JOSE Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track September 15, 2013 Expires: March 19, 2014 JSON Web Key (JWK) draft-ietf-jose-json-web-key-16 Abstract A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data structure that represents a cryptographic key. This specification also defines a JSON Web Key Set (JWK Set) JSON data structure for representing a set of JWKs. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries defined by that specification. 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 Jones Expires March 19, 2014 [Page 1] Internet-Draft JWK September 2013 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. JSON Web Key (JWK) Format . . . . . . . . . . . . . . . . . . 5 3.1. "kty" (Key Type) Parameter . . . . . . . . . . . . . . . . 5 3.2. "use" (Key Use) Parameter . . . . . . . . . . . . . . . . 6 3.3. "alg" (Algorithm) Parameter . . . . . . . . . . . . . . . 6 3.4. "kid" (Key ID) Parameter . . . . . . . . . . . . . . . . . 6 3.5. "x5u" (X.509 URL) Parameter . . . . . . . . . . . . . . . 6 3.6. "x5t" (X.509 Certificate SHA-1 Thumbprint) Parameter . . . 7 3.7. "x5c" (X.509 Certificate Chain) Parameter . . . . . . . . 7 4. JSON Web Key Set (JWK Set) Format . . . . . . . . . . . . . . 7 4.1. "keys" Parameter . . . . . . . . . . . . . . . . . . . . . 8 5. String Comparison Rules . . . . . . . . . . . . . . . . . . . 8 6. Encrypted JWK and Encrypted JWK Set Formats . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7.1. JSON Web Key Parameters Registry . . . . . . . . . . . . . 10 7.1.1. Registration Template . . . . . . . . . . . . . . . . 10 7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 11 7.2. JSON Web Key Use Registry . . . . . . . . . . . . . . . . 11 7.2.1. Registration Template . . . . . . . . . . . . . . . . 12 7.2.2. Initial Registry Contents . . . . . . . . . . . . . . 12 7.3. JSON Web Key Set Parameters Registry . . . . . . . . . . . 12 7.3.1. Registration Template . . . . . . . . . . . . . . . . 12 7.3.2. Initial Registry Contents . . . . . . . . . . . . . . 13 7.4. JSON Web Signature and Encryption Type Values Registration . . . . . . . . . . . . . . . . . . . . . . . 13 7.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 13 7.5. Media Type Registration . . . . . . . . . . . . . . . . . 14 7.5.1. Registry Contents . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . . 17 Appendix A. Example JSON Web Key Sets . . . . . . . . . . . . . . 17 A.1. Example Public Keys . . . . . . . . . . . . . . . . . . . 17 A.2. Example Private Keys . . . . . . . . . . . . . . . . . . . 18 A.3. Example Symmetric Keys . . . . . . . . . . . . . . . . . . 20 Appendix B. Example Use of "x5c" (X.509 Certificate Chain) Parameter . . . . . . . . . . . . . . . . . . . . . . 20 Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 21 Appendix D. Document History . . . . . . . . . . . . . . . . . . 22 Jones Expires March 19, 2014 [Page 2] Internet-Draft JWK September 2013 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 25 Jones Expires March 19, 2014 [Page 3] Internet-Draft JWK September 2013 1. Introduction A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) [RFC4627] data structure that represents a cryptographic key. This specification also defines a JSON Web Key Set (JWK Set) JSON data structure for representing a set of JWKs. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] specification and IANA registries defined by that specification. Goals for this specification do not include representing certificate chains, representing certified keys, and replacing X.509 certificates. JWKs and JWK Sets are used in the JSON Web Signature (JWS) [JWS] and JSON Web Encryption (JWE) [JWE] specifications. 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 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. 