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Internet Engineering Task Force (IETF)                          M. JonesRequest for Comments: 7518                                     MicrosoftCategory: Standards Track                                       May 2015ISSN: 2070-1721JSON Web Algorithms (JWA)Abstract   This specification registers cryptographic algorithms and identifiers   to be used with the JSON Web Signature (JWS), JSON Web Encryption   (JWE), and JSON Web Key (JWK) specifications.  It defines several   IANA registries for these identifiers.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7518.Copyright Notice   Copyright (c) 2015 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Jones                        Standards Track                    [Page 1]

RFC 7518                JSON Web Algorithms (JWA)               May 2015Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .41.1.  Notational Conventions  . . . . . . . . . . . . . . . . .42.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .53.  Cryptographic Algorithms for Digital Signatures and MACs  . .63.1.  "alg" (Algorithm) Header Parameter Values for JWS . . . .63.2.  HMAC with SHA-2 Functions . . . . . . . . . . . . . . . .73.3.  Digital Signature with RSASSA-PKCS1-v1_5  . . . . . . . .83.4.  Digital Signature with ECDSA  . . . . . . . . . . . . . .93.5.  Digital Signature with RSASSA-PSS . . . . . . . . . . . .103.6.  Using the Algorithm "none"  . . . . . . . . . . . . . . .114.  Cryptographic Algorithms for Key Management . . . . . . . . .114.1.  "alg" (Algorithm) Header Parameter Values for JWE . . . .124.2.  Key Encryption with RSAES-PKCS1-v1_5  . . . . . . . . . .134.3.  Key Encryption with RSAES OAEP  . . . . . . . . . . . . .144.4.  Key Wrapping with AES Key Wrap  . . . . . . . . . . . . .144.5.  Direct Encryption with a Shared Symmetric Key . . . . . .15     4.6.  Key Agreement with Elliptic Curve Diffie-Hellman           Ephemeral Static (ECDH-ES)  . . . . . . . . . . . . . . .154.6.1.  Header Parameters Used for ECDH Key Agreement . . . .164.6.1.1.  "epk" (Ephemeral Public Key) Header Parameter . .164.6.1.2.  "apu" (Agreement PartyUInfo) Header Parameter . .174.6.1.3.  "apv" (Agreement PartyVInfo) Header Parameter . .174.6.2.  Key Derivation for ECDH Key Agreement . . . . . . . .174.7.  Key Encryption with AES GCM . . . . . . . . . . . . . . .184.7.1.  Header Parameters Used for AES GCM Key Encryption . .194.7.1.1.  "iv" (Initialization Vector) Header Parameter . .194.7.1.2.  "tag" (Authentication Tag) Header Parameter . . .194.8.  Key Encryption with PBES2 . . . . . . . . . . . . . . . .204.8.1.  Header Parameters Used for PBES2 Key Encryption . . .204.8.1.1.  "p2s" (PBES2 Salt Input) Header Parameter . . . .214.8.1.2.  "p2c" (PBES2 Count) Header Parameter  . . . . . .215.  Cryptographic Algorithms for Content Encryption . . . . . . .21     5.1.  "enc" (Encryption Algorithm) Header Parameter Values for           JWE . . . . . . . . . . . . . . . . . . . . . . . . . . .225.2.  AES_CBC_HMAC_SHA2 Algorithms  . . . . . . . . . . . . . .225.2.1.  Conventions Used in Defining AES_CBC_HMAC_SHA2  . . .235.2.2.  Generic AES_CBC_HMAC_SHA2 Algorithm . . . . . . . . .235.2.2.1.  AES_CBC_HMAC_SHA2 Encryption  . . . . . . . . . .235.2.2.2.  AES_CBC_HMAC_SHA2 Decryption  . . . . . . . . . .255.2.3.  AES_128_CBC_HMAC_SHA_256  . . . . . . . . . . . . . .255.2.4.  AES_192_CBC_HMAC_SHA_384  . . . . . . . . . . . . . .265.2.5.  AES_256_CBC_HMAC_SHA_512  . . . . . . . . . . . . . .265.2.6.  Content Encryption with AES_CBC_HMAC_SHA2 . . . . . .265.3.  Content Encryption with AES GCM . . . . . . . . . . . . .276.  Cryptographic Algorithms for Keys . . . . . . . . . . . . . .276.1.  "kty" (Key Type) Parameter Values . . . . . . . . . . . .28Jones                        Standards Track                    [Page 2]

RFC 7518                JSON Web Algorithms (JWA)               May 20156.2.  Parameters for Elliptic Curve Keys  . . . . . . . . . . .286.2.1.  Parameters for Elliptic Curve Public Keys . . . . . .286.2.1.1.  "crv" (Curve) Parameter . . . . . . . . . . . . .286.2.1.2.  "x" (X Coordinate) Parameter  . . . . . . . . . .296.2.1.3.  "y" (Y Coordinate) Parameter  . . . . . . . . . .296.2.2.  Parameters for Elliptic Curve Private Keys  . . . . .296.2.2.1.  "d" (ECC Private Key) Parameter . . . . . . . . .296.3.  Parameters for RSA Keys . . . . . . . . . . . . . . . . .306.3.1.  Parameters for RSA Public Keys  . . . . . . . . . . .306.3.1.1.  "n" (Modulus) Parameter . . . . . . . . . . . . .306.3.1.2.  "e" (Exponent) Parameter  . . . . . . . . . . . .306.3.2.  Parameters for RSA Private Keys . . . . . . . . . . .306.3.2.1.  "d" (Private Exponent) Parameter  . . . . . . . .306.3.2.2.  "p" (First Prime Factor) Parameter  . . . . . . .316.3.2.3.  "q" (Second Prime Factor) Parameter . . . . . . .316.3.2.4.  "dp" (First Factor CRT Exponent) Parameter  . . .316.3.2.5.  "dq" (Second Factor CRT Exponent) Parameter . . .316.3.2.6.  "qi" (First CRT Coefficient) Parameter  . . . . .316.3.2.7.  "oth" (Other Primes Info) Parameter . . . . . . .316.4.  Parameters for Symmetric Keys . . . . . . . . . . . . . .326.4.1.  "k" (Key Value) Parameter . . . . . . . . . . . . . .327.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .327.1.  JSON Web Signature and Encryption Algorithms Registry . .337.1.1.  Registration Template . . . . . . . . . . . . . . . .347.1.2.  Initial Registry Contents . . . . . . . . . . . . . .357.2.  Header Parameter Names Registration . . . . . . . . . . .427.2.1.  Registry Contents . . . . . . . . . . . . . . . . . .427.3.  JSON Web Encryption Compression Algorithms Registry . . .437.3.1.  Registration Template . . . . . . . . . . . . . . . .437.3.2.  Initial Registry Contents . . . . . . . . . . . . . .447.4.  JSON Web Key Types Registry . . . . . . . . . . . . . . .447.4.1.  Registration Template . . . . . . . . . . . . . . . .447.4.2.  Initial Registry Contents . . . . . . . . . . . . . .457.5.  JSON Web Key Parameters Registration  . . . . . . . . . .457.5.1.  Registry Contents . . . . . . . . . . . . . . . . . .467.6.  JSON Web Key Elliptic Curve Registry  . . . . . . . . . .487.6.1.  Registration Template . . . . . . . . . . . . . . . .487.6.2.  Initial Registry Contents . . . . . . . . . . . . . .498.  Security Considerations . . . . . . . . . . . . . . . . . . .498.1.  Cryptographic Agility . . . . . . . . . . . . . . . . . .508.2.  Key Lifetimes . . . . . . . . . . . . . . . . . . . . . .508.3.  RSAES-PKCS1-v1_5 Security Considerations  . . . . . . . .508.4.  AES GCM Security Considerations . . . . . . . . . . . . .508.5.  Unsecured JWS Security Considerations . . . . . . . . . .518.6.  Denial-of-Service Attacks . . . . . . . . . . . . . . . .518.7.  Reusing Key Material when Encrypting Keys . . . . . . . .518.8.  Password Considerations . . . . . . . . . . . . . . . . .528.9.  Key Entropy and Random Values . . . . . . . . . . . . . .52Jones                        Standards Track                    [Page 3]

RFC 7518                JSON Web Algorithms (JWA)               May 20158.10. Differences between Digital Signatures and MACs . . . . .528.11. Using Matching Algorithm Strengths  . . . . . . . . . . .538.12. Adaptive Chosen-Ciphertext Attacks  . . . . . . . . . . .538.13. Timing Attacks  . . . . . . . . . . . . . . . . . . . . .538.14. RSA Private Key Representations and Blinding  . . . . . .539.  Internationalization Considerations . . . . . . . . . . . . .5310. References  . . . . . . . . . . . . . . . . . . . . . . . . .5310.1.  Normative References . . . . . . . . . . . . . . . . . .5310.2.  Informative References . . . . . . . . . . . . . . . . .56Appendix A.  Algorithm Identifier Cross-Reference . . . . . . . .59     A.1.  Digital Signature/MAC Algorithm Identifier Cross-           Reference . . . . . . . . . . . . . . . . . . . . . . . .60A.2.  Key Management Algorithm Identifier Cross-Reference . . .61     A.3.  Content Encryption Algorithm Identifier Cross-Reference .  62Appendix B.  Test Cases for AES_CBC_HMAC_SHA2 Algorithms  . . . .62B.1.  Test Cases for AES_128_CBC_HMAC_SHA_256 . . . . . . . . .63B.2.  Test Cases for AES_192_CBC_HMAC_SHA_384 . . . . . . . . .64B.3.  Test Cases for AES_256_CBC_HMAC_SHA_512 . . . . . . . . .65Appendix C.  Example ECDH-ES Key Agreement Computation  . . . . .66   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .69   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .691.  Introduction   This specification registers cryptographic algorithms and identifiers   to be used with the JSON Web Signature (JWS) [JWS], JSON Web   Encryption (JWE) [JWE], and JSON Web Key (JWK) [JWK] specifications.   It defines several IANA registries for these identifiers.  All these   specifications utilize JSON-based [RFC7159] data structures.  This   specification also describes the semantics and operations that are   specific to these algorithms and key types.   Registering the algorithms and identifiers here, rather than in the   JWS, JWE, and 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 also allows   changes to the JWS, JWE, and JWK specifications without changing this   document.   Names defined by this specification are short because a core goal is   for the resulting representations to be compact.1.1.  Notational Conventions   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and   "OPTIONAL" in this document are to be interpreted as described in   "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].Jones                        Standards Track                    [Page 4]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   The interpretation should only be applied when the terms appear in   all capital letters.   BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per   Section 2 of [JWS].   UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] representation   of STRING, where STRING is a sequence of zero or more Unicode   [UNICODE] characters.   ASCII(STRING) denotes the octets of the ASCII [RFC20] representation   of STRING, where STRING is a sequence of zero or more ASCII   characters.   The concatenation of two values A and B is denoted as A || B.2.  Terminology   The terms "JSON Web Signature (JWS)", "Base64url Encoding", "Header   Parameter", "JOSE Header", "JWS Payload", "JWS Protected Header",   "JWS Signature", "JWS Signing Input", and "Unsecured JWS" are defined   by the JWS specification [JWS].   The terms "JSON Web Encryption (JWE)", "Additional Authenticated Data   (AAD)", "Authentication Tag", "Content Encryption Key (CEK)", "Direct   Encryption", "Direct Key Agreement", "JWE Authentication Tag", "JWE   Ciphertext", "JWE Encrypted Key", "JWE Initialization Vector", "JWE   Protected Header", "Key Agreement with Key Wrapping", "Key   Encryption", "Key Management Mode", and "Key Wrapping" are defined by   the JWE specification [JWE].   The terms "JSON Web Key (JWK)" and "JWK Set" are defined by the JWK   specification [JWK].   The terms "Ciphertext", "Digital Signature", "Initialization Vector",   "Message Authentication Code (MAC)", and "Plaintext" are defined by   the "Internet Security Glossary, Version 2" [RFC4949].   This term is defined by this specification:   Base64urlUInt      The representation of a positive or zero integer value as the      base64url encoding of the value's unsigned big-endian      representation as an octet sequence.  The octet sequence MUST      utilize the minimum number of octets needed to represent the      value.  Zero is represented as BASE64URL(single zero-valued      octet), which is "AA".Jones                        Standards Track                    [Page 5]

RFC 7518                JSON Web Algorithms (JWA)               May 20153.  Cryptographic Algorithms for Digital Signatures and MACs   JWS uses cryptographic algorithms to digitally sign or create a MAC   of the contents of the JWS Protected Header and the JWS Payload.3.1.  "alg" (Algorithm) Header Parameter Values for JWS   The table below is the set of "alg" (algorithm) Header Parameter   values defined by this specification for use with JWS, each of which   is explained in more detail in the following sections:   +--------------+-------------------------------+--------------------+   | "alg" Param  | Digital Signature or MAC      | Implementation     |   | Value        | Algorithm                     | Requirements       |   +--------------+-------------------------------+--------------------+   | HS256        | HMAC using SHA-256            | Required           |   | HS384        | HMAC using SHA-384            | Optional           |   | HS512        | HMAC using SHA-512            | Optional           |   | RS256        | RSASSA-PKCS1-v1_5 using       | Recommended        |   |              | SHA-256                       |                    |   | RS384        | RSASSA-PKCS1-v1_5 using       | Optional           |   |              | SHA-384                       |                    |   | RS512        | RSASSA-PKCS1-v1_5 using       | Optional           |   |              | SHA-512                       |                    |   | ES256        | ECDSA using P-256 and SHA-256 | Recommended+       |   | ES384        | ECDSA using P-384 and SHA-384 | Optional           |   | ES512        | ECDSA using P-521 and SHA-512 | Optional           |   | PS256        | RSASSA-PSS using SHA-256 and  | Optional           |   |              | MGF1 with SHA-256             |                    |   | PS384        | RSASSA-PSS using SHA-384 and  | Optional           |   |              | MGF1 with SHA-384             |                    |   | PS512        | RSASSA-PSS using SHA-512 and  | Optional           |   |              | MGF1 with SHA-512             |                    |   | none         | No digital signature or MAC   | Optional           |   |              | performed                     |                    |   +--------------+-------------------------------+--------------------+   The use of "+" in the Implementation Requirements column indicates   that the requirement strength is likely to be increased in a future   version of the specification.   SeeAppendix A.1 for a table cross-referencing the JWS digital   signature and MAC "alg" (algorithm) values defined in this   specification with the equivalent identifiers used by other standards   and software packages.Jones                        Standards Track                    [Page 6]

