JOSE Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track September 15, 2013 Expires: March 19, 2014 JSON Web Algorithms (JWA) draft-ietf-jose-json-web-algorithms-16 Abstract The JSON Web Algorithms (JWA) 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 Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on March 19, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect 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 Expires March 19, 2014 [Page 1]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Terms Incorporated from the JWS Specification . . . . . . 5 2.2. Terms Incorporated from the JWE Specification . . . . . . 6 2.3. Terms Incorporated from the JWK Specification . . . . . . 9 2.4. Defined Terms . . . . . . . . . . . . . . . . . . . . . . 9 3. Cryptographic Algorithms for Digital Signatures and MACs . . . 9 3.1. "alg" (Algorithm) Header Parameter Values for JWS . . . . 9 3.2. HMAC with SHA-2 Functions . . . . . . . . . . . . . . . . 10 3.3. Digital Signature with RSASSA-PKCS1-V1_5 . . . . . . . . . 11 3.4. Digital Signature with ECDSA . . . . . . . . . . . . . . . 12 3.5. Digital Signature with RSASSA-PSS . . . . . . . . . . . . 14 3.6. Using the Algorithm "none" . . . . . . . . . . . . . . . . 15 4. Cryptographic Algorithms for Encryption . . . . . . . . . . . 15 4.1. "alg" (Algorithm) Header Parameter Values for JWE . . . . 15 4.2. "enc" (Encryption Method) Header Parameter Values for JWE . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.3. Key Encryption with RSAES-PKCS1-V1_5 . . . . . . . . . . . 21 4.4. Key Encryption with RSAES OAEP . . . . . . . . . . . . . . 21 4.5. Key Wrapping with AES Key Wrap . . . . . . . . . . . . . . 21 4.6. Direct Encryption with a Shared Symmetric Key . . . . . . 21 4.7. Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES) . . . . . . . . . . . . . . . . 22 4.7.1. Header Parameters Used for ECDH Key Agreement . . . . 22 4.7.1.1. "epk" (Ephemeral Public Key) Header Parameter . . 22 4.7.1.2. "apu" (Agreement PartyUInfo) Header Parameter . . 23 4.7.1.3. "apv" (Agreement PartyVInfo) Header Parameter . . 23 4.7.2. Key Derivation for ECDH Key Agreement . . . . . . . . 23 4.8. Key Encryption with AES GCM . . . . . . . . . . . . . . . 24 4.8.1. Header Parameters Used for AES GCM Key Encryption . . 25 4.8.1.1. "iv" (Initialization Vector) Header Parameter . . 25 4.8.1.2. "tag" (Authentication Tag) Header Parameter . . . 25 4.9. Key Encryption with PBES2 . . . . . . . . . . . . . . . . 25 4.9.1. Header Parameters Used for PBES2 Key Encryption . . . 26 4.9.1.1. "p2s" (PBES2 salt) Parameter . . . . . . . . . . . 26 4.9.1.2. "p2c" (PBES2 count) Parameter . . . . . . . . . . 26 4.10. AES_CBC_HMAC_SHA2 Algorithms . . . . . . . . . . . . . . . 26 4.10.1. Conventions Used in Defining AES_CBC_HMAC_SHA2 . . . . 27 4.10.2. Generic AES_CBC_HMAC_SHA2 Algorithm . . . . . . . . . 27 4.10.2.1. AES_CBC_HMAC_SHA2 Encryption . . . . . . . . . . . 27 4.10.2.2. AES_CBC_HMAC_SHA2 Decryption . . . . . . . . . . . 29 4.10.3. AES_128_CBC_HMAC_SHA_256 . . . . . . . . . . . . . . . 29 4.10.4. AES_192_CBC_HMAC_SHA_384 . . . . . . . . . . . . . . . 30 4.10.5. AES_256_CBC_HMAC_SHA_512 . . . . . . . . . . . . . . . 30 4.10.6. Plaintext Encryption with AES_CBC_HMAC_SHA2 . . . . . 30 Jones Expires March 19, 2014 [Page 2]
Internet-Draft JSON Web Algorithms (JWA) September 2013 4.11. Plaintext Encryption with AES GCM . . . . . . . . . . . . 31 5. Cryptographic Algorithms for Keys . . . . . . . . . . . . . . 31 5.1. "kty" (Key Type) Parameter Values . . . . . . . . . . . . 31 5.2. Parameters for Elliptic Curve Keys . . . . . . . . . . . . 32 5.2.1. Parameters for Elliptic Curve Public Keys . . . . . . 32 5.2.1.1. "crv" (Curve) Parameter . . . . . . . . . . . . . 32 5.2.1.2. "x" (X Coordinate) Parameter . . . . . . . . . . . 33 5.2.1.3. "y" (Y Coordinate) Parameter . . . . . . . . . . . 33 5.2.2. Parameters for Elliptic Curve Private Keys . . . . . . 33 5.2.2.1. "d" (ECC Private Key) Parameter . . . . . . . . . 33 5.3. Parameters for RSA Keys . . . . . . . . . . . . . . . . . 33 5.3.1. Parameters for RSA Public Keys . . . . . . . . . . . . 33 5.3.1.1. "n" (Modulus) Parameter . . . . . . . . . . . . . 33 5.3.1.2. "e" (Exponent) Parameter . . . . . . . . . . . . . 34 5.3.2. Parameters for RSA Private Keys . . . . . . . . . . . 34 5.3.2.1. "d" (Private Exponent) Parameter . . . . . . . . . 34 5.3.2.2. "p" (First Prime Factor) Parameter . . . . . . . . 34 5.3.2.3. "q" (Second Prime Factor) Parameter . . . . . . . 34 5.3.2.4. "dp" (First Factor CRT Exponent) Parameter . . . . 35 5.3.2.5. "dq" (Second Factor CRT Exponent) Parameter . . . 35 5.3.2.6. "qi" (First CRT Coefficient) Parameter . . . . . . 35 5.3.2.7. "oth" (Other Primes Info) Parameter . . . . . . . 35 5.4. Parameters for Symmetric Keys . . . . . . . . . . . . . . 36 5.4.1. "k" (Key Value) Parameter . . . . . . . . . . . . . . 36 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 6.1. JSON Web Signature and Encryption Algorithms Registry . . 37 6.1.1. Template . . . . . . . . . . . . . . . . . . . . . . . 38 6.1.2. Initial Registry Contents . . . . . . . . . . . . . . 38 6.2. JWE Header Parameter Names Registration . . . . . . . . . 43 6.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 43 6.3. JSON Web Encryption Compression Algorithms Registry . . . 44 6.3.1. Registration Template . . . . . . . . . . . . . . . . 44 6.3.2. Initial Registry Contents . . . . . . . . . . . . . . 45 6.4. JSON Web Key Types Registry . . . . . . . . . . . . . . . 45 6.4.1. Registration Template . . . . . . . . . . . . . . . . 45 6.4.2. Initial Registry Contents . . . . . . . . . . . . . . 46 6.5. JSON Web Key Parameters Registration . . . . . . . . . . . 46 6.5.1. Registry Contents . . . . . . . . . . . . . . . . . . 46 6.6. JSON Web Key Elliptic Curve Registry . . . . . . . . . . . 48 6.6.1. Registration Template . . . . . . . . . . . . . . . . 48 6.6.2. Initial Registry Contents . . . . . . . . . . . . . . 49 7. Security Considerations . . . . . . . . . . . . . . . . . . . 49 7.1. Algorithms and Key Sizes will be Deprecated . . . . . . . 50 7.2. Key Lifetimes . . . . . . . . . . . . . . . . . . . . . . 50 7.3. RSAES-PKCS1-v1_5 Security Considerations . . . . . . . . . 50 7.4. AES GCM Security Considerations . . . . . . . . . . . . . 50 7.5. Plaintext JWS Security Considerations . . . . . . . . . . 51 7.6. Denial of Service Attacks . . . . . . . . . . . . . . . . 51 Jones Expires March 19, 2014 [Page 3]
Internet-Draft JSON Web Algorithms (JWA) September 2013 7.7. Reusing Key Material when Encrypting Keys . . . . . . . . 52 7.8. Password Considerations . . . . . . . . . . . . . . . . . 52 8. Internationalization Considerations . . . . . . . . . . . . . 52 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 53 9.1. Normative References . . . . . . . . . . . . . . . . . . . 53 9.2. Informative References . . . . . . . . . . . . . . . . . . 55 Appendix A. Digital Signature/MAC Algorithm Identifier Cross-Reference . . . . . . . . . . . . . . . . . . . 56 Appendix B. Encryption Algorithm Identifier Cross-Reference . . . 57 Appendix C. Test Cases for AES_CBC_HMAC_SHA2 Algorithms . . . . . 58 C.1. Test Cases for AES_128_CBC_HMAC_SHA_256 . . . . . . . . . 59 C.2. Test Cases for AES_192_CBC_HMAC_SHA_384 . . . . . . . . . 60 C.3. Test Cases for AES_256_CBC_HMAC_SHA_512 . . . . . . . . . 61 Appendix D. Example ECDH-ES Key Agreement Computation . . . . . . 62 Appendix E. Acknowledgements . . . . . . . . . . . . . . . . . . 64 Appendix F. Document History . . . . . . . . . . . . . . . . . . 65 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 72 Jones Expires March 19, 2014 [Page 4]
Internet-Draft JSON Web Algorithms (JWA) September 2013 1. Introduction The JSON Web Algorithms (JWA) 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 JavaScript Object Notation (JSON) [RFC4627] based 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", "MAY", and "OPTIONAL" in this document are to be interpreted as described in Key words for use in RFCs to Indicate Requirement Levels [RFC2119]. If these words are used without being spelled in uppercase then they are to be interpreted with their normal natural language meanings. 2. Terminology 2.1. Terms Incorporated from the JWS Specification These terms defined by the JSON Web Signature (JWS) [JWS] specification are incorporated into this specification: JSON Web Signature (JWS) A data structure representing a digitally signed or MACed message. The structure represents three values: the JWS Header, the JWS Payload, and the JWS Signature. JSON Text Object A UTF-8 [RFC3629] encoded text string representing a JSON object; the syntax of JSON objects is defined in Section 2.2 of [RFC4627]. Jones Expires March 19, 2014 [Page 5]
Internet-Draft JSON Web Algorithms (JWA) September 2013 JWS Header A JSON Text Object (or JSON Text Objects, when using the JWS JSON Serialization) that describes the digital signature or MAC operation applied to create the JWS Signature value. The members of the JWS Header object(s) are Header Parameters. JWS Payload The sequence of octets to be secured -- a.k.a., the message. The payload can contain an arbitrary sequence of octets. JWS Signature A sequence of octets containing the cryptographic material that ensures the integrity of the JWS Protected Header and the JWS Payload. The JWS Signature value is a digital signature or MAC value calculated over the JWS Signing Input using the parameters specified in the JWS Header. JWS Protected Header A JSON Text Object that contains the portion of the JWS Header that is integrity protected. For the JWS Compact Serialization, this comprises the entire JWS Header. For the JWS JSON Serialization, this is one component of the JWS Header. Base64url Encoding Base64 encoding using the URL- and filename-safe character set defined in Section 5 of RFC 4648 [RFC4648], with all trailing '=' characters omitted (as permitted by Section 3.2). (See Appendix C of [JWS] for notes on implementing base64url encoding without padding.) Encoded JWS Header Base64url encoding of the JWS Protected Header. Encoded JWS Payload Base64url encoding of the JWS Payload. Encoded JWS Signature Base64url encoding of the JWS Signature. JWS Signing Input The concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload. 2.2. Terms Incorporated from the JWE Specification These terms defined by the JSON Web Encryption (JWE) [JWE] specification are incorporated into this specification: JSON Web Encryption (JWE) A data structure representing an encrypted message. The structure represents five values: the JWE Header, the JWE Encrypted Key, the JWE Initialization Vector, the JWE Ciphertext, and the JWE Authentication Tag. Authenticated Encryption An Authenticated Encryption algorithm is one that provides an integrated content integrity check. Authenticated Encryption algorithms accept two inputs, the Plaintext and the Additional Authenticated Data value, and produce Jones Expires March 19, 2014 [Page 6]
Internet-Draft JSON Web Algorithms (JWA) September 2013 two outputs, the Ciphertext and the Authentication Tag value. AES Galois/Counter Mode (GCM) is one such algorithm. Plaintext The sequence of octets to be encrypted -- a.k.a., the message. The plaintext can contain an arbitrary sequence of octets. Ciphertext An encrypted representation of the Plaintext. Additional Authenticated Data (AAD) An input to an Authenticated Encryption operation that is integrity protected but not encrypted. Authentication Tag An output of an Authenticated Encryption operation that ensures the integrity of the Ciphertext and the Additional Authenticated Data. Note that some algorithms may not use an Authentication Tag, in which case this value is the empty octet sequence. Content Encryption Key (CEK) A symmetric key for the Authenticated Encryption algorithm used to encrypt the Plaintext for the recipient to produce the Ciphertext and the Authentication Tag. JWE Header A JSON Text Object (or JSON Text Objects, when using the JWE JSON Serialization) that describes the encryption operations applied to create the JWE Encrypted Key, the JWE Ciphertext, and the JWE Authentication Tag. The members of the JWE Header object(s) are Header Parameters. JWE Encrypted Key The result of encrypting the Content Encryption Key (CEK) with the intended recipient's key using the specified algorithm. Note that for some algorithms, the JWE Encrypted Key value is specified as being the empty octet sequence. JWE Initialization Vector A sequence of octets containing the Initialization Vector used when encrypting the Plaintext. Note that some algorithms may not use an Initialization Vector, in which case this value is the empty octet sequence. JWE Ciphertext A sequence of octets containing the Ciphertext for a JWE. JWE Authentication Tag A sequence of octets containing the Authentication Tag for a JWE. Jones Expires March 19, 2014 [Page 7]