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.) Collision Resistant Name A name in a namespace that enables names to be allocated in a manner such that they are highly unlikely to collide with other names. Examples of collision resistant namespaces include: Domain Names, Object Identifiers (OIDs) as Jones Expires March 19, 2014 [Page 4] Internet-Draft JWK September 2013 defined in the ITU-T X.660 and X.670 Recommendation series, and Universally Unique IDentifiers (UUIDs) [RFC4122]. When using an administratively delegated namespace, the definer of a name needs to take reasonable precautions to ensure they are in control of the portion of the namespace they use to define the name. 3. JSON Web Key (JWK) Format A JSON Web Key (JWK) is a JSON object containing specific members, as specified below. Those members that are common to multiple key types are defined below. In addition to the common parameters, each JWK will have members that are specific to the kind of key being represented. These members represent the parameters of the key. Section 5 of the JSON Web Algorithms (JWA) [JWA] specification defines multiple kinds of cryptographic keys and their associated members. The member names within a JWK MUST be unique; recipients MUST either reject JWKs with duplicate member names or use a JSON parser that returns only the lexically last duplicate member name, as specified in Section 15.12 (The JSON Object) of ECMAScript 5.1 [ECMAScript]. Additional members MAY be present in the JWK. If not understood by implementations encountering them, they MUST be ignored. Member names used for representing key parameters for different kinds of keys need not be distinct. Any new member name SHOULD either be registered in the IANA JSON Web Key Parameters registry defined in Section 7.1 or be a value that contains a Collision Resistant Name. 3.1. "kty" (Key Type) Parameter The "kty" (key type) member identifies the cryptographic algorithm family used with the key. "kty" values SHOULD either be registered in the IANA JSON Web Key Types registry defined in [JWA] or be a value that contains a Collision Resistant Name. The "kty" value is a case sensitive string. Use of this member is REQUIRED. A list of defined "kty" values can be found in the IANA JSON Web Key Types registry defined in [JWA]; the initial contents of this registry are the values defined in Section 5.1 of the JSON Web Algorithms (JWA) [JWA] specification. Additional members used with these "kty" values can be found in the IANA JSON Web Key Parameters registry defined in Section 7.1; the initial contents of this registry are the values defined in Sections 5.2 and 5.3 of the JSON Web Algorithms (JWA) [JWA] specification. Jones Expires March 19, 2014 [Page 5] Internet-Draft JWK September 2013 3.2. "use" (Key Use) Parameter The "use" (key use) member identifies the intended use of the key. Values defined by this specification are: o "sig" (signature or MAC operation) o "enc" (encryption) Other values MAY be used. Key Use values can be registered in the IANA JSON Web Key Use registry defined in Section 7.2. The "use" value is a case sensitive string. A "use" member SHOULD be present, unless the application uses another means or convention to determine the intended key usage. When a key is used to wrap another key and a key use designation for the first key is desired, the "enc" (encryption) key use value SHOULD be used, since key wrapping is a kind of encryption. (The "alg" member can be used to specify the particular kind of encryption to be performed, when desired.) 3.3. "alg" (Algorithm) Parameter The "alg" (algorithm) member identifies the algorithm intended for use with the key. The values used SHOULD either be registered in the IANA JSON Web Signature and Encryption Algorithms registry defined in [JWA] or be a value that contains a Collision Resistant Name. Use of this member is OPTIONAL. 3.4. "kid" (Key ID) Parameter The "kid" (key ID) member can be used to match a specific key. This can be used, for instance, to choose among a set of keys within a JWK Set during key rollover. The interpretation of the "kid" value is unspecified. When "kid" values are used within a JWK Set, different keys within the JWK Set SHOULD use distinct "kid" values. The "kid" value is a case sensitive string. Use of this member is OPTIONAL. When used with JWS or JWE, the "kid" value can be used to match a JWS or JWE "kid" header parameter value. 