RFC 7518                JSON Web Algorithms (JWA)               May 20153.2.  HMAC with SHA-2 Functions   Hash-based Message Authentication Codes (HMACs) enable one to use a   secret plus a cryptographic hash function to generate a MAC.  This   can be used to demonstrate that whoever generated the MAC was in   possession of the MAC key.  The algorithm for implementing and   validating HMACs is provided inRFC 2104 [RFC2104].   A key of the same size as the hash output (for instance, 256 bits for   "HS256") or larger MUST be used with this algorithm.  (This   requirement is based onSection 5.3.4 (Security Effect of the HMAC   Key) of NIST SP 800-117 [NIST.800-107], which states that the   effective security strength is the minimum of the security strength   of the key and two times the size of the internal hash value.)   The HMAC SHA-256 MAC is generated perRFC 2104, using SHA-256 as the   hash algorithm "H", using the JWS Signing Input as the "text" value,   and using the shared key.  The HMAC output value is the JWS   Signature.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWS Signature is an HMAC value computed using the   corresponding algorithm:                +-------------------+--------------------+                | "alg" Param Value | MAC Algorithm      |                +-------------------+--------------------+                | HS256             | HMAC using SHA-256 |                | HS384             | HMAC using SHA-384 |                | HS512             | HMAC using SHA-512 |                +-------------------+--------------------+   The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC   value perRFC 2104, using SHA-256 as the hash algorithm "H", using   the received JWS Signing Input as the "text" value, and using the   shared key.  This computed HMAC value is then compared to the result   of base64url decoding the received encoded JWS Signature value.  The   comparison of the computed HMAC value to the JWS Signature value MUST   be done in a constant-time manner to thwart timing attacks.   Alternatively, the computed HMAC value can be base64url encoded and   compared to the received encoded JWS Signature value (also in a   constant-time manner), as this comparison produces the same result as   comparing the unencoded values.  In either case, if the values match,   the HMAC has been validated.Jones                        Standards Track                    [Page 7]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   Securing content and validation with the HMAC SHA-384 and HMAC   SHA-512 algorithms is performed identically to the procedure for HMAC   SHA-256 -- just using the corresponding hash algorithms with   correspondingly larger minimum key sizes and result values: 384 bits   each for HMAC SHA-384 and 512 bits each for HMAC SHA-512.   An example using this algorithm is shown inAppendix A.1 of [JWS].3.3.  Digital Signature with RSASSA-PKCS1-v1_5   This section defines the use of the RSASSA-PKCS1-v1_5 digital   signature algorithm as defined inSection 8.2 of RFC 3447 [RFC3447]   (commonly known as PKCS #1), using SHA-2 [SHS] hash functions.   A key of size 2048 bits or larger MUST be used with these algorithms.   The RSASSA-PKCS1-v1_5 SHA-256 digital signature is generated as   follows: generate a digital signature of the JWS Signing Input using   RSASSA-PKCS1-v1_5-SIGN and the SHA-256 hash function with the desired   private key.  This is the JWS Signature value.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWS Signature is a digital signature value computed   using the corresponding algorithm:          +-------------------+---------------------------------+          | "alg" Param Value | Digital Signature Algorithm     |          +-------------------+---------------------------------+          | RS256             | RSASSA-PKCS1-v1_5 using SHA-256 |          | RS384             | RSASSA-PKCS1-v1_5 using SHA-384 |          | RS512             | RSASSA-PKCS1-v1_5 using SHA-512 |          +-------------------+---------------------------------+   The RSASSA-PKCS1-v1_5 SHA-256 digital signature for a JWS is   validated as follows: submit the JWS Signing Input, the JWS   Signature, 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.   Signing and validation with the RSASSA-PKCS1-v1_5 SHA-384 and RSASSA-   PKCS1-v1_5 SHA-512 algorithms is performed identically to the   procedure for RSASSA-PKCS1-v1_5 SHA-256 -- just using the   corresponding hash algorithms instead of SHA-256.   An example using this algorithm is shown inAppendix A.2 of [JWS].Jones                        Standards Track                    [Page 8]

RFC 7518                JSON Web Algorithms (JWA)               May 20153.4.  Digital Signature with ECDSA   The Elliptic Curve Digital Signature Algorithm (ECDSA) [DSS] provides   for the use of Elliptic Curve Cryptography, which is able to provide   equivalent security to RSA cryptography but using shorter key sizes   and with greater processing speed for many operations.  This means   that ECDSA digital signatures will be substantially smaller in terms   of length than equivalently strong RSA digital signatures.   This specification defines the use of ECDSA with the P-256 curve and   the SHA-256 cryptographic hash function, ECDSA with the P-384 curve   and the SHA-384 hash function, and ECDSA with the P-521 curve and the   SHA-512 hash function.  The P-256, P-384, and P-521 curves are   defined in [DSS].   The ECDSA P-256 SHA-256 digital signature is generated as follows:   1.  Generate a digital signature of the JWS Signing Input using ECDSA       P-256 SHA-256 with the desired private key.  The output will be       the pair (R, S), where R and S are 256-bit unsigned integers.   2.  Turn R and S into octet sequences in big-endian order, with each       array being be 32 octets long.  The octet sequence       representations MUST NOT be shortened to omit any leading zero       octets contained in the values.   3.  Concatenate the two octet sequences in the order R and then S.       (Note that many ECDSA implementations will directly produce this       concatenation as their output.)   4.  The resulting 64-octet sequence is the JWS Signature value.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWS Signature is a digital signature value computed   using the corresponding algorithm:           +-------------------+-------------------------------+           | "alg" Param Value | Digital Signature Algorithm   |           +-------------------+-------------------------------+           | ES256             | ECDSA using P-256 and SHA-256 |           | ES384             | ECDSA using P-384 and SHA-384 |           | ES512             | ECDSA using P-521 and SHA-512 |           +-------------------+-------------------------------+Jones                        Standards Track                    [Page 9]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   The ECDSA P-256 SHA-256 digital signature for a JWS is validated as   follows:   1.  The JWS Signature value MUST be a 64-octet sequence.  If it is       not a 64-octet sequence, the validation has failed.   2.  Split the 64-octet sequence into two 32-octet sequences.  The       first octet sequence represents R and the second S.  The values R       and S are represented as octet sequences using the Integer-to-       OctetString Conversion defined inSection 2.3.7 of SEC1 [SEC1]       (in big-endian octet order).   3.  Submit the JWS Signing Input, R, S, and the public key (x, y) to       the ECDSA P-256 SHA-256 validator.   Signing and validation with the ECDSA P-384 SHA-384 and ECDSA P-521   SHA-512 algorithms is performed identically to the procedure for   ECDSA P-256 SHA-256 -- just using the corresponding hash algorithms   with correspondingly larger result values.  For ECDSA P-384 SHA-384,   R and S will be 384 bits each, resulting in a 96-octet sequence.  For   ECDSA P-521 SHA-512, R and S will be 521 bits each, resulting in a   132-octet sequence.  (Note that the Integer-to-OctetString Conversion   defined inSection 2.3.7 of SEC1 [SEC1] used to represent R and S as   octet sequences adds zero-valued high-order padding bits when needed   to round the size up to a multiple of 8 bits; thus, each 521-bit   integer is represented using 528 bits in 66 octets.)   Examples using these algorithms are shown in Appendices A.3 and A.4   of [JWS].3.5.  Digital Signature with RSASSA-PSS   This section defines the use of the RSASSA-PSS digital signature   algorithm as defined inSection 8.1 of RFC 3447 [RFC3447] with the   MGF1 mask generation function and SHA-2 hash functions, always using   the same hash function for both the RSASSA-PSS hash function and the   MGF1 hash function.  The size of the salt value is the same size as   the hash function output.  All other algorithm parameters use the   defaults specified inAppendix A.2.3 of RFC 3447.   A key of size 2048 bits or larger MUST be used with this algorithm.   The RSASSA-PSS SHA-256 digital signature is generated as follows:   generate a digital signature of the JWS Signing Input using RSASSA-   PSS-SIGN, the SHA-256 hash function, and the MGF1 mask generation   function with SHA-256 with the desired private key.  This is the JWS   Signature value.Jones                        Standards Track                   [Page 10]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWS Signature is a digital signature value computed   using the corresponding algorithm:   +-------------------+-----------------------------------------------+   | "alg" Param Value | Digital Signature Algorithm                   |   +-------------------+-----------------------------------------------+   | PS256             | RSASSA-PSS using SHA-256 and MGF1 with        |   |                   | SHA-256                                       |   | PS384             | RSASSA-PSS using SHA-384 and MGF1 with        |   |                   | SHA-384                                       |   | PS512             | RSASSA-PSS using SHA-512 and MGF1 with        |   |                   | SHA-512                                       |   +-------------------+-----------------------------------------------+   The RSASSA-PSS SHA-256 digital signature for a JWS is validated as   follows: submit the JWS Signing Input, the JWS Signature, and the   public key corresponding to the private key used by the signer to the   RSASSA-PSS-VERIFY algorithm using SHA-256 as the hash function and   using MGF1 as the mask generation function with SHA-256.   Signing and validation with the RSASSA-PSS SHA-384 and RSASSA-PSS   SHA-512 algorithms is performed identically to the procedure for   RSASSA-PSS SHA-256 -- just using the alternative hash algorithm in   both roles.3.6.  Using the Algorithm "none"   JWSs MAY also be created that do not provide integrity protection.   Such a JWS is called an Unsecured JWS.  An Unsecured JWS uses the   "alg" value "none" and is formatted identically to other JWSs, but   MUST use the empty octet sequence as its JWS Signature value.   Recipients MUST verify that the JWS Signature value is the empty   octet sequence.   Implementations that support Unsecured JWSs MUST NOT accept such   objects as valid unless the application specifies that it is   acceptable for a specific object to not be integrity protected.   Implementations MUST NOT accept Unsecured JWSs by default.  In order   to mitigate downgrade attacks, applications MUST NOT signal   acceptance of Unsecured JWSs at a global level, and SHOULD signal   acceptance on a per-object basis.  SeeSection 8.5 for security   considerations associated with using this algorithm.4.  Cryptographic Algorithms for Key Management   JWE uses cryptographic algorithms to encrypt or determine the Content   Encryption Key (CEK).Jones                        Standards Track                   [Page 11]

RFC 7518                JSON Web Algorithms (JWA)               May 20154.1.  "alg" (Algorithm) Header Parameter Values for JWE   The table below is the set of "alg" (algorithm) Header Parameter   values that are defined by this specification for use with JWE.   These algorithms are used to encrypt the CEK, producing the JWE   Encrypted Key, or to use key agreement to agree upon the CEK.   +--------------------+--------------------+--------+----------------+   | "alg" Param Value  | Key Management     | More   | Implementation |   |                    | Algorithm          | Header | Requirements   |   |                    |                    | Params |                |   +--------------------+--------------------+--------+----------------+   | RSA1_5             | RSAES-PKCS1-v1_5   | (none) | Recommended-   |   | RSA-OAEP           | RSAES OAEP using   | (none) | Recommended+   |   |                    | default parameters |        |                |   | RSA-OAEP-256       | RSAES OAEP using   | (none) | Optional       |   |                    | SHA-256 and MGF1   |        |                |   |                    | with SHA-256       |        |                |   | A128KW             | AES Key Wrap with  | (none) | Recommended    |   |                    | default initial    |        |                |   |                    | value using        |        |                |   |                    | 128-bit key        |        |                |   | A192KW             | AES Key Wrap with  | (none) | Optional       |   |                    | default initial    |        |                |   |                    | value using        |        |                |   |                    | 192-bit key        |        |                |   | A256KW             | AES Key Wrap with  | (none) | Recommended    |   |                    | default initial    |        |                |   |                    | value using        |        |                |   |                    | 256-bit key        |        |                |   | dir                | Direct use of a    | (none) | Recommended    |   |                    | shared symmetric   |        |                |   |                    | key as the CEK     |        |                |   | ECDH-ES            | Elliptic Curve     | "epk", | Recommended+   |   |                    | Diffie-Hellman     | "apu", |                |   |                    | Ephemeral Static   | "apv"  |                |   |                    | key agreement      |        |                |   |                    | using Concat KDF   |        |                |   | ECDH-ES+A128KW     | ECDH-ES using      | "epk", | Recommended    |   |                    | Concat KDF and CEK | "apu", |                |   |                    | wrapped with       | "apv"  |                |   |                    | "A128KW"           |        |                |   | ECDH-ES+A192KW     | ECDH-ES using      | "epk", | Optional       |   |                    | Concat KDF and CEK | "apu", |                |   |                    | wrapped with       | "apv"  |                |   |                    | "A192KW"           |        |                |Jones                        Standards Track                   [Page 12]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   | ECDH-ES+A256KW     | ECDH-ES using      | "epk", | Recommended    |   |                    | Concat KDF and CEK | "apu", |                |   |                    | wrapped with       | "apv"  |                |   |                    | "A256KW"           |        |                |   | A128GCMKW          | Key wrapping with  | "iv",  | Optional       |   |                    | AES GCM using      | "tag"  |                |   |                    | 128-bit key        |        |                |   | A192GCMKW          | Key wrapping with  | "iv",  | Optional       |   |                    | AES GCM using      | "tag"  |                |   |                    | 192-bit key        |        |                |   | A256GCMKW          | Key wrapping with  | "iv",  | Optional       |   |                    | AES GCM using      | "tag"  |                |   |                    | 256-bit key        |        |                |   | PBES2-HS256+A128KW | PBES2 with HMAC    | "p2s", | Optional       |   |                    | SHA-256 and        | "p2c"  |                |   |                    | "A128KW" wrapping  |        |                |   | PBES2-HS384+A192KW | PBES2 with HMAC    | "p2s", | Optional       |   |                    | SHA-384 and        | "p2c"  |                |   |                    | "A192KW" wrapping  |        |                |   | PBES2-HS512+A256KW | PBES2 with HMAC    | "p2s", | Optional       |   |                    | SHA-512 and        | "p2c"  |                |   |                    | "A256KW" wrapping  |        |                |   +--------------------+--------------------+--------+----------------+   The More Header Params column indicates what additional Header   Parameters are used by the algorithm, beyond "alg", which all use.   All but "dir" and "ECDH-ES" also produce a JWE Encrypted Key value.   The use of "+" in the Implementation Requirements column 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.   SeeAppendix A.2 for a table cross-referencing the JWE "alg"   (algorithm) values defined in this specification with the equivalent   identifiers used by other standards and software packages.4.2.  Key Encryption with RSAES-PKCS1-v1_5   This section defines the specifics of encrypting a JWE CEK with   RSAES-PKCS1-v1_5 [RFC3447].  The "alg" (algorithm) Header Parameter   value "RSA1_5" is used for this algorithm.   A key of size 2048 bits or larger MUST be used with this algorithm.   An example using this algorithm is shown inAppendix A.2 of [JWE].Jones                        Standards Track                   [Page 13]

