypted Key.
      Otherwise, when key agreement is employed, the JWS MUST be rejected.

   Alternatively, JWE Encrypted Key
      is the Encoded JWS Signature MAY be base64url decoded to
   produce empty byte array.

   JWE Ciphertext  A byte array containing the JWS Signature and this Ciphertext.

   JWE Integrity Value  A byte array containing a MAC value can be compared with the
   computed HMAC value, as this comparison produces the same result as
   comparing that ensures
      the encoded values.

   Securing content with integrity of the HMAC SHA-384 Ciphertext and HMAC SHA-512 algorithms is
   performed identically the parameters used to create
      it.

   Encoded JWE Header  Base64url encoding of the procedure for HMAC SHA-256 - just with
   correspondingly larger minimum key sizes and result values.

3.3.  Digital Signature with RSA SHA-256, RSA SHA-384, or RSA SHA-512

   This section defines bytes of the use UTF-8
      [RFC3629] representation 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 JWE Header.

   Encoded JWE Encrypted Key  Base64url encoding of the
   hash function.  The RSASSA-PKCS1-v1_5 JWE Encrypted
      Key.

   Encoded JWE Ciphertext  Base64url encoding of the JWE Ciphertext.

   Encoded JWE Integrity Value  Base64url encoding of the JWE Integrity
      Value.

   AEAD Algorithm  An Authenticated Encryption with Associated Data
      (AEAD) [RFC5116] encryption algorithm is described in FIPS
   186-3 [FIPS.186-3], Section 5.5, and one that provides an
      integrated content integrity check.  AES Galois/Counter Mode (GCM)
      is one such algorithm.

2.3.  Terms Incorporated from the SHA-256, SHA-384, and SHA-
   512 cryptographic hash functions are JWK Specification

   These terms defined in FIPS 180-3
   [FIPS.180-3].  The "alg" (algorithm) header parameter values "RS256",
   "RS384", and "RS512" are used in by the JWS Header to indicate JSON Web Key (JWK) [JWK] specification are
   incorporated into this specification:

   JSON Web Key (JWK)  A JSON data structure that the
   Encoded JWS Signature contains represents a base64url encoded RSA digital
   signature using the respective hash function. public
      key.

   JSON Web Key Set (JWK Set)  A key of size 2048 bits or larger MUST be used with these algorithms.

   Note JSON object that while Section 8 contains an array of RFC 3447 [RFC3447] explicitly calls for
   people not to adopt RSASSA-PKCS1 for new applications and instead
   requests that people transition to RSASSA-PSS,
      JWKs as a member.

2.4.  Defined Terms

   These terms are defined for interoperability
   reasons, this specification does use RSASSA-PKCS1 because it commonly
   implemented. by this specification:

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

   1.  Generate name of a digital signature member of the bytes JSON object
      representing a JWS Header or JWE Header.

   Header Parameter Value  The value of the UTF-8
       representation a member of the JSON object
      representing a JWS Secured Input (which is Header or JWE Header.

3.  Cryptographic Algorithms for JWS

   JWS uses cryptographic algorithms to digitally sign or create a
   Message Authentication Codes (MAC) of the same as contents of the
       ASCII representation) using RSASSA-PKCS1-V1_5-SIGN JWS Header
   and the SHA-
       256 hash function with the desired private key. JWS Payload.  The output will
       be a byte array.

   2.  Base64url encode use of the resulting byte array.

   The output following algorithms for
   producing JWSs is the Encoded JWS Signature defined in this section.

3.1.  "alg" (Algorithm) Header Parameter Values for that JWS. JWS

   The RSA SHA-256 digital signature for a JWS table below 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.  Submit the bytes of the UTF-8 representation set of the JWS Secured
       Input (which is the same as the ASCII representation) 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 larger result values.

3.4.  Digital Signature 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 "alg" (algorithm) header parameter
   values defined by
   FIPS 186-3 [FIPS.186-3].  ECDSA provides this specification for the use with JWS, each of Elliptic
   Curve cryptography, which
   is able to provide equivalent security to
   RSA cryptography but using shorter key sizes and with greater
   processing speed.  This means that ECDSA digital signatures will be
   substantially smaller explained in more detail in terms of length than equivalently strong RSA
   digital signatures.

   This specification defines the use of ECDSA with the P-256 curve and the following sections:

   +--------------+--------------------------------+-------------------+
   | alg          | Digital Signature or MAC       | Implementation    |
   | Parameter    | Algorithm                      | Requirements      |
   | Value        |                                |                   |
   +--------------+--------------------------------+-------------------+
   | HS256        | HMAC using SHA-256 cryptographic hash function, ECDSA with the P-384 curve
   and the        | REQUIRED          |
   |              | algorithm                      |                   |
   | HS384        | HMAC using SHA-384 hash function, and ECDSA with the P-521 curve and the        | OPTIONAL          |
   |              | algorithm                      |                   |
   | HS512        | HMAC using 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        | OPTIONAL          |
   |              | algorithm                      |                   |
   | RS256        | RSASSA using SHA-256 hash      | RECOMMENDED       |
   |              | algorithm                      |                   |
   | RS384        | RSASSA using SHA-384 hash      | OPTIONAL          |
   |              | algorithm                      |                   |
   | RS512        | RSASSA using SHA-512 hash      | OPTIONAL          |
   |              | algorithm                      |                   |
   | ES256        | ECDSA using P-256 SHA-256, curve and    | RECOMMENDED+      |
   |              | SHA-256 hash algorithm         |                   |
   | ES384        | ECDSA using P-384 SHA-384, or curve and    | OPTIONAL          |
   |              | SHA-384 hash algorithm         |                   |
   | ES512        | ECDSA using P-521 curve and    | OPTIONAL          |
   |              | SHA-512 digital
   signature, respectively.

   A key of size 160 bits or larger MUST be used with these algorithms.

   The ECDSA P-256 SHA-256 hash algorithm         |                   |
   | none         | No digital signature is generated as follows:

   1.  Generate or MAC    | REQUIRED          |
   |              | value included                 |                   |
   +--------------+--------------------------------+-------------------+

   All the names are short because a digital signature core goal of JWS is for the bytes
   representations to be compact.  However, there is no a priori length
   restriction on "alg" values.

   The use of "+" in the UTF-8
       representation of Implementation Requirements indicates that the JWS Secured Input (which
   requirement strength is likely to be increased in a future version of
   the same as specification.

   See Appendix A for a table cross-referencing the
       ASCII representation) using ECDSA P-256 SHA-256 digital signature
   and MAC "alg" (algorithm) values used in this specification with the desired
       private key.  The output will be the EC point (R, S), where R and
       S are unsigned integers.

   2.  Turn R
   equivalent identifiers used by other standards and S into byte arrays in big endian order.  Each array
       will software packages.

3.2.  MAC 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 32 bytes long.

   3.  Concatenate used to demonstrate that the two byte arrays
   MAC matches the hashed content, in this case the order R and then S.

   4.  Base64url encode JWS Secured Input,
   which therefore demonstrates that whoever generated the resulting 64 byte array. MAC was in
   possession of the secret.  The output means of exchanging the shared key is
   outside the Encoded JWS Signature scope of this specification.

   The algorithm for implementing and validating HMACs is provided in
   RFC 2104 [RFC2104].  This section defines the JWS. use of the HMAC SHA-
   256, HMAC SHA-384, and HMAC SHA-512 functions [SHS].  The ECDSA P-256 SHA-256 digital signature for a "alg"
   (algorithm) header parameter values "HS256", "HS384", and "HS512" are
   used in the JWS is validated as
   follows:

   1.  Take Header to indicate that the Encoded JWS Signature and base64url decode it into
   contains a
       byte array.  If decoding fails, base64url encoded HMAC value using the JWS respective hash
   function.

   A key of the same size as the hash output (for instance, 256 bits for
   "HS256") or larger MUST be rejected.

   2. used with this algorithm.

   The output HMAC SHA-256 MAC is generated per RFC 2104, using SHA-256 as the
   hash algorithm "H", using the bytes of the base64url decoding MUST be a 64 byte array.

   3.  Split ASCII [USASCII]
   representation of the 64 byte array into two 32 byte arrays.  The first array
       will be R JWS Secured Input as the "text" value, and
   using the second S (with both being in big endian byte
       order).

   4.  Submit shared key.  The HMAC output value is the JWS Signature.
   The JWS signature is base64url encoded to produce the Encoded JWS
   Signature.

   The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC
   value per RFC 2104, using SHA-256 as the hash algorithm "H", using
   the bytes of the UTF-8 ASCII representation of the received JWS Secured
       Input (which is the same
   input as the ASCII representation), R, S "text" value, and using the public key (x, y) shared key.  This computed
   HMAC value is then compared to the ECDSA P-256 SHA-256 validator.

   5.  If the validation fails, result of base64url decoding the
   received Encoded JWS MUST be rejected.

   The ECDSA validator will then determine if the digital signature is
   valid, given signature.  Alternatively, the inputs.  Note that ECDSA digital signature contains
   a computed HMAC
   value referred can be base64url encoded and compared to the received Encoded
   JWS Signature, as K, which is a random number generated for each
   digital signature instance.  This means that two ECDSA digital
   signatures using exactly this comparison produces the same input parameters will output
   different signature values because their K result as
   comparing the unencoded values.  In either case, if the values will be different.
   The consequence of this is that one must validate an ECDSA digital
   signature by submitting match,
   the previously specified inputs to an ECDSA
   validator.