3.5. "x5u" (X.509 URL) Parameter The "x5u" (X.509 URL) member is a URI [RFC3986] that refers to a resource for an X.509 public key certificate or certificate chain [RFC5280]. The identified resource MUST provide a representation of the certificate or certificate chain that conforms to RFC 5280 [RFC5280] in PEM encoded form [RFC1421]. The key in the first Jones Expires March 19, 2014 [Page 6] Internet-Draft JWK September 2013 certificate MUST match the bare public key represented by other members of the JWK. The protocol used to acquire the resource MUST provide integrity protection; an HTTP GET request to retrieve the certificate MUST use TLS [RFC2818] [RFC5246]; the identity of the server MUST be validated, as per Section 3.1 of HTTP Over TLS [RFC2818]. Use of this member is OPTIONAL. 3.6. "x5t" (X.509 Certificate SHA-1 Thumbprint) Parameter The "x5t" (X.509 Certificate SHA-1 Thumbprint) member is a base64url encoded SHA-1 thumbprint (a.k.a. digest) of the DER encoding of an X.509 certificate [RFC5280]. The key in the certificate MUST match the bare public key represented by other members of the JWK. Use of this member is OPTIONAL. If, in the future, certificate thumbprints need to be computed using hash functions other than SHA-1, it is suggested that additional related JWK parameters be defined for that purpose. For example, it is suggested that a new "x5t#S256" (X.509 Certificate Thumbprint using SHA-256) JWK parameter could be defined by registering it in the IANA JSON Web Key Parameters registry defined in Section 7.1. 3.7. "x5c" (X.509 Certificate Chain) Parameter The "x5c" (X.509 Certificate Chain) member contains a chain of one or more PKIX certificates [RFC5280]. The certificate chain is represented as a JSON array of certificate value strings. Each string in the array is a base64 encoded ([RFC4648] Section 4 -- not base64url encoded) DER [ITU.X690.1994] PKIX certificate value. The PKIX certificate containing the key value MUST be the first certificate. This MAY be followed by additional certificates, with each subsequent certificate being the one used to certify the previous one. The key in the first certificate MUST match the bare public key represented by other members of the JWK. Use of this member is OPTIONAL. 4. JSON Web Key Set (JWK Set) Format A JSON Web Key Set (JWK Set) is a JSON object that contains an array of JWK values as the value of its "keys" member. The member names within a JWK Set MUST be unique; recipients MUST either reject JWK Sets with duplicate member names or use a JSON parser that returns only the lexically last duplicate member name, as specified in Section 15.12 (The JSON Object) of ECMAScript 5.1 [ECMAScript]. Jones Expires March 19, 2014 [Page 7] Internet-Draft JWK September 2013 Additional members MAY be present in the JWK Set. If not understood by implementations encountering them, they MUST be ignored. Parameters for representing additional properties of JWK Sets SHOULD either be registered in the IANA JSON Web Key Set Parameters registry defined in Section 7.3 or be a value that contains a Collision Resistant Name. Implementations SHOULD ignore JWKs within a JWK Set that use "kty" (key type) values that are not understood by them. 4.1. "keys" Parameter The value of the "keys" member is an array of JWK values. By default, the order of the JWK values within the array does not imply an order of preference among them, although applications of JWK Sets can choose to assign a meaning to the order for their purposes, if desired. Use of this member is REQUIRED. 5. String Comparison Rules Processing a JWK inevitably requires comparing known strings to values in JSON objects. For example, in checking what the key type is, the Unicode string encoding "kty" will be checked against the member names in the JWK to see if there is a matching name. Comparisons between JSON strings and other Unicode strings MUST be performed by comparing Unicode code points without normalization as specified in the String Comparison Rules in Section 5.3 of [JWS]. 