RFC 7518                JSON Web Algorithms (JWA)               May 20154.3.  Key Encryption with RSAES OAEP   This section defines the specifics of encrypting a JWE CEK with RSAES   using Optimal Asymmetric Encryption Padding (OAEP) [RFC3447].  Two   sets of parameters for using OAEP are defined, which use different   hash functions.  In the first case, the default parameters specified   inAppendix A.2.1 of RFC 3447 are used.  (Those default parameters   are the SHA-1 hash function and the MGF1 with SHA-1 mask generation   function.)  In the second case, the SHA-256 hash function and the   MGF1 with SHA-256 mask generation function are used.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWE Encrypted Key is the result of encrypting the   CEK using the corresponding algorithm:   +-------------------+-----------------------------------------------+   | "alg" Param Value | Key Management Algorithm                      |   +-------------------+-----------------------------------------------+   | RSA-OAEP          | RSAES OAEP using default parameters           |   | RSA-OAEP-256      | RSAES OAEP using SHA-256 and MGF1 with        |   |                   | SHA-256                                       |   +-------------------+-----------------------------------------------+   A key of size 2048 bits or larger MUST be used with these algorithms.   (This requirement is based on Table 4 (Security-strength time frames)   of NIST SP 800-57 [NIST.800-57], which requires 112 bits of security   for new uses, and Table 2 (Comparable strengths) of the same, which   states that 2048-bit RSA keys provide 112 bits of security.)   An example using RSAES OAEP with the default parameters is shown inAppendix A.1 of [JWE].4.4.  Key Wrapping with AES Key Wrap   This section defines the specifics of encrypting a JWE CEK with the   Advanced Encryption Standard (AES) Key Wrap Algorithm [RFC3394] using   the default initial value specified inSection 2.2.3.1 of that   document.Jones                        Standards Track                   [Page 14]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWE Encrypted Key is the result of encrypting the   CEK using the corresponding algorithm and key size:   +-----------------+-------------------------------------------------+   | "alg" Param     | Key Management Algorithm                        |   | Value           |                                                 |   +-----------------+-------------------------------------------------+   | A128KW          | AES Key Wrap with default initial value using   |   |                 | 128-bit key                                     |   | A192KW          | AES Key Wrap with default initial value using   |   |                 | 192-bit key                                     |   | A256KW          | AES Key Wrap with default initial value using   |   |                 | 256-bit key                                     |   +-----------------+-------------------------------------------------+   An example using this algorithm is shown inAppendix A.3 of [JWE].4.5.  Direct Encryption with a Shared Symmetric Key   This section defines the specifics of directly performing symmetric   key encryption without performing a key wrapping step.  In this case,   the shared symmetric key is used directly as the Content Encryption   Key (CEK) value for the "enc" algorithm.  An empty octet sequence is   used as the JWE Encrypted Key value.  The "alg" (algorithm) Header   Parameter value "dir" is used in this case.   Refer to the security considerations on key lifetimes inSection 8.2   and AES GCM inSection 8.4 when considering utilizing direct   encryption.4.6.  Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static      (ECDH-ES)   This section defines the specifics of key agreement with Elliptic   Curve Diffie-Hellman Ephemeral Static [RFC6090], in combination with   the Concat KDF, as defined in Section 5.8.1 of [NIST.800-56A].  The   key agreement result can be used in one of two ways:   1.  directly as the Content Encryption Key (CEK) for the "enc"       algorithm, in the Direct Key Agreement mode, or   2.  as a symmetric key used to wrap the CEK with the "A128KW",       "A192KW", or "A256KW" algorithms, in the Key Agreement with Key       Wrapping mode.   A new ephemeral public key value MUST be generated for each key   agreement operation.Jones                        Standards Track                   [Page 15]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   In Direct Key Agreement mode, the output of the Concat KDF MUST be a   key of the same length as that used by the "enc" algorithm.  In this   case, the empty octet sequence is used as the JWE Encrypted Key   value.  The "alg" (algorithm) Header Parameter value "ECDH-ES" is   used in the Direct Key Agreement mode.   In Key Agreement with Key Wrapping mode, the output of the Concat KDF   MUST be a key of the length needed for the specified key wrapping   algorithm.  In this case, the JWE Encrypted Key is the CEK wrapped   with the agreed-upon key.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWE Encrypted Key is the result of encrypting the   CEK using the result of the key agreement algorithm as the key   encryption key for the corresponding key wrapping algorithm:   +-----------------+-------------------------------------------------+   | "alg" Param     | Key Management Algorithm                        |   | Value           |                                                 |   +-----------------+-------------------------------------------------+   | ECDH-ES+A128KW  | ECDH-ES using Concat KDF and CEK wrapped with   |   |                 | "A128KW"                                        |   | ECDH-ES+A192KW  | ECDH-ES using Concat KDF and CEK wrapped with   |   |                 | "A192KW"                                        |   | ECDH-ES+A256KW  | ECDH-ES using Concat KDF and CEK wrapped with   |   |                 | "A256KW"                                        |   +-----------------+-------------------------------------------------+4.6.1.  Header Parameters Used for ECDH Key Agreement   The following Header Parameter names are used for key agreement as   defined below.4.6.1.1.  "epk" (Ephemeral Public Key) Header Parameter   The "epk" (ephemeral public key) value created by the originator for   the use in key agreement algorithms.  This key is represented as a   JSON Web Key [JWK] public key value.  It MUST contain only public key   parameters and SHOULD contain only the minimum JWK parameters   necessary to represent the key; other JWK parameters included can be   checked for consistency and honored, or they can be ignored.  This   Header Parameter MUST be present and MUST be understood and processed   by implementations when these algorithms are used.Jones                        Standards Track                   [Page 16]

RFC 7518                JSON Web Algorithms (JWA)               May 20154.6.1.2.  "apu" (Agreement PartyUInfo) Header Parameter   The "apu" (agreement PartyUInfo) value for key agreement algorithms   using it (such as "ECDH-ES"), represented as a base64url-encoded   string.  When used, the PartyUInfo value contains information about   the producer.  Use of this Header Parameter is OPTIONAL.  This Header   Parameter MUST be understood and processed by implementations when   these algorithms are used.4.6.1.3.  "apv" (Agreement PartyVInfo) Header Parameter   The "apv" (agreement PartyVInfo) value for key agreement algorithms   using it (such as "ECDH-ES"), represented as a base64url encoded   string.  When used, the PartyVInfo value contains information about   the recipient.  Use of this Header Parameter is OPTIONAL.  This   Header Parameter MUST be understood and processed by implementations   when these algorithms are used.4.6.2.  Key Derivation for ECDH Key Agreement   The key derivation process derives the agreed-upon key from the   shared secret Z established through the ECDH algorithm, per   Section 6.2.2.2 of [NIST.800-56A].   Key derivation is performed using the Concat KDF, as defined in   Section 5.8.1 of [NIST.800-56A], where the Digest Method is SHA-256.   The Concat KDF parameters are set as follows:   Z      This is set to the representation of the shared secret Z as an      octet sequence.   keydatalen      This is set to the number of bits in the desired output key.  For      "ECDH-ES", this is length of the key used by the "enc" algorithm.      For "ECDH-ES+A128KW", "ECDH-ES+A192KW", and "ECDH-ES+A256KW", this      is 128, 192, and 256, respectively.   AlgorithmID      The AlgorithmID value is of the form Datalen || Data, where Data      is a variable-length string of zero or more octets, and Datalen is      a fixed-length, big-endian 32-bit counter that indicates the      length (in octets) of Data.  In the Direct Key Agreement case,      Data is set to the octets of the ASCII representation of the "enc"      Header Parameter value.  In the Key Agreement with Key Wrapping      case, Data is set to the octets of the ASCII representation of the      "alg" (algorithm) Header Parameter value.Jones                        Standards Track                   [Page 17]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   PartyUInfo      The PartyUInfo value is of the form Datalen || Data, where Data is      a variable-length string of zero or more octets, and Datalen is a      fixed-length, big-endian 32-bit counter that indicates the length      (in octets) of Data.  If an "apu" (agreement PartyUInfo) Header      Parameter is present, Data is set to the result of base64url      decoding the "apu" value and Datalen is set to the number of      octets in Data.  Otherwise, Datalen is set to 0 and Data is set to      the empty octet sequence.   PartyVInfo      The PartyVInfo value is of the form Datalen || Data, where Data is      a variable-length string of zero or more octets, and Datalen is a      fixed-length, big-endian 32-bit counter that indicates the length      (in octets) of Data.  If an "apv" (agreement PartyVInfo) Header      Parameter is present, Data is set to the result of base64url      decoding the "apv" value and Datalen is set to the number of      octets in Data.  Otherwise, Datalen is set to 0 and Data is set to      the empty octet sequence.   SuppPubInfo      This is set to the keydatalen represented as a 32-bit big-endian      integer.   SuppPrivInfo      This is set to the empty octet sequence.   Applications need to specify how the "apu" and "apv" Header   Parameters are used for that application.  The "apu" and "apv" values   MUST be distinct, when used.  Applications wishing to conform to   [NIST.800-56A] need to provide values that meet the requirements of   that document, e.g., by using values that identify the producer and   consumer.  Alternatively, applications MAY conduct key derivation in   a manner similar to "Diffie-Hellman Key Agreement Method" [RFC2631]:   in that case, the "apu" parameter MAY either be omitted or represent   a random 512-bit value (analogous to PartyAInfo in Ephemeral-Static   mode inRFC 2631) and the "apv" parameter SHOULD NOT be present.   SeeAppendix C for an example key agreement computation using this   method.4.7.  Key Encryption with AES GCM   This section defines the specifics of encrypting a JWE Content   Encryption Key (CEK) with Advanced Encryption Standard (AES) in   Galois/Counter Mode (GCM) ([AES] and [NIST.800-38D]).Jones                        Standards Track                   [Page 18]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   Use of an Initialization Vector (IV) of size 96 bits is REQUIRED with   this algorithm.  The IV is represented in base64url-encoded form as   the "iv" (initialization vector) Header Parameter value.   The Additional Authenticated Data value used is the empty octet   string.   The requested size of the Authentication Tag output MUST be 128 bits,   regardless of the key size.   The JWE Encrypted Key value is the ciphertext output.   The Authentication Tag output is represented in base64url-encoded   form as the "tag" (authentication tag) Header Parameter value.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWE Encrypted Key is the result of encrypting the   CEK using the corresponding algorithm and key size:    +-------------------+---------------------------------------------+    | "alg" Param Value | Key Management Algorithm                    |    +-------------------+---------------------------------------------+    | A128GCMKW         | Key wrapping with AES GCM using 128-bit key |    | A192GCMKW         | Key wrapping with AES GCM using 192-bit key |    | A256GCMKW         | Key wrapping with AES GCM using 256-bit key |    +-------------------+---------------------------------------------+4.7.1.  Header Parameters Used for AES GCM Key Encryption   The following Header Parameters are used for AES GCM key encryption.4.7.1.1.  "iv" (Initialization Vector) Header Parameter   The "iv" (initialization vector) Header Parameter value is the   base64url-encoded representation of the 96-bit IV value used for the   key encryption operation.  This Header Parameter MUST be present and   MUST be understood and processed by implementations when these   algorithms are used.4.7.1.2.  "tag" (Authentication Tag) Header Parameter   The "tag" (authentication tag) Header Parameter value is the   base64url-encoded representation of the 128-bit Authentication Tag   value resulting from the key encryption operation.  This Header   Parameter MUST be present and MUST be understood and processed by   implementations when these algorithms are used.Jones                        Standards Track                   [Page 19]

RFC 7518                JSON Web Algorithms (JWA)               May 20154.8.  Key Encryption with PBES2   This section defines the specifics of performing password-based   encryption of a JWE CEK, by first deriving a key encryption key from   a user-supplied password using PBES2 schemes as specified inSection 6.2 of [RFC2898], then by encrypting the JWE CEK using the   derived key.   These algorithms use HMAC SHA-2 algorithms as the Pseudorandom   Function (PRF) for the PBKDF2 key derivation and AES Key Wrap   [RFC3394] for the encryption scheme.  The PBES2 password input is an   octet sequence; if the password to be used is represented as a text   string rather than an octet sequence, the UTF-8 encoding of the text   string MUST be used as the octet sequence.  The salt parameter MUST   be computed from the "p2s" (PBES2 salt input) Header Parameter value   and the "alg" (algorithm) Header Parameter value as specified in the   "p2s" definition below.  The iteration count parameter MUST be   provided as the "p2c" (PBES2 count) Header Parameter value.  The   algorithms respectively use HMAC SHA-256, HMAC SHA-384, and HMAC   SHA-512 as the PRF and use 128-, 192-, and 256-bit AES Key Wrap keys.   Their derived-key lengths respectively are 16, 24, and 32 octets.   The following "alg" (algorithm) Header Parameter values are used to   indicate that the JWE Encrypted Key is the result of encrypting the   CEK using the result of the corresponding password-based encryption   algorithm as the key encryption key for the corresponding key   wrapping algorithm:   +--------------------+----------------------------------------------+   | "alg" Param Value  | Key Management Algorithm                     |   +--------------------+----------------------------------------------+   | PBES2-HS256+A128KW | PBES2 with HMAC SHA-256 and "A128KW"         |   |                    | wrapping                                     |   | PBES2-HS384+A192KW | PBES2 with HMAC SHA-384 and "A192KW"         |   |                    | wrapping                                     |   | PBES2-HS512+A256KW | PBES2 with HMAC SHA-512 and "A256KW"         |   |                    | wrapping                                     |   +--------------------+----------------------------------------------+   SeeAppendix C of the JWK specification [JWK] for an example key   encryption computation using "PBES2-HS256+A128KW".4.8.1.  Header Parameters Used for PBES2 Key Encryption   The following Header Parameters are used for Key Encryption with   PBES2.Jones                        Standards Track                   [Page 20]

RFC 7518                JSON Web Algorithms (JWA)               May 20154.8.1.1.  "p2s" (PBES2 Salt Input) Header Parameter   The "p2s" (PBES2 salt input) Header Parameter encodes a Salt Input   value, which is used as part of the PBKDF2 salt value.  The "p2s"   value is BASE64URL(Salt Input).  This Header Parameter MUST be   present and MUST be understood and processed by implementations when   these algorithms are used.   The salt expands the possible keys that can be derived from a given   password.  A Salt Input value containing 8 or more octets MUST be   used.  A new Salt Input value MUST be generated randomly for every   encryption operation; seeRFC 4086 [RFC4086] for considerations on   generating random values.  The salt value used is (UTF8(Alg) || 0x00   || Salt Input), where Alg is the "alg" (algorithm) Header Parameter   value.4.8.1.2.  "p2c" (PBES2 Count) Header Parameter   The "p2c" (PBES2 count) Header Parameter contains the PBKDF2   iteration count, represented as a positive JSON integer.  This Header   Parameter MUST be present and MUST be understood and processed by   implementations when these algorithms are used.   The iteration count adds computational expense, ideally compounded by   the possible range of keys introduced by the salt.  A minimum   iteration count of 1000 is RECOMMENDED.5.  Cryptographic Algorithms for Content Encryption   JWE uses cryptographic algorithms to encrypt and integrity-protect   the plaintext and to integrity-protect the Additional Authenticated   Data.Jones                        Standards Track                   [Page 21]