   Signing HMAC has been validated.  If the validation fails, the JWS MUST
   be rejected.

   Securing content with the ECDSA P-384 HMAC SHA-384 and ECDSA P-521 HMAC SHA-512 algorithms is
   performed identically to the procedure for ECDSA P-256 HMAC SHA-256 - just with correspondingly using
   the corresponding hash algorithm with correspondingly larger minimum
   key sizes and result values.

3.5.  Creating a Plaintext JWS

   To support values: 384 bits each for HMAC SHA-384 and 512
   bits each for HMAC SHA-512.

3.3.  Digital Signature with RSA SHA-256, RSA SHA-384, or RSA SHA-512

   This section defines the use cases where of the content is secured by a means other
   than a RSASSA-PKCS1-V1_5 digital
   signature algorithm as defined in Section 8.2 of RFC 3447 [RFC3447],
   (commonly known as PKCS #1), using SHA-256, SHA-384, or MAC value, JWSs MAY also be created
   without them.  These are called "Plaintext JWSs".  Plaintext JWSs
   MUST use SHA-512 [SHS]
   as the hash functions.  The "alg" value "none", (algorithm) header parameter values
   "RS256", "RS384", and "RS512" are formatted identically used in the JWS Header to
   other JWSs, but with an empty indicate
   that the Encoded JWS Signature value.

3.6.  Additional Digital Signature/MAC Algorithms and Parameters

   Additional algorithms MAY contains a base64url encoded RSA
   digital signature using the respective hash function.

   A key of size 2048 bits or larger MUST 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 these algorithms.

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

   1.  Generate a digital signature of the IANA JSON Web Signature bytes of the ASCII
       representation of the JWS Secured Input using RSASSA-PKCS1-V1_5-
       SIGN and Encryption Algorithms registry
   Section 6.2 or the SHA-256 hash function with the desired private key.
       The output will be a URI byte array.

   2.  Base64url encode the resulting byte array.

   The output is the Encoded JWS Signature for that contains JWS.

   The RSA SHA-256 digital signature for a collision resistant
   namespace.  In particular, it JWS is permissible to use the algorithm
   identifiers defined in XML DSIG [RFC3275], XML DSIG 2.0
   [W3C.CR-xmldsig-core2-20120124], and related specifications validated as "alg"
   values.

   As indicated by follows:

   1.  Take the common registry, JWSs Encoded JWS Signature and JWEs share base64url decode it into a common
   "alg" value space.  The values used by
       byte array.  If decoding fails, the two specifications JWS MUST be
   distinct, as rejected.

   2.  Submit the "alg" value MAY be used to determine whether bytes of the
   object is a JWS or JWE.

   Likewise, additional reserved header parameter names MAY be defined
   via ASCII representation of the IANA JSON Web Signature JWS Secured
       Input and Encryption Header Parameters
   registry Section 6.1.  As indicated by the common registry, JWSs and
   JWEs share a common header parameter space; when a parameter is public key corresponding to the private key used by both specifications, its usage must
       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 compatible between rejected.

   Signing with the
   specifications.

4.  Cryptographic Algorithms for JWE

   JWE uses cryptographic RSA SHA-384 and RSA SHA-512 algorithms is performed
   identically to encrypt the Content Master Key
   (CMK) and procedure for RSA SHA-256 - just using the Plaintext.  This section specifies a set of specific
   algorithms
   corresponding hash algorithm with correspondingly larger result
   values: 384 bits for these purposes.

4.1.  "alg" (Algorithm) Header Parameter Values RSA SHA-384 and 512 bits for JWE RSA SHA-512.

3.4.  Digital Signature with ECDSA P-256 SHA-256, ECDSA P-384 SHA-384,
      or ECDSA P-521 SHA-512

   The table below is Elliptic Curve Digital Signature Algorithm (ECDSA) [DSS] provides
   for the set use of "alg" (algorithm) header parameter
   values that are defined by this specification for use with JWE.
   These algorithms are used to encrypt the CMK, producing the JWE
   Encrypted Key, or Elliptic Curve cryptography, which is able to use key agreement provide
   equivalent security to agree upon the CMK.

   +-----------+-------------------------------------------------------+
   | alg       | Key Encryption or Agreement Algorithm                 |
   | Parameter |                                                       |
   | Value     |                                                       |
   +-----------+-------------------------------------------------------+
   | RSA1_5    | RSA cryptography but using RSA-PKCS1-1.5 padding, as defined shorter key sizes
   and with greater processing speed.  This means that ECDSA digital
   signatures will be substantially smaller in RFC    |
   |           | 3447 [RFC3447]                                        |
   | RSA-OAEP  | terms of length than
   equivalently strong 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 digital signatures.

   This specification defines the Concat   |
   |           | KDF, as defined in Section 5.8.1 use of [NIST.800-56A],   |
   |           | where ECDSA with the P-256 curve and
   the Digest Method is SHA-256 cryptographic hash function, ECDSA with the P-384 curve
   and all OtherInfo  |
   |           | parameters are the empty bit string                   |
   | A128KW    | Advanced Encryption Standard (AES) Key Wrap Algorithm |
   |           | using 128 bit keys, as 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
   defined in RFC 3394 [RFC3394]  |
   | A256KW    | Advanced Encryption Standard (AES) Key Wrap Algorithm |
   |           | using 256 bit keys, as defined [DSS].  The "alg" (algorithm) header parameter values
   "ES256", "ES384", and "ES512" are used in RFC 3394 [RFC3394]  |
   +-----------+-------------------------------------------------------+

4.2.  "enc" (Encryption Method) the JWS Header Parameter Values for JWE 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 table below ECDSA P-256 SHA-256 digital signature is generated as follows:

   1.  Generate a digital signature of the set bytes 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, which
   produces ASCII
       representation of the Ciphertext.

   +-----------+-------------------------------------------------------+
   | enc       | Block Encryption Algorithm                            |
   | Parameter |                                                       |
   | Value     |                                                       |
   +-----------+-------------------------------------------------------+
   | A128CBC   | Advanced Encryption Standard (AES) using 128 bit keys |
   |           | in Cipher Block Chaining (CBC) mode JWS Secured Input using PKCS #5     |
   |           | padding, as defined in [FIPS.197] ECDSA P-256 SHA-256
       with the desired private key.  The output will be the EC point
       (R, S), where R and [NIST.800-38A]  |
   | A256CBC   | Advanced Encryption Standard (AES) using 256 bit keys |
   |           | in Cipher Block Chaining (CBC) mode using PKCS #5     |
   |           | padding, as defined in [FIPS.197] S are unsigned integers.

   2.  Turn R and [NIST.800-38A]  |
   | A128GCM   | Advanced Encryption Standard (AES) using 128 bit keys |
   |           | S into byte arrays in Galois/Counter Mode (GCM), as defined big endian order, with each
       array being be 32 bytes long.

   3.  Concatenate the two byte arrays in           |
   |           | [FIPS.197] the order R and [NIST.800-38D]                         |
   | A256GCM   | Advanced Encryption Standard (AES) using 256 bit keys |
   |           | in Galois/Counter Mode (GCM), then S. (Note
       that many ECDSA implementations will directly produce this
       concatenation as defined in           |
   |           | [FIPS.197] and [NIST.800-38D]                         |
   +-----------+-------------------------------------------------------+

   See Appendix B their output.)

   4.  Base64url encode the resulting 64 byte array.

   The output is the Encoded JWS Signature for the JWS.

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

   1.  Take the encryption "alg"
   (algorithm) Encoded JWS Signature and "enc" (encryption method) values used in this
   specification with base64url decode it into a
       byte array.  If decoding fails, the equivalent identifiers used by other standards
   and software packages.

   Of these "alg" and "enc" algorithms, only RSA-PKCS1-1.5 with 2048 bit
   keys, AES-128-KW, AES-256-KW, AES-128-CBC, and AES-256-CBC JWS 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.

4.3.  "int" (Integrity Algorithm) Header Parameter Values for JWE rejected.

   2.  The table below is the set output of "int" (integrity algorithm) header
   parameter values defined by this specification for use with JWE.
   Note that these are the HMAC SHA subset of base64url decoding MUST be a 64 byte array.  If
       decoding does not result in a 64 byte array, the "alg" (algorithm)
   header parameter values defined for use with JWS Section 3.1. />

        +---------------------+-----------------------------------+
        | int Parameter Value | Algorithm                         |
        +---------------------+-----------------------------------+
        | HS256               | HMAC using SHA-256 hash algorithm |
        | HS384               | HMAC using SHA-384 hash algorithm |
        | HS512               | HMAC using SHA-512 hash algorithm |
        +---------------------+-----------------------------------+

   Of these "int" algorithms, only HMAC SHA-256 MUST be implemented by
   conforming JWE implementations.  It is RECOMMENDED that
   implementations also support
       rejected.

   3.  Split the RSA SHA-256 64 byte array into two 32 byte arrays.  The first array
       will be R and ECDSA P-256 SHA-256
   algorithms.

4.4.  Key Encryption with RSA using RSA-PKCS1-1.5 Padding

   This section defines the specifics of encrypting a JWE CMK with RSA
   using RSA-PKCS1-1.5 padding, as defined in RFC 3447 [RFC3447].  The
   "alg" header parameter value "RSA1_5" is used in this case.