Internet-Draft JSON Web Algorithms (JWA) September 2013 JWE Protected Header A JSON Text Object that contains the portion of the JWE Header that is integrity protected. For the JWE Compact Serialization, this comprises the entire JWE Header. For the JWE JSON Serialization, this is one component of the JWE Header. Encoded JWE Header Base64url encoding of the JWE Protected Header. Encoded JWE Encrypted Key Base64url encoding of the JWE Encrypted Key. Encoded JWE Initialization Vector Base64url encoding of the JWE Initialization Vector. Encoded JWE Ciphertext Base64url encoding of the JWE Ciphertext. Encoded JWE Authentication Tag Base64url encoding of the JWE Authentication Tag. Key Management Mode A method of determining the Content Encryption Key (CEK) value to use. Each algorithm used for determining the CEK value uses a specific Key Management Mode. Key Management Modes employed by this specification are Key Encryption, Key Wrapping, Direct Key Agreement, Key Agreement with Key Wrapping, and Direct Encryption. Key Encryption A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using an asymmetric encryption algorithm. Key Wrapping A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using a symmetric key wrapping algorithm. Direct Key Agreement A Key Management Mode in which a key agreement algorithm is used to agree upon the Content Encryption Key (CEK) value. Key Agreement with Key Wrapping A Key Management Mode in which a key agreement algorithm is used to agree upon a symmetric key used to encrypt the Content Encryption Key (CEK) value to the intended recipient using a symmetric key wrapping algorithm. Direct Encryption A Key Management Mode in which the Content Encryption Key (CEK) value used is the secret symmetric key value shared between the parties. Jones Expires March 19, 2014 [Page 8]
Internet-Draft JSON Web Algorithms (JWA) September 2013 2.3. Terms Incorporated from the JWK Specification These terms defined by the JSON Web Key (JWK) [JWK] specification are incorporated into this specification: JSON Web Key (JWK) A JSON object that represents a cryptographic key. JSON Web Key Set (JWK Set) A JSON object that contains an array of JWKs as the value of its "keys" member. 2.4. Defined Terms These terms are defined for use by this specification: Header Parameter A name/value pair that is member of a JWS Header or JWE Header. Header Parameter Name The name of a member of a JSON object representing a JWS Header or JWE Header. Header Parameter Value The value of a member of a JSON object representing a JWS Header or JWE Header. 3. Cryptographic Algorithms for Digital Signatures and MACs JWS uses cryptographic algorithms to digitally sign or create a Message Authentication Codes (MAC) of the contents of the JWS 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: Jones Expires March 19, 2014 [Page 9]
Internet-Draft JSON Web Algorithms (JWA) September 2013 +-----------+--------------------------------------+----------------+ | alg | Digital Signature or MAC Algorithm | Implementation | | Parameter | | Requirements | | Value | | | +-----------+--------------------------------------+----------------+ | HS256 | HMAC using SHA-256 hash algorithm | Required | | HS384 | HMAC using SHA-384 hash algorithm | Optional | | HS512 | HMAC using SHA-512 hash algorithm | Optional | | RS256 | RSASSA-PKCS-v1_5 using SHA-256 hash | Recommended | | | algorithm | | | RS384 | RSASSA-PKCS-v1_5 using SHA-384 hash | Optional | | | algorithm | | | RS512 | RSASSA-PKCS-v1_5 using SHA-512 hash | Optional | | | algorithm | | | ES256 | ECDSA using P-256 curve and SHA-256 | Recommended+ | | | hash algorithm | | | ES384 | ECDSA using P-384 curve and SHA-384 | Optional | | | hash algorithm | | | ES512 | ECDSA using P-521 curve and SHA-512 | Optional | | | hash algorithm | | | PS256 | RSASSA-PSS using SHA-256 hash | Optional | | | algorithm and MGF1 mask generation | | | | function with SHA-256 | | | PS384 | RSASSA-PSS using SHA-384 hash | Optional | | | algorithm and MGF1 mask generation | | | | function with SHA-384 | | | PS512 | RSASSA-PSS using SHA-512 hash | Optional | | | algorithm and MGF1 mask generation | | | | function with SHA-512 | | | none | No digital signature or MAC value | Optional | | | included | | +-----------+--------------------------------------+----------------+ The use of "+" in the Implementation Requirements indicates that the requirement strength is likely to be increased in a future version of the specification. See Appendix A for a table cross-referencing the digital signature and MAC "alg" (algorithm) values used in this specification with the equivalent identifiers used by other standards and software packages. 3.2. 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 Message Authentication Code (MAC). This can be used to demonstrate that whoever generated the MAC was in possession of the MAC key. Jones Expires March 19, 2014 [Page 10]
Internet-Draft JSON Web Algorithms (JWA) September 2013 The algorithm for implementing and validating HMACs is provided in RFC 2104 [RFC2104]. This section defines the use of the HMAC SHA- 256, HMAC SHA-384, and HMAC SHA-512 functions [SHS]. The "alg" (algorithm) header parameter values "HS256", "HS384", and "HS512" are used in the JWS Header to indicate that the Encoded JWS Signature contains a base64url encoded HMAC value using the respective hash function. A key of the same size as the hash output (for instance, 256 bits for "HS256") or larger MUST be used with this algorithm. The HMAC SHA-256 MAC is generated per RFC 2104, using SHA-256 as the hash algorithm "H", using the octets of the ASCII [USASCII] representation of the JWS Signing Input as the "text" value, and using the shared key. The HMAC output value is the JWS Signature. The JWS signature is base64url encoded to produce the Encoded JWS Signature. The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC value per RFC 2104, using SHA-256 as the hash algorithm "H", using the octets of the ASCII representation of 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. Alternatively, the computed HMAC value can be base64url encoded and compared to the received Encoded JWS Signature, as this comparison produces the same result as comparing the unencoded values. In either case, if the values match, the HMAC has been validated. Securing content 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 in Appendix 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 in Section 8.2 of RFC 3447 [RFC3447] (commonly known as PKCS #1), using SHA-256, SHA-384, or SHA-512 [SHS] as the hash functions. The "alg" (algorithm) header parameter values "RS256", "RS384", and "RS512" are used in the JWS Header to indicate that the Encoded JWS Signature contains a base64url encoded RSASSA- PKCS1-V1_5 digital signature using the respective hash function. A key of size 2048 bits or larger MUST be used with these algorithms. Jones Expires March 19, 2014 [Page 11]
Internet-Draft JSON Web Algorithms (JWA) September 2013 The RSASSA-PKCS1-V1_5 SHA-256 digital signature is generated as follows: 1. Generate a digital signature of the octets of the ASCII representation of the JWS Signing Input using RSASSA-PKCS1-V1_5- SIGN and the SHA-256 hash function with the desired private key. The output will be an octet sequence. 2. Base64url encode the resulting octet sequence. The output is the Encoded JWS Signature for that JWS. The RSASSA-PKCS1-V1_5 SHA-256 digital signature for a JWS is validated as follows: 1. Take the Encoded JWS Signature and base64url decode it into an octet sequence. If decoding fails, the validation has failed. 2. Submit the octets of the ASCII representation of the JWS Signing Input and the public key corresponding to the private key used by the signer to the RSASSA-PKCS1-V1_5-VERIFY algorithm using SHA- 256 as the hash function. Signing 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 in Appendix A.2 of [JWS]. 3.4. 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. 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 "alg" (algorithm) header parameter values "ES256", "ES384", and "ES512" are used in the JWS Header to indicate that the Encoded JWS Signature contains a base64url encoded ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA P-521 SHA-512 digital signature, respectively. Jones Expires March 19, 2014 [Page 12]
Internet-Draft JSON Web Algorithms (JWA) September 2013 The ECDSA P-256 SHA-256 digital signature is generated as follows: 1. Generate a digital signature of the octets of the ASCII representation 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. Base64url encode the resulting 64 octet sequence. The output is the Encoded JWS Signature for the JWS. The ECDSA P-256 SHA-256 digital signature for a JWS is validated as follows: 1. Take the Encoded JWS Signature and base64url decode it into an octet sequence. If decoding fails, the validation has failed. 2. The output of the base64url decoding MUST be a 64 octet sequence. If decoding does not result in a 64 octet sequence, the validation has failed. 3. Split the 64 octet sequence into two 32 octet sequences. The first array will be R and the second S (with both being in big endian octet order). 4. Submit the octets of the ASCII representation of the JWS Signing Input R, S and the public key (x, y) to the ECDSA P-256 SHA-256 validator. Signing with the ECDSA P-384 SHA-384 and ECDSA P-521 SHA-512 algorithms is performed identically to the procedure for ECDSA P-256 SHA-256 - just 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. Examples using these algorithms are shown in Appendices A.3 and A.4 of [JWS]. Jones Expires March 19, 2014 [Page 13]
Internet-Draft JSON Web Algorithms (JWA) September 2013 3.5. Digital Signature with RSASSA-PSS This section defines the use of the RSASSA-PSS digital signature algorithm as defined in Section 8.1 of RFC 3447 [RFC3447] with the MGF1 mask generation function, always using the same hash function for both the RSASSA-PSS hash function and the MGF1 hash function. Use of SHA-256, SHA-384, and SHA-512 as these hash functions is defined. The size of the salt value is the same size as the hash function output. All other algorithm parameters use the defaults specified in Section A.2.3 of RFC 3447. The "alg" (algorithm) header parameter values "PS256", "PS384", and "PS512" are used in the JWS Header to indicate that the Encoded JWS Signature contains a base64url encoded RSASSA-PSS digital signature using the respective hash function in both roles. 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: 1. Generate a digital signature of the octets of the ASCII representation 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. The output will be an octet sequence. 2. Base64url encode the resulting octet sequence. The output is the Encoded JWS Signature for that JWS. The RSASSA-PSS SHA-256 digital signature for a JWS is validated as follows: 1. Take the Encoded JWS Signature and base64url decode it into an octet sequence. If decoding fails, the validation has failed. 2. Submit the octets of the ASCII representation of the JWS Signing Input 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 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. Jones Expires March 19, 2014 [Page 14]