RFC 7518                JSON Web Algorithms (JWA)               May 20155.1.  "enc" (Encryption Algorithm) Header Parameter Values for JWE   The table below is the set of "enc" (encryption algorithm) Header   Parameter values that are defined by this specification for use with   JWE.   +---------------+----------------------------------+----------------+   | "enc" Param   | Content Encryption Algorithm     | Implementation |   | Value         |                                  | Requirements   |   +---------------+----------------------------------+----------------+   | A128CBC-HS256 | AES_128_CBC_HMAC_SHA_256         | Required       |   |               | authenticated encryption         |                |   |               | algorithm, as defined in Section |                |   |               | 5.2.3                            |                |   | A192CBC-HS384 | AES_192_CBC_HMAC_SHA_384         | Optional       |   |               | authenticated encryption         |                |   |               | algorithm, as defined in Section |                |   |               | 5.2.4                            |                |   | A256CBC-HS512 | AES_256_CBC_HMAC_SHA_512         | Required       |   |               | authenticated encryption         |                |   |               | algorithm, as defined in Section |                |   |               | 5.2.5                            |                |   | A128GCM       | AES GCM using 128-bit key        | Recommended    |   | A192GCM       | AES GCM using 192-bit key        | Optional       |   | A256GCM       | AES GCM using 256-bit key        | Recommended    |   +---------------+----------------------------------+----------------+   All also use a JWE Initialization Vector value and produce JWE   Ciphertext and JWE Authentication Tag values.   SeeAppendix A.3 for a table cross-referencing the JWE "enc"   (encryption algorithm) values defined in this specification with the   equivalent identifiers used by other standards and software packages.5.2.  AES_CBC_HMAC_SHA2 Algorithms   This section defines a family of authenticated encryption algorithms   built using a composition of AES [AES] in Cipher Block Chaining (CBC)   mode [NIST.800-38A] with PKCS #7 padding operations perSection 6.3   of [RFC5652] and HMAC ([RFC2104] and [SHS]) operations.  This   algorithm family is called AES_CBC_HMAC_SHA2.  It also defines three   instances of this family: the first using 128-bit CBC keys and HMAC   SHA-256, the second using 192-bit CBC keys and HMAC SHA-384, and the   third using 256-bit CBC keys and HMAC SHA-512.  Test cases for these   algorithms can be found inAppendix B.Jones                        Standards Track                   [Page 22]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   These algorithms are based upon "Authenticated Encryption with AES-   CBC and HMAC-SHA" [AEAD-CBC-SHA], performing the same cryptographic   computations, but with the Initialization Vector (IV) and   Authentication Tag values remaining separate, rather than being   concatenated with the ciphertext value in the output representation.   This option is discussed inAppendix B of that specification.  This   algorithm family is a generalization of the algorithm family in   [AEAD-CBC-SHA] and can be used to implement those algorithms.5.2.1.  Conventions Used in Defining AES_CBC_HMAC_SHA2   We use the following notational conventions.      CBC-PKCS7-ENC(X, P) denotes the AES-CBC encryption of P using PKCS      #7 padding utilizing the cipher with the key X.      MAC(Y, M) denotes the application of the MAC to the message M      using the key Y.5.2.2.  Generic AES_CBC_HMAC_SHA2 Algorithm   This section defines AES_CBC_HMAC_SHA2 in a manner that is   independent of the AES-CBC key size or hash function to be used.   Sections5.2.2.1 and5.2.2.2 define the generic encryption and   decryption algorithms.  Sections5.2.3 through5.2.5 define instances   of AES_CBC_HMAC_SHA2 that specify those details.5.2.2.1.  AES_CBC_HMAC_SHA2 Encryption   The authenticated encryption algorithm takes as input four octet   strings: a secret key K, a plaintext P, Additional Authenticated Data   A, and an Initialization Vector IV.  The authenticated ciphertext   value E and the Authentication Tag value T are provided as outputs.   The data in the plaintext are encrypted and authenticated, and the   Additional Authenticated Data are authenticated, but not encrypted.   The encryption process is as follows, or uses an equivalent set of   steps:   1.  The secondary keys MAC_KEY and ENC_KEY are generated from the       input key K as follows.  Each of these two keys is an octet       string.          MAC_KEY consists of the initial MAC_KEY_LEN octets of K, in          order.          ENC_KEY consists of the final ENC_KEY_LEN octets of K, in          order.Jones                        Standards Track                   [Page 23]

RFC 7518                JSON Web Algorithms (JWA)               May 2015       The number of octets in the input key K MUST be the sum of       MAC_KEY_LEN and ENC_KEY_LEN.  The values of these parameters are       specified by the Authenticated Encryption algorithms in Sections       5.2.3 through 5.2.5.  Note that the MAC key comes before the       encryption key in the input key K; this is in the opposite order       of the algorithm names in the identifier "AES_CBC_HMAC_SHA2".   2.  The IV used is a 128-bit value generated randomly or       pseudorandomly for use in the cipher.   3.  The plaintext is CBC encrypted using PKCS #7 padding using       ENC_KEY as the key and the IV.  We denote the ciphertext output       from this step as E.   4.  The octet string AL is equal to the number of bits in the       Additional Authenticated Data A expressed as a 64-bit unsigned       big-endian integer.   5.  A message Authentication Tag T is computed by applying HMAC       [RFC2104] to the following data, in order:          the Additional Authenticated Data A,          the Initialization Vector IV,          the ciphertext E computed in the previous step, and          the octet string AL defined above.       The string MAC_KEY is used as the MAC key.  We denote the output       of the MAC computed in this step as M.  The first T_LEN octets of       M are used as T.   6.  The ciphertext E and the Authentication Tag T are returned as the       outputs of the authenticated encryption.   The encryption process can be illustrated as follows.  Here K, P, A,   IV, and E denote the key, plaintext, Additional Authenticated Data,   Initialization Vector, and ciphertext, respectively.      MAC_KEY = initial MAC_KEY_LEN octets of K,      ENC_KEY = final ENC_KEY_LEN octets of K,      E = CBC-PKCS7-ENC(ENC_KEY, P),      M = MAC(MAC_KEY, A || IV || E || AL),      T = initial T_LEN octets of M.Jones                        Standards Track                   [Page 24]

RFC 7518                JSON Web Algorithms (JWA)               May 20155.2.2.2.  AES_CBC_HMAC_SHA2 Decryption   The authenticated decryption operation has five inputs: K, A, IV, E,   and T as defined above.  It has only a single output: either a   plaintext value P or a special symbol FAIL that indicates that the   inputs are not authentic.  The authenticated decryption algorithm is   as follows, or uses an equivalent set of steps:   1.  The secondary keys MAC_KEY and ENC_KEY are generated from the       input key K as in Step 1 ofSection 5.2.2.1.   2.  The integrity and authenticity of A and E are checked by       computing an HMAC with the inputs as in Step 5 ofSection 5.2.2.1.  The value T, from the previous step, is       compared to the first MAC_KEY length bits of the HMAC output.  If       those values are identical, then A and E are considered valid,       and processing is continued.  Otherwise, all of the data used in       the MAC validation are discarded, and the authenticated       decryption operation returns an indication that it failed, and       the operation halts.  (But see Section 11.5 of [JWE] for security       considerations on thwarting timing attacks.)   3.  The value E is decrypted and the PKCS #7 padding is checked and       removed.  The value IV is used as the Initialization Vector.  The       value ENC_KEY is used as the decryption key.   4.  The plaintext value is returned.5.2.3.  AES_128_CBC_HMAC_SHA_256   This algorithm is a concrete instantiation of the generic   AES_CBC_HMAC_SHA2 algorithm above.  It uses the HMAC message   authentication code [RFC2104] with the SHA-256 hash function [SHS] to   provide message authentication, with the HMAC output truncated to 128   bits, corresponding to the HMAC-SHA-256-128 algorithm defined in   [RFC4868].  For encryption, it uses AES in the CBC mode of operation   as defined in Section 6.2 of [NIST.800-38A], with PKCS #7 padding and   a 128-bit IV value.   The AES_CBC_HMAC_SHA2 parameters specific to AES_128_CBC_HMAC_SHA_256   are:      The input key K is 32 octets long.      ENC_KEY_LEN is 16 octets.      MAC_KEY_LEN is 16 octets.      The SHA-256 hash algorithm is used for the HMAC.      The HMAC-SHA-256 output is truncated to T_LEN=16 octets, by      stripping off the final 16 octets.Jones                        Standards Track                   [Page 25]

RFC 7518                JSON Web Algorithms (JWA)               May 20155.2.4.  AES_192_CBC_HMAC_SHA_384   AES_192_CBC_HMAC_SHA_384 is based on AES_128_CBC_HMAC_SHA_256, but   with the following differences:      The input key K is 48 octets long instead of 32.      ENC_KEY_LEN is 24 octets instead of 16.      MAC_KEY_LEN is 24 octets instead of 16.      SHA-384 is used for the HMAC instead of SHA-256.      The HMAC SHA-384 value is truncated to T_LEN=24 octets instead of      16.5.2.5.  AES_256_CBC_HMAC_SHA_512   AES_256_CBC_HMAC_SHA_512 is based on AES_128_CBC_HMAC_SHA_256, but   with the following differences:      The input key K is 64 octets long instead of 32.      ENC_KEY_LEN is 32 octets instead of 16.      MAC_KEY_LEN is 32 octets instead of 16.      SHA-512 is used for the HMAC instead of SHA-256.      The HMAC SHA-512 value is truncated to T_LEN=32 octets instead of      16.5.2.6.  Content Encryption with AES_CBC_HMAC_SHA2   This section defines the specifics of performing authenticated   encryption with the AES_CBC_HMAC_SHA2 algorithms.   The CEK is used as the secret key K.   The following "enc" (encryption algorithm) Header Parameter values   are used to indicate that the JWE Ciphertext and JWE Authentication   Tag values have been computed using the corresponding algorithm:   +---------------+---------------------------------------------------+   | "enc" Param   | Content Encryption Algorithm                      |   | Value         |                                                   |   +---------------+---------------------------------------------------+   | A128CBC-HS256 | AES_128_CBC_HMAC_SHA_256 authenticated encryption |   |               | algorithm, as defined inSection 5.2.3            |   | A192CBC-HS384 | AES_192_CBC_HMAC_SHA_384 authenticated encryption |   |               | algorithm, as defined inSection 5.2.4            |   | A256CBC-HS512 | AES_256_CBC_HMAC_SHA_512 authenticated encryption |   |               | algorithm, as defined inSection 5.2.5            |   +---------------+---------------------------------------------------+Jones                        Standards Track                   [Page 26]

RFC 7518                JSON Web Algorithms (JWA)               May 20155.3.  Content Encryption with AES GCM   This section defines the specifics of performing authenticated   encryption with AES in Galois/Counter Mode (GCM) ([AES] and   [NIST.800-38D]).   The CEK is used as the encryption key.   Use of an IV of size 96 bits is REQUIRED with this algorithm.   The requested size of the Authentication Tag output MUST be 128 bits,   regardless of the key size.   The following "enc" (encryption algorithm) Header Parameter values   are used to indicate that the JWE Ciphertext and JWE Authentication   Tag values have been computed using the corresponding algorithm and   key size:           +-------------------+------------------------------+           | "enc" Param Value | Content Encryption Algorithm |           +-------------------+------------------------------+           | A128GCM           | AES GCM using 128-bit key    |           | A192GCM           | AES GCM using 192-bit key    |           | A256GCM           | AES GCM using 256-bit key    |           +-------------------+------------------------------+   An example using this algorithm is shown inAppendix A.1 of [JWE].6.  Cryptographic Algorithms for Keys   A JSON Web Key (JWK) [JWK] is a JSON data structure that represents a   cryptographic key.  These keys can be either asymmetric or symmetric.   They can hold both public and private information about the key.   This section defines the parameters for keys using the algorithms   specified by this document.Jones                        Standards Track                   [Page 27]

RFC 7518                JSON Web Algorithms (JWA)               May 20156.1.  "kty" (Key Type) Parameter Values   The table below is the set of "kty" (key type) parameter values that   are defined by this specification for use in JWKs.   +-------------+--------------------------------+--------------------+   | "kty" Param | Key Type                       | Implementation     |   | Value       |                                | Requirements       |   +-------------+--------------------------------+--------------------+   | EC          | Elliptic Curve [DSS]           | Recommended+       |   | RSA         | RSA [RFC3447]                  | Required           |   | oct         | Octet sequence (used to        | Required           |   |             | represent symmetric keys)      |                    |   +-------------+--------------------------------+--------------------+   The use of "+" in the Implementation Requirements column indicates   that the requirement strength is likely to be increased in a future   version of the specification.6.2.  Parameters for Elliptic Curve Keys   JWKs can represent Elliptic Curve [DSS] keys.  In this case, the   "kty" member value is "EC".6.2.1.  Parameters for Elliptic Curve Public Keys   An Elliptic Curve public key is represented by a pair of coordinates   drawn from a finite field, which together define a point on an   Elliptic Curve.  The following members MUST be present for all   Elliptic Curve public keys:   o  "crv"   o  "x"   The following member MUST also be present for Elliptic Curve public   keys for the three curves defined in the following section:   o  "y"6.2.1.1.  "crv" (Curve) Parameter   The "crv" (curve) parameter 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"Jones                        Standards Track                   [Page 28]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   These values are registered in the IANA "JSON Web Key Elliptic Curve"   registry defined inSection 7.6.  Additional "crv" values can be   registered by other specifications.  Specifications registering   additional curves must define what parameters are used to represent   keys for the curves registered.  The "crv" value is a case-sensitive   string.   SEC1 [SEC1] point compression is not supported for any of these three   curves.6.2.1.2.  "x" (X Coordinate) Parameter   The "x" (x coordinate) parameter contains the x coordinate for the   Elliptic Curve point.  It is represented as the base64url encoding of   the octet string representation of the coordinate, as defined inSection 2.3.5 of SEC1 [SEC1].  The length of this octet string MUST   be the full size of a coordinate for the curve specified in the "crv"   parameter.  For example, if the value of "crv" is "P-521", the octet   string must be 66 octets long.6.2.1.3.  "y" (Y Coordinate) Parameter   The "y" (y coordinate) parameter contains the y coordinate for the   Elliptic Curve point.  It is represented as the base64url encoding of   the octet string representation of the coordinate, as defined inSection 2.3.5 of SEC1 [SEC1].  The length of this octet string MUST   be the full size of a coordinate for the curve specified in the "crv"   parameter.  For example, if the value of "crv" is "P-521", the octet   string must be 66 octets long.6.2.2.  Parameters for Elliptic Curve Private Keys   In addition to the members used to represent Elliptic Curve public   keys, the following member MUST be present to represent Elliptic   Curve private keys.6.2.2.1.  "d" (ECC Private Key) Parameter   The "d" (ECC private key) parameter contains the Elliptic Curve   private key value.  It is represented as the base64url encoding of   the octet string representation of the private key value, as defined   inSection 2.3.7 of SEC1 [SEC1].  The length of this octet string   MUST be ceiling(log-base-2(n)/8) octets (where n is the order of the   curve).Jones                        Standards Track                   [Page 29]