   A key of size 2048 bits or larger MUST be used with this algorithm.

4.5.  Key Encryption with RSA using Optimal Asymmetric Encryption
      Padding (OAEP)

   This section defines the specifics of encrypting a JWE CMK with RSA
   using Optimal Asymmetric Encryption Padding (OAEP), as defined in RFC
   3447 [RFC3447].  The "alg" header parameter value "RSA-OAEP" is used second S (with both being in this case.

   A key of size 2048 bits or larger MUST be used with this algorithm.

4.6.  Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static
      (ECDH-ES)

   This section defines big endian byte
       order).

   4.  Submit the specifics bytes of agreeing upon a JWE CMK with
   Elliptic Curve Diffie-Hellman Ephemeral Static, as defined in RFC
   6090 [RFC6090], and using the Concat KDF, as defined in Section 5.8.1 ASCII representation of [NIST.800-56A], where the Digest Method is SHA-256 JWS Secured
       Input R, S and all
   OtherInfo parameters are the empty bit string.  The "alg" header
   parameter value "ECDH-ES" is used in this case.

   A public key of size 160 bits or larger MUST be used for (x, y) to the Elliptic Curve
   keys used with this algorithm.  The output of ECDSA P-256 SHA-256
       validator.

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

   Note that ECDSA digital signature contains a key of the same length value referred to as K,
   which is a random number generated for each digital signature
   instance.  This means that used by two ECDSA digital signatures using exactly
   the "enc" algorithm.

   An "epk" (ephemeral public key) value MUST only same input parameters will output different signature values
   because their K values will be used for a single
   key agreement transaction.

4.7.  Key Encryption with AES Key Wrap

   This section defines the specifics different.  A consequence of encrypting a JWE CMK with the
   Advanced Encryption Standard (AES) Key Wrap Algorithm using 128 or
   256 bit keys, as defined in RFC 3394 [RFC3394].  The "alg" header
   parameter values "A128KW" or "A256KW" are used in this case.

4.8.  Plaintext Encryption with AES Cipher Block Chaining (CBC) Mode

   This section defines is
   that one cannot validate an ECDSA signature by recomputing the specifics of encrypting
   signature and comparing the JWE Plaintext results.

   Signing with Advanced Encryption Standard (AES) in Cipher Block Chaining
   (CBC) mode using PKCS #5 padding using 128 or 256 bit keys, as
   defined in [FIPS.197] the ECDSA P-384 SHA-384 and [NIST.800-38A].  The "enc" header parameter
   values "A128CBC" or "A256CBC" are used in this case.

   Use of an Initialization Vector (IV) of size 128 bits ECDSA P-521 SHA-512
   algorithms is RECOMMENDED
   with this algorithm.

4.9.  Plaintext Encryption with AES Galois/Counter Mode (GCM)

   This section defines performed identically to the specifics of encrypting procedure for ECDSA P-256
   SHA-256 - just using the JWE Plaintext corresponding hash algorithm with Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM)
   using 128 or 256 bit keys, as defined in [FIPS.197]
   correspondingly larger result values.  For ECDSA P-384 SHA-384, R and
   [NIST.800-38D].  The "enc" header parameter values "A128GCM" or
   "A256GCM" are used
   S will be 48 bytes each, resulting in this case.

   Use of an Initialization Vector (IV) of size a 96 bits is REQUIRED with
   this algorithm.

   The "additional authenticated data" parameter value for the
   encryption is the concatenation of the Encoded JWE Header, a period
   ('.') character, byte array.  For ECDSA
   P-521 SHA-512, R and the Encoded JWE Encrypted Key.

   The requested size of the "authentication tag" output MUST S will be 66 bytes each (so they can represent a
   521-bit integer), resulting in a 132 byte array.

3.5.  Using the
   same as the key size (for instance, 128 bits for "A128GCM").

   As GCM is an AEAD algorithm, the JWE Integrity Value is set to Algorithm "none"

   JWSs MAY also be created that do not provide integrity protection.
   Such a JWS is called a "Plaintext JWS".  Plaintext JWSs MUST use the
   "authentication tag"
   "alg" value produced by the encryption.

4.10.  Integrity Calculation with HMAC SHA-256, HMAC SHA-384, or HMAC
       SHA-512

   This section defines the specifics of computing a JWE Integrity Value
   with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512 as defined in FIPS
   180-3 [FIPS.180-3].  The "int" header parameter values "HS256",
   "HS384", or "HS512" "none", and are used in this case.

   A key of the same size as the hash output (for instance, 256 bits for
   "HS256") or larger MUST be used formatted identically to other JWSs, but
   with this algorithm.

4.11. an empty JWS Signature value.

3.6.  Additional Encryption Digital Signature/MAC Algorithms and Parameters

   Additional algorithms MAY be used to protect JWEs JWSs with corresponding
   "alg" (algorithm), "enc" (encryption method), and "int" (integrity
   algorithm) (algorithm) header parameter values being defined to refer to
   them.  New "alg", "enc", and "int" "alg" header parameter values SHOULD either be
   defined registered
   in the IANA JSON Web Signature and Encryption Algorithms registry
   Section 6.2 6.1 or be a URI that contains a collision resistant
   namespace. Collision Resistant
   Namespace.  In particular, it is permissible to use the algorithm
   identifiers defined in XML Encryption [W3C.REC-xmlenc-core-20021210], DSIG [RFC3275], XML Encryption 1.1 [W3C.CR-xmlenc-core1-20120313], DSIG 2.0
   [W3C.CR-xmldsig-core2-20120124], and related specifications as "alg", "enc", and "int" "alg"
   values.

   As indicated by the common registry, JWSs and JWEs share a common
   "alg" value space.  The values used by the two specifications MUST be
   distinct, as the "alg" value MAY be used to determine whether the
   object is a JWS or JWE.

   Likewise, additional reserved header parameter names MAY be defined
   via the IANA JSON Web Signature and Encryption Header Parameters
   registry Section 6.1. [JWS].  As indicated by the common registry, JWSs and JWEs
   share a common header parameter space; when a parameter is used by
   both specifications, its usage must be compatible between the
   specifications.

5.

4.  Cryptographic Algorithms for JWK

   A JSON Web JWE

   JWE uses cryptographic algorithms to encrypt the Content Master Key (JWK) [JWK] is a JSON data structure that represents a
   public key.  A JSON Web Key Set (JWK Set) is a JSON data structure
   for representing a set of JWKs.  This section specifies
   (CMK) and the Plaintext.  This section specifies a set of
   algorithm families to be used for those public keys and the algorithm
   family specific parameters
   algorithms for representing those keys.

5.1. these purposes.

4.1.  "alg" (Algorithm Family) (Algorithm) Header Parameter Values for JWK JWE

   The table below is the set of "alg" (algorithm family) (algorithm) header parameter
   values that are defined by this specification for use in JWKs.

     +---------------------+----------------------------------------+ with JWE.
   These algorithms are used to encrypt the CMK, producing the JWE
   Encrypted Key, or to use key agreement to agree upon the CMK.

   +-----------+--------------------------------------+----------------+
   | alg       | Key Encryption or Agreement          | Implementation |
   | Parameter Value | Algorithm Family                            |
     +---------------------+----------------------------------------+ Requirements   | EC
   | Elliptic Curve [FIPS.186-3] key family Value     |                                      | RSA                | RSA
   +-----------+--------------------------------------+----------------+
   | RSA1_5    | RSAES-PKCS1-V1_5 [RFC3447] key family           |
     +---------------------+----------------------------------------+

5.2.  JWK Parameters for Elliptic Curve Keys

   JWKs can represent Elliptic Curve [FIPS.186-3] keys.  In this case,
   the "alg" member value MUST be "EC".  Furthermore, these additional
   members MUST be present:

5.2.1.  "crv" (Curve) Parameter

   The "crv" (curve) member identifies the cryptographic curve used REQUIRED       |
   | RSA-OAEP  | RSAES using Optimal Asymmetric       | OPTIONAL       |
   |           | Encryption Padding (OAEP) [RFC3447], |                |
   |           | with the key.  Values defined by this specification are "P-256", "P-384"
   and "P-521".  Additional "crv" values MAY be used, provided they are
   understood default parameters          |                |
   |           | specified by implementations using that RFC 3447 in Section     |                |
   |           | A.2.1                                |                |
   | ECDH-ES   | Elliptic Curve key.  The
   "crv" value is case sensitive.  Its value MUST be a string.

5.2.2.  "x" (X Coordinate) Parameter

   The "x" (x coordinate) member contains the x coordinate for Diffie-Hellman        | RECOMMENDED+   |
   |           | Ephemeral Static [RFC6090], and      |                |
   |           | using the
   elliptic curve point.  It is represented Concat KDF, as the base64url encoding of
   the coordinate's big endian representation.

5.2.3.  "y" (Y Coordinate) Parameter

   The "y" (y coordinate) member contains the y coordinate for the
   elliptic curve point.  It is represented as the base64url encoding defined in  |                |
   |           | Section 5.8.1 of [NIST.800-56A],     |                |
   |           | where the coordinate's big endian representation.