Internet-Draft JSON Web Algorithms (JWA) September 2013 3.6. Using the Algorithm "none" JWSs MAY also be created that do not provide integrity protection. Such a JWS is called a "Plaintext JWS". Plaintext JWSs MUST use the "alg" value "none", and are formatted identically to other JWSs, but with the empty string for its JWS Signature value. See Section 7.5 for security considerations associated with using this algorithm. 4. Cryptographic Algorithms for Encryption JWE uses cryptographic algorithms to encrypt the Content Encryption Key (CEK) and the Plaintext. 4.1. "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 Parameter | Key Management | Additional | Implementation | | Value | Algorithm | Header | Requirements | | | | Parameters | | +-------------------+-----------------+------------+----------------+ | RSA1_5 | RSAES-PKCS1-V1_ | (none) | Required | | | 5[RFC3447] | | | | RSA-OAEP | RSAES using | (none) | Optional | | | Optimal | | | | | Asymmetric | | | | | Encryption | | | | | Padding (OAEP) | | | | | [RFC3447], with | | | | | the default | | | | | parameters | | | | | specified by | | | | | RFC 3447 in | | | | | Section A.2.1 | | | Jones Expires March 19, 2014 [Page 15]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | A128KW | Advanced | (none) | Recommended | | | Encryption | | | | | Standard (AES) | | | | | Key Wrap | | | | | Algorithm | | | | | [RFC3394] using | | | | | the default | | | | | initial value | | | | | specified in | | | | | Section 2.2.3.1 | | | | | and using 128 | | | | | bit keys | | | | A192KW | AES Key Wrap | (none) | Optional | | | Algorithm using | | | | | the default | | | | | initial value | | | | | specified in | | | | | Section 2.2.3.1 | | | | | and using 192 | | | | | bit keys | | | | A256KW | AES Key Wrap | (none) | Recommended | | | Algorithm using | | | | | the default | | | | | initial value | | | | | specified in | | | | | Section 2.2.3.1 | | | | | and using 256 | | | | | bit keys | | | | dir | Direct use of a | (none) | Recommended | | | shared | | | | | symmetric key | | | | | as the Content | | | | | Encryption Key | | | | | (CEK) for the | | | | | content | | | | | encryption step | | | | | (rather than | | | | | using the | | | | | symmetric key | | | | | to wrap the | | | | | CEK) | | | Jones Expires March 19, 2014 [Page 16]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | ECDH-ES | Elliptic Curve | "epk", | Recommended+ | | | Diffie-Hellman | "apu", | | | | Ephemeral | "apv" | | | | Static | | | | | [RFC6090] key | | | | | agreement using | | | | | the Concat KDF, | | | | | as defined in | | | | | Section 5.8.1 | | | | | of | | | | | [NIST.800-56A], | | | | | with the | | | | | agreed-upon key | | | | | being used | | | | | directly as the | | | | | Content | | | | | Encryption Key | | | | | (CEK) (rather | | | | | than being used | | | | | to wrap the | | | | | CEK), as | | | | | specified in | | | | | Section 4.7 | | | | ECDH-ES+A128KW | Elliptic Curve | "epk", | Recommended | | | Diffie-Hellman | "apu", | | | | Ephemeral | "apv" | | | | Static key | | | | | agreement per | | | | | "ECDH-ES" and | | | | | Section 4.7, | | | | | where the | | | | | agreed-upon key | | | | | is used to wrap | | | | | the Content | | | | | Encryption Key | | | | | (CEK) with the | | | | | "A128KW" | | | | | function | | | | | (rather than | | | | | being used | | | | | directly as the | | | | | CEK) | | | Jones Expires March 19, 2014 [Page 17]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | ECDH-ES+A192KW | Elliptic Curve | "epk", | Optional | | | Diffie-Hellman | "apu", | | | | Ephemeral | "apv" | | | | Static key | | | | | agreement, | | | | | where the | | | | | agreed-upon key | | | | | is used to wrap | | | | | the Content | | | | | Encryption Key | | | | | (CEK) with the | | | | | "A192KW" | | | | | function | | | | | (rather than | | | | | being used | | | | | directly as the | | | | | CEK) | | | | ECDH-ES+A256KW | Elliptic Curve | "epk", | Recommended | | | Diffie-Hellman | "apu", | | | | Ephemeral | "apv" | | | | Static key | | | | | agreement, | | | | | where the | | | | | agreed-upon key | | | | | is used to wrap | | | | | the Content | | | | | Encryption Key | | | | | (CEK) with the | | | | | "A256KW" | | | | | function | | | | | (rather than | | | | | being used | | | | | directly as the | | | | | CEK) | | | | A128GCMKW | AES in | "iv", | Optional | | | Galois/Counter | "tag" | | | | Mode (GCM) | | | | | [AES] | | | | | [NIST.800-38D] | | | | | using 128 bit | | | | | keys | | | | A192GCMKW | AES GCM using | "iv", | Optional | | | 192 bit keys | "tag" | | | A256GCMKW | AES GCM using | "iv", | Optional | | | 256 bit keys | "tag" | | Jones Expires March 19, 2014 [Page 18]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | PBES2-HS256+A128K | PBES2 [RFC2898] | "p2s", | Optional | | W | with HMAC | "p2c" | | | | SHA-256 as the | | | | | PRF and AES Key | | | | | Wrap [RFC3394] | | | | | using 128 bit | | | | | keys for the | | | | | encryption | | | | | scheme | | | | PBES2-HS384+A192K | PBES2 with HMAC | "p2s", | Optional | | W | SHA-256 as the | "p2c" | | | | PRF and AES Key | | | | | Wrap using 192 | | | | | bit keys for | | | | | the encryption | | | | | scheme | | | | PBES2-HS512+A256K | PBES2 with HMAC | "p2s", | Optional | | W | SHA-256 as the | "p2c" | | | | PRF and AES Key | | | | | Wrap using 256 | | | | | bit keys for | | | | | the encryption | | | | | scheme | | | +-------------------+-----------------+------------+----------------+ The Additional Header Parameters 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 indicates that the requirement strength is likely to be increased in a future version of the specification. 4.2. "enc" (Encryption Method) Header Parameter Values for JWE The table below is the set of "enc" (encryption method) header parameter values that are defined by this specification for use with JWE. These algorithms are used to encrypt the Plaintext, which produces the Ciphertext. Jones Expires March 19, 2014 [Page 19]
Internet-Draft JSON Web Algorithms (JWA) September 2013 +-------------+------------------------+------------+---------------+ | enc | Content Encryption | Additional | Implementatio | | Parameter | Algorithm | Header | nRequirements | | Value | | Parameters | | +-------------+------------------------+------------+---------------+ | A128CBC-HS2 | The | (none) | Required | | 56 | AES_128_CBC_HMAC_SHA_2 | | | | | 56 authenticated | | | | | encryption algorithm, | | | | | as defined in | | | | | Section 4.10.3. This | | | | | algorithm uses a 256 | | | | | bit key. | | | | A192CBC-HS3 | The | (none) | Optional | | 84 | AES_192_CBC_HMAC_SHA_3 | | | | | 84 authenticated | | | | | encryption algorithm, | | | | | as defined in | | | | | Section 4.10.4. This | | | | | algorithm uses a 384 | | | | | bit key. | | | | A256CBC-HS5 | The | (none) | Required | | 12 | AES_256_CBC_HMAC_SHA_5 | | | | | 12 authenticated | | | | | encryption algorithm, | | | | | as defined in | | | | | Section 4.10.5. This | | | | | algorithm uses a 512 | | | | | bit key. | | | | A128GCM | AES in Galois/Counter | (none) | Recommended | | | Mode (GCM) [AES] | | | | | [NIST.800-38D] using | | | | | 128 bit keys | | | | A192GCM | AES GCM using 192 bit | (none) | Optional | | | keys | | | | A256GCM | AES GCM using 256 bit | (none) | Recommended | | | keys | | | +-------------+------------------------+------------+---------------+ The Additional Header Parameters column indicates what additional Header Parameters are used by the algorithm, beyond "enc", which all use. All also use a JWE Initialization Vector value and produce JWE Ciphertext and JWE Authentication Tag values. See Appendix B for a table cross-referencing the encryption "alg" (algorithm) and "enc" (encryption method) values used in this specification with the equivalent identifiers used by other standards and software packages. Jones Expires March 19, 2014 [Page 20]
Internet-Draft JSON Web Algorithms (JWA) September 2013 4.3. 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" header parameter value "RSA1_5" is used in this case. A key of size 2048 bits or larger MUST be used with this algorithm. An example using this algorithm is shown in Appendix A.2 of [JWE]. 4.4. Key Encryption with RSAES OAEP This section defines the specifics of encrypting a JWE CEK with RSAES using Optimal Asymmetric Encryption Padding (OAEP) [RFC3447], with the default parameters specified by RFC 3447 in Section A.2.1. (Those default parameters are using a hash function of SHA-1 and a mask generation function of MGF1 with SHA-1.) The "alg" header parameter value "RSA-OAEP" is used in this case. A key of size 2048 bits or larger MUST be used with this algorithm. An example using this algorithm is shown in Appendix A.1 of [JWE]. 4.5. 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 in Section 2.2.3.1 using 128, 192, or 256 bit keys. The "alg" header parameter values "A128KW", "A192KW", or "A256KW" are respectively used in this case. An example using this algorithm is shown in Appendix A.3 of [JWE]. 4.6. 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" header parameter value "dir" is used in this case. Refer to the security considerations on key lifetimes in Section 7.2 and AES GCM in Section 7.4 when considering utilizing direct encryption. Jones Expires March 19, 2014 [Page 21]
Internet-Draft JSON Web Algorithms (JWA) September 2013 4.7. 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. The "alg" header parameter value "ECDH-ES" is used in the Direct Key Agreement mode and the values "ECDH-ES+A128KW", "ECDH-ES+A192KW", or "ECDH-ES+A256KW" are used in the Key Agreement with Key Wrapping mode. In the Direct Key Agreement case, 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. In the Key Agreement with Key Wrapping case, the output of the Concat KDF MUST be a key of the length needed for the specified key wrapping algorithm, one of 128, 192, or 256 bits respectively. A new ephemeral public key value MUST be generated for each key agreement operation. 4.7.1. Header Parameters Used for ECDH Key Agreement The following Header Parameter Names are used for key agreement as defined below. 4.7.1.1. "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 can be ignored. This Header Parameter is REQUIRED and MUST be understood and processed by implementations when these algorithms are used. Jones Expires March 19, 2014 [Page 22]
Internet-Draft JSON Web Algorithms (JWA) September 2013 4.7.1.2. "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 sender. Use of this Header Parameter is OPTIONAL. This Header Parameter MUST be understood and processed by implementations when these algorithms are used. 4.7.1.3. "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 receiver. Use of this Header Parameter is OPTIONAL. This Header Parameter MUST be understood and processed by implementations when these algorithms are used. 4.7.2. 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, with || being concatenation. In the Direct Key Agreement case, Data is set to the octets of the UTF-8 representation of the "enc" header parameter value. In the Key Agreement with Key Wrapping case, Data is set to the octets of the UTF-8 representation of the "alg" header parameter value. Jones Expires March 19, 2014 [Page 23]
Internet-Draft JSON Web Algorithms (JWA) September 2013 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, with || being concatenation. 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, with || being concatenation. 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 MUST specify what values should be used in the "apu" and "apv" parameters. The "apu" and "apv" values MUST be distinct. 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 sender and recipient. Alternatively, applications MAY conduct key derivation in a manner similar to The Diffie-Hellman Key Agreement Method [RFC2631]: In that case, the "apu" field MAY either be omitted or represent a random 512-bit value (analogous to PartyAInfo in Ephemeral-Static mode in [RFC2631]) and the "apv" field should not be present. See Appendix D for an example key agreement computation using this method. 4.8. 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] [NIST.800-38D] using 128, 192, or 256 bit keys. The "alg" header parameter values "A128GCMKW", "A192GCMKW", or "A256GCMKW" are respectively used in this case. Use of an Initialization Vector of size 96 bits is REQUIRED with this Jones Expires March 19, 2014 [Page 24]