RFC 7518                JSON Web Algorithms (JWA)               May 20156.3.  Parameters for RSA Keys   JWKs can represent RSA [RFC3447] keys.  In this case, the "kty"   member value is "RSA".  The semantics of the parameters defined below   are the same as those defined in Sections3.1 and3.2 ofRFC 3447.6.3.1.  Parameters for RSA Public Keys   The following members MUST be present for RSA public keys.6.3.1.1.  "n" (Modulus) Parameter   The "n" (modulus) parameter contains the modulus value for the RSA   public key.  It is represented as a Base64urlUInt-encoded value.   Note that implementers have found that some cryptographic libraries   prefix an extra zero-valued octet to the modulus representations they   return, for instance, returning 257 octets for a 2048-bit key, rather   than 256.  Implementations using such libraries will need to take   care to omit the extra octet from the base64url-encoded   representation.6.3.1.2.  "e" (Exponent) Parameter   The "e" (exponent) parameter contains the exponent value for the RSA   public key.  It is represented as a Base64urlUInt-encoded value.   For instance, when representing the value 65537, the octet sequence   to be base64url-encoded MUST consist of the three octets [1, 0, 1];   the resulting representation for this value is "AQAB".6.3.2.  Parameters for RSA Private Keys   In addition to the members used to represent RSA public keys, the   following members are used to represent RSA private keys.  The   parameter "d" is REQUIRED for RSA private keys.  The others enable   optimizations and SHOULD be included by producers of JWKs   representing RSA private keys.  If the producer includes any of the   other private key parameters, then all of the others MUST be present,   with the exception of "oth", which MUST only be present when more   than two prime factors were used.6.3.2.1.  "d" (Private Exponent) Parameter   The "d" (private exponent) parameter contains the private exponent   value for the RSA private key.  It is represented as a Base64urlUInt-   encoded value.Jones                        Standards Track                   [Page 30]

RFC 7518                JSON Web Algorithms (JWA)               May 20156.3.2.2.  "p" (First Prime Factor) Parameter   The "p" (first prime factor) parameter contains the first prime   factor.  It is represented as a Base64urlUInt-encoded value.6.3.2.3.  "q" (Second Prime Factor) Parameter   The "q" (second prime factor) parameter contains the second prime   factor.  It is represented as a Base64urlUInt-encoded value.6.3.2.4.  "dp" (First Factor CRT Exponent) Parameter   The "dp" (first factor CRT exponent) parameter contains the Chinese   Remainder Theorem (CRT) exponent of the first factor.  It is   represented as a Base64urlUInt-encoded value.6.3.2.5.  "dq" (Second Factor CRT Exponent) Parameter   The "dq" (second factor CRT exponent) parameter contains the CRT   exponent of the second factor.  It is represented as a Base64urlUInt-   encoded value.6.3.2.6.  "qi" (First CRT Coefficient) Parameter   The "qi" (first CRT coefficient) parameter contains the CRT   coefficient of the second factor.  It is represented as a   Base64urlUInt-encoded value.6.3.2.7.  "oth" (Other Primes Info) Parameter   The "oth" (other primes info) parameter contains an array of   information about any third and subsequent primes, should they exist.   When only two primes have been used (the normal case), this parameter   MUST be omitted.  When three or more primes have been used, the   number of array elements MUST be the number of primes used minus two.   For more information on this case, see the description of the   OtherPrimeInfo parameters inAppendix A.1.2 of RFC 3447 [RFC3447],   upon which the following parameters are modeled.  If the consumer of   a JWK does not support private keys with more than two primes and it   encounters a private key that includes the "oth" parameter, then it   MUST NOT use the key.  Each array element MUST be an object with the   following members.6.3.2.7.1.  "r" (Prime Factor)   The "r" (prime factor) parameter within an "oth" array member   represents the value of a subsequent prime factor.  It is represented   as a Base64urlUInt-encoded value.Jones                        Standards Track                   [Page 31]

RFC 7518                JSON Web Algorithms (JWA)               May 20156.3.2.7.2.  "d" (Factor CRT Exponent)   The "d" (factor CRT exponent) parameter within an "oth" array member   represents the CRT exponent of the corresponding prime factor.  It is   represented as a Base64urlUInt-encoded value.6.3.2.7.3.  "t" (Factor CRT Coefficient)   The "t" (factor CRT coefficient) parameter within an "oth" array   member represents the CRT coefficient of the corresponding prime   factor.  It is represented as a Base64urlUInt-encoded value.6.4.  Parameters for Symmetric Keys   When the JWK "kty" member value is "oct" (octet sequence), the member   "k" (seeSection 6.4.1) is used to represent a symmetric key (or   another key whose value is a single octet sequence).  An "alg" member   SHOULD also be present to identify the algorithm intended to be used   with the key, unless the application uses another means or convention   to determine the algorithm used.6.4.1.  "k" (Key Value) Parameter   The "k" (key value) parameter contains the value of the symmetric (or   other single-valued) key.  It is represented as the base64url   encoding of the octet sequence containing the key value.7.  IANA Considerations   The following registration procedure is used for all the registries   established by this specification.   The registration procedure for values is Specification Required   [RFC5226] after a three-week review period on the   jose-reg-review@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 Experts may approve registration   once they are satisfied that such a specification will be published.   Registration requests sent to the mailing list for review should use   an appropriate subject (e.g., "Request to register algorithm:   example").   Within the review period, the Designated Experts 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.Jones                        Standards Track                   [Page 32]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   Registration requests that are undetermined for a period longer than   21 days can be brought to the IESG's attention (using the   iesg@ietf.org mailing list) for resolution.   Criteria that should be applied by the Designated Experts include   determining whether the proposed registration duplicates existing   functionality, whether it is likely to be of general applicability or   useful only for a single application, and whether the registration   description is clear.   IANA must only accept registry updates from the Designated Experts   and should direct all requests for registration to the review mailing   list.   It is suggested that multiple Designated Experts be appointed who are   able to represent the perspectives of different applications using   this specification, in order to enable broadly informed review of   registration decisions.  In cases where a registration decision could   be perceived as creating a conflict of interest for a particular   Expert, that Expert should defer to the judgment of the other   Experts.7.1.  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) and "enc" (encryption algorithm) Header Parameters.  The   registry records the algorithm name, the algorithm description, the   algorithm usage locations, the implementation requirements, the   change controller, and a reference to the specification that defines   it.  The same algorithm name can be registered multiple times,   provided that the sets of usage locations are disjoint.   It is suggested that the length of the key be included in the   algorithm name when multiple variations of algorithms are being   registered that use keys of different lengths and the key lengths for   each need to be fixed (for instance, because they will be created by   key derivation functions).  This allows readers of the JSON text to   more easily make security decisions.   The Designated Experts should perform reasonable due diligence that   algorithms being registered either are currently considered   cryptographically credible or are being registered as Deprecated or   Prohibited.Jones                        Standards Track                   [Page 33]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   The implementation requirements of an algorithm may be changed over   time 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.  Changes of   implementation requirements are only permitted on a Specification   Required basis after review by the Designated Experts, with the new   specification defining the revised implementation requirements level.7.1.1.  Registration Template   Algorithm Name:      The name requested (e.g., "HS256").  This name is a case-sensitive      ASCII string.  Names may not match other registered names in a      case-insensitive manner unless the Designated Experts state that      there is a compelling reason to allow an exception.   Algorithm Description:      Brief description of the algorithm (e.g., "HMAC using SHA-256").   Algorithm Usage Location(s):      The algorithm usage locations.  This must be one or more of the      values "alg" or "enc" if the algorithm is to be used with JWS or      JWE.  The value "JWK" is used if the algorithm identifier will be      used as a JWK "alg" member value, but will not be used with JWS or      JWE; this could be the case, for instance, for non-authenticated      encryption algorithms.  Other values may be used with the approval      of a Designated Expert.   JOSE Implementation Requirements:      The algorithm implementation requirements for JWS and JWE, which      must be one the words Required, Recommended, Optional, Deprecated,      or Prohibited.  Optionally, the word can 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.  Any      identifiers registered for non-authenticated encryption algorithms      or other algorithms that are otherwise unsuitable for direct use      as JWS or JWE algorithms must be registered as "Prohibited".   Change Controller:      For Standards Track RFCs, list the "IESG".  For others, give the      name of the responsible party.  Other details (e.g., postal      address, email address, home page URI) may also be included.Jones                        Standards Track                   [Page 34]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   Specification Document(s):      Reference to the document or documents that specify the parameter,      preferably including URIs that can be used to retrieve copies of      the documents.  An indication of the relevant sections may also be      included but is not required.   Algorithm Analysis Documents(s):      References to a publication or publications in well-known      cryptographic conferences, by national standards bodies, or by      other authoritative sources analyzing the cryptographic soundness      of the algorithm to be registered.  The Designated Experts may      require convincing evidence of the cryptographic soundness of a      new algorithm to be provided with the registration request unless      the algorithm is being registered as Deprecated or Prohibited.      Having gone through working group and IETF review, the initial      registrations made by this document are exempt from the need to      provide this information.7.1.2.  Initial Registry Contents   o  Algorithm Name: "HS256"   o  Algorithm Description: HMAC using SHA-256   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Required   o  Change Controller: IESG   o  Specification Document(s):Section 3.2 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "HS384"   o  Algorithm Description: HMAC using SHA-384   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.2 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "HS512"   o  Algorithm Description: HMAC using SHA-512   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.2 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 35]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "RS256"   o  Algorithm Description: RSASSA-PKCS1-v1_5 using SHA-256   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 3.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "RS384"   o  Algorithm Description: RSASSA-PKCS1-v1_5 using SHA-384   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "RS512"   o  Algorithm Description: RSASSA-PKCS1-v1_5 using SHA-512   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ES256"   o  Algorithm Description: ECDSA using P-256 and SHA-256   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended+   o  Change Controller: IESG   o  Specification Document(s):Section 3.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ES384"   o  Algorithm Description: ECDSA using P-384 and SHA-384   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ES512"   o  Algorithm Description: ECDSA using P-521 and SHA-512   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 36]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "PS256"   o  Algorithm Description: RSASSA-PSS using SHA-256 and MGF1 with      SHA-256   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.5 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "PS384"   o  Algorithm Description: RSASSA-PSS using SHA-384 and MGF1 with      SHA-384   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.5 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "PS512"   o  Algorithm Description: RSASSA-PSS using SHA-512 and MGF1 with      SHA-512   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.5 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "none"   o  Algorithm Description: No digital signature or MAC performed   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 3.6 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "RSA1_5"   o  Algorithm Description: RSAES-PKCS1-v1_5   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended-   o  Change Controller: IESG   o  Specification Document(s):Section 4.2 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 37]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "RSA-OAEP"   o  Algorithm Description: RSAES OAEP using default parameters   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended+   o  Change Controller: IESG   o  Specification Document(s):Section 4.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "RSA-OAEP-256"   o  Algorithm Description: RSAES OAEP using SHA-256 and MGF1 with      SHA-256   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A128KW"   o  Algorithm Description: AES Key Wrap using 128-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 4.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A192KW"   o  Algorithm Description: AES Key Wrap using 192-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A256KW"   o  Algorithm Description: AES Key Wrap using 256-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 4.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "dir"   o  Algorithm Description: Direct use of a shared symmetric key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 4.5 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 38]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "ECDH-ES"   o  Algorithm Description: ECDH-ES using Concat KDF   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended+   o  Change Controller: IESG   o  Specification Document(s):Section 4.6 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ECDH-ES+A128KW"   o  Algorithm Description: ECDH-ES using Concat KDF and "A128KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 4.6 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ECDH-ES+A192KW"   o  Algorithm Description: ECDH-ES using Concat KDF and "A192KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.6 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "ECDH-ES+A256KW"   o  Algorithm Description: ECDH-ES using Concat KDF and "A256KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 4.6 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A128GCMKW"   o  Algorithm Description: Key wrapping with AES GCM using 128-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.7 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 39]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "A192GCMKW"   o  Algorithm Description: Key wrapping with AES GCM using 192-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.7 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A256GCMKW"   o  Algorithm Description: Key wrapping with AES GCM using 256-bit key   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.7 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "PBES2-HS256+A128KW"   o  Algorithm Description: PBES2 with HMAC SHA-256 and "A128KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.8 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "PBES2-HS384+A192KW"   o  Algorithm Description: PBES2 with HMAC SHA-384 and "A192KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.8 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "PBES2-HS512+A256KW"   o  Algorithm Description: PBES2 with HMAC SHA-512 and "A256KW"      wrapping   o  Algorithm Usage Location(s): "alg"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 4.8 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 40]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "A128CBC-HS256"   o  Algorithm Description: AES_128_CBC_HMAC_SHA_256 authenticated      encryption algorithm   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Required   o  Change Controller: IESG   o  Specification Document(s):Section 5.2.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A192CBC-HS384"   o  Algorithm Description: AES_192_CBC_HMAC_SHA_384 authenticated      encryption algorithm   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 5.2.4 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A256CBC-HS512"   o  Algorithm Description: AES_256_CBC_HMAC_SHA_512 authenticated      encryption algorithm   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Required   o  Change Controller: IESG   o  Specification Document(s):Section 5.2.5 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A128GCM"   o  Algorithm Description: AES GCM using 128-bit key   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 5.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a   o  Algorithm Name: "A192GCM"   o  Algorithm Description: AES GCM using 192-bit key   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 5.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/aJones                        Standards Track                   [Page 41]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Algorithm Name: "A256GCM"   o  Algorithm Description: AES GCM using 256-bit key   o  Algorithm Usage Location(s): "enc"   o  JOSE Implementation Requirements: Recommended   o  Change Controller: IESG   o  Specification Document(s):Section 5.3 of RFC 7518   o  Algorithm Analysis Documents(s): n/a7.2.  Header Parameter Names Registration   This section registers the Header Parameter names defined in Sections   4.6.1, 4.7.1, and 4.8.1 of this specification in the IANA "JSON Web   Signature and Encryption Header Parameters" registry established by   [JWS].7.2.1.  Registry Contents   o  Header Parameter Name: "epk"   o  Header Parameter Description: Ephemeral Public Key   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.6.1.1 of RFC 7518   o  Header Parameter Name: "apu"   o  Header Parameter Description: Agreement PartyUInfo   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.6.1.2 of RFC 7518   o  Header Parameter Name: "apv"   o  Header Parameter Description: Agreement PartyVInfo   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.6.1.3 of RFC 7518   o  Header Parameter Name: "iv"   o  Header Parameter Description: Initialization Vector   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.7.1.1 of RFC 7518   o  Header Parameter Name: "tag"   o  Header Parameter Description: Authentication Tag   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.7.1.2 of RFC 7518Jones                        Standards Track                   [Page 42]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Header Parameter Name: "p2s"   o  Header Parameter Description: PBES2 Salt Input   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.8.1.1 of RFC 7518   o  Header Parameter Name: "p2c"   o  Header Parameter Description: PBES2 Count   o  Header Parameter Usage Location(s): JWE   o  Change Controller: IESG   o  Specification Document(s):Section 4.8.1.2 of RFC 75187.3.  JSON Web Encryption Compression Algorithms Registry   This specification establishes the IANA "JSON Web Encryption   Compression Algorithms" registry for JWE "zip" member values.  The   registry records the compression algorithm value and a reference to   the specification that defines it.7.3.1.  Registration Template   Compression Algorithm Value:      The name requested (e.g., "DEF").  Because a core goal of this      specification is for the resulting representations to be compact,      it is RECOMMENDED that the name be short -- not to exceed 8      characters without a compelling reason to do so.  This name is      case sensitive.  Names may not match other registered names in a      case-insensitive manner unless the Designated Experts state that      there is a compelling reason to allow an exception.   Compression Algorithm Description:      Brief description of the compression algorithm (e.g., "DEFLATE").   Change Controller:      For Standards Track RFCs, list "IESG".  For others, give the name      of the responsible party.  Other details (e.g., postal address,      email address, home page URI) may also be included.   Specification Document(s):      Reference to the document or documents that specify the parameter,      preferably including URIs that can be used to retrieve copies of      the documents.  An indication of the relevant sections may also be      included but is not required.Jones                        Standards Track                   [Page 43]