5.3.  JWK Parameters for RSA Keys

   JWKs can represent RSA [RFC3447] keys.  In this case, Digest Method is SHA-256   |                |
   |           | and all OtherInfo parameters are the "alg"
   member value MUST be "RSA".  Furthermore, these additional members
   MUST be present:

5.3.1.  "mod" (Modulus) Parameter |                |
   |           | empty bit string                     |                |
   | A128KW    | Advanced Encryption Standard (AES)   | RECOMMENDED    |
   |           | Key Wrap Algorithm [RFC3394] using   |                |
   |           | 128 bit keys                         |                |
   | A256KW    | AES Key Wrap Algorithm using 256 bit | RECOMMENDED    |
   |           | keys                                 |                |
   +-----------+--------------------------------------+----------------+

   The "mod" (modulus) member contains use of "+" in the modulus value for Implementation Requirements indicates that the RSA
   public key.  It
   requirement strength is represented as the base64url encoding likely to be increased in a future version of
   the
   value's big endian representation.

5.3.2.  "exp" (Exponent) specification.

4.2.  "enc" (Encryption Method) Header Parameter

   The "exp" (exponent) member contains the exponent value Values for the RSA
   public key.  It JWE

   The table below is represented as the base64url encoding set of the
   value's big endian representation.

5.4.  Additional Key Algorithm Families and Parameters

   Public keys using additional algorithm families MAY be represented
   using JWK data structures with corresponding "alg" (algorithm family) "enc" (encryption method) header
   parameter values being that are defined by this specification for use with
   JWE.  These algorithms are used to refer to them.  New "alg" parameter
   values SHOULD either be defined in encrypt the IANA JSON Web Key Plaintext, which
   produces the Ciphertext.

   +-----------+--------------------------------------+----------------+
   | enc       | Block Encryption Algorithm
   Families registry Section 6.5 or be a URI that contains a collision
   resistant namespace.

   Likewise, parameters for representing           | Implementation |
   | Parameter |                                      | Requirements   |
   | Value     |                                      |                |
   +-----------+--------------------------------------+----------------+
   | A128CBC   | Advanced Encryption Standard (AES)   | REQUIRED       |
   |           | in Cipher Block Chaining (CBC) mode  |                |
   |           | with PKCS #5 padding [AES]           |                |
   |           | [NIST.800-38A] using 128 bit keys for additional algorithm
   families or additional key properties SHOULD either be defined    |                |
   | A256CBC   | AES in CBC mode with PKCS #5 padding | REQUIRED       |
   |           | using 256 bit keys                   |                |
   | A128GCM   | AES in Galois/Counter Mode (GCM)     | RECOMMENDED    |
   |           | [AES] [NIST.800-38D] using 128 bit   |                |
   |           | keys                                 |                |
   | A256GCM   | AES GCM using 256 bit keys           | RECOMMENDED    |
   +-----------+--------------------------------------+----------------+

   All the
   IANA JSON Web Key Parameters registry Section 6.4 or names are short because a core goal of JWE is for the
   representations to be compact.  However, there is no a URI that
   contains priori length
   restriction on "alg" values.

   See Appendix B for a collision resistant namespace.

6.  IANA Considerations

6.1.  JSON Web Signature table cross-referencing the encryption "alg"
   (algorithm) and Encryption Header Parameters Registry

   This "enc" (encryption method) values used in this
   specification establishes with the IANA JSON Web Signature equivalent identifiers used by other standards
   and
   Encryption software packages.

4.3.  "int" (Integrity Algorithm) Header Parameters registry Parameter Values for reserved JWS and JWE header
   parameter names.  Inclusion in the registry

   The table below is RFC Required in the
   RFC 5226 [RFC5226] sense.  The registry records the reserved header
   parameter name and a reference to the RFC that defines it.  This
   specification registers the set of "int" (integrity algorithm) header
   parameter names values defined in JSON
   Web Signature (JWS) [JWS], Section 4.1 and JSON Web Encryption (JWE)
   [JWE], Section 4.1.

6.2.  JSON Web Signature and Encryption Algorithms Registry

   This by this specification establishes the IANA JSON Web Signature and
   Encryption Algorithms registry for values use with JWE.
   Note that these are the HMAC SHA subset of the JWS and JWE "alg"
   (algorithm), "enc" (encryption method), and "int" (integrity
   algorithm) (algorithm)
   header parameters.  Inclusion in the registry is RFC
   Required in the RFC 5226 [RFC5226] sense.  The registry records the
   algorithm usage "alg", "enc", or "int", the value, and a pointer to
   the RFC that defines it.  This specification registers the parameter values defined in Section 3.1, Section 4.1, Section 4.2, and for use with JWS Section 4.3.

6.3.  JSON Web Signature and Encryption "typ" Values Registry

   This specification establishes the IANA JSON Web Signature and
   Encryption "typ" 3.1.

   +-----------------+-------------------------+-----------------------+
   | int Parameter   | Algorithm               | Implementation        |
   | Value           |                         | Requirements          |
   +-----------------+-------------------------+-----------------------+
   | HS256           | HMAC using SHA-256 hash | REQUIRED              |
   |                 | algorithm               |                       |
   | HS384           | HMAC using SHA-384 hash | OPTIONAL              |
   |                 | algorithm               |                       |
   | HS512           | HMAC using SHA-512 hash | OPTIONAL              |
   |                 | algorithm               |                       |
   +-----------------+-------------------------+-----------------------+

4.4.  "kdf" (Key Derivation Function) Header Parameter Values registry for values of the JWS and JWE "typ"
   (type) header parameter.  Inclusion in the registry

   The table below is RFC Required
   in the RFC 5226 [RFC5226] sense.  It is RECOMMENDED that all
   registered "typ" set of "kdf" (key derivation function) header
   parameter values also register a MIME Media Type RFC 2045
   [RFC2045] that the registered value is a short name for.  The
   registry records the "typ" value, the MIME type value that it is an
   abbreviation defined by this specification for (if any), and a pointer to use with JWE.

   +-----------+--------------------------------------+----------------+
   | kdf       | Algorithm                            | Implementation |
   | Parameter |                                      | Requirements   |
   | Value     |                                      |                |
   +-----------+--------------------------------------+----------------+
   | CS256     | Concat KDF, as defined in Section    | REQUIRED       |
   |           | 5.8.1 of [NIST.800-56A], with        |                |
   |           | parameters per Section 4.12, using   |                |
   |           | SHA-256 as the RFC that defines it.

   MIME Media Type RFC 2045 [RFC2045] values MUST NOT be directly
   registered digest method         |                |
   | CS384     | Concat KDF with parameters per       | OPTIONAL       |
   |           | Section 4.12, using SHA-384 as new "typ" values; rather, new "typ" values MAY be
   registered the   |                |
   |           | digest method                        |                |
   | CS512     | Concat KDF with parameters per       | OPTIONAL       |
   |           | Section 4.12, using SHA-512 as short names for MIME types.

6.4.  JSON Web the   |                |
   |           | digest method                        |                |
   +-----------+--------------------------------------+----------------+

4.5.  Key Parameters Registry Encryption with RSAES-PKCS1-V1_5

   This specification establishes section defines the IANA JSON Web Key Parameters
   registry for reserved JWK specifics of encrypting a JWE CMK with
   RSAES-PKCS1-V1_5 [RFC3447].  The "alg" header parameter names.  Inclusion in the registry value
   "RSA1_5" is RFC Required used in this case.

   A key of size 2048 bits or larger MUST be used with this algorithm.

4.6.  Key Encryption with RSAES OAEP

   This section defines the RFC 5226 [RFC5226] sense.  The registry
   records the reserved parameter name and specifics of encrypting a reference to JWE CMK with RSAES
   using Optimal Asymmetric Encryption Padding (OAEP) [RFC3447], with
   the default parameters specified by RFC that
   defines it.  This specification registers the parameter names defined 3447 in JSON Web Key (JWK) [JWK], Section 4.2, JSON Web Encryption (JWE)
   [JWE], Section 4.1, Section 5.2, and Section 5.3.

6.5.  JSON Web Key Algorithm Families Registry

   This specification establishes the IANA JSON Web Key Algorithm
   Families registry for values of the JWK A.2.1.  The
   "alg" (algorithm family)
   parameter.  Inclusion in the registry header parameter value "RSA-OAEP" is RFC Required used in this case.

   A key of size 2048 bits or larger MUST be used with this algorithm.

4.7.  Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static
      (ECDH-ES)

   This section defines the RFC 5226
   [RFC5226] sense.  The registry records the "alg" value and specifics of agreeing upon a pointer
   to the RFC that defines it.  This specification registers JWE CMK with
   Elliptic Curve Diffie-Hellman Ephemeral Static [RFC6090], and using
   the values Concat KDF, as defined in Section 5.1.

7.  Security Considerations

   The security considerations in 5.8.1 of [NIST.800-56A], where
   the JWS, JWE, Digest Method is SHA-256 and JWK specifications
   also apply to this specification.

   Eventually all OtherInfo parameters are the algorithms and/or key sizes currently described
   empty bit string.  The "alg" header parameter value "ECDH-ES" is used
   in this specification will no longer be considered sufficiently secure
   and will be removed.  Therefore, implementers and deployments must be
   prepared for this eventuality.

8.  Open Issues and Things To Be Done (TBD) case.

   The following items remain to output of the Concat KDF MUST be done in this draft:

   o  Find values for encryption algorithm cross-reference table
      currently listed a key of the same length as "TBD" or determine that they do not exist.

9.  References

9.1.  Normative References

   [FIPS.180-3]
              National Institute
   used by the "enc" algorithm.