Internet-Draft JSON Web Algorithms (JWA) September 2013 algorithm. The Initialization Vector 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. 4.8.1. Header Parameters Used for AES GCM Key Encryption The following Header Parameters are used for AES GCM key encryption. 4.8.1.1. "iv" (Initialization Vector) Header Parameter The "iv" (initialization vector) header parameter value is the base64url encoded representation of the Initialization Vector value used for the key encryption operation. This Header Parameter is REQUIRED and MUST be understood and processed by implementations when these algorithms are used. 4.8.1.2. "tag" (Authentication Tag) Header Parameter The "tag" (authentication tag) header parameter value is the base64url encoded representation of the Authentication Tag value resulting from the key encryption operation. This Header Parameter is REQUIRED and MUST be understood and processed by implementations when these algorithms are used. 4.9. Key Encryption with PBES2 The "PBES2-HS256+A128KW", "PBES2-HS384+A192KW", and "PBES2-HS512+A256KW" composite algorithms are used to perform password-based encryption of a JWE CEK, by first deriving a key encryption key from a user-supplied password, then encrypting the JWE CEK using the derived key. These algorithms are PBES2 schemes as specified in Section 6.2 of [RFC2898]. These algorithms use HMAC SHA-2 algorithms as the Pseudo-Random Function (PRF) for the PBKDF2 key derivation and AES Key Wrap [RFC3394] for the encryption scheme. The salt MUST be provided as the "p2s" header parameter value, and MUST be base64url decoded to Jones Expires March 19, 2014 [Page 25]
Internet-Draft JSON Web Algorithms (JWA) September 2013 obtain the value. The iteration count parameter MUST be provided as the "p2c" 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. 4.9.1. Header Parameters Used for PBES2 Key Encryption The following Header Parameters are used for Key Encryption with PBES2. 4.9.1.1. "p2s" (PBES2 salt) Parameter The "p2s" (PBES2 salt) header parameter contains the PBKDF2 salt value, encoded using base64url. This Header Parameter is REQUIRED 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 value containing 8 or more octets MUST be used. A new salt value MUST be generated randomly for every encryption operation; see [RFC4086] for considerations on generating random values. 4.9.1.2. "p2c" (PBES2 count) Parameter The "p2c" (PBES2 count) header parameter contains the PBKDF2 iteration count, represented as a positive integer. This Header Parameter is REQUIRED 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. 4.10. AES_CBC_HMAC_SHA2 Algorithms This section defines a family of authenticated encryption algorithms built using a composition of Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with PKCS #5 padding [AES] [NIST.800-38A] operations and HMAC [RFC2104] [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 in Appendix C. These algorithms are based upon Authenticated Encryption with AES-CBC Jones Expires March 19, 2014 [Page 26]
Internet-Draft JSON Web Algorithms (JWA) September 2013 and HMAC-SHA [I-D.mcgrew-aead-aes-cbc-hmac-sha2], performing the same cryptographic computations, but with the Initialization Vector and Authentication Tag values remaining separate, rather than being concatenated with the Ciphertext value in the output representation. This option is discussed in Appendix B of that specification. This algorithm family is a generalization of the algorithm family in [I-D.mcgrew-aead-aes-cbc-hmac-sha2], and can be used to implement those algorithms. 4.10.1. Conventions Used in Defining AES_CBC_HMAC_SHA2 We use the following notational conventions. CBC-PKCS5-ENC(X, P) denotes the AES CBC encryption of P using PKCS #5 padding using the cipher with the key X. MAC(Y, M) denotes the application of the Message Authentication Code (MAC) to the message M, using the key Y. The concatenation of two octet strings A and B is denoted as A || B. 4.10.2. 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. Section 4.10.2.1 and Section 4.10.2.2 define the generic encryption and decryption algorithms. Section 4.10.3 and Section 4.10.5 define instances of AES_CBC_HMAC_SHA2 that specify those details. 4.10.2.1. AES_CBC_HMAC_SHA2 Encryption The authenticated encryption algorithm takes as input four octet strings: a secret key K, a plaintext P, associated 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 associated 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. Jones Expires March 19, 2014 [Page 27]
Internet-Draft JSON Web Algorithms (JWA) September 2013 ENC_KEY consists of the final ENC_KEY_LEN octets of K, in order. Here we denote the number of octets in the MAC_KEY as MAC_KEY_LEN, and the number of octets in ENC_KEY as ENC_KEY_LEN; the values of these parameters are specified by the AEAD algorithms (in Section 4.10.3 and Section 4.10.5). The number of octets in the input key K is the sum of MAC_KEY_LEN and ENC_KEY_LEN. When generating the secondary keys from K, MAC_KEY and ENC_KEY MUST NOT overlap. 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 Initialization Vector (IV) used is a 128 bit value generated randomly or pseudorandomly for use in the cipher. 3. The plaintext is CBC encrypted using PKCS #5 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 A expressed as a 64-bit unsigned integer in network byte order. 5. A message authentication tag T is computed by applying HMAC [RFC2104] to the following data, in order: the associated 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 bits 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, associated data, initialization vector, and ciphertext, respectively. MAC_KEY = initial MAC_KEY_LEN bytes of K, Jones Expires March 19, 2014 [Page 28]
Internet-Draft JSON Web Algorithms (JWA) September 2013 ENC_KEY = final ENC_KEY_LEN bytes of K, E = CBC-PKCS5-ENC(ENC_KEY, P), M = MAC(MAC_KEY, A || IV || E || AL), T = initial T_LEN bytes of M. 4.10.2.2. AES_CBC_HMAC_SHA2 Decryption The authenticated decryption operation has four inputs: K, A, 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 of Section 4.10.2.1. 2. The integrity and authenticity of A and E are checked by computing an HMAC with the inputs as in Step 5 of Section 4.10.2.1. 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 AEAD decryption operation returns an indication that it failed, and the operation halts. (But see Section 10 of [JWE] for security considerations on thwarting timing attacks.) 3. The value E is decrypted and the PKCS #5 padding is 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. 4.10.3. 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 Cipher Block Chaining (CBC) mode of operation as defined in Section 6.2 of [NIST.800-38A], with PKCS #5 padding. The input key K is 32 octets long. Jones Expires March 19, 2014 [Page 29]
Internet-Draft JSON Web Algorithms (JWA) September 2013 The AES CBC IV is 16 octets long. ENC_KEY_LEN is 16 octets. The SHA-256 hash algorithm is used in HMAC. MAC_KEY_LEN is 16 octets. The HMAC-SHA-256 output is truncated to T_LEN=16 octets, by stripping off the final 16 octets. 4.10.4. 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: A 192 bit AES CBC key is used instead of 128. SHA-384 is used in HMAC instead of SHA-256. ENC_KEY_LEN is 24 octets instead of 16. MAC_KEY_LEN is 24 octets instead of 16. The length of the input key K is 48 octets instead of 32. The HMAC SHA-384 value is truncated to T_LEN=24 octets instead of 16. 4.10.5. 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: A 256 bit AES CBC key is used instead of 128. SHA-512 is used in HMAC instead of SHA-256. ENC_KEY_LEN is 32 octets instead of 16. MAC_KEY_LEN is 32 octets instead of 16. The length of the input key K is 64 octets instead of 32. The HMAC SHA-512 value is truncated to T_LEN=32 octets instead of 16. 4.10.6. Plaintext Encryption with AES_CBC_HMAC_SHA2 The algorithm value "A128CBC-HS256" is used as the "alg" value when using AES_128_CBC_HMAC_SHA_256 with JWE. The algorithm value "A192CBC-HS384" is used as the "alg" value when using AES_192_CBC_HMAC_SHA_384 with JWE. The algorithm value Jones Expires March 19, 2014 [Page 30]
Internet-Draft JSON Web Algorithms (JWA) September 2013 "A256CBC-HS512" is used as the "alg" value when using AES_256_CBC_HMAC_SHA_512 with JWE. The Additional Authenticated Data value used is the octets of the ASCII representation of the Encoded JWE Header value. The JWE Initialization Vector value used is the IV value. 4.11. Plaintext Encryption with AES GCM This section defines the specifics of encrypting the JWE Plaintext with Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) [AES] [NIST.800-38D] using 128, 192, or 256 bit keys. The "enc" header parameter values "A128GCM", "A192GCM", or "A256GCM" are respectively used in this case. The CEK is used as the encryption key. Use of an initialization vector of size 96 bits is REQUIRED with this algorithm. The Additional Authenticated Data value used is the octets of the ASCII representation of the Encoded JWE Header value. The requested size of the Authentication Tag output MUST be 128 bits, regardless of the key size. The JWE Authentication Tag is set to be the Authentication Tag value produced by the encryption. During decryption, the received JWE Authentication Tag is used as the Authentication Tag value. An example using this algorithm is shown in Appendix A.1 of [JWE]. 5. 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. 5.1. "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. Jones Expires March 19, 2014 [Page 31]
Internet-Draft JSON Web Algorithms (JWA) September 2013 +--------------+--------------------------------+-------------------+ | kty | Key Type | Implementation | | Parameter | | Requirements | | Value | | | +--------------+--------------------------------+-------------------+ | 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 indicates that the requirement strength is likely to be increased in a future version of the specification. 5.2. Parameters for Elliptic Curve Keys JWKs can represent Elliptic Curve [DSS] keys. In this case, the "kty" member value MUST be "EC". 5.2.1. 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 elliptic curve public keys: o "crv" o "x" o "y" 5.2.1.1. "crv" (Curve) Parameter The "crv" (curve) member identifies the cryptographic curve used with the key. Curve values from [DSS] used by this specification are: o "P-256" o "P-384" o "P-521" These values are registered in the IANA JSON Web Key Elliptic Curve registry defined in Section 6.6. Additional "crv" values MAY be used, provided they are understood by implementations using that Elliptic Curve key. The "crv" value is a case sensitive string. Jones Expires March 19, 2014 [Page 32]
Internet-Draft JSON Web Algorithms (JWA) September 2013 5.2.1.2. "x" (X Coordinate) Parameter The "x" (x coordinate) member contains the x coordinate for the elliptic curve point. It is represented as the base64url encoding of the octet string representation of the coordinate, as defined in Section 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. 5.2.1.3. "y" (Y Coordinate) Parameter The "y" (y coordinate) member contains the y coordinate for the elliptic curve point. It is represented as the base64url encoding of the octet string representation of the coordinate, as defined in Section 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. 5.2.2. 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. 5.2.2.1. "d" (ECC Private Key) Parameter The "d" (ECC private key) member contains the Elliptic Curve private key value. It is represented as the base64url encoding of the octet string representation of the private key value, as defined in Sections C.4 and 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). 5.3. Parameters for RSA Keys JWKs can represent RSA [RFC3447] keys. In this case, the "kty" member value MUST be "RSA". 5.3.1. Parameters for RSA Public Keys The following members MUST be present for RSA public keys. 5.3.1.1. "n" (Modulus) Parameter The "n" (modulus) member contains the modulus value for the RSA public key. It is represented as the base64url encoding of the Jones Expires March 19, 2014 [Page 33]