6. Encrypted JWK and Encrypted JWK Set Formats JWKs containing non-public key material will need to be encrypted in some contexts to prevent the disclosure of private or symmetric key values to unintended parties. The use of an Encrypted JWK, which is a JWE with a JWK as its plaintext value, is RECOMMENED for this purpose. The processing of Encrypted JWKs is identical to the processing of other JWEs. A "cty" (content type) header parameter value of "JWK" MUST be used to indicate that the content of the JWE is a JWK, unless the application knows that the encrypted content is a JWK by another means or convention. JWK Sets containing non-public key material will similarly need to be encrypted. The use of an Encrypted JWK Set, which is a JWE with a JWK Set as its plaintext value, is RECOMMENED for this purpose. The processing of Encrypted JWK Sets is identical to the processing of other JWEs. A "cty" (content type) header parameter value of Jones Expires March 19, 2014 [Page 8] Internet-Draft JWK September 2013 "JWK-SET" MUST be used to indicate that the content of the JWE is a JWK Set, unless the application knows that the encrypted content is a JWK Set by another means or convention. 7. IANA Considerations The following registration procedure is used for all the registries established by this specification. Values are registered with a Specification Required [RFC5226] after a two-week review period on the [TBD]@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of values prior to publication, the Designated Expert(s) may approve registration once they are satisfied that such a specification will be published. Registration requests must be sent to the [TBD]@ietf.org mailing list for review and comment, with an appropriate subject (e.g., "Request for access token type: example"). [[ Note to 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). Jones Expires March 19, 2014 [Page 9] Internet-Draft JWK September 2013 7.1. JSON Web Key Parameters Registry This specification establishes the IANA JSON Web Key Parameters registry for JWK parameter names. The registry records the parameter name, the key type(s) that the parameter is used with, and a reference to the specification that defines it. It also records whether the parameter conveys public or private information. This specification registers the parameter names defined in Section 3. The same JWK parameter name may be registered multiple times, provided that duplicate parameter registrations are only for key type specific JWK parameters; in this case, the meaning of the duplicate parameter name is disambiguated by the "kty" value of the JWK containing it. 7.1.1. Registration Template Parameter 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 case insensitive manner unless the Designated Expert(s) state that there is a compelling reason to allow an exception in this particular case. Used with "kty" Value(s): The key type parameter value(s) that the parameter name is to be used with, or the value "*" if the parameter value is used with all key types. Parameter Information Class: Registers whether the parameter conveys public or private information. Its value must be one the words Public or Private. 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 10] Internet-Draft JWK September 2013 7.1.2. Initial Registry Contents o Parameter Name: "kty" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.1 of [[ this document ]] o Parameter Name: "use" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.2 of [[ this document ]] o Parameter Name: "alg" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.3 of [[ this document ]] o Parameter Name: "kid" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.4 of [[ this document ]] o Parameter Name: "x5u" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.5 of [[ this document ]] o Parameter Name: "x5t" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.6 of [[ this document ]] o Parameter Name: "x5c" o Used with "kty" Value(s): * o Parameter Information Class: Public o Change Controller: IESG o Specification Document(s): Section 3.7 of [[ this document ]] 7.2. JSON Web Key Use Registry This specification establishes the IANA JSON Web Key Use registry for JWK "use" member values. The registry records the key use value and Jones Expires March 19, 2014 [Page 11] Internet-Draft JWK September 2013 a reference to the specification that defines it. This specification registers the parameter names defined in Section 3.2. 7.2.1. Registration Template Use Member 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. 