   A new "epk" (ephemeral public key) value MUST be generated for each
   key agreement transaction.

4.8.  Key Encryption with AES Key Wrap

   This section defines the specifics of Standards and Technology, "Secure
              Hash encrypting a JWE CMK with the
   Advanced Encryption 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.

   [FIPS.197]
              National Institute (AES) Key Wrap Algorithm [RFC3394] using
   128 or 256 bit keys.  The "alg" header parameter values "A128KW" or
   "A256KW" are used in this case.

4.9.  Plaintext Encryption with AES CBC Mode

   This section defines the specifics of Standards and Technology (NIST),
              "Advanced encrypting the JWE Plaintext
   with Advanced Encryption Standard (AES)", FIPS PUB 197,
              November 2001.

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

   [JWK]      Jones, M., "JSON Web Key (JWK)", May 2012.

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

   [NIST.800-38A]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Block (AES) in Cipher Modes Block Chaining
   (CBC) mode with PKCS #5 padding [AES] [NIST.800-38A] using 128 or 256
   bit keys.  The "enc" header parameter values "A128CBC" or "A256CBC"
   are used in this case.

   Use of Operation",
              NIST PUB 800-38A, December 2001.

   [NIST.800-38D]
              National Institute an initialization vector of Standards and Technology (NIST),
              "Recommendation for Block Cipher Modes size 128 bits is REQUIRED with
   this algorithm.

4.10.  Plaintext Encryption with AES GCM

   This section defines the specifics of Operation: encrypting the JWE Plaintext
   with Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) and GMAC", NIST PUB 800-38D,
              December 2001.

   [NIST.800-56A]
              National Institute
   [AES] [NIST.800-38D] using 128 or 256 bit keys.  The "enc" header
   parameter values "A128GCM" or "A256GCM" are used in this case.

   Use of Standards an initialization vector of size 96 bits is REQUIRED with this
   algorithm.

   The "additional authenticated data" parameter is used to secure the
   header and Technology (NIST),
              "Recommendation for Pair-Wise Key Establishment Schemes
              Using Discrete Logarithm Cryptography (Revised)", NIST PUB
              800-56A, March 2007.

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

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

   [RFC2119]  Bradner, S., "Key words key values, as specified for use AEAD algorithms in RFCs Section 5
   of [JWE].

   The requested size of the "authentication tag" output MUST be 128
   bits, regardless of the key size.

   As GCM is an AEAD algorithm, the JWE Integrity Value is set to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3394]  Schaad, J. be the
   "authentication tag" value produced by the encryption.

4.11.  Integrity Calculation with HMAC SHA-256, HMAC SHA-384, or HMAC
       SHA-512

   This section defines the specifics of computing a JWE Integrity Value
   with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512 [SHS].  Other than
   as stated below, these computations are performed identically to
   those specified in Section 3.2.

   A key of the same size as the hash output (for instance, 256 bits for
   "HS256") MUST be used with this algorithm.

   Per Section 9 of [JWE], the JWS Secured Input value used contains the
   header, encrypted key, and R. Housley, "Advanced Encryption Standard
              (AES) ciphertext.

4.12.  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. Derivation with Concat KDF and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6090]  McGrew, D., Igoe, K., SHA-256, SHA-384, or SHA-512

   The key derivation process derives CEK and M. Salter, "Fundamental Elliptic
              Curve Cryptography Algorithms", RFC 6090, February 2011.

9.2.  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.

   [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-xmldsig-core2-20120124]
              Eastlake, D., Reagle, J., Yiu, K., Solo, D., Datta, P.,
              Hirsch, F., Cantor, S., and T. Roessler, "XML Signature
              Syntax and Processing Version 2.0", World Wide Web
              Consortium CR CR-xmldsig-core2-20120124, January 2012,
              <http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124>.

   [W3C.CR-xmlenc-core1-20120313]
              Eastlake, D., Reagle, J., Roessler, T., and F. Hirsch,
              "XML Encryption Syntax and Processing Version 1.1", World
              Wide Web Consortium CR CR-xmlenc-core1-20120313,
              March 2012,
              <http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313>.

   [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/MAC Algorithm Identifier Cross-Reference

   This appendix contains CIK values from the CMK.
   It uses as a table cross-referencing primitive a Key Derivation Function (KDF) which
   notionally takes three arguments:

   MasterKey:  The master key used to compute the digital
   signature and MAC "alg" (algorithm) values individual use keys
   Label:  The use key label, used to differentiate individual use keys

   Length:  The desired length of the use key

   This section defines the specifics of using the Concat KDF, as
   defined in this specification
   with Section 5.8.1 of [NIST.800-56A], where the equivalent identifiers used by other standards Digest Method
   is one of SHA-256, SHA-384, or SHA-512, the SuppPubInfo parameter is
   the Label, and software
   packages.  See XML DSIG [RFC3275], XML DSIG 2.0
   [W3C.CR-xmldsig-core2-20120124], the remaining OtherInfo parameters are the empty bit
   string.

   The "kdf" (key derivation function) header parameter values "CS256",
   "CS384", and Java Cryptography Architecture
   [JCA] "CS512" are respectively used in the JWE Header to
   indicate the use of the Concat KDF as above with the respective
   digest methods.  If the "kdf" header parameter is omitted when an
   AEAD "enc" algorithm is not used, this is equivalent to specifying
   use of the "CS256" key derivation function.

   To compute the CEK from the CMK, the ASCII label "Encryption" ([69,
   110, 99, 114, 121, 112, 116, 105, 111, 110]) is used.  Use the key
   size for more information about the names "enc" algorithm as the CEK desired key length.

   To compute the CIK from the CMK, the ASCII label "Integrity" ([73,
   110, 116, 101, 103, 114, 105, 116, 121]) is used.  Use the minimum
   key size for the "int" algorithm (for instance, 256 bits for "HS256")
   as the CIK desired key length.

4.13.  Additional Encryption Algorithms and Parameters

   Additional algorithms MAY be used to protect JWEs with corresponding
   "alg" (algorithm), "enc" (encryption method), and "int" (integrity
   algorithm) header parameter values being defined to refer to them.
   New "alg", "enc", and "int" header parameter values SHOULD either be
   registered in the IANA JSON Web Signature and Encryption Algorithms
   registry Section 6.1 or be a URI that contains a Collision Resistant
   Namespace.  In particular, it is permissible to use the algorithm
   identifiers defined in XML Encryption [W3C.REC-xmlenc-core-20021210],
   XML Encryption 1.1 [W3C.CR-xmlenc-core1-20120313], and related
   specifications as "alg", "enc", and "int" values.

   As indicated by those
   documents.

   +-------+-----+----------------------------+----------+-------------+
   | Algor | the common registry, JWSs and JWEs share a common
   "alg" value space.  The values used by the two specifications MUST be
   distinct, as the "alg" value MAY be used to determine whether the
   object is a JWS or JWE.

   Likewise, additional reserved header parameter names MAY be defined
   via the IANA JSON Web Signature and Encryption Header Parameters
   registry [JWS].  As indicated by the common registry, JWSs and JWEs
   share a common header parameter space; when a parameter is used by
   both specifications, its usage must be compatible between the
   specifications.

5.  Cryptographic Algorithms for JWK

   A JSON Web Key (JWK) [JWK] is a JavaScript Object Notation (JSON)
   [RFC4627] data structure that represents a public key.  A JSON Web
   Key Set (JWK Set) is a JSON data structure for representing a set of
   JWKs.  This section specifies a set of algorithm families to be used
   for those public keys and the algorithm family specific parameters
   for representing those keys.

5.1.  "alg" (Algorithm Family) Parameter Values for JWK

   The table below is the set of "alg" (algorithm family) parameter
   values that are defined by this specification for use in JWKs.

   +-----------------+-------------------------+-----------------------+
   | 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 alg Parameter   | Algorithm Family        | Implementation        |
   | Value           |                         | 84 Requirements          |
   +-----------------+-------------------------+-----------------------+
   | EC              | Elliptic Curve [DSS]    | RECOMMENDED+          |
   |  hash                 | key family              |                       |
   | RSA             | RSA [RFC3447] key       |  algo REQUIRED              |
   |                 | family                  |                       |
   | rithm |     |                            |          |             |
   | HMAC  | HS5 | http://www.w3.org/2001/04/ | HmacSHA5 | 1.2.840.113 |
   |
   +-----------------+-------------------------+-----------------------+

   All the names are short because a core goal of JWK is for the
   representations to be compact.  However, there is no a priori length
   restriction on "alg" values.

   The use of "+" in the Implementation Requirements indicates that the
   requirement strength is likely to be increased in a future version of
   the specification.

5.2.  JWK Parameters for Elliptic Curve Keys

   JWKs can represent Elliptic Curve [DSS] keys.  In this case, the
   "alg" member value MUST be "EC".  Furthermore, these additional
   members MUST be present:

5.2.1.  "crv" (Curve) Parameter

   The "crv" (curve) member identifies the cryptographic curve used with
   the key.  Curve values from [DSS] used by this specification are:

   o  "P-256"

   o  "P-384"

   o  "P-521"

   Additional "crv" values MAY be used, provided they are understood by
   implementations using | 12  | xmldsig-more#hmac-sha512   | 12       | 549.2.11    |
   | SHA-5 |     |                            |          |             |
   | 12    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | that Elliptic Curve key.  The "crv" value is
   case sensitive.  Its value MUST be a string.