RFC 7518                JSON Web Algorithms (JWA)               May 20157.3.2.  Initial Registry Contents   o  Compression Algorithm Value: "DEF"   o  Compression Algorithm Description: DEFLATE   o  Change Controller: IESG   o  Specification Document(s): JSON Web Encryption (JWE) [JWE]7.4.  JSON Web Key Types Registry   This specification establishes the IANA "JSON Web Key Types" registry   for values of the JWK "kty" (key type) parameter.  The registry   records the "kty" value, implementation requirements, and a reference   to the specification that defines it.   The implementation requirements of a key type may be changed over   time as the cryptographic landscape evolves, for instance, to change   the status of a key type to Deprecated or to change the status of a   key type from Optional to Recommended+ or Required.  Changes of   implementation requirements are only permitted on a Specification   Required basis after review by the Designated Experts, with the new   specification defining the revised implementation requirements level.7.4.1.  Registration Template   "kty" Parameter Value:      The name requested (e.g., "EC").  Because a core goal of this      specification is for the resulting representations to be compact,      it is RECOMMENDED that the name be short -- not to exceed 8      characters without a compelling reason to do so.  This name is      case sensitive.  Names may not match other registered names in a      case-insensitive manner unless the Designated Experts state that      there is a compelling reason to allow an exception.   Key Type Description:      Brief description of the Key Type (e.g., "Elliptic Curve").   Change Controller:      For Standards Track RFCs, list "IESG".  For others, give the name      of the responsible party.  Other details (e.g., postal address,      email address, home page URI) may also be included.Jones                        Standards Track                   [Page 44]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   JOSE Implementation Requirements:      The key type implementation requirements for JWS and JWE, which      must be one the words Required, Recommended, Optional, Deprecated,      or Prohibited.  Optionally, the word can 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 or documents that specify the parameter,      preferably including URIs that can be used to retrieve copies of      the documents.  An indication of the relevant sections may also be      included but is not required.7.4.2.  Initial Registry Contents   This section registers the values defined inSection 6.1.   o  "kty" Parameter Value: "EC"   o  Key Type Description: Elliptic Curve   o  JOSE Implementation Requirements: Recommended+   o  Change Controller: IESG   o  Specification Document(s):Section 6.2 of RFC 7518   o  "kty" Parameter Value: "RSA"   o  Key Type Description: RSA   o  JOSE Implementation Requirements: Required   o  Change Controller: IESG   o  Specification Document(s):Section 6.3 of RFC 7518   o  "kty" Parameter Value: "oct"   o  Key Type Description: Octet Sequence   o  JOSE Implementation Requirements: Required   o  Change Controller: IESG   o  Specification Document(s):Section 6.4 of RFC 75187.5.  JSON Web Key Parameters Registration   This section registers the parameter names defined in Sections6.2,   6.3, and 6.4 of this specification in the IANA "JSON Web Key   Parameters" registry established by [JWK].Jones                        Standards Track                   [Page 45]

RFC 7518                JSON Web Algorithms (JWA)               May 20157.5.1.  Registry Contents   o  Parameter Name: "crv"   o  Parameter Description: Curve   o  Used with "kty" Value(s): "EC"   o  Parameter Information Class: Public   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.1 of RFC 7518   o  Parameter Name: "x"   o  Parameter Description: X Coordinate   o  Used with "kty" Value(s): "EC"   o  Parameter Information Class: Public   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.2 of RFC 7518   o  Parameter Name: "y"   o  Parameter Description: Y Coordinate   o  Used with "kty" Value(s): "EC"   o  Parameter Information Class: Public   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.3 of RFC 7518   o  Parameter Name: "d"   o  Parameter Description: ECC Private Key   o  Used with "kty" Value(s): "EC"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.2.1 of RFC 7518   o  Parameter Name: "n"   o  Parameter Description: Modulus   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Public   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.1.1 of RFC 7518   o  Parameter Name: "e"   o  Parameter Description: Exponent   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Public   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.1.2 of RFC 7518Jones                        Standards Track                   [Page 46]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Parameter Name: "d"   o  Parameter Description: Private Exponent   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.1 of RFC 7518   o  Parameter Name: "p"   o  Parameter Description: First Prime Factor   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.2 of RFC 7518   o  Parameter Name: "q"   o  Parameter Description: Second Prime Factor   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.3 of RFC 7518   o  Parameter Name: "dp"   o  Parameter Description: First Factor CRT Exponent   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.4 of RFC 7518   o  Parameter Name: "dq"   o  Parameter Description: Second Factor CRT Exponent   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.5 of RFC 7518   o  Parameter Name: "qi"   o  Parameter Description: First CRT Coefficient   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.6 of RFC 7518Jones                        Standards Track                   [Page 47]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   o  Parameter Name: "oth"   o  Parameter Description: Other Primes Info   o  Used with "kty" Value(s): "RSA"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.3.2.7 of RFC 7518   o  Parameter Name: "k"   o  Parameter Description: Key Value   o  Used with "kty" Value(s): "oct"   o  Parameter Information Class: Private   o  Change Controller: IESG   o  Specification Document(s):Section 6.4.1 of RFC 75187.6.  JSON Web Key Elliptic Curve Registry   This section establishes the IANA "JSON Web Key Elliptic Curve"   registry for JWK "crv" member values.  The registry records the curve   name, implementation requirements, and a reference to the   specification that defines it.  This specification registers the   parameter names defined inSection 6.2.1.1.   The implementation requirements of a curve may be changed over time   as the cryptographic landscape evolves, for instance, to change the   status of a curve to Deprecated or to change the status of a curve   from Optional to Recommended+ or Required.  Changes of implementation   requirements are only permitted on a Specification Required basis   after review by the Designated Experts, with the new specification   defining the revised implementation requirements level.7.6.1.  Registration Template   Curve Name:      The name requested (e.g., "P-256").  Because a core goal of this      specification is for the resulting representations to be compact,      it is RECOMMENDED that the name be short -- not to exceed 8      characters without a compelling reason to do so.  This name is      case sensitive.  Names may not match other registered names in a      case-insensitive manner unless the Designated Experts state that      there is a compelling reason to allow an exception.   Curve Description:      Brief description of the curve (e.g., "P-256 Curve").   JOSE Implementation Requirements:      The curve implementation requirements for JWS and JWE, which must      be one the words Required, Recommended, Optional, Deprecated, or      Prohibited.  Optionally, the word can be followed by a "+" or "-".Jones                        Standards Track                   [Page 48]

RFC 7518                JSON Web Algorithms (JWA)               May 2015      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, list "IESG".  For others, give the name      of the responsible party.  Other details (e.g., postal address,      email address, home page URI) may also be included.   Specification Document(s):      Reference to the document or documents that specify the parameter,      preferably including URIs that can be used to retrieve copies of      the documents.  An indication of the relevant sections may also be      included but is not required.7.6.2.  Initial Registry Contents   o  Curve Name: "P-256"   o  Curve Description: P-256 Curve   o  JOSE Implementation Requirements: Recommended+   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.1 of RFC 7518   o  Curve Name: "P-384"   o  Curve Description: P-384 Curve   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.1 of RFC 7518   o  Curve Name: "P-521"   o  Curve Description: P-521 Curve   o  JOSE Implementation Requirements: Optional   o  Change Controller: IESG   o  Specification Document(s):Section 6.2.1.1 of RFC 75188.  Security Considerations   All of the security issues that are pertinent to any cryptographic   application must be addressed by JWS/JWE/JWK agents.  Among these   issues are protecting the user's asymmetric private and symmetric   secret keys and employing countermeasures to various attacks.   The security considerations in [AES], [DSS], [JWE], [JWK], [JWS],   [NIST.800-38D], [NIST.800-56A], [NIST.800-107], [RFC2104], [RFC3394],   [RFC3447], [RFC5116], [RFC6090], and [SHS] apply to this   specification.Jones                        Standards Track                   [Page 49]

RFC 7518                JSON Web Algorithms (JWA)               May 20158.1.  Cryptographic Agility   Implementers should be aware that cryptographic algorithms become   weaker with time.  As new cryptanalysis techniques are developed and   computing performance improves, the work factor to break a particular   cryptographic algorithm will be reduced.  Therefore, implementers and   deployments must be prepared for the set of algorithms that are   supported and used to change over time.  Thus, cryptographic   algorithm implementations should be modular, allowing new algorithms   to be readily inserted.8.2.  Key Lifetimes   Many algorithms have associated security considerations related to   key lifetimes and/or the number of times that a key may be used.   Those security considerations continue to apply when using those   algorithms with JOSE data structures.  See NIST SP 800-57   [NIST.800-57] for specific guidance on key lifetimes.8.3.  RSAES-PKCS1-v1_5 Security Considerations   WhileSection 8 of RFC 3447 [RFC3447] explicitly calls for people not   to adopt RSASSA-PKCS1-v1_5 for new applications and instead requests   that people transition to RSASSA-PSS, this specification does include   RSASSA-PKCS1-v1_5, for interoperability reasons, because it is   commonly implemented.   Keys used with RSAES-PKCS1-v1_5 must follow the constraints inSection 7.2 of RFC 3447.  Also, keys with a low public key exponent   value, as described inSection 3 of "Twenty Years of Attacks on the   RSA Cryptosystem" [Boneh99], must not be used.8.4.  AES GCM Security Considerations   Keys used with AES GCM must follow the constraints in Section 8.3 of   [NIST.800-38D], which states: "The total number of invocations of the   authenticated encryption function shall not exceed 2^32, including   all IV lengths and all instances of the authenticated encryption   function with the given key".  In accordance with this rule, AES GCM   MUST NOT be used with the same key value more than 2^32 times.   An IV value MUST NOT ever be used multiple times with the same AES   GCM key.  One way to prevent this is to store a counter with the key   and increment it with every use.  The counter can also be used to   prevent exceeding the 2^32 limit above.   This security consideration does not apply to the composite AES-CBC   HMAC SHA-2 or AES Key Wrap algorithms.Jones                        Standards Track                   [Page 50]

RFC 7518                JSON Web Algorithms (JWA)               May 20158.5.  Unsecured JWS Security Considerations   Unsecured JWSs (JWSs that use the "alg" value "none") provide no   integrity protection.  Thus, they must only be used in contexts in   which the payload is secured by means other than a digital signature   or MAC value, or they need not be secured.   An example means of preventing accepting Unsecured JWSs by default is   for the "verify" method of a hypothetical JWS software library to   have a Boolean "acceptUnsecured" parameter that indicates "none" is   an acceptable "alg" value.  As another example, the "verify" method   might take a list of algorithms that are acceptable to the   application as a parameter and would reject Unsecured JWS values if   "none" is not in that list.   The following example illustrates the reasons for not accepting   Unsecured JWSs at a global level.  Suppose an application accepts   JWSs over two channels, (1) HTTP and (2) HTTPS with client   authentication.  It requires a JWS Signature on objects received over   HTTP, but accepts Unsecured JWSs over HTTPS.  If the application were   to globally indicate that "none" is acceptable, then an attacker   could provide it with an Unsecured JWS over HTTP and still have that   object successfully validate.  Instead, the application needs to   indicate acceptance of "none" for each object received over HTTPS   (e.g., by setting "acceptUnsecured" to "true" for the first   hypothetical JWS software library above), but not for each object   received over HTTP.8.6.  Denial-of-Service Attacks   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   supply content using keys that would result in excessive   cryptographic processing, for example, keys larger than those   mandated in this specification.  Implementations should set and   enforce upper limits on the key sizes they accept.Section 5.6.1   (Comparable Algorithm Strengths) of NIST SP 800-57 [NIST.800-57]   contains statements on largest approved key sizes that may be   applicable.8.7.  Reusing Key Material when Encrypting Keys   It is NOT RECOMMENDED to reuse the same entire set of key material   (Key Encryption Key, Content Encryption Key, Initialization Vector,   etc.) to encrypt multiple JWK or JWK Set objects, or to encrypt the   same JWK or JWK Set object multiple times.  One suggestion forJones                        Standards Track                   [Page 51]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   preventing reuse is to always generate at least one new piece of key   material for each encryption operation (e.g., a new Content   Encryption Key, a new IV, and/or a new PBES2 Salt), based on the   considerations noted in this document as well as fromRFC 4086   [RFC4086].8.8.  Password Considerations   Passwords are vulnerable to a number of attacks.  To help mitigate   some of these limitations, this document applies principles fromRFC2898 [RFC2898] to derive cryptographic keys from user-supplied   passwords.   However, the strength of the password still has a significant impact.   A high-entropy password has greater resistance to dictionary attacks.   [NIST.800-63-2] contains guidelines for estimating password entropy,   which can help applications and users generate stronger passwords.   An ideal password is one that is as large as (or larger than) the   derived key length.  However, passwords larger than a certain   algorithm-specific size are first hashed, which reduces an attacker's   effective search space to the length of the hash algorithm.  It is   RECOMMENDED that a password used for "PBES2-HS256+A128KW" be no   shorter than 16 octets and no longer than 128 octets and a password   used for "PBES2-HS512+A256KW" be no shorter than 32 octets and no   longer than 128 octets long.   Still, care needs to be taken in where and how password-based   encryption is used.  These algorithms can still be susceptible to   dictionary-based attacks if the iteration count is too small; this is   of particular concern if these algorithms are used to protect data   that an attacker can have indefinite number of attempts to circumvent   the protection, such as protected data stored on a file system.8.9.  Key Entropy and Random Values   See Section 10.1 of [JWS] for security considerations on key entropy   and random values.8.10.  Differences between Digital Signatures and MACs   See Section 10.5 of [JWS] for security considerations on differences   between digital signatures and MACs.Jones                        Standards Track                   [Page 52]