7.2.2. Initial Registry Contents o Use Member Value: "sig" o Change Controller: IESG o Specification Document(s): Section 3.2 of [[ this document ]] o Use Member Value: "enc" o Change Controller: IESG o Specification Document(s): Section 3.2 of [[ this document ]] 7.3. JSON Web Key Set Parameters Registry This specification establishes the IANA JSON Web Key Set Parameters registry for JWK Set parameter names. The registry records the parameter name and a reference to the specification that defines it. This specification registers the parameter names defined in Section 4. 7.3.1. Registration Template Jones Expires March 19, 2014 [Page 12] Internet-Draft JWK September 2013 Parameter 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 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. 7.3.2. Initial Registry Contents o Parameter Name: "keys" o Change Controller: IESG o Specification Document(s): Section 4.1 of [[ this document ]] 7.4. JSON Web Signature and Encryption Type Values Registration 7.4.1. Registry Contents This specification registers the "JWK" and "JWK-SET" type values in the IANA JSON Web Signature and Encryption Type Values registry defined in [JWS], which can be used to indicate, respectively, that the content is a JWK or a JWK Set. o "typ" Header Parameter Value: "JWK" o Abbreviation for MIME Type: application/jwk+json o Change Controller: IESG o Specification Document(s): Section 3 of [[ this document ]] o "typ" Header Parameter Value: "JWK-SET" o Abbreviation for MIME Type: application/jwk-set+json o Change Controller: IESG o Specification Document(s): Section 4 of [[ this document ]] Jones Expires March 19, 2014 [Page 13] Internet-Draft JWK September 2013 7.5. Media Type Registration 7.5.1. Registry Contents This specification registers the "application/jwk+json" and "application/jwk-set+json" Media Types [RFC2046] in the MIME Media Types registry [IANA.MediaTypes], which can be used to indicate, respectively, that the content is a JWK or a JWK Set. o Type Name: application o Subtype Name: jwk+json o Required Parameters: n/a o Optional Parameters: n/a o Encoding considerations: 8bit; application/jwk+json values are represented as JSON object; UTF-8 encoding SHOULD be employed for the JSON object. o Security Considerations: See the Security Considerations section of [[ this document ]] o Interoperability Considerations: n/a o Published Specification: [[ this document ]] o Applications that use this media type: TBD o Additional Information: Magic number(s): n/a, File extension(s): n/a, Macintosh file type code(s): n/a o Person & email address to contact for further information: Michael B. Jones, mbj@microsoft.com o Intended Usage: COMMON o Restrictions on Usage: none o Author: Michael B. Jones, mbj@microsoft.com o Change Controller: IESG o Type Name: application o Subtype Name: jwk-set+json o Required Parameters: n/a o Optional Parameters: n/a o Encoding considerations: 8bit; application/jwk-set+json values are represented as a JSON Object; UTF-8 encoding SHOULD be employed for the JSON object. o Security Considerations: See the Security Considerations section of [[ this document ]] o Interoperability Considerations: n/a o Published Specification: [[ this document ]] o Applications that use this media type: TBD o Additional Information: Magic number(s): n/a, File extension(s): n/a, Macintosh file type code(s): n/a o Person & email address to contact for further information: Michael B. Jones, mbj@microsoft.com Jones Expires March 19, 2014 [Page 14] Internet-Draft JWK September 2013 o Intended Usage: COMMON o Restrictions on Usage: none o Author: Michael B. Jones, mbj@microsoft.com o Change Controller: IESG 8. 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 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. A key is no more trustworthy than the method by which it was received. Private and symmetric keys MUST be protected from disclosure to unintended parties. One recommended means of doing so is to encrypt JWKs or JWK Sets containing them by using the JWK or JWK Set value as the plaintext of a JWE. The security considerations in RFC 3447 [RFC3447] and RFC 6030 [RFC6030] about protecting private and symmetric keys also apply to this specification. The security considerations in XML DSIG 2.0 [W3C.CR-xmldsig-core2-20120124], about key representations also apply to this specification, other than those that are XML specific. The TLS Requirements in [JWS] also apply to this specification. 