5.2.2.  "x" (X Coordinate) Parameter

   The "x" (x coordinate) member contains the x coordinate for the
   elliptic curve point.  It is represented as the base64url encoding of
   the coordinate's big endian representation.

5.2.3.  "y" (Y Coordinate) Parameter

   The "y" (y coordinate) member contains the y coordinate for the
   elliptic curve point.  It is represented as the base64url encoding of
   the coordinate's big endian representation.

5.3.  JWK Parameters for 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 |     |                            |          |             |
   | Keys

   JWKs can represent RSA   | RS3 | http://www.w3.org/2001/04/ | SHA384wi | 1.2.840.113 |
   | [RFC3447] keys.  In this case, the "alg"
   member value MUST be "RSA".  Furthermore, these additional members
   MUST be present:

5.3.1.  "mod" (Modulus) Parameter

   The "mod" (modulus) member contains the modulus value for the RSA
   public key.  It is represented as the base64url encoding of the
   value's unsigned big endian representation.

5.3.2.  "exp" (Exponent) Parameter

   The "exp" (exponent) member contains the exponent value for the RSA
   public key.  It is represented as the base64url encoding of the
   value's unsigned big endian representation.

5.4.  Additional Key Algorithm Families and Parameters

   Public keys using additional algorithm families MAY be represented
   using JWK data structures with corresponding "alg" (algorithm family)
   parameter values being defined to refer to them.  New "alg" parameter
   values SHOULD either be registered in the IANA JSON Web Key Algorithm
   Families registry Section 6.2 or be a URI that contains a Collision
   Resistant Namespace.

   Likewise, parameters for representing keys for additional algorithm
   families or additional key properties SHOULD either be registered in
   the IANA JSON Web Key Parameters registry [JWK] or be a URI that
   contains a Collision Resistant Namespace.

6.  IANA Considerations

   The following registration procedure is used for all the registries
   established by this specification.

   Values are registered with a Specification Required [RFC5226] after a
   two week review period on the [TBD]@ietf.org mailing list, on the
   advice of one or more Designated Experts.  However, to allow for the
   allocation of values prior to publication, the Designated Expert(s)
   may approve registration once they are satisfied that such a
   specification will be published.

   Registration requests must be sent to the [TBD]@ietf.org mailing list
   for review and comment, with an appropriate subject (e.g., "Request
   for access token type: example"). [[ Note to RFC-EDITOR: The name of
   the mailing list should be determined in consultation with the IESG
   and IANA.  Suggested name: jose-reg-review. ]]

   Within the review period, the Designated Expert(s) will either
   approve or deny the registration request, communicating this decision
   to the review list and IANA.  Denials should include an explanation
   and, if applicable, suggestions as to how to make the request
   successful.

   IANA must only accept registry updates from the Designated Expert(s),
   and should direct all requests for registration to the review mailing
   list.

6.1.  JSON Web Signature and Encryption Algorithms Registry

   This specification establishes the IANA JSON Web Signature and
   Encryption Algorithms registry for values of the JWS and JWE "alg"
   (algorithm), "enc" (encryption method), and "int" (integrity
   algorithm) header parameters.  The registry records the algorithm
   name, the algorithm usage locations from the set "alg", "enc", and
   "int", implementation requirements, and a reference to the
   specification that defines it.  The same algorithm name may be
   registered multiple times, provided that the sets of usage locations
   are disjoint.  The implementation requirements of an algorithm may be
   changed over time by the Designated Experts(s) as the cryptographic
   landscape evolves, for instance, to change the status of an algorithm
   to DEPRECATED, or to change the status of an algorithm from OPTIONAL
   to RECOMMENDED or REQUIRED.

6.1.1.  Registration Template

   Algorithm Name:
      The name requested (e.g., "example").

   Algorithm Usage Location(s):
      The algorithm usage, which must be one or more of the values
      "alg", "enc", "int", or "kdf".

   Implementation Requirements:
      The algorithm implementation requirements, which must be one the
      words REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.  Optionally,
      the word may be followed by a "+" or "-".  The use of "+"
      indicates that the requirement strength is likely to be increased
      in a future version of the specification.  The use of "-"
      indicates that the requirement strength is likely to be decreased
      in a future version of the specification.

   Change Controller:
      For standards-track RFCs, state "IETF".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      e-mail address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document that specifies the parameter, preferably
      including a URI that can be used to retrieve a copy of the
      document.  An indication of the relevant sections may also be
      included, but is not required.

6.1.2.  Initial Registry Contents

   o  Algorithm Name: "HS256"

   o  Algorithm Usage Location(s): "alg", "int"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 and Section 4.3 of [[ this
      document ]]

   o  Algorithm Name: "HS384"

   o  Algorithm Usage Location(s): "alg", "int"
   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 and Section 4.3 of [[ this
      document ]]

   o  Algorithm Name: "HS512"

   o  Algorithm Usage Location(s): "alg", "int"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 and Section 4.3 of [[ this
      document ]]

   o  Algorithm Name: "RS256"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: RECOMMENDED

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "RS384"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "RS512"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Name: "ES256"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: RECOMMENDED+

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "ES384"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "ES512"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "none"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF

   o  Specification Document(s): Section 3.1 of [[ this document ]]

   o  Algorithm Name: "RSA1_5"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Algorithm Name: "RSA-OAEP"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Algorithm Name: "ECDH-ES"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: RECOMMENDED+

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Algorithm Name: "A128KW"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: RECOMMENDED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Algorithm Name: "A256KW"

   o  Algorithm Usage Location(s): "alg"

   o  Implementation Requirements: RECOMMENDED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Algorithm Name: "A128CBC"

   o  Algorithm Usage Location(s): "enc"

   o  Implementation Requirements: REQUIRED
   o  Change Controller: IETF

   o  Specification Document(s): Section 4.2 of [[ this document ]]

   o  Algorithm Name: "A256CBC"

   o  Algorithm Usage Location(s): "enc"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.2 of [[ this document ]]

   o  Algorithm Name: "A128GCM"

   o  Algorithm Usage Location(s): "enc"

   o  Implementation Requirements: RECOMMENDED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.2 of [[ this document ]]

   o  Algorithm Name: "A256GCM"

   o  Algorithm Usage Location(s): "enc"

   o  Implementation Requirements: RECOMMENDED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.2 of [[ this document ]]

   o  Algorithm Name: "CS256"

   o  Algorithm Usage Location(s): "kdf"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.4 of [[ this document ]]

   o  Algorithm Name: "CS384"

   o  Algorithm Usage Location(s): "kdf"
   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.4 of [[ this document ]]

   o  Algorithm Name: "CS512"

   o  Algorithm Usage Location(s): "kdf"

   o  Implementation Requirements: OPTIONAL

   o  Change Controller: IETF

   o  Specification Document(s): Section 4.4 of [[ this document ]]

6.2.  JSON Web Key Algorithm Families Registry

   This specification establishes the IANA JSON Web Key Algorithm
   Families registry for values of the JWK "alg" (algorithm family)
   parameter.  The registry records the "alg" value and a reference to
   the specification that defines it.  This specification registers the
   values defined in Section 5.1.

6.2.1.  Registration Template

   "alg" Parameter Value:
      The name requested (e.g., "example").

   Change Controller:
      For standards-track RFCs, state "IETF".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      e-mail address, home page URI) may also be included.

   Implementation Requirements:
      The algorithm implementation requirements, which must be one the
      words REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.  Optionally,
      the word may be followed by a "+" or "-".  The use of "+"
      indicates that the requirement strength is likely to be increased
      in a future version of the specification.  The use of "-"
      indicates that the requirement strength is likely to be decreased
      in a future version of the specification.

   Specification Document(s):
      Reference to the document that specifies the parameter, preferably
      including a URI that can be used to retrieve a copy of the
      document.  An indication of the relevant sections may also be
      included, but is not required.

6.2.2.  Initial Registry Contents

   o  "alg" Parameter Value: "EC"

   o  Implementation Requirements: RECOMMENDED+

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.1 of [[ this document ]]

   o  "alg" Parameter Value: "RSA"

   o  Implementation Requirements: REQUIRED

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.1 of [[ this document ]]

6.3.  JSON Web Key Parameters Registration

   This specification registers the parameter names defined in
   Section 5.2 and Section 5.3 in the IANA JSON Web Key Parameters
   registry [JWK].

6.3.1.  Registry Contents

   o  Parameter Name: "crv"

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.2.1 of [[ this document ]]

   o  Parameter Name: "x"

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.2.2 of [[ this document ]]

   o  Parameter Name: "y"

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.2.3 of [[ this document ]]

   o  Parameter Name: "mod"

   o  Change Controller: IETF
   o  Specification Document(s): Section 5.3.1 of [[ this document ]]

   o  Parameter Name: "exp"

   o  Change Controller: IETF

   o  Specification Document(s): Section 5.3.2 of [[ this document ]]

7.  Security Considerations

   All of the security issues faced by any cryptographic application
   must be faced by a JWS/JWE/JWK agent.  Among these issues are
   protecting the user's private key, preventing various attacks, and
   helping the user avoid mistakes such as inadvertently encrypting a
   message for the wrong recipient.  The entire list of security
   considerations is beyond the scope of this document, but some
   significant concerns are listed here.