RFC 7518                JSON Web Algorithms (JWA)               May 20158.11.  Using Matching Algorithm Strengths   See Section 11.3 of [JWE] for security considerations on using   matching algorithm strengths.8.12.  Adaptive Chosen-Ciphertext Attacks   See Section 11.4 of [JWE] for security considerations on adaptive   chosen-ciphertext attacks.8.13.  Timing Attacks   See Section 10.9 of [JWS] andSection 11.5 of [JWE] for security   considerations on timing attacks.8.14.  RSA Private Key Representations and Blinding   See Section 9.3 of [JWK] for security considerations on RSA private   key representations and blinding.9.  Internationalization Considerations   Passwords obtained from users are likely to require preparation and   normalization to account for differences of octet sequences generated   by different input devices, locales, etc.  It is RECOMMENDED that   applications perform the steps outlined in [PRECIS] to prepare a   password supplied directly by a user before performing key derivation   and encryption.10.  References10.1.  Normative References   [AES]      National Institute of Standards and Technology (NIST),              "Advanced Encryption Standard (AES)", FIPS PUB 197,              November 2001, <http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf>.   [Boneh99]  "Twenty Years of Attacks on the RSA Cryptosystem", Notices              of the American Mathematical Society (AMS), Vol. 46,              No. 2, pp. 203-213, 1999, <http://crypto.stanford.edu/~dabo/pubs/papers/RSA-survey.pdf>.Jones                        Standards Track                   [Page 53]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   [DSS]      National Institute of Standards and Technology (NIST),              "Digital Signature Standard (DSS)", FIPS PUB 186-4, July              2013, <http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf>.   [JWE]      Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",RFC 7516, DOI 10.17487/RFC7516, May 2015,              <http://www.rfc-editor.org/info/rfc7516>.   [JWK]      Jones, M., "JSON Web Key (JWK)",RFC 7517,              DOI 10.17487/RFC7517, May 2015,              <http://www.rfc-editor.org/info/rfc7517>.   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web              Signature (JWS)",RFC 7515, DOI 10.17487/RFC7515, May              2015, <http://www.rfc-editor.org/info/rfc7515>.   [NIST.800-38A]              National Institute of Standards and Technology (NIST),              "Recommendation for Block Cipher Modes of Operation", NIST              Special Publication 800-38A, December 2001,              <http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf>.   [NIST.800-38D]              National Institute of Standards and Technology (NIST),              "Recommendation for Block Cipher Modes of Operation:              Galois/Counter Mode (GCM) and GMAC", NIST Special              Publication 800-38D, December 2001,              <http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf>.   [NIST.800-56A]              National Institute of Standards and Technology (NIST),              "Recommendation for Pair-Wise Key Establishment Schemes              Using Discrete Logarithm Cryptography", NIST Special              Publication 800-56A, Revision 2, May 2013,              <http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar2.pdf>.   [NIST.800-57]              National Institute of Standards and Technology (NIST),              "Recommendation for Key Management - Part 1: General              (Revision 3)", NIST Special Publication 800-57, Part 1,              Revision 3, July 2012, <http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57_part1_rev3_general.pdf>.Jones                        Standards Track                   [Page 54]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   [RFC20]    Cerf, V., "ASCII format for Network Interchange", STD 80,RFC 20, DOI 10.17487/RFC0020, October 1969,              <http://www.rfc-editor.org/info/rfc20>.   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC:              Keyed-Hashing for Message Authentication",RFC 2104,              DOI 10.17487/RFC2104, February 1997,              <http://www.rfc-editor.org/info/rfc2104>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.   [RFC2898]  Kaliski, B., "PKCS #5: Password-Based Cryptography              Specification Version 2.0",RFC 2898,              DOI 10.17487/RFC2898, September 2000,              <http://www.rfc-editor.org/info/rfc2898>.   [RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard              (AES) Key Wrap Algorithm",RFC 3394, DOI 10.17487/RFC3394,              September 2002, <http://www.rfc-editor.org/info/rfc3394>.   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography              Standards (PKCS) #1: RSA Cryptography Specifications              Version 2.1",RFC 3447, DOI 10.17487/RFC3447, February              2003, <http://www.rfc-editor.org/info/rfc3447>.   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO              10646", STD 63,RFC 3629, DOI 10.17487/RFC3629, November              2003, <http://www.rfc-editor.org/info/rfc3629>.   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256,              HMAC-SHA-384, and HMAC-SHA-512 with IPsec",RFC 4868,              DOI 10.17487/RFC4868, May 2007,              <http://www.rfc-editor.org/info/rfc4868>.   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",              FYI 36,RFC 4949, DOI 10.17487/RFC4949, August 2007,              <http://www.rfc-editor.org/info/rfc4949>.   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,RFC 5652, DOI 10.17487/RFC5652, September 2009,              <http://www.rfc-editor.org/info/rfc5652>.Jones                        Standards Track                   [Page 55]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   [RFC6090]  McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic              Curve Cryptography Algorithms",RFC 6090,              DOI 10.17487/RFC6090, February 2011,              <http://www.rfc-editor.org/info/rfc6090>.   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data              Interchange Format",RFC 7159, DOI 10.17487/RFC7159, March              2014, <http://www.rfc-editor.org/info/rfc7159>.   [SEC1]     Standards for Efficient Cryptography Group, "SEC 1:              Elliptic Curve Cryptography", Version 2.0, May 2009,              <http://www.secg.org/sec1-v2.pdf>.   [SHS]      National Institute of Standards and Technology (NIST),              "Secure Hash Standard (SHS)", FIPS PUB 180-4, March 2012,              <http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf>.   [UNICODE]  The Unicode Consortium, "The Unicode Standard",              <http://www.unicode.org/versions/latest/>.10.2.  Informative References   [AEAD-CBC-SHA]              McGrew, D., Foley, J., and K. Paterson, "Authenticated              Encryption with AES-CBC and HMAC-SHA", Work in Progress,draft-mcgrew-aead-aes-cbc-hmac-sha2-05, July 2014.   [CanvasApp]              Facebook, "Canvas Applications", 2010,              <http://developers.facebook.com/docs/authentication/canvas>.   [JCA]      Oracle, "Java Cryptography Architecture (JCA) Reference              Guide", 2014, <http://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html>.   [JSE]      Bradley, J. and N. Sakimura (editor), "JSON Simple              Encryption", September 2010,              <http://jsonenc.info/enc/1.0/>.   [JSMS]     Rescorla, E. and J. Hildebrand, "JavaScript Message              Security Format", Work in Progress,draft-rescorla-jsms-00, March 2011.   [JSS]      Bradley, J. and N. Sakimura, Ed., "JSON Simple Sign 1.0",              Draft 01, September 2010, <http://jsonenc.info/jss/1.0/>.Jones                        Standards Track                   [Page 56]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   [JWE-JWK]  Miller, M., "Using JavaScript Object Notation (JSON) Web              Encryption (JWE) for Protecting JSON Web Key (JWK)              Objects", Work in Progress,draft-miller-jose-jwe-protected-jwk-02, June 2013.   [MagicSignatures]              Panzer, J., Ed., Laurie, B., and D. Balfanz, "Magic              Signatures", January 2011,              <http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html>.   [NIST.800-107]              National Institute of Standards and Technology (NIST),              "Recommendation for Applications Using Approved Hash              Algorithms", NIST Special Publication 800-107, Revision 1,              August 2012, <http://csrc.nist.gov/publications/nistpubs/800-107-rev1/sp800-107-rev1.pdf>.   [NIST.800-63-2]              National Institute of Standards and Technology (NIST),              "Electronic Authentication Guideline", NIST Special              Publication 800-63-2, August 2013,              <http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-63-2.pdf>.   [PRECIS]   Saint-Andre, P. and A. Melnikov, "Preparation,              Enforcement, and Comparison of Internationalized Strings              Representing Usernames and Passwords", Work in Progress,draft-ietf-precis-saslprepbis-16, April 2015.   [RFC2631]  Rescorla, E., "Diffie-Hellman Key Agreement Method",RFC 2631, DOI 10.17487/RFC2631, June 1999,              <http://www.rfc-editor.org/info/rfc2631>.   [RFC3275]  Eastlake 3rd, D., Reagle, J., and D. Solo, "(Extensible              Markup Language) XML-Signature Syntax and Processing",RFC 3275, DOI 10.17487/RFC3275, March 2002,              <http://www.rfc-editor.org/info/rfc3275>.   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,              "Randomness Requirements for Security",BCP 106,RFC 4086,              DOI 10.17487/RFC4086, June 2005,              <http://www.rfc-editor.org/info/rfc4086>.   [RFC5116]  McGrew, D., "An Interface and Algorithms for Authenticated              Encryption",RFC 5116, DOI 10.17487/RFC5116, January 2008,              <http://www.rfc-editor.org/info/rfc5116>.Jones                        Standards Track                   [Page 57]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              DOI 10.17487/RFC5226, May 2008,              <http://www.rfc-editor.org/info/rfc5226>.   [W3C.NOTE-xmldsig-core2-20130411]              Eastlake, D., Reagle, J., Solo, D., Hirsch, F., Roessler,              T., Yiu, K., Datta, P., and S. Cantor, "XML Signature              Syntax and Processing Version 2.0", World Wide Web              Consortium Note NOTE-xmldsig-core2-20130411, April 2013,              <http://www.w3.org/TR/2013/NOTE-xmldsig-core2-20130411/>.   [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>.   [W3C.REC-xmlenc-core1-20130411]              Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler,              "XML Encryption Syntax and Processing Version 1.1", World              Wide Web Consortium Recommendation REC-xmlenc-              core1-20130411, April 2013,              <http://www.w3.org/TR/2013/REC-xmlenc-core1-20130411/>.Jones                        Standards Track                   [Page 58]

RFC 7518                JSON Web Algorithms (JWA)               May 2015Appendix A.  Algorithm Identifier Cross-Reference   This appendix contains tables cross-referencing the cryptographic   algorithm identifier values defined in this specification with the   equivalent identifiers used by other standards and software packages.   See XML DSIG [RFC3275], XML DSIG 2.0   [W3C.NOTE-xmldsig-core2-20130411], XML Encryption   [W3C.REC-xmlenc-core-20021210], XML Encryption 1.1   [W3C.REC-xmlenc-core1-20130411], and Java Cryptography Architecture   [JCA] for more information about the names defined by those   documents.Jones                        Standards Track                   [Page 59]

RFC 7518                JSON Web Algorithms (JWA)               May 2015A.1.  Digital Signature/MAC Algorithm Identifier Cross-Reference   This section contains a table cross-referencing the JWS digital   signature and MAC "alg" (algorithm) values defined in this   specification with the equivalent identifiers used by other standards   and software packages.   +-------------------------------------------------------------------+   | JWS      | XML DSIG                                               |   | | JCA                                   | OID                     |   +-------------------------------------------------------------------+   | HS256    |http://www.w3.org/2001/04/xmldsig-more#hmac-sha256     |   | | HmacSHA256                            | 1.2.840.113549.2.9      |   +-------------------------------------------------------------------+   | HS384    |http://www.w3.org/2001/04/xmldsig-more#hmac-sha384     |   | | HmacSHA384                            | 1.2.840.113549.2.10     |   +-------------------------------------------------------------------+   | HS512    |http://www.w3.org/2001/04/xmldsig-more#hmac-sha512     |   | | HmacSHA512                            | 1.2.840.113549.2.11     |   +-------------------------------------------------------------------+   | RS256    |http://www.w3.org/2001/04/xmldsig-more#rsa-sha256      |   | | SHA256withRSA                         | 1.2.840.113549.1.1.11   |   +-------------------------------------------------------------------+   | RS384    |http://www.w3.org/2001/04/xmldsig-more#rsa-sha384      |   | | SHA384withRSA                         | 1.2.840.113549.1.1.12   |   +-------------------------------------------------------------------+   | RS512    |http://www.w3.org/2001/04/xmldsig-more#rsa-sha512      |   | | SHA512withRSA                         | 1.2.840.113549.1.1.13   |   +-------------------------------------------------------------------+   | ES256    |http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256    |   | | SHA256withECDSA                       | 1.2.840.10045.4.3.2     |   +-------------------------------------------------------------------+   | ES384    |http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384    |   | | SHA384withECDSA                       | 1.2.840.10045.4.3.3     |   +-------------------------------------------------------------------+   | ES512    |http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512    |   | | SHA512withECDSA                       | 1.2.840.10045.4.3.4     |   +-------------------------------------------------------------------+   | PS256    |http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1 |   | | SHA256withRSAandMGF1                  | 1.2.840.113549.1.1.10   |   +-------------------------------------------------------------------+   | PS384    |http://www.w3.org/2007/05/xmldsig-more#sha384-rsa-MGF1 |   | | SHA384withRSAandMGF1                  | 1.2.840.113549.1.1.10   |   +-------------------------------------------------------------------+   | PS512    |http://www.w3.org/2007/05/xmldsig-more#sha512-rsa-MGF1 |   | | SHA512withRSAandMGF1                  | 1.2.840.113549.1.1.10   |   +-------------------------------------------------------------------+Jones                        Standards Track                   [Page 60]

RFC 7518                JSON Web Algorithms (JWA)               May 2015A.2.  Key Management Algorithm Identifier Cross-Reference   This section contains a table cross-referencing the JWE "alg"   (algorithm) values defined in this specification with the equivalent   identifiers used by other standards and software packages.   +-------------------------------------------------------------------+   | JWE           | XML ENC                                           |   | | JCA                                   | OID                     |   +-------------------------------------------------------------------+   | RSA1_5        |http://www.w3.org/2001/04/xmlenc#rsa-1_5          |   | | RSA/ECB/PKCS1Padding                  | 1.2.840.113549.1.1.1    |   +-------------------------------------------------------------------+   | RSA-OAEP      |http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p   |   | | RSA/ECB/OAEPWithSHA-1AndMGF1Padding   | 1.2.840.113549.1.1.7    |   +-------------------------------------------------------------------+   | RSA-OAEP-256  |http://www.w3.org/2009/xmlenc11#rsa-oaep          |   |               | &http://www.w3.org/2009/xmlenc11#mgf1sha256      |   | | RSA/ECB/OAEPWithSHA-256AndMGF1Padding |                         |   | | & MGF1ParameterSpec.SHA256            | 1.2.840.113549.1.1.7    |   +-------------------------------------------------------------------+   | ECDH-ES       |http://www.w3.org/2009/xmlenc11#ECDH-ES           |   | | ECDH                                  | 1.3.132.1.12            |   +-------------------------------------------------------------------+   | A128KW        |http://www.w3.org/2001/04/xmlenc#kw-aes128        |   | | AESWrap                               | 2.16.840.1.101.3.4.1.5  |   +-------------------------------------------------------------------+   | A192KW        |http://www.w3.org/2001/04/xmlenc#kw-aes192        |   | | AESWrap                               | 2.16.840.1.101.3.4.1.25 |   +-------------------------------------------------------------------+   | A256KW        |http://www.w3.org/2001/04/xmlenc#kw-aes256        |   | | AESWrap                               | 2.16.840.1.101.3.4.1.45 |   +-------------------------------------------------------------------+Jones                        Standards Track                   [Page 61]