9. References 9.1. Normative References [ECMAScript] Ecma International, "ECMAScript Language Specification, 5.1 Edition", ECMA 262, June 2011. [IANA.MediaTypes] Internet Assigned Numbers Authority (IANA), "MIME Media Types", 2005. [ITU.X690.1994] Jones Expires March 19, 2014 [Page 15] Internet-Draft JWK September 2013 International Telecommunications Union, "Information Technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)", ITU-T Recommendation X.690, 1994. [JWA] Jones, M., "JSON Web Algorithms (JWA)", draft-ietf-jose-json-web-algorithms (work in progress), September 2013. [JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web Encryption (JWE)", draft-ietf-jose-json-web-encryption (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. [RFC1421] Linn, J., "Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures", RFC 1421, February 1993. [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 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. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008. Jones Expires March 19, 2014 [Page 16] Internet-Draft JWK September 2013 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, May 2008. [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, . 9.2. Informative References [MagicSignatures] Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic Signatures", January 2011. [RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1", RFC 3447, February 2003. [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005. [RFC6030] Hoyer, P., Pei, M., and S. Machani, "Portable Symmetric Key Container (PSKC)", RFC 6030, October 2010. Appendix A. Example JSON Web Key Sets A.1. Example Public Keys The following example JWK Set contains two public keys represented as JWKs: one using an Elliptic Curve algorithm and a second one using an RSA algorithm. The first specifies that the key is to be used for encryption. The second specifies that the key is to be used with the "RS256" algorithm. Both provide a Key ID for key matching purposes. In both cases, integers are represented using the base64url encoding of their big endian representations. (Long lines are broken are for display purposes only.) Jones Expires March 19, 2014 [Page 17] Internet-Draft JWK September 2013 {"keys": [ {"kty":"EC", "crv":"P-256", "x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4", "y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM", "use":"enc", "kid":"1"}, {"kty":"RSA", "n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx 4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs tn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2 QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI SD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqb w0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw", "e":"AQAB", "alg":"RS256", "kid":"2011-04-29"} ] } A.2. Example Private Keys The following example JWK Set contains two keys represented as JWKs containing both public and private key values: one using an Elliptic Curve algorithm and a second one using an RSA algorithm. This example extends the example in the previous section, adding private key values. (Line breaks are for display purposes only.) Jones Expires March 19, 2014 [Page 18] Internet-Draft JWK September 2013 {"keys": [ {"kty":"EC", "crv":"P-256", "x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4", "y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM", "d":"870MB6gfuTJ4HtUnUvYMyJpr5eUZNP4Bk43bVdj3eAE", "use":"enc", "kid":"1"}, {"kty":"RSA", "n":"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4 cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMst n64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2Q vzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbIS D08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw 0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw", "e":"AQAB", "d":"X4cTteJY_gn4FYPsXB8rdXix5vwsg1FLN5E3EaG6RJoVH-HLLKD9 