   The security considerations in [AES], [DSS], [JWE], [JWK], [JWS],
   [NIST.800-38A], [NIST.800-38D], [NIST.800-56A], [RFC2104], [RFC3394],
   [RFC3447], [RFC5116], [RFC6090], and [SHS] apply to this
   specification.

   Eventually the algorithms and/or key sizes currently described in
   this specification will no longer be considered sufficiently secure
   and will be removed.  Therefore, implementers and deployments must be
   prepared for this eventuality.

   Algorithms of matching strength should be used together whenever
   possible.  For instance, when AES Key Wrap is used with a given key
   size, using the same key size for AES CBC or GCM is recommended.
   Likewise, when AES CBC is used with a 128 bit key, using HMAC SHA-256
   as the integrity algorithm is recommended, whereas when AES CBC is
   used with a 256 bit key, using HMAC SHA-512 as the integrity
   algorithm is recommended.

   While Section 8 of RFC 3447 [RFC3447] explicitly calls for people not
   to adopt RSASSA-PKCS1 for new applications and instead requests that
   people transition to RSASSA-PSS, this specification does include
   RSASSA-PKCS1, for interoperability reasons, because it commonly
   implemented.

   Keys used with RSAES-PKCS1-v1_5 must follow the constraints in
   Section 7.2 of RFC 3447 [RFC3447].  In particular, keys with a low
   public key exponent value must not be used.

   Plaintext JWSs (JWSs that use the "alg" value "none") provide no
   integrity protection.  Thus, they must only be used in contexts where
   the payload is secured by means other than a digital signature or MAC
   value, or need not be secured.

   Receiving agents that validate signatures and sending agents that
   encrypt messages need to be cautious of cryptographic processing
   usage when validating signatures and encrypting messages using keys
   larger than those mandated in this specification.  An attacker could
   send certificates with keys that would result in excessive
   cryptographic processing, for example, keys larger than those
   mandated in this specification, which could swamp the processing
   element.  Agents that use such keys without first validating the
   certificate to a trust anchor are advised to have some sort of
   cryptographic resource management system to prevent such attacks.

8.  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  Should we use the "alg" value as the AlgorithmID input to the
      Concat KDF when doing key agreement?  Or is an AlgorithmID value
      unnecessary in the way that we are using Concat?

   o  Should we use the "enc" and "int" values as AlgorithmID inputs to
      the Concat KDF when doing key derivation?  Or is an AlgorithmID
      value unnecessary in the way that we are using Concat?

   o  Do we want to add AES ECB as a (non-authenticated) key wrap
      algorithm?

9.  References

9.1.  Normative References

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

   [DSS]      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)", July 2012.

   [JWK]      Jones, M., "JSON Web Key (JWK)", July 2012.

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

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

   [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.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, October 2006.

   [RFC5116]  McGrew, D., "An Interface and Algorithms for Authenticated
              Encryption", RFC 5116, January 2008.

   [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.

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

   [USASCII]  American National Standards Institute, "Coded Character
              Set -- 7-bit American Standard Code for Information
              Interchange", ANSI X3.4, 1986.

9.2.  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.

   [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.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.

   [W3C.CR-xmldsig-core2-20120124]
              Reagle, J., Solo, D., Datta, P., Hirsch, F., Eastlake, D.,
              Roessler, T., Cantor, S., and K. Yiu, "XML Signature
              Syntax and Processing Version 2.0", World Wide Web
              Consortium CR CR-xmldsig-core2-20120124, January 2012,
              <http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124>.

   [W3C.CR-xmlenc-core1-20120313]
              Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler,
              "XML Encryption Syntax and Processing Version 1.1", World
              Wide Web Consortium CR CR-xmlenc-core1-20120313,
              March 2012,
              <http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313>.

   [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/MAC Algorithm Identifier Cross-Reference

   This appendix contains a table cross-referencing the digital
   signature and MAC "alg" (algorithm) values used in this specification
   with the equivalent identifiers used by other standards and software
   packages.  See XML DSIG [RFC3275], XML DSIG 2.0
   [W3C.CR-xmldsig-core2-20120124], and Java Cryptography Architecture
   [JCA] for more information about the names defined by those
   documents.

   +-------+-----+----------------------------+----------+-------------+
   | 84  | xmldsig-more#rsa-sha384    | thRSA    | 549.1.1.12  |
   | SHA-3 |     |                            |          |             |
   | 84    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo Algor | JWS | XML DSIG                   | JCA      | OID         |
   | rithm ithm  |     |                            |          |             |
   +-------+-----+----------------------------+----------+-------------+
   | RSA HMAC  | RS5 HS2 | http://www.w3.org/2001/04/ | SHA512wi HmacSHA2 | 1.2.840.113 |
   | using | 12 56  | xmldsig-more#rsa-sha512 xmldsig-more#hmac-sha256   | thRSA 56       | 549.1.1.13 549.2.9     |
   | SHA-5 SHA-2 |     |                            |          |             |
   | 12 56    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | ECDSA HMAC  | ES2 HS3 | http://www.w3.org/2001/04/ | SHA256wi HmacSHA3 | 1.2.840.100 1.2.840.113 |
   | using | 56  | xmldsig-more#ecdsa-sha256  | thECDSA  | 45.4.3.2    |
   | P-256 |     |                            |          |             |
   | curve |     |                            |          |             |
   | and   | 84  | xmldsig-more#hmac-sha384   | 84       | 549.2.10    |
   | SHA-2 SHA-3 |     |                            |          |             |
   | 56 84    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | ECDSA HMAC  | ES3 HS5 | http://www.w3.org/2001/04/ | SHA384wi HmacSHA5 | 1.2.840.100 1.2.840.113 |
   | using | 84  | xmldsig-more#ecdsa-sha384  | thECDSA  | 45.4.3.3    |
   | P-384 |     |                            |          |             |
   | curve |     |                            |          |             |
   | and   | 12  | xmldsig-more#hmac-sha512   | 12       | 549.2.11    |
   | SHA-3 SHA-5 |     |                            |          |             |
   | 84 12    |     |                            |          |             |
   |  hash |     |                            |          |             |
   |  algo |     |                            |          |             |
   | rithm |     |                            |          |             |
   | ECDSA RSASS | ES5 RS2 | 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   |     |                            | SHA256wi | 1.2.840.113 |
   | SHA-5 A     | 56  | xmldsig-more#rsa-sha256    | thRSA    | 549.1.1.11  |
   | 12  usin |     |                            |          |             |
   |  hash gSHA- |     |                            |          |             |
   |  algo 256   |     |                            |          |             |
   | rithm   has |     |                            |          |             |
   +-------+-----+----------------------------+----------+-------------+

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-core1-20120313], and Java Cryptography Architecture
   [JCA] for more information about the names defined by those
   documents.

   +---------+-------+---------------------------+---------------------+
   | Algorit h alg | JWE     | XML ENC                            | JCA          |             | hm
   | orith |     |                            |
   +---------+-------+---------------------------+---------------------+          | RSA             | RSA1_
   | http://www.w3.org/2001/04 m     | RSA/ECB/PKCS1Paddin     |                            | using          | 5             | /xmlenc#rsa-1_5
   | g RSASS | RS3 | RSA-PKC http://www.w3.org/2001/04/ | SHA384wi | 1.2.840.113 |
   | A     | S1-1.5 84  | xmldsig-more#rsa-sha384    | thRSA    | 549.1.1.12  |
   |  paddin  usin |     |                            |          |             | g
   | gSHA- |     |                            |          | RSA             | RSA-O
   | http://www.w3.org/2001/04 384   | RSA/ECB/OAEPWithSHA     |                            | using          | AEP             | /xmlenc#rsa-oaep-mgf1p
   | -1AndMGF1Padding   has |     | Optimal                            |          |             |
   | h alg | Asymmet     |                            |          |             |
   | ric orith |     |                            |          |             |  Encryp
   | m     |     |                            |          | tion             |
   | RSASS | RS5 | http://www.w3.org/2001/04/ |   Paddi SHA512wi | 1.2.840.113 |
   | A     | 12  | ng(OAEP xmldsig-more#rsa-sha512    | thRSA    | 549.1.1.13  |
   |  usin | )     |                            |          |             |
   | Ellipti gSHA- | ECDH-     | http://www.w3.org/2009/xm                            | TBD          |             | cCurve
   | ES 512   | lenc11#ECDH-ES     |                            |          |  Diffie             |
   |   has |     |                            | -Hellma          |             |
   | h alg |     | n Ephem                            |          |             |
   | orith | eral     |                            |          |             |
   |    Stat m     |     |                            |          |             | ic
   | ECDSA | ES2 | http://www.w3.org/2001/04/ | SHA256wi | Advance 1.2.840.100 | A128K
   | http://www.w3.org/2001/04 using | TBD 56  | xmldsig-more#ecdsa-sha256  | d thECDSA  | W 45.4.3.2    | /xmlenc#kw-aes128
   | P-256 |     |  Encryp                            |          |             |
   | curve | tion     |                            |          |             |
   |   Stand and   |     |                            |          |             | ard(AES
   | SHA-2 |     |                            |          | )  Key             |
   | 56    |     |                            |    Wrap          |             |
   |  hash |     |                            |          |             |    Algo
   |  algo |     |                            |          |             |
   | rithm R |     |                            |          |             | FC  339
   | ECDSA | ES3 | http://www.w3.org/2001/04/ | SHA384wi | 1.2.840.100 | 4   [RF
   | using | 84  | xmldsig-more#ecdsa-sha384  | thECDSA  | C3394] 45.4.3.3    |
   | P-384 |     |                            | using12          |             |
   | curve |     | 8 bitke                            |          |             |
   | and   | ys     |                            |          |             |
   | Advance SHA-3 | A256K     | http://www.w3.org/2001/04                            | TBD          |             | d
   | W 84    | /xmlenc#kw-aes256     |                            |          |  Encryp             |
   |  hash |     |                            | tion          |             |
   |  algo |     |   Stand                            |          |             |
   | rithm | ard(AES     |                            |          |             |
   | )  Key ECDSA | ES5 | http://www.w3.org/2001/04/ | SHA512wi | 1.2.840.100 |
   |    Wrap using | 12  | xmldsig-more#ecdsa-sha512  | thECDSA  | 45.4.3.4    |    Algo
   | P-521 |     |                            |          | rithm R             |
   | curve |     |                            | FC  339          |             |
   | and   |     | 4   [RF                            |          |             |
   | SHA-5 | C3394]     |                            |          |             |
   | using25 12    |     |                            |          |             | 6 bitke
   |  hash |     |                            |          | ys             |
   |  algo |     |                            | Advance          | A128C             | http://www.w3.org/2001/04
   | AES/CBC/PKCS5Paddin rithm |     | d                            | BC          | /xmlenc#aes128-cbc             | g
   +-------+-----+----------------------------+----------+-------------+