RFC 7518                JSON Web Algorithms (JWA)               May 2015A.3.  Content Encryption Algorithm Identifier Cross-Reference   This section contains a table cross-referencing the JWE "enc"   (encryption algorithm) values defined in this specification with the   equivalent identifiers used by other standards and software packages.   For the composite algorithms "A128CBC-HS256", "A192CBC-HS384", and   "A256CBC-HS512", the corresponding AES-CBC algorithm identifiers are   listed.   +-------------------------------------------------------------------+   | JWE           | XML ENC                                           |   | | JCA                                   | OID                     |   +-------------------------------------------------------------------+   | A128CBC-HS256 |http://www.w3.org/2001/04/xmlenc#aes128-cbc       |   | | AES/CBC/PKCS5Padding                  | 2.16.840.1.101.3.4.1.2  |   +-------------------------------------------------------------------+   | A192CBC-HS384 |http://www.w3.org/2001/04/xmlenc#aes192-cbc       |   | | AES/CBC/PKCS5Padding                  | 2.16.840.1.101.3.4.1.22 |   +-------------------------------------------------------------------+   | A256CBC-HS512 |http://www.w3.org/2001/04/xmlenc#aes256-cbc       |   | | AES/CBC/PKCS5Padding                  | 2.16.840.1.101.3.4.1.42 |   +-------------------------------------------------------------------+   | A128GCM       |http://www.w3.org/2009/xmlenc11#aes128-gcm        |   | | AES/GCM/NoPadding                     | 2.16.840.1.101.3.4.1.6  |   +-------------------------------------------------------------------+   | A192GCM       |http://www.w3.org/2009/xmlenc11#aes192-gcm        |   | | AES/GCM/NoPadding                     | 2.16.840.1.101.3.4.1.26 |   +-------------------------------------------------------------------+   | A256GCM       |http://www.w3.org/2009/xmlenc11#aes256-gcm        |   | | AES/GCM/NoPadding                     | 2.16.840.1.101.3.4.1.46 |   +-------------------------------------------------------------------+Appendix B.  Test Cases for AES_CBC_HMAC_SHA2 Algorithms   The following test cases can be used to validate implementations of   the AES_CBC_HMAC_SHA2 algorithms defined inSection 5.2.  They are   also intended to correspond to test cases that may appear in a future   version of [AEAD-CBC-SHA], demonstrating that the cryptographic   computations performed are the same.   The variable names are those defined inSection 5.2.  All values are   hexadecimal.Jones                        Standards Track                   [Page 62]

RFC 7518                JSON Web Algorithms (JWA)               May 2015B.1.  Test Cases for AES_128_CBC_HMAC_SHA_256   AES_128_CBC_HMAC_SHA_256     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f     ENC_KEY = 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20               4b 65 72 63 6b 68 6f 66 66 73     AL =      00 00 00 00 00 00 01 50     E =       c8 0e df a3 2d df 39 d5 ef 00 c0 b4 68 83 42 79               a2 e4 6a 1b 80 49 f7 92 f7 6b fe 54 b9 03 a9 c9               a9 4a c9 b4 7a d2 65 5c 5f 10 f9 ae f7 14 27 e2               fc 6f 9b 3f 39 9a 22 14 89 f1 63 62 c7 03 23 36               09 d4 5a c6 98 64 e3 32 1c f8 29 35 ac 40 96 c8               6e 13 33 14 c5 40 19 e8 ca 79 80 df a4 b9 cf 1b               38 4c 48 6f 3a 54 c5 10 78 15 8e e5 d7 9d e5 9f               bd 34 d8 48 b3 d6 95 50 a6 76 46 34 44 27 ad e5               4b 88 51 ff b5 98 f7 f8 00 74 b9 47 3c 82 e2 db     M =       65 2c 3f a3 6b 0a 7c 5b 32 19 fa b3 a3 0b c1 c4               e6 e5 45 82 47 65 15 f0 ad 9f 75 a2 b7 1c 73 ef     T =       65 2c 3f a3 6b 0a 7c 5b 32 19 fa b3 a3 0b c1 c4Jones                        Standards Track                   [Page 63]

RFC 7518                JSON Web Algorithms (JWA)               May 2015B.2.  Test Cases for AES_192_CBC_HMAC_SHA_384     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f               20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f               10 11 12 13 14 15 16 17     ENC_KEY = 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27               28 29 2a 2b 2c 2d 2e 2f     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20               4b 65 72 63 6b 68 6f 66 66 73     AL =      00 00 00 00 00 00 01 50     E =       ea 65 da 6b 59 e6 1e db 41 9b e6 2d 19 71 2a e5               d3 03 ee b5 00 52 d0 df d6 69 7f 77 22 4c 8e db               00 0d 27 9b dc 14 c1 07 26 54 bd 30 94 42 30 c6               57 be d4 ca 0c 9f 4a 84 66 f2 2b 22 6d 17 46 21               4b f8 cf c2 40 0a dd 9f 51 26 e4 79 66 3f c9 0b               3b ed 78 7a 2f 0f fc bf 39 04 be 2a 64 1d 5c 21               05 bf e5 91 ba e2 3b 1d 74 49 e5 32 ee f6 0a 9a               c8 bb 6c 6b 01 d3 5d 49 78 7b cd 57 ef 48 49 27               f2 80 ad c9 1a c0 c4 e7 9c 7b 11 ef c6 00 54 e3     M =       84 90 ac 0e 58 94 9b fe 51 87 5d 73 3f 93 ac 20               75 16 80 39 cc c7 33 d7 45 94 f8 86 b3 fa af d4               86 f2 5c 71 31 e3 28 1e 36 c7 a2 d1 30 af de 57     T =       84 90 ac 0e 58 94 9b fe 51 87 5d 73 3f 93 ac 20               75 16 80 39 cc c7 33 d7Jones                        Standards Track                   [Page 64]

RFC 7518                JSON Web Algorithms (JWA)               May 2015B.3.  Test Cases for AES_256_CBC_HMAC_SHA_512     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f               20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f               30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f     ENC_KEY = 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f               30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20               4b 65 72 63 6b 68 6f 66 66 73     AL =      00 00 00 00 00 00 01 50     E =       4a ff aa ad b7 8c 31 c5 da 4b 1b 59 0d 10 ff bd               3d d8 d5 d3 02 42 35 26 91 2d a0 37 ec bc c7 bd               82 2c 30 1d d6 7c 37 3b cc b5 84 ad 3e 92 79 c2               e6 d1 2a 13 74 b7 7f 07 75 53 df 82 94 10 44 6b               36 eb d9 70 66 29 6a e6 42 7e a7 5c 2e 08 46 a1               1a 09 cc f5 37 0d c8 0b fe cb ad 28 c7 3f 09 b3               a3 b7 5e 66 2a 25 94 41 0a e4 96 b2 e2 e6 60 9e               31 e6 e0 2c c8 37 f0 53 d2 1f 37 ff 4f 51 95 0b               be 26 38 d0 9d d7 a4 93 09 30 80 6d 07 03 b1 f6     M =       4d d3 b4 c0 88 a7 f4 5c 21 68 39 64 5b 20 12 bf               2e 62 69 a8 c5 6a 81 6d bc 1b 26 77 61 95 5b c5               fd 30 a5 65 c6 16 ff b2 f3 64 ba ec e6 8f c4 07               53 bc fc 02 5d de 36 93 75 4a a1 f5 c3 37 3b 9c     T =       4d d3 b4 c0 88 a7 f4 5c 21 68 39 64 5b 20 12 bf               2e 62 69 a8 c5 6a 81 6d bc 1b 26 77 61 95 5b c5Jones                        Standards Track                   [Page 65]

RFC 7518                JSON Web Algorithms (JWA)               May 2015Appendix C.  Example ECDH-ES Key Agreement Computation   This example uses ECDH-ES Key Agreement and the Concat KDF to derive   the CEK in the manner described inSection 4.6.  In this example, the   ECDH-ES Direct Key Agreement mode ("alg" value "ECDH-ES") is used to   produce an agreed-upon key for AES GCM with a 128-bit key ("enc"   value "A128GCM").   In this example, a producer Alice is encrypting content to a consumer   Bob.  The producer (Alice) generates an ephemeral key for the key   agreement computation.  Alice's ephemeral key (in JWK format) used   for the key agreement computation in this example (including the   private part) is:     {"kty":"EC",      "crv":"P-256",      "x":"gI0GAILBdu7T53akrFmMyGcsF3n5dO7MmwNBHKW5SV0",      "y":"SLW_xSffzlPWrHEVI30DHM_4egVwt3NQqeUD7nMFpps",      "d":"0_NxaRPUMQoAJt50Gz8YiTr8gRTwyEaCumd-MToTmIo"     }   The consumer's (Bob's) key (in JWK format) used for the key agreement   computation in this example (including the private part) is:     {"kty":"EC",      "crv":"P-256",      "x":"weNJy2HscCSM6AEDTDg04biOvhFhyyWvOHQfeF_PxMQ",      "y":"e8lnCO-AlStT-NJVX-crhB7QRYhiix03illJOVAOyck",      "d":"VEmDZpDXXK8p8N0Cndsxs924q6nS1RXFASRl6BfUqdw"     }   Header Parameter values used in this example are as follows.  The   "apu" (agreement PartyUInfo) Header Parameter value is the base64url   encoding of the UTF-8 string "Alice" and the "apv" (agreement   PartyVInfo) Header Parameter value is the base64url encoding of the   UTF-8 string "Bob".  The "epk" (ephemeral public key) Header   Parameter is used to communicate the producer's (Alice's) ephemeral   public key value to the consumer (Bob).Jones                        Standards Track                   [Page 66]

RFC 7518                JSON Web Algorithms (JWA)               May 2015     {"alg":"ECDH-ES",      "enc":"A128GCM",      "apu":"QWxpY2U",      "apv":"Qm9i",      "epk":       {"kty":"EC",        "crv":"P-256",        "x":"gI0GAILBdu7T53akrFmMyGcsF3n5dO7MmwNBHKW5SV0",        "y":"SLW_xSffzlPWrHEVI30DHM_4egVwt3NQqeUD7nMFpps"       }     }   The resulting Concat KDF [NIST.800-56A] parameter values are:   Z      This is set to the ECDH-ES key agreement output.  (This value is      often not directly exposed by libraries, due to NIST security      requirements, and only serves as an input to a KDF.)  In this      example, Z is following the octet sequence (using JSON array      notation):      [158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132,      38, 156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121,      140, 254, 144, 196].   keydatalen      This value is 128 - the number of bits in the desired output key      (because "A128GCM" uses a 128-bit key).   AlgorithmID      This is set to the octets representing the 32-bit big-endian value      7 - [0, 0, 0, 7] - the number of octets in the AlgorithmID content      "A128GCM", followed, by the octets representing the ASCII string      "A128GCM" - [65, 49, 50, 56, 71, 67, 77].   PartyUInfo      This is set to the octets representing the 32-bit big-endian value      5 - [0, 0, 0, 5] - the number of octets in the PartyUInfo content      "Alice", followed, by the octets representing the UTF-8 string      "Alice" - [65, 108, 105, 99, 101].   PartyVInfo      This is set to the octets representing the 32-bit big-endian value      3 - [0, 0, 0, 3] - the number of octets in the PartyUInfo content      "Bob", followed, by the octets representing the UTF-8 string "Bob"      - [66, 111, 98].Jones                        Standards Track                   [Page 67]

RFC 7518                JSON Web Algorithms (JWA)               May 2015   SuppPubInfo      This is set to the octets representing the 32-bit big-endian value      128 - [0, 0, 0, 128] - the keydatalen value.   SuppPrivInfo      This is set to the empty octet sequence.   Concatenating the parameters AlgorithmID through SuppPubInfo results   in an OtherInfo value of:   [0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105,   99, 101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]   Concatenating the round number 1 ([0, 0, 0, 1]), Z, and the OtherInfo   value results in the Concat KDF round 1 hash input of:   [0, 0, 0, 1,   158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132, 38,   156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121, 140,   254, 144, 196,   0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105, 99,   101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]   The resulting derived key, which is the first 128 bits of the round 1   hash output is:   [86, 170, 141, 234, 248, 35, 109, 32, 92, 34, 40, 205, 113, 167, 16,   26]   The base64url-encoded representation of this derived key is:     VqqN6vgjbSBcIijNcacQGgJones                        Standards Track                   [Page 68]

RFC 7518                JSON Web Algorithms (JWA)               May 2015Acknowledgements   Solutions for signing and encrypting JSON content were previously   explored by "Magic Signatures" [MagicSignatures], "JSON Simple Sign   1.0" [JSS], "Canvas Applications" [CanvasApp], "JSON Simple   Encryption" [JSE], and "JavaScript Message Security Format" [JSMS],   all of which influenced this document.   The "Authenticated Encryption with AES-CBC and HMAC-SHA"   [AEAD-CBC-SHA] specification, upon which the AES_CBC_HMAC_SHA2   algorithms are based, was written by David A. McGrew and Kenny   Paterson.  The test cases for AES_CBC_HMAC_SHA2 are based upon those   for [AEAD-CBC-SHA] by John Foley.   Matt Miller wrote "Using JavaScript Object Notation (JSON) Web   Encryption (JWE) for Protecting JSON Web Key (JWK) Objects"   [JWE-JWK], upon which the password-based encryption content of this   document is based.   This specification is the work of the JOSE working group, which   includes dozens of active and dedicated participants.  In particular,   the following individuals contributed ideas, feedback, and wording   that influenced this specification:   Dirk Balfanz, Richard Barnes, Carsten Bormann, John Bradley, Brian   Campbell, Alissa Cooper, Breno de Medeiros, Vladimir Dzhuvinov, Roni   Even, Stephen Farrell, Yaron Y. Goland, Dick Hardt, Joe Hildebrand,   Jeff Hodges, Edmund Jay, Charlie Kaufman, Barry Leiba, James Manger,   Matt Miller, Kathleen Moriarty, Tony Nadalin, Axel Nennker, John   Panzer, Emmanuel Raviart, Eric Rescorla, Pete Resnick, Nat Sakimura,   Jim Schaad, Hannes Tschofenig, and Sean Turner.   Jim Schaad and Karen O'Donoghue chaired the JOSE working group and   Sean Turner, Stephen Farrell, and Kathleen Moriarty served as   Security Area Directors during the creation of this specification.Author's Address   Michael B. Jones   Microsoft   EMail: mbj@microsoft.com   URI:http://self-issued.info/Jones                        Standards Track                   [Page 69]
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May 2015
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