M7dx5oo7GURknchnrRweUkC7hT5fJLM0WbFAKNLWY2vv7B6NqXSzUvxT0_YSfqij wp3RTzlBaCxWp4doFk5N2o8Gy_nHNKroADIkJ46pRUohsXywbReAdYaMwFs9tv8d _cPVY3i07a3t8MN6TNwm0dSawm9v47UiCl3Sk5ZiG7xojPLu4sbg1U2jx4IBTNBz nbJSzFHK66jT8bgkuqsk0GjskDJk19Z4qwjwbsnn4j2WBii3RL-Us2lGVkY8fkFz me1z0HbIkfz0Y6mqnOYtqc0X4jfcKoAC8Q", "p":"83i-7IvMGXoMXCskv73TKr8637FiO7Z27zv8oj6pbWUQyLPQBQxtPV nwD20R-60eTDmD2ujnMt5PoqMrm8RfmNhVWDtjjMmCMjOpSXicFHj7XOuVIYQyqV WlWEh6dN36GVZYk93N8Bc9vY41xy8B9RzzOGVQzXvNEvn7O0nVbfs", "q":"3dfOR9cuYq-0S-mkFLzgItgMEfFzB2q3hWehMuG0oCuqnb3vobLyum qjVZQO1dIrdwgTnCdpYzBcOfW5r370AFXjiWft_NGEiovonizhKpo9VVS78TzFgx kIdrecRezsZ-1kYd_s1qDbxtkDEgfAITAG9LUnADun4vIcb6yelxk", "dp":"G4sPXkc6Ya9y8oJW9_ILj4xuppu0lzi_H7VTkS8xj5SdX3coE0oim YwxIi2emTAue0UOa5dpgFGyBJ4c8tQ2VF402XRugKDTP8akYhFo5tAA77Qe_Nmtu YZc3C3m3I24G2GvR5sSDxUyAN2zq8Lfn9EUms6rY3Ob8YeiKkTiBj0", "dq":"s9lAH9fggBsoFR8Oac2R_E2gw282rT2kGOAhvIllETE1efrA6huUU vMfBcMpn8lqeW6vzznYY5SSQF7pMdC_agI3nG8Ibp1BUb0JUiraRNqUfLhcQb_d9 GF4Dh7e74WbRsobRonujTYN1xCaP6TO61jvWrX-L18txXw494Q_cgk", "qi":"GyM_p6JrXySiz1toFgKbWV-JdI3jQ4ypu9rbMWx3rQJBfmt0FoYzg UIZEVFEcOqwemRN81zoDAaa-Bk0KWNGDjJHZDdDmFhW3AN7lI-puxk_mHZGJ11rx yR8O55XLSe3SPmRfKwZI6yU24ZxvQKFYItdldUKGzO6Ia6zTKhAVRU", "alg":"RS256", "kid":"2011-04-29"} ] } Jones Expires March 19, 2014 [Page 19] Internet-Draft JWK September 2013 A.3. Example Symmetric Keys The following example JWK Set contains two symmetric keys represented as JWKs: one designated as being for use with the AES Key Wrap algorithm and a second one that is an HMAC key. (Line breaks are for display purposes only.) {"keys": [ {"kty":"oct", "alg":"A128KW", "k":"GawgguFyGrWKav7AX4VKUg"}, {"kty":"oct", "k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75 aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow", "kid":"HMAC key used in JWS A.1 example"} ] } Appendix B. Example Use of "x5c" (X.509 Certificate Chain) Parameter Jones Expires March 19, 2014 [Page 20] Internet-Draft JWK September 2013 The following is an example of a JWK with a RSA signing key represented both as a bare public key and as an X.509 certificate using the "x5c" parameter: {"kty":"RSA", "use":"sig", "kid":"1b94c", "n":"vrjOfz9Ccdgx5nQudyhdoR17V-IubWMeOZCwX_jj0hgAsz2J_pqYW08 PLbK_PdiVGKPrqzmDIsLI7sA25VEnHU1uCLNwBuUiCO11_-7dYbsr4iJmG0Q u2j8DsVyT1azpJC_NG84Ty5KKthuCaPod7iI7w0LK9orSMhBEwwZDCxTWq4a YWAchc8t-emd9qOvWtVMDC2BXksRngh6X5bUYLy6AyHKvj-nUy1wgzjYQDwH MTplCoLtU-o-8SNnZ1tmRoGE9uJkBLdh5gFENabWnU5m1ZqZPdwS-qo-meMv VfJb6jJVWRpl2SUtCnYG2C32qvbWbjZ_jBPD5eunqsIo1vQ", "e":"AQAB", "x5c": ["MIIDQjCCAiqgAwIBAgIGATz/FuLiMA0GCSqGSIb3DQEBBQUAMGIxCzAJB gNVBAYTAlVTMQswCQYDVQQIEwJDTzEPMA0GA1UEBxMGRGVudmVyMRwwGgYD VQQKExNQaW5nIElkZW50aXR5IENvcnAuMRcwFQYDVQQDEw5CcmlhbiBDYW1 wYmVsbDAeFw0xMzAyMjEyMzI5MTVaFw0xODA4MTQyMjI5MTVaMGIxCzAJBg NVBAYTAlVTMQswCQYDVQQIEwJDTzEPMA0GA1UEBxMGRGVudmVyMRwwGgYDV QQKExNQaW5nIElkZW50aXR5IENvcnAuMRcwFQYDVQQDEw5CcmlhbiBDYW1w YmVsbDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAL64zn8/QnH YMeZ0LncoXaEde1fiLm1jHjmQsF/449IYALM9if6amFtPDy2yvz3YlRij66 s5gyLCyO7ANuVRJx1NbgizcAblIgjtdf/u3WG7K+IiZhtELto/A7Fck9Ws6 SQvzRvOE8uSirYbgmj6He4iO8NCyvaK0jIQRMMGQwsU1quGmFgHIXPLfnpn fajr1rVTAwtgV5LEZ4Iel+W1GC8ugMhyr4/p1MtcIM42EA8BzE6ZQqC7VPq PvEjZ2dbZkaBhPbiZAS3YeYBRDWm1p1OZtWamT3cEvqqPpnjL1XyW+oyVVk aZdklLQp2Btgt9qr21m42f4wTw+Xrp6rCKNb0CAwEAATANBgkqhkiG9w0BA QUFAAOCAQEAh8zGlfSlcI0o3rYDPBB07aXNswb4ECNIKG0CETTUxmXl9KUL +9gGlqCz5iWLOgWsnrcKcY0vXPG9J1r9AqBNTqNgHq2G03X09266X5CpOe1 zFo+Owb1zxtp3PehFdfQJ610CDLEaS9V9Rqp17hCyybEpOGVwe8fnk+fbEL 2Bo3UPGrpsHzUoaGpDftmWssZkhpBJKVMJyf/RuP2SmmaIzmnw9JiSlYhzo 4tpzd5rFXhjRbg4zW9C+2qok+2+qDM1iJ684gPHMIY8aLWrdgQTxkumGmTq gawR+N5MDtdPTEQ0XfIBc2cJEUyMTY5MPvACWpkA6SdS4xSvdXK3IVfOWA=="] } Appendix C. Acknowledgements A JSON representation for RSA public keys was previously introduced by John Panzer, Ben Laurie, and Dirk Balfanz in Magic Signatures [MagicSignatures]. 