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-core1-20120313], and Java Cryptography Architecture
   [JCA] for more information about the names defined by those
   documents.

   +----------+------+---------------------------+---------------------+
   | Algorith | JWE  |  Encryp XML ENC                   | JCA                 |
   | m        |      | tion                           |                     |
   +----------+------+---------------------------+---------------------+
   | RSAES-PK | RSA1 |   Stand http://www.w3.org/2001/04 | RSA/None/PKCS1Paddi |
   | CS1-V1_5 | _5   | ard(AES /xmlenc#rsa-1_5           | ng                  |
   | RSAES    | RSA- | )  usin http://www.w3.org/2001/04 | RSA/None/OAEPWithSH |
   | using    | OAEP | g  128 /xmlenc#rsa-oaep-mgf1p    | A-1AndMGF1Padding   |
   | Optimal  |      |                           | bitkeys                     |
   | Asymmetr |      |                           |  inCiph                     |
   | ic       |      |                           | er Bloc                     |
   |  Encrypt |      |                           | k  Chai                     |
   | ion      |      |                           | ning(CB                     |
   |   Paddin |      |                           | C)  mod                     |
   | g (OAEP) |      |                           | e   usi                     |
   | Elliptic | ECDH | http://www.w3.org/2009/xm | ng  PKC                     |
   | Curve    | -ES  | lenc11#ECDH-ES            | S #5pad                     |
   | Diffie-H |      |                           | ding                     |
   | ellman   |      |                           | Advance                     | A256C
   |  Ephemer |      |                           |                     |
   | alStatic |      |                           |                     |
   | Advanced | A128 | http://www.w3.org/2001/04 | AES/CBC/PKCS5Paddin                     |
   | d Encrypti | BC KW   | /xmlenc#aes256-cbc /xmlenc#kw-aes128         | g                     |
   |  Encryp on       |      |                           |                     |
   | tion  Standar |      |                           |                     |
   |   Stand d(AES)   |      |                           |                     |
   | ard(AES  Key Wra |      |                           |                     |
   | )  usin pAlgorit |      |                           |                     |
   | g  256 hmusing  |      |                           |                     |
   | bitkeys   128 bi |      |                           |                     |
   |  inCiph t keys   |      |                           |                     |
   | er Bloc AES Key  | A256 | http://www.w3.org/2001/04 |                     |
   | k  Chai Wrap     | KW   | /xmlenc#kw-aes256         |                     |
   | ning(CB Algorith |      |                           |                     |
   | C)  mod musing   |      |                           |                     |
   | e   usi  256 bit |      |                           |                     |
   | ng  PKC  keys    |      |                           |                     |
   | AES in   | A128 | http://www.w3.org/2001/04 | AES/CBC/PKCS5Paddin |
   | Cipher   | CBC  | /xmlenc#aes128-cbc        | g                   |
   | S #5pad Block    |      |                           |                     |
   | ding Chaining |      |                           |                     |
   | Advance (CBC)    | A128G      | http://www.w3.org/2009/xm                           | AES/GCM/NoPadding                     |
   | d mode     | CM      | lenc11#aes128-gcm                           |                     |
   |  Encryp with     |      |                           |                     |
   | tion PKCS #5  |      |                           |                     |
   |   Stand padding  |      |                           |                     |
   | ard(AES using    |      |                           |                     |
   | )  usin 128 bit  |      |                           |                     |
   | g  128 keys     |      |                           |                     |
   | bitkeys AES in   | A256 | http://www.w3.org/2001/04 | AES/CBC/PKCS5Paddin |
   |  inGalo CBC mode | CBC  | /xmlenc#aes256-cbc        | g                   |
   | is/Coun with     |      |                           |                     |
   | ter Mod PKCS #5  |      |                           |                     |
   | e   (GC padding  |      |                           |                     |
   | M) using    |      |                           |                     |
   | Advance 256 bit  | A256G      | http://www.w3.org/2009/xm                           | AES/GCM/NoPadding                     |
   | d keys     | CM      | lenc11#aes256-gcm                           |                     |
   |  Encryp AES in   | A128 | http://www.w3.org/2009/xm | AES/GCM/NoPadding   |
   | tion Galois/C | GCM  | lenc11#aes128-gcm         |                     |
   |   Stand ounter   |      |                           |                     |
   | ard(AES  Mode    |      |                           |                     |
   | )  usin  (GCM)   |      |                           |                     |
   | g  256  using   |      |                           |                     |
   | bitkeys  128 bit |      |                           |                     |
   |  inGalo  keys    |      |                           |                     |
   | is/Coun AES GCM  | A256 | http://www.w3.org/2009/xm | AES/GCM/NoPadding   |
   | ter Mod using    | GCM  | lenc11#aes256-gcm         |                     |
   | e   (GC 256 bit  |      |                           |                     |
   | M) keys     |      |                           |                     |
   +---------+-------+---------------------------+---------------------+
   +----------+------+---------------------------+---------------------+

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

   [[ to be removed by the RFC editor before publication as an RFC ]]

   -03

   o  Always use a 128 bit "authentication tag" size for AES GCM,
      regardless of the key size.

   o  Specified that use of a 128 bit IV is REQUIRED with AES CBC.  It
      was previously RECOMMENDED.

   o  Removed key size language for ECDSA algorithms, since the key size
      is implied by the algorithm being used.

   o  Stated that the "int" key size must be the same as the hash output
      size (and not larger, as was previously allowed) so that its size
      is defined for key generation purposes.

   o  Added the "kdf" (key derivation function) header parameter to
      provide crypto agility for key derivation.  The default KDF
      remains the Concat KDF with the SHA-256 digest function.

   o  Clarified that the "mod" and "exp" values are unsigned.

   o  Added Implementation Requirements columns to algorithm tables and
      Implementation Requirements entries to algorithm registries.

   o  Changed AES Key Wrap to RECOMMENDED.

   o  Moved registries JSON Web Signature and Encryption Header
      Parameters and JSON Web Signature and Encryption Type Values to
      the JWS specification.

   o  Moved JSON Web Key Parameters registry to the JWK specification.

   o  Changed registration requirements from RFC Required to
      Specification Required with Expert Review.

   o  Added Registration Template sections for defined registries.

   o  Added Registry Contents sections to populate registry values.

   o  No longer say "the UTF-8 representation of the JWS Secured Input
      (which is the same as the ASCII representation)".  Just call it
      "the ASCII representation of the JWS Secured Input".

   o  Added "Collision Resistant Namespace" to the terminology section.

   o  Numerous editorial improvements.

   -02

   o  For AES GCM, use the "additional authenticated data" parameter to
      provide integrity for the header, encrypted key, and ciphertext
      and use the resulting "authentication tag" value as the JWE
      Integrity Value.

   o  Defined minimum required key sizes for algorithms without
      specified key sizes.

   o  Defined KDF output key sizes.

   o  Specified the use of PKCS #5 padding with AES-CBC.

   o  Generalized text to allow key agreement to be employed as an
      alternative to key wrapping or key encryption.

   o  Clarified that ECDH-ES is a key agreement algorithm.

   o  Required implementation of AES-128-KW and AES-256-KW.

   o  Removed the use of "A128GCM" and "A256GCM" for key wrapping.

   o  Removed "A512KW" since it turns out that it's not a standard
      algorithm.

   o  Clarified the relationship between "typ" header parameter values
      and MIME types.

   o  Generalized language to refer to Message Authentication Codes
      (MACs) rather than Hash-based Message Authentication Codes (HMACs)
      unless in a context specific to HMAC algorithms.

   o  Established registries: JSON Web Signature and Encryption Header
      Parameters, JSON Web Signature and Encryption Algorithms, JSON Web
      Signature and Encryption "typ" Values, JSON Web Key Parameters,
      and JSON Web Key Algorithm Families.

   o  Moved algorithm-specific definitions from JWK to JWA.

   o  Reformatted to give each member definition its own section
      heading.

   -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".

Author's Address

   Michael B. Jones
   Microsoft

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