Internet-Draft JSON Web Algorithms (JWA) September 2013 value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.1.2. "e" (Exponent) Parameter The "e" (exponent) member contains the exponent value for the RSA public key. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. For instance, when representing the value 65537, the octet sequence to be base64url encoded MUST consist of the three octets [1, 0, 1]. 5.3.2. 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. The consumer of a JWK MAY choose to accept an RSA private key that does not contain a complete set of the private key parameters other than "d", including JWKs in which "d" is the only RSA private key parameter included. 5.3.2.1. "d" (Private Exponent) Parameter The "d" (private exponent) member contains the private exponent value for the RSA private key. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.2. "p" (First Prime Factor) Parameter The "p" (first prime factor) member contains the first prime factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.3. "q" (Second Prime Factor) Parameter The "q" (second prime factor) member contains the second prime factor, a positive integer. It is represented as the base64url Jones Expires March 19, 2014 [Page 34]
Internet-Draft JSON Web Algorithms (JWA) September 2013 encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.4. "dp" (First Factor CRT Exponent) Parameter The "dp" (first factor CRT exponent) member contains the Chinese Remainder Theorem (CRT) exponent of the first factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.5. "dq" (Second Factor CRT Exponent) Parameter The "dq" (second factor CRT exponent) member contains the Chinese Remainder Theorem (CRT) exponent of the second factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.6. "qi" (First CRT Coefficient) Parameter The "dp" (first CRT coefficient) member contains the Chinese Remainder Theorem (CRT) coefficient of the second factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.7. "oth" (Other Primes Info) Parameter The "oth" (other primes info) member contains an array of information about any third and subsequent primes, should they exist. When only two primes have been used (the normal case), this parameter MUST be omitted. When three or more primes have been used, the number of array elements MUST be the number of primes used minus two. Each array element MUST be an object with the following members: 5.3.2.7.1. "r" (Prime Factor) The "r" (prime factor) parameter within an "oth" array member represents the value of a subsequent prime factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. Jones Expires March 19, 2014 [Page 35]
Internet-Draft JSON Web Algorithms (JWA) September 2013 5.3.2.7.2. "d" (Factor CRT Exponent) The "d" (Factor CRT Exponent) parameter within an "oth" array member represents the CRT exponent of the corresponding prime factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.3.2.7.3. "t" (Factor CRT Coefficient) The "t" (factor CRT coefficient) parameter within an "oth" array member represents the CRT coefficient of the corresponding prime factor, a positive integer. It is represented as the base64url encoding of the value's unsigned big endian representation as an octet sequence. The octet sequence MUST utilize the minimum number of octets to represent the value. 5.4. Parameters for Symmetric Keys When the JWK "kty" member value is "oct" (octet sequence), the member "k" 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. 5.4.1. "k" (Key Value) Parameter The "k" (key value) member 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. 6. IANA Considerations The following registration procedure is used for all the registries established by this specification. Values are registered with a Specification Required [RFC5226] after a two-week review period on the [TBD]@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of values prior to publication, the Designated Expert(s) may approve registration once they are satisfied that such a specification will be published. Registration requests must be sent to the [TBD]@ietf.org mailing list for review and comment, with an appropriate subject (e.g., "Request Jones Expires March 19, 2014 [Page 36]
Internet-Draft JSON Web Algorithms (JWA) September 2013 for access token type: example"). [[ Note to the RFC Editor: The name of the mailing list should be determined in consultation with the IESG and IANA. Suggested name: jose-reg-review. ]] Within the review period, the Designated Expert(s) will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. Registration requests that are undetermined for a period longer than 21 days can be brought to the IESG's attention (using the iesg@iesg.org mailing list) for resolution. Criteria that should be applied by the Designated Expert(s) includes determining whether the proposed registration duplicates existing functionality, determining whether it is likely to be of general applicability or whether it is useful only for a single application, and whether the registration makes sense. IANA must only accept registry updates from the Designated Expert(s) 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 Expert(s). 6.1. JSON Web Signature and Encryption Algorithms Registry This specification establishes the IANA JSON Web Signature and Encryption Algorithms registry for values of the JWS and JWE "alg" (algorithm) and "enc" (encryption method) header parameters. The registry records the algorithm name, the algorithm usage locations from the set "alg" and "enc", implementation requirements, and a reference to the specification that defines it. The same algorithm name MAY be registered multiple times, provided that the sets of usage locations are disjoint. It is suggested that when algorithms can use keys of different lengths, that the length of the key be included in the algorithm name. This allows readers of the JSON text to easily make security consideration decisions. The implementation requirements of an algorithm MAY be changed over time by the Designated Experts(s) as the cryptographic landscape Jones Expires March 19, 2014 [Page 37]
Internet-Draft JSON Web Algorithms (JWA) September 2013 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, with the new specification defining the revised implementation requirements level. 6.1.1. Template Algorithm Name: The name requested (e.g., "example"). This name is case sensitive. Names may not match other registered names in a case insensitive manner unless the Designated Expert(s) state that there is a compelling reason to allow an exception in this particular case. Algorithm Usage Location(s): The algorithm usage, which must be one or more of the values "alg" or "enc". Implementation Requirements: The algorithm implementation requirements, which must be one the words Required, Recommended, Optional, or Deprecated. 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. Change Controller: For Standards Track RFCs, state "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(s) that specify the parameter, preferably including URI(s) that can be used to retrieve copies of the document(s). An indication of the relevant sections may also be included but is not required. 6.1.2. Initial Registry Contents o Algorithm Name: "HS256" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Required o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] Jones Expires March 19, 2014 [Page 38]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Algorithm Name: "HS384" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "HS512" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "RS256" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "RS384" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "RS512" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "ES256" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended+ o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "ES384" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "ES512" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG Jones Expires March 19, 2014 [Page 39]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "PS256" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "PS384" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "PS512" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "none" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Algorithm Name: "RSA1_5" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Required o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "RSA-OAEP" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "A128KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "A192KW" o Algorithm Usage Location(s): "alg" Jones Expires March 19, 2014 [Page 40]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "A256KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "dir" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "ECDH-ES" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended+ o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "ECDH-ES+A128KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "ECDH-ES+A192KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "ECDH-ES+A256KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] o Algorithm Name: "A128GCMKW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.8 of [[ this document ]] Jones Expires March 19, 2014 [Page 41]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Algorithm Name: "A192GCMKW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.8 of [[ this document ]] o Algorithm Name: "A256GCMKW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.8 of [[ this document ]] o Algorithm Name: "PBES2-HS256+A128KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.9 of [[ this document ]] o Algorithm Name: "PBES2-HS384+A192KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.9 of [[ this document ]] o Algorithm Name: "PBES2-HS512+A256KW" o Algorithm Usage Location(s): "alg" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.9 of [[ this document ]] o Algorithm Name: "A128CBC-HS256" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Required o Change Controller: IESG o Specification Document(s): Section 4.2 of [[ this document ]] o Algorithm Name: "A192CBC-HS384" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.2 of [[ this document ]] o Algorithm Name: "A256CBC-HS512" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Required o Change Controller: IESG Jones Expires March 19, 2014 [Page 42]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Specification Document(s): Section 4.2 of [[ this document ]] o Algorithm Name: "A128GCM" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.2 of [[ this document ]] o Algorithm Name: "A192GCM" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 4.2 of [[ this document ]] o Algorithm Name: "A256GCM" o Algorithm Usage Location(s): "enc" o Implementation Requirements: Recommended o Change Controller: IESG o Specification Document(s): Section 4.2 of [[ this document ]] 6.2. JWE Header Parameter Names Registration This specification registers the Header Parameter Names defined in Section 4.7.1, Section 4.8.1, and Section 4.9.1 in the IANA JSON Web Signature and Encryption Header Parameters registry defined in [JWS]. 6.2.1. Registry Contents o Header Parameter Name: "epk" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.7.1.1 of [[ this document ]] o Header Parameter Name: "apu" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.7.1.2 of [[ this document ]] o Header Parameter Name: "apv" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.7.1.3 of [[ this document ]] o Header Parameter Name: "iv" o Header Parameter Usage Location(s): JWE o Change Controller: IESG Jones Expires March 19, 2014 [Page 43]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Specification Document(s): Section 4.8.1.1 of [[ this document ]] o Header Parameter Name: "tag" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.8.1.2 of [[ this document ]] o Header Parameter Name: "p2s" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.9.1.1 of [[ this document ]] o Header Parameter Name: "p2c" o Header Parameter Usage Location(s): JWE o Change Controller: IESG o Specification Document(s): Section 4.9.1.2 of [[ this document ]] 6.3. 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. 6.3.1. Registration Template Compression Algorithm Value: The name requested (e.g., "example"). 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 Expert(s) state that there is a compelling reason to allow an exception in this particular case. Change Controller: For Standards Track RFCs, state "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(s) that specify the parameter, preferably including URI(s) that can be used to retrieve copies of the document(s). An indication of the relevant sections may also be included but is not required. Jones Expires March 19, 2014 [Page 44]