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: Jones Expires March 19, 2014 [Page 21] Internet-Draft JWK September 2013 Dirk Balfanz, Richard Barnes, John Bradley, Brian Campbell, Breno de Medeiros, Joe Hildebrand, Edmund Jay, Ben Laurie, James Manger, Matt Miller, Tony Nadalin, Axel Nennker, John Panzer, Eric Rescorla, Nat Sakimura, Jim Schaad, Paul Tarjan, 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 D. Document History [[ to be removed by the RFC Editor before publication as an RFC ]] -16 o Changes to address editorial and minor issues #41, #42, #43, #47, #51, #67, #71, #76, #80, #83, #84, #85, #86, #87, and #88. -15 o Changes to address editorial issues #48, #64, #65, #66, and #91. -14 o Relaxed language introducing key parameters since some parameters are applicable to multiple, but not all, key types. -13 o Applied spelling and grammar corrections. -12 o Stated that recipients MUST either reject JWKs and JWK Sets with duplicate member names or use a JSON parser that returns only the lexically last duplicate member name. -11 o Stated that when "kid" values are used within a JWK Set, different keys within the JWK Set SHOULD use distinct "kid" values. o Added optional "x5u" (X.509 URL), "x5t" (X.509 Certificate Thumbprint), and "x5c" (X.509 Certificate Chain) JWK parameters. Jones Expires March 19, 2014 [Page 22] Internet-Draft JWK September 2013 o Added section on Encrypted JWK and Encrypted JWK Set Formats. o Added a Parameter Information Class value to the JSON Web Key Parameters registry, which registers whether the parameter conveys public or private information. o Registered "application/jwk+json" and "application/jwk-set+json" MIME types and "JWK" and "JWK-SET" typ header parameter values, addressing issue #21. -10 o No changes were made, other than to the version number and date. -09 o Expanded the scope of the JWK specification to include private and symmetric key representations, as specified by draft-jones-jose-json-private-and-symmetric-key-00. o Defined that members that are not understood must be ignored. -08 o Changed the name of the JWK key type parameter from "alg" to "kty" to enable use of "alg" to indicate the particular algorithm that the key is intended to be used with. o Clarified statements of the form "This member is OPTIONAL" to "Use of this member is OPTIONAL". o Referenced String Comparison Rules in JWS. o Added seriesInfo information to Internet Draft references. -07 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. -06 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 Jones Expires March 19, 2014 [Page 23] Internet-Draft JWK September 2013 specification.) o Clarify that the "alg" (algorithm family) member is REQUIRED. o Correct an instance of "JWK" that should have been "JWK Set". o Applied changes made by the RFC Editor to RFC 6749's registry language to this specification. -05 o Indented artwork elements to better distinguish them from the body text. -04 o Refer to the registries as the primary sources of defined values and then secondarily reference the sections defining the initial contents of the registries. o Normatively reference XML DSIG 2.0 [W3C.CR-xmldsig-core2-20120124] for its security considerations. 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 Clarified that "kid" values need not be unique within a JWK Set. o Moved JSON Web Key Parameters registry to the JWK specification. o Added "Collision Resistant Namespace" to the terminology section. 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 Numerous editorial improvements. Jones Expires March 19, 2014 [Page 24] Internet-Draft JWK September 2013 -02 o Simplified JWK terminology to get replace the "JWK Key Object" and "JWK Container Object" terms with simply "JSON Web Key (JWK)" and "JSON Web Key Set (JWK Set)" and to eliminate potential confusion between single keys and sets of keys. As part of this change, the top-level member name for a set of keys was changed from "jwk" to "keys". o Clarified that values with duplicate member names MUST be rejected. o Established JSON Web Key Set Parameters registry. o Explicitly listed non-goals in the introduction. o Moved algorithm-specific definitions from JWK to JWA. o Reformatted to give each member definition its own section heading. -01 o Corrected the Magic Signatures reference. -00 o Created the initial IETF draft based upon draft-jones-json-web-key-03 with no normative changes. Author's Address Michael B. Jones Microsoft Email: mbj@microsoft.com URI: http://self-issued.info/ Jones Expires March 19, 2014 [Page 25]