Internet-Draft JSON Web Algorithms (JWA) September 2013 6.3.2. Initial Registry Contents o Compression Algorithm Value: "DEF" o Change Controller: IESG o Specification Document(s): JSON Web Encryption (JWE) [JWE] 6.4. 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 by the Designated Experts(s) 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, with the new specification defining the revised implementation requirements level. 6.4.1. Registration Template "kty" Parameter Value: The name requested (e.g., "example"). 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 Expert(s) state that there is a compelling reason to allow an exception in this particular case. Change Controller: For Standards Track RFCs, state "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. Implementation Requirements: The key type implementation requirements, which must be one the words Required, Recommended, Optional, or Deprecated. 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. Jones Expires March 19, 2014 [Page 45]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Specification Document(s): Reference to the document(s) that specify the parameter, preferably including URI(s) that can be used to retrieve copies of the document(s). An indication of the relevant sections may also be included but is not required. 6.4.2. Initial Registry Contents This specification registers the values defined in Section 5.1. o "kty" Parameter Value: "EC" o Implementation Requirements: Recommended+ o Change Controller: IESG o Specification Document(s): Section 5.2 of [[ this document ]] o "kty" Parameter Value: "RSA" o Implementation Requirements: Required o Change Controller: IESG o Specification Document(s): Section 5.3 of [[ this document ]] o "kty" Parameter Value: "oct" o Implementation Requirements: Required o Change Controller: IESG o Specification Document(s): Section 5.4 of [[ this document ]] 6.5. JSON Web Key Parameters Registration This specification registers the parameter names defined in Sections 5.2, 5.3, and 5.4 in the IANA JSON Web Key Parameters registry defined in [JWK]. 6.5.1. Registry Contents o Parameter Name: "crv" o Used with "kty" Value(s): "EC" o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 5.2.1.1 of [[ this document ]] o Parameter Name: "x" o Used with "kty" Value(s): "EC" o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 5.2.1.2 of [[ this document ]] o Parameter Name: "y" Jones Expires March 19, 2014 [Page 46]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Used with "kty" Value(s): "EC" o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 5.2.1.3 of [[ this document ]] o Parameter Name: "d" o Used with "kty" Value(s): "EC" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.2.2.1 of [[ this document ]] o Parameter Name: "n" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 5.3.1.1 of [[ this document ]] o Parameter Name: "e" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 5.3.1.2 of [[ this document ]] o Parameter Name: "d" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.1 of [[ this document ]] o Parameter Name: "p" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.2 of [[ this document ]] o Parameter Name: "q" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.3 of [[ this document ]] o Parameter Name: "dp" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.4 of [[ this document ]] Jones Expires March 19, 2014 [Page 47]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Parameter Name: "dq" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.5 of [[ this document ]] o Parameter Name: "qi" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.6 of [[ this document ]] o Parameter Name: "oth" o Used with "kty" Value(s): "RSA" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.3.2.7 of [[ this document ]] o Parameter Name: "k" o Used with "kty" Value(s): "oct" o Parameter Information Class: Private o Change Controller: IESG o Specification Document(s): Section 5.4.1 of [[ this document ]] 6.6. JSON Web Key Elliptic Curve Registry This specification 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 in Section 5.2.1.1. The implementation requirements of a curve MAY be changed over time by the Designated Experts(s) 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, with the new specification defining the revised implementation requirements level. 6.6.1. Registration Template Curve Name: The name requested (e.g., "example"). 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 Jones Expires March 19, 2014 [Page 48]
Internet-Draft JSON Web Algorithms (JWA) September 2013 case insensitive manner unless the Designated Expert(s) state that there is a compelling reason to allow an exception in this particular case. Implementation Requirements: The curve implementation requirements, which must be one the words Required, Recommended, Optional, or Deprecated. 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. Change Controller: For Standards Track RFCs, state "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(s) that specify the parameter, preferably including URI(s) that can be used to retrieve copies of the document(s). An indication of the relevant sections may also be included but is not required. 6.6.2. Initial Registry Contents o Curve Name: "P-256" o Implementation Requirements: Recommended+ o Change Controller: IESG o Specification Document(s): Section 5.2.1.1 of [[ this document ]] o Curve Name: "P-384" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 5.2.1.1 of [[ this document ]] o Curve Name: "P-521" o Implementation Requirements: Optional o Change Controller: IESG o Specification Document(s): Section 5.2.1.1 of [[ this document ]] 7. Security Considerations All of the security issues faced by any cryptographic application must be faced by a JWS/JWE/JWK agent. Among these issues are protecting the user's private and symmetric keys, preventing various attacks, and helping the user avoid mistakes such as inadvertently Jones Expires March 19, 2014 [Page 49]
Internet-Draft JSON Web Algorithms (JWA) September 2013 encrypting a message for the wrong recipient. The entire list of security considerations is beyond the scope of this document, but some significant considerations are listed here. The security considerations in [AES], [DSS], [JWE], [JWK], [JWS], [NIST.800-38A], [NIST.800-38D], [NIST.800-56A], [RFC2104], [RFC3394], [RFC3447], [RFC5116], [RFC6090], and [SHS] apply to this specification. Algorithms of matching strengths should be used together whenever possible. For instance, when AES Key Wrap is used with a given key size, using the same key size is recommended when AES GCM is also used. 7.1. Algorithms and Key Sizes will be Deprecated Eventually the algorithms and/or key sizes currently described in this specification will no longer be considered sufficiently secure and will be removed. Therefore, implementers and deployments must be prepared for this eventuality. 7.2. 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. 7.3. RSAES-PKCS1-v1_5 Security Considerations While Section 8 of RFC 3447 [RFC3447] explicitly calls for people not to adopt RSASSA-PKCS-v1_5 for new applications and instead requests that people transition to RSASSA-PSS, this specification does include RSASSA-PKCS-v1_5, for interoperability reasons, because it commonly implemented. Keys used with RSAES-PKCS1-v1_5 must follow the constraints in Section 7.2 of RFC 3447 [RFC3447]. In particular, keys with a low public key exponent value must not be used. 7.4. 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. Jones Expires March 19, 2014 [Page 50]
Internet-Draft JSON Web Algorithms (JWA) September 2013 An Initialization Vector value MUST never 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. 7.5. Plaintext JWS Security Considerations Plaintext JWSs (JWSs that use the "alg" value "none") provide no integrity protection. Thus, they must only be used in contexts where the payload is secured by means other than a digital signature or MAC value, or need not be secured. Implementations that support plaintext JWS objects 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 plaintext JWS objects by default. For example, the "verify" method of a hypothetical JWS software library might have a Boolean "acceptUnsigned" 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 plaintext JWS values if "none" is not in that list. In order to mitigate downgrade attacks, applications MUST NOT signal acceptance of plaintext JWS objects at a global level, and SHOULD signal acceptance on a per-object basis. For example, suppose an application accepts JWS objects over two channels, (1) HTTP and (2) HTTPS with client authentication. It requires a JWS signature on objects received over HTTP, but accepts plaintext JWS objects over HTTPS. If the application were to globally indicate that "none" is acceptable, then an attacker could provide it with an unsigned object 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 "acceptUnsigned" to "true" for the first hypothetical JWS software library above), but not for each object received over HTTP. 7.6. 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 send certificates with keys that would result in excessive cryptographic processing, for example, keys larger than those Jones Expires March 19, 2014 [Page 51]
Internet-Draft JSON Web Algorithms (JWA) September 2013 mandated in this specification, which could swamp the processing element. Agents that use such keys without first validating the certificate to a trust anchor are advised to have some sort of cryptographic resource management system to prevent such attacks. 7.7. Reusing Key Material when Encrypting Keys It is NOT RECOMMENDED to reuse the same 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 for preventing re-use is to always generate a new set key material for each encryption operation, based on the considerations noted in this document as well as from [RFC4086]. 7.8. Password Considerations While convenient for end users, passwords are vulnerable to a number of attacks. To help mitigate some of these limitations, this document applies principles from [RFC2898] to derive cryptographic keys from user-supplied passwords. However, the strength of the password still has a significant impact. A high-entry password has greater resistance to dictionary attacks. [NIST-800-63-1] contains guidelines for estimating password entropy, which can help applications and users generate stronger passwords. An ideal password is one that is as large (or larger) than the derived key length but less than the PRF's block size. Passwords larger than the PRF's block size are first hashed, which reduces an attacker's effective search space to the length of the hash algorithm (32 octets for HMAC SHA-256). It is RECOMMENDED that the password be no longer than 64 octets long for "PBES2-HS512+A256KW". Still, care needs to be taken in where and how password-based encryption is used. Such algorithms MUST NOT be used where the attacker can make an indefinite number of attempts to circumvent the protection. 8. 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 to perform the steps outlined in [I-D.melnikov-precis-saslprepbis] to prepare a password supplied directly by a user before performing key derivation and encryption. Jones Expires March 19, 2014 [Page 52]
Internet-Draft JSON Web Algorithms (JWA) September 2013 9. References 9.1. Normative References [AES] National Institute of Standards and Technology (NIST), "Advanced Encryption Standard (AES)", FIPS PUB 197, November 2001. [DSS] National Institute of Standards and Technology, "Digital Signature Standard (DSS)", FIPS PUB 186-4, July 2013. [I-D.melnikov-precis-saslprepbis] Saint-Andre, P. and A. Melnikov, "Preparation and Comparison of Internationalized Strings Representing Simple User Names and Passwords", draft-melnikov-precis-saslprepbis-04 (work in progress), September 2012. [JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web Encryption (JWE)", draft-ietf-jose-json-web-encryption (work in progress), September 2013. [JWK] Jones, M., "JSON Web Key (JWK)", draft-ietf-jose-json-web-key (work in progress), September 2013. [JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", draft-ietf-jose-json-web-signature (work in progress), September 2013. [NIST.800-38A] National Institute of Standards and Technology (NIST), "Recommendation for Block Cipher Modes of Operation", NIST PUB 800-38A, December 2001. [NIST.800-38D] National Institute of Standards and Technology (NIST), "Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC", NIST PUB 800-38D, December 2001. [NIST.800-56A] National Institute of Standards and Technology (NIST), "Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography", NIST Special Publication 800-56A, Revision 2, May 2013. [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Jones Expires March 19, 2014 [Page 53]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Hashing for Message Authentication", RFC 2104, February 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography Specification Version 2.0", RFC 2898, September 2000. [RFC3394] Schaad, J. and R. Housley, "Advanced Encryption Standard (AES) Key Wrap Algorithm", RFC 3394, September 2002. [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003. [RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, June 2005. [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006. [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007. [RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated Encryption", RFC 5116, January 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC6090] McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic Curve Cryptography Algorithms", RFC 6090, February 2011. [SEC1] Standards for Efficient Cryptography Group, "SEC 1: Elliptic Curve Cryptography", May 2009. [SHS] National Institute of Standards and Technology, "Secure Hash Standard (SHS)", FIPS PUB 180-3, October 2008. [USASCII] American National Standards Institute, "Coded Character Set -- 7-bit American Standard Code for Information Interchange", ANSI X3.4, 1986. Jones Expires March 19, 2014 [Page 54]
Internet-Draft JSON Web Algorithms (JWA) September 2013 9.2. Informative References [CanvasApp] Facebook, "Canvas Applications", 2010. [I-D.mcgrew-aead-aes-cbc-hmac-sha2] McGrew, D., Foley, J., and K. Paterson, "Authenticated Encryption with AES-CBC and HMAC-SHA", draft-mcgrew-aead-aes-cbc-hmac-sha2-02 (work in progress), July 2013. [I-D.miller-jose-jwe-protected-jwk] Miller, M., "Using JavaScript Object Notation (JSON) Web Encryption (JWE) for Protecting JSON Web Key (JWK) Objects", draft-miller-jose-jwe-protected-jwk-02 (work in progress), June 2013. [I-D.rescorla-jsms] Rescorla, E. and J. Hildebrand, "JavaScript Message Security Format", draft-rescorla-jsms-00 (work in progress), March 2011. [JCA] Oracle, "Java Cryptography Architecture", 2013. [JSE] Bradley, J. and N. Sakimura (editor), "JSON Simple Encryption", September 2010. [JSS] Bradley, J. and N. Sakimura (editor), "JSON Simple Sign", September 2010. [MagicSignatures] Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic Signatures", January 2011. [NIST-800-63-1] National Institute of Standards and Technology (NIST), "Electronic Authentication Guideline", NIST 800-63-1, December 2011. [RFC2631] Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC 2631, June 1999. [RFC3275] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Jones Expires March 19, 2014 [Page 55]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Version 2.1", RFC 3447, February 2003. [W3C.CR-xmldsig-core2-20120124] Eastlake, D., Reagle, J., Yiu, K., Solo, D., Datta, P., Hirsch, F., Cantor, S., and T. Roessler, "XML Signature Syntax and Processing Version 2.0", World Wide Web Consortium CR CR-xmldsig-core2-20120124, January 2012, <http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124>. [W3C.CR-xmlenc-core1-20120313] Eastlake, D., Reagle, J., Roessler, T., and F. Hirsch, "XML Encryption Syntax and Processing Version 1.1", World Wide Web Consortium CR CR-xmlenc-core1-20120313, March 2012, <http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313>. [W3C.REC-xmlenc-core-20021210] Eastlake, D. and J. Reagle, "XML Encryption Syntax and Processing", World Wide Web Consortium Recommendation REC- xmlenc-core-20021210, December 2002, <http://www.w3.org/TR/2002/REC-xmlenc-core-20021210>. Appendix A. Digital Signature/MAC Algorithm Identifier Cross-Reference This appendix contains a table cross-referencing the digital signature and MAC "alg" (algorithm) values used in this specification with the equivalent identifiers used by other standards and software packages. See XML DSIG [RFC3275], XML DSIG 2.0 [W3C.CR-xmldsig-core2-20120124], and Java Cryptography Architecture [JCA] for more information about the names defined by those documents. +-----+---------------------------------+-----------+---------------+ | JWS | XML DSIG | JCA | OID | +-----+---------------------------------+-----------+---------------+ | HS2 | http://www.w3.org/2001/04/xmlds | HmacSHA25 | 1.2.840.11354 | | 56 | ig-more#hmac-sha256 | 6 | 9.2.9 | | HS3 | http://www.w3.org/2001/04/xmlds | HmacSHA38 | 1.2.840.11354 | | 84 | ig-more#hmac-sha384 | 4 | 9.2.10 | | HS5 | http://www.w3.org/2001/04/xmlds | HmacSHA51 | 1.2.840.11354 | | 12 | ig-more#hmac-sha512 | 2 | 9.2.11 | | RS2 | http://www.w3.org/2001/04/xmlds | SHA256wit | 1.2.840.11354 | | 56 | ig-more#rsa-sha256 | hRSA | 9.1.1.11 | | RS3 | http://www.w3.org/2001/04/xmlds | SHA384wit | 1.2.840.11354 | | 84 | ig-more#rsa-sha384 | hRSA | 9.1.1.12 | | RS5 | http://www.w3.org/2001/04/xmlds | SHA512wit | 1.2.840.11354 | | 12 | ig-more#rsa-sha512 | hRSA | 9.1.1.13 | Jones Expires March 19, 2014 [Page 56]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | ES2 | http://www.w3.org/2001/04/xmlds | SHA256wit | 1.2.840.10045 | | 56 | ig-more#ecdsa-sha256 | hECDSA | .4.3.2 | | ES3 | http://www.w3.org/2001/04/xmlds | SHA384wit | 1.2.840.10045 | | 84 | ig-more#ecdsa-sha384 | hECDSA | .4.3.3 | | ES5 | http://www.w3.org/2001/04/xmlds | SHA512wit | 1.2.840.10045 | | 12 | ig-more#ecdsa-sha512 | hECDSA | .4.3.4 | | PS2 | http://www.w3.org/2007/05/xmlds | | 1.2.840.11354 | | 56 | ig-more#sha256-rsa-MGF1 | | 9.1.1.10 | | PS3 | http://www.w3.org/2007/05/xmlds | | 1.2.840.11354 | | 84 | ig-more#sha384-rsa-MGF1 | | 9.1.1.10 | | PS5 | http://www.w3.org/2007/05/xmlds | | 1.2.840.11354 | | 12 | ig-more#sha512-rsa-MGF1 | | 9.1.1.10 | +-----+---------------------------------+-----------+---------------+ Appendix B. Encryption Algorithm Identifier Cross-Reference This appendix contains a table cross-referencing the "alg" (algorithm) and "enc" (encryption method) values used in this specification with the equivalent identifiers used by other standards and software packages. See XML Encryption [W3C.REC-xmlenc-core-20021210], XML Encryption 1.1 [W3C.CR-xmlenc-core1-20120313], and Java Cryptography Architecture [JCA] for more information about the names defined by those documents. For the composite algorithms "A128CBC-HS256", "A192CBC-HS384", and "A256CBC-HS512", the corresponding AES CBC algorithm identifiers are listed. +--------+-----------------------+-------------------+--------------+ | JWE | XML ENC | JCA | OID | +--------+-----------------------+-------------------+--------------+ | RSA1_5 | http://www.w3.org/200 | RSA/ECB/PKCS1Padd | 1.2.840.1135 | | | 1/04/xmlenc#rsa-1_5 | ing | 49.1.1.1 | | RSA-OA | http://www.w3.org/200 | RSA/ECB/OAEPWithS | 1.2.840.1135 | | EP | 1/04/xmlenc#rsa-oaep- | HA-1AndMGF1Paddin | 49.1.1.7 | | | mgf1p | g | | | ECDH-E | http://www.w3.org/200 | | 1.3.132.1.12 | | S | 9/xmlenc11#ECDH-ES | | | | A128KW | http://www.w3.org/200 | | 2.16.840.1.1 | | | 1/04/xmlenc#kw-aes128 | | 01.3.4.1.5 | | A192KW | http://www.w3.org/200 | | 2.16.840.1.1 | | | 1/04/xmlenc#kw-aes192 | | 01.3.4.1.25 | | A256KW | http://www.w3.org/200 | | 2.16.840.1.1 | | | 1/04/xmlenc#kw-aes256 | | 01.3.4.1.45 | Jones Expires March 19, 2014 [Page 57]
Internet-Draft JSON Web Algorithms (JWA) September 2013 | A128CB | http://www.w3.org/200 | AES/CBC/PKCS5Padd | 2.16.840.1.1 | | C-HS25 | 1/04/xmlenc#aes128-cb | ing | 01.3.4.1.2 | | 6 | c | | | | A192CB | http://www.w3.org/200 | AES/CBC/PKCS5Padd | 2.16.840.1.1 | | C-HS38 | 1/04/xmlenc#aes192-cb | ing | 01.3.4.1.22 | | 4 | c | | | | A256CB | http://www.w3.org/200 | AES/CBC/PKCS5Padd | 2.16.840.1.1 | | C-HS51 | 1/04/xmlenc#aes256-cb | ing | 01.3.4.1.42 | | 2 | c | | | | A128GC | http://www.w3.org/200 | AES/GCM/NoPadding | 2.16.840.1.1 | | M | 9/xmlenc11#aes128-gcm | | 01.3.4.1.6 | | A192GC | http://www.w3.org/200 | AES/GCM/NoPadding | 2.16.840.1.1 | | M | 9/xmlenc11#aes192-gcm | | 01.3.4.1.26 | | A256GC | http://www.w3.org/200 | AES/GCM/NoPadding | 2.16.840.1.1 | | M | 9/xmlenc11#aes256-gcm | | 01.3.4.1.46 | +--------+-----------------------+-------------------+--------------+ Appendix C. 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 in Section 4.10. They are also intended to correspond to test cases that may appear in a future version of [I-D.mcgrew-aead-aes-cbc-hmac-sha2], demonstrating that the cryptographic computations performed are the same. The variable names are those defined in Section 4.10. All values are hexadecimal. Jones Expires March 19, 2014 [Page 58]
Internet-Draft JSON Web Algorithms (JWA) September 2013 C.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 c4 Jones Expires March 19, 2014 [Page 59]
Internet-Draft JSON Web Algorithms (JWA) September 2013 C.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 d7 Jones Expires March 19, 2014 [Page 60]
Internet-Draft JSON Web Algorithms (JWA) September 2013 C.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 c5 Jones Expires March 19, 2014 [Page 61]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Appendix D. Example ECDH-ES Key Agreement Computation This example uses ECDH-ES Key Agreement and the Concat KDF to derive the Content Encryption Key (CEK) in the manner described in Section 4.7. 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 128 bit keys ("enc" value "A128GCM"). In this example, a sender Alice is encrypting content to a recipient Bob. The sender (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 recipient'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. In this example, the "apu" (agreement PartyUInfo) parameter value is the base64url encoding of the UTF-8 string "Alice" and the "apv" (agreement PartyVInfo) parameter value is the base64url encoding of the UTF-8 string "Bob". The "epk" parameter is used to communicate the sender's (Alice's) ephemeral public key value to the recipient (Bob). Jones Expires March 19, 2014 [Page 62]
Internet-Draft JSON Web Algorithms (JWA) September 2013 {"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 the octet sequence: [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 UTF-8 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]. 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: Jones Expires March 19, 2014 [Page 63]
Internet-Draft JSON Web Algorithms (JWA) September 2013 [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: usEpwFIC_qrmBExntFwxMA Appendix E. Acknowledgements Solutions for signing and encrypting JSON content were previously explored by Magic Signatures [MagicSignatures], JSON Simple Sign [JSS], Canvas Applications [CanvasApp], JSON Simple Encryption [JSE], and JavaScript Message Security Format [I-D.rescorla-jsms], all of which influenced this draft. The Authenticated Encryption with AES-CBC and HMAC-SHA [I-D.mcgrew-aead-aes-cbc-hmac-sha2] 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 [I-D.mcgrew-aead-aes-cbc-hmac-sha2] by John Foley. Matt Miller wrote Using JavaScript Object Notation (JSON) Web Encryption (JWE) for Protecting JSON Web Key (JWK) Objects [I-D.miller-jose-jwe-protected-jwk], which the password-based encryption content of this draft is based upon. 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, John Bradley, Brian Campbell, Breno de Jones Expires March 19, 2014 [Page 64]
Internet-Draft JSON Web Algorithms (JWA) September 2013 Medeiros, Yaron Y. Goland, Dick Hardt, Jeff Hodges, Edmund Jay, James Manger, Matt Miller, Tony Nadalin, Axel Nennker, John Panzer, Emmanuel Raviart, Nat Sakimura, Jim Schaad, Hannes Tschofenig, and Sean Turner. Jim Schaad and Karen O'Donoghue chaired the JOSE working group and Sean Turner and Stephen Farrell served as Security area directors during the creation of this specification. Appendix F. Document History [[ to be removed by the RFC Editor before publication as an RFC ]] -16 o Added a DataLen prefix to the AlgorithmID value in the Concat KDF computation. o Added OIDs for encryption algorithms, additional signature algorithm OIDs, and additional XML DSIG/ENC URIs in the algorithm cross-reference tables. o Changes to address editorial and minor issues #28, #36, #39, #52, #53, #55, #127, #128, #136, #137, #141, #150, #151, #152, and #155. -15 o Changed statements about rejecting JWSs to statements about validation failing, addressing issue #35. o Stated that changes of implementation requirements are only permitted on a Specification Required basis, addressing issue #38. o Made "oct" a required key type, addressing issue #40. o Updated the example ECDH-ES key agreement values. o Changes to address editorial and minor issues #34, #37, #49, #63, #123, #124, #125, #130, #132, #133, #138, #139, #140, #142, #143, #144, #145, #148, #149, #150, and #162. -14 o Removed "PBKDF2" key type and added "p2s" and "p2c" header parameters for use with the PBES2 algorithms. Jones Expires March 19, 2014 [Page 65]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Made the RSA private key parameters that are there to enable optimizations be RECOMMENDED rather than REQUIRED. o Added algorithm identifiers for AES algorithms using 192 bit keys and for RSASSA-PSS using HMAC SHA-384. o Added security considerations about key lifetimes, addressing issue #18. o Added an example ECDH-ES key agreement computation. -13 o Added key encryption with AES GCM as specified in draft-jones-jose-aes-gcm-key-wrap-01, addressing issue #13. o Added security considerations text limiting the number of times that an AES GCM key can be used for key encryption or direct encryption, per Section 8.3 of NIST SP 800-38D, addressing issue #28. o Added password-based key encryption as specified in draft-miller-jose-jwe-protected-jwk-02. -12 o In the Direct Key Agreement case, the Concat KDF AlgorithmID is set to the octets of the UTF-8 representation of the "enc" header parameter value. o Restored the "apv" (agreement PartyVInfo) parameter. o Moved the "epk", "apu", and "apv" Header Parameter definitions to be with the algorithm descriptions that use them. o Changed terminology from "block encryption" to "content encryption". -11 o Removed the Encrypted Key value from the AAD computation since it is already effectively integrity protected by the encryption process. The AAD value now only contains the representation of the JWE Encrypted Header. o Removed "apv" (agreement PartyVInfo) since it is no longer used. Jones Expires March 19, 2014 [Page 66]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Added more information about the use of PartyUInfo during key agreement. o Use the keydatalen as the SuppPubInfo value for the Concat KDF when doing key agreement, as RFC 2631 does. o Added algorithm identifiers for RSASSA-PSS with SHA-256 and SHA- 512. o Added a Parameter Information Class value to the JSON Web Key Parameters registry, which registers whether the parameter conveys public or private information. -10 o Changed the JWE processing rules for multiple recipients so that a single AAD value contains the header parameters and encrypted key values for all the recipients, enabling AES GCM to be safely used for multiple recipients. -09 o Expanded the scope of the JWK parameters to include private and symmetric key representations, as specified by draft-jones-jose-json-private-and-symmetric-key-00. o Changed term "JWS Secured Input" to "JWS Signing Input". o Changed from using the term "byte" to "octet" when referring to 8 bit values. o Specified that AES Key Wrap uses the default initial value specified in Section 2.2.3.1 of RFC 3394. This addressed issue #19. o Added Key Management Mode definitions to terminology section and used the defined terms to provide clearer key management instructions. This addressed issue #5. o Replaced "A128CBC+HS256" and "A256CBC+HS512" with "A128CBC-HS256" and "A256CBC-HS512". The new algorithms perform the same cryptographic computations as [I-D.mcgrew-aead-aes-cbc-hmac-sha2], but with the Initialization Vector and Authentication Tag values remaining separate from the Ciphertext value in the output representation. Also deleted the header parameters "epu" (encryption PartyUInfo) and "epv" (encryption PartyVInfo), since they are no longer used. Jones Expires March 19, 2014 [Page 67]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Changed from using the term "Integrity Value" to "Authentication Tag". -08 o Changed the name of the JWK key type parameter from "alg" to "kty". o Replaced uses of the term "AEAD" with "Authenticated Encryption", since the term AEAD in the RFC 5116 sense implied the use of a particular data representation, rather than just referring to the class of algorithms that perform authenticated encryption with associated data. o Applied editorial improvements suggested by Jeff Hodges. Many of these simplified the terminology used. o Added seriesInfo information to Internet Draft references. -07 o Added a data length prefix to PartyUInfo and PartyVInfo values. o Changed the name of the JWK RSA modulus parameter from "mod" to "n" and the name of the JWK RSA exponent parameter from "xpo" to "e", so that the identifiers are the same as those used in RFC 3447. o Made several local editorial changes to clean up loose ends left over from to the decision to only support block encryption methods providing integrity. -06 o Removed the "int" and "kdf" parameters and defined the new composite Authenticated Encryption algorithms "A128CBC+HS256" and "A256CBC+HS512" to replace the former uses of AES CBC, which required the use of separate integrity and key derivation functions. o Included additional values in the Concat KDF calculation -- the desired output size and the algorithm value, and optionally PartyUInfo and PartyVInfo values. Added the optional header parameters "apu" (agreement PartyUInfo), "apv" (agreement PartyVInfo), "epu" (encryption PartyUInfo), and "epv" (encryption PartyVInfo). Jones Expires March 19, 2014 [Page 68]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Changed the name of the JWK RSA exponent parameter from "exp" to "xpo" so as to allow the potential use of the name "exp" for a future extension that might define an expiration parameter for keys. (The "exp" name is already used for this purpose in the JWT specification.) o Applied changes made by the RFC Editor to RFC 6749's registry language to this specification. -05 o Support both direct encryption using a shared or agreed upon symmetric key, and the use of a shared or agreed upon symmetric key to key wrap the CMK. Specifically, added the "alg" values "dir", "ECDH-ES+A128KW", and "ECDH-ES+A256KW" to finish filling in this set of capabilities. o Updated open issues. -04 o Added text requiring that any leading zero bytes be retained in base64url encoded key value representations for fixed-length values. o Added this language to Registration Templates: "This name is case sensitive. Names that match other registered names in a case insensitive manner SHOULD NOT be accepted." o Described additional open issues. o Applied editorial suggestions. -03 o Always use a 128 bit "authentication tag" size for AES GCM, regardless of the key size. o Specified that use of a 128 bit IV is REQUIRED with AES CBC. It was previously RECOMMENDED. o Removed key size language for ECDSA algorithms, since the key size is implied by the algorithm being used. o Stated that the "int" key size must be the same as the hash output size (and not larger, as was previously allowed) so that its size is defined for key generation purposes. Jones Expires March 19, 2014 [Page 69]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Added the "kdf" (key derivation function) header parameter to provide crypto agility for key derivation. The default KDF remains the Concat KDF with the SHA-256 digest function. o Clarified that the "mod" and "exp" values are unsigned. o Added Implementation Requirements columns to algorithm tables and Implementation Requirements entries to algorithm registries. o Changed AES Key Wrap to RECOMMENDED. o Moved registries JSON Web Signature and Encryption Header Parameters and JSON Web Signature and Encryption Type Values to the JWS specification. o Moved JSON Web Key Parameters registry to the JWK specification. o Changed registration requirements from RFC Required to Specification Required with Expert Review. o Added Registration Template sections for defined registries. o Added Registry Contents sections to populate registry values. o No longer say "the UTF-8 representation of the JWS Secured Input (which is the same as the ASCII representation)". Just call it "the ASCII representation of the JWS Secured Input". o Added "Collision Resistant Namespace" to the terminology section. o Numerous editorial improvements. -02 o For AES GCM, use the "additional authenticated data" parameter to provide integrity for the header, encrypted key, and ciphertext and use the resulting "authentication tag" value as the JWE Authentication Tag. o Defined minimum required key sizes for algorithms without specified key sizes. o Defined KDF output key sizes. o Specified the use of PKCS #5 padding with AES CBC. o Generalized text to allow key agreement to be employed as an alternative to key wrapping or key encryption. Jones Expires March 19, 2014 [Page 70]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Clarified that ECDH-ES is a key agreement algorithm. o Required implementation of AES-128-KW and AES-256-KW. o Removed the use of "A128GCM" and "A256GCM" for key wrapping. o Removed "A512KW" since it turns out that it's not a standard algorithm. o Clarified the relationship between "typ" header parameter values and MIME types. o Generalized language to refer to Message Authentication Codes (MACs) rather than Hash-based Message Authentication Codes (HMACs) unless in a context specific to HMAC algorithms. o Established registries: JSON Web Signature and Encryption Header Parameters, JSON Web Signature and Encryption Algorithms, JSON Web Signature and Encryption "typ" Values, JSON Web Key Parameters, and JSON Web Key Algorithm Families. o Moved algorithm-specific definitions from JWK to JWA. o Reformatted to give each member definition its own section heading. -01 o Moved definition of "alg":"none" for JWSs here from the JWT specification since this functionality is likely to be useful in more contexts that just for JWTs. o Added Advanced Encryption Standard (AES) Key Wrap Algorithm using 512 bit keys ("A512KW"). o Added text "Alternatively, the Encoded JWS Signature MAY be base64url decoded to produce the JWS Signature and this value can be compared with the computed HMAC value, as this comparison produces the same result as comparing the encoded values". o Corrected the Magic Signatures reference. o Made other editorial improvements suggested by JOSE working group participants. -00 Jones Expires March 19, 2014 [Page 71]
Internet-Draft JSON Web Algorithms (JWA) September 2013 o Created the initial IETF draft based upon draft-jones-json-web-signature-04 and draft-jones-json-web-encryption-02 with no normative changes. o Changed terminology to no longer call both digital signatures and HMACs "signatures". Author's Address Michael B. Jones Microsoft Email: mbj@microsoft.com URI: http://self-issued.info/ Jones Expires March 19, 2014 [Page 72]