| JOSE Working Group | M.B. Jones |
| Internet-Draft | Microsoft |
| Intended status: Standards Track | J. Bradley |
| Expires: July 24, 2014 | Ping Identity |
| N. Sakimura | |
| NRI | |
| January 20, 2014 |
JSON Web Signature (JWS)
draft-ietf-jose-json-web-signature-20
JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JavaScript Object Notation (JSON) based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification.
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JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JavaScript Object Notation (JSON) [I-D.ietf-json-rfc4627bis] based data structures. The JWS cryptographic mechanisms provide integrity protection for an arbitrary sequence of octets.
Two closely related serializations for JWS objects are defined. The JWS Compact Serialization is a compact, URL-safe representation intended for space constrained environments such as HTTP Authorization headers and URI query parameters. The JWS JSON Serialization represents JWS objects as JSON objects and enables multiple signatures and/or MACs to be applied to the same content. Both share the same cryptographic underpinnings.
Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) [JWE] specification.
Names defined by this specification are short because a core goal is for the resulting representations to be compact.
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.
BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per Section 2.
UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] representation of STRING.
ASCII(STRING) denotes the octets of the ASCII [USASCII] representation of STRING.
The concatenation of two values A and B is denoted as A || B.
JWS represents digitally signed or MACed content using JSON data structures and base64url encoding. A JWS represents these logical values:
The JWS Header represents the combination of these values:
This document defines two serializations for JWS objects: a compact, URL-safe serialization called the JWS Compact Serialization and a JSON serialization called the JWS JSON Serialization. In both serializations, the JWS Protected Header, JWS Payload, and JWS Signature are base64url encoded for transmission, since JSON lacks a way to directly represent octet sequences.
In the JWS Compact Serialization, no JWS Unprotected Header is used. In this case, the JWS Header and the JWS Protected Header are the same.
In the JWS Compact Serialization, a JWS object is represented as the combination of these three string values,
In the JWS JSON Serialization, one or both of the JWS Protected Header and JWS Unprotected Header MUST be present. In this case, the members of the JWS Header are the combination of the members of the JWS Protected Header and the JWS Unprotected Header values that are present.
In the JWS JSON Serialization, a JWS object is represented as the combination of these four values, Section 7.2 for more information about the JWS JSON Serialization.
with the three base64url encoding result strings and the JWS Unprotected Header value being represented as members within a JSON object. The inclusion of some of these values is OPTIONAL. The JWS JSON Serialization can also represent multiple signature and/or MAC values, rather than just one. See
This section provides an example of a JWS. Its computation is described in more detail in Appendix A.1, including specifying the exact octet sequences representing the JSON values used and the key value used.
The following example JWS Protected Header declares that the encoded object is a JSON Web Token (JWT) [JWT] and the JWS Protected Header and the JWS Payload are secured using the HMAC SHA-256 algorithm:
{"typ":"JWT",
"alg":"HS256"}
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
The UTF-8 representation of following JSON object is used as the JWS Payload. (Note that the payload can be any content, and need not be a representation of a JSON object.)
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Encoding this JWS Payload as BASE64URL(JWS Payload) gives this value (with line breaks for display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
Computing the HMAC of the JWS Signing Input ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)) with the HMAC SHA-256 algorithm using the key specified in Appendix A.1 and base64url encoding the result yields this BASE64URL(JWS Signature) value:
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
Concatenating these values in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS representation using the JWS Compact Serialization (with line breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ . dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
See Appendix A for additional examples.
The members of the JSON object(s) representing the JWS Header describe the digital signature or MAC applied to the JWS Protected Header and the JWS Payload and optionally additional properties of the JWS. The Header Parameter names within the JWS Header MUST be unique; recipients MUST either reject JWSs with duplicate Header Parameter 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].
Implementations are required to understand the specific Header Parameters defined by this specification that are designated as "MUST be understood" and process them in the manner defined in this specification. All other Header Parameters defined by this specification that are not so designated MUST be ignored when not understood. Unless listed as a critical Header Parameter, per Section 4.1.10, all Header Parameters not defined by this specification MUST be ignored when not understood.
There are three classes of Header Parameter names: Registered Header Parameter names, Public Header Parameter names, and Private Header Parameter names.
The following Header Parameter names are registered in the IANA JSON Web Signature and Encryption Header Parameters registry defined in Section 9.1, with meanings as defined below.
As indicated by the common registry, JWSs and JWEs share a common Header Parameter space; when a parameter is used by both specifications, its usage must be compatible between the specifications.
The alg (algorithm) Header Parameter identifies the cryptographic algorithm used to secure the JWS. The signature, MAC, or plaintext value is not valid if the alg value does not represent a supported algorithm, or if there is not a key for use with that algorithm associated with the party that digitally signed or MACed the content. alg values 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. The alg value is a case-sensitive string containing a StringOrURI value. This Header Parameter MUST be present and MUST be understood and processed by implementations.
A list of defined alg values for this use can be found in the IANA JSON Web Signature and Encryption Algorithms registry defined in [JWA]; the initial contents of this registry are the values defined in Section 3.1 of the JSON Web Algorithms (JWA) [JWA] specification.
The jku (JWK Set URL) Header Parameter is a URI [RFC3986] that refers to a resource for a set of JSON-encoded public keys, one of which corresponds to the key used to digitally sign the JWS. The keys MUST be encoded as a JSON Web Key Set (JWK Set) [JWK]. The protocol used to acquire the resource MUST provide integrity protection; an HTTP GET request to retrieve the JWK Set 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 Header Parameter is OPTIONAL.
The jwk (JSON Web Key) Header Parameter is the public key that corresponds to the key used to digitally sign the JWS. This key is represented as a JSON Web Key [JWK]. Use of this Header Parameter is OPTIONAL.
The kid (key ID) Header Parameter is a hint indicating which key was used to secure the JWS. This parameter allows originators to explicitly signal a change of key to recipients. The structure of the kid value is unspecified. Its value MUST be a string. Use of this Header Parameter is OPTIONAL.
When used with a JWK, the kid value is used to match a JWK kid parameter value.
The x5u (X.509 URL) Header Parameter is a URI [RFC3986] that refers to a resource for the X.509 public key certificate or certificate chain [RFC5280] corresponding to the key used to digitally sign the JWS. 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 certificate containing the public key corresponding to the key used to digitally sign the JWS 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 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 Header Parameter is OPTIONAL.
The x5c (X.509 Certificate Chain) Header Parameter contains the X.509 public key certificate or certificate chain [RFC5280] corresponding to the key used to digitally sign the JWS. The certificate or 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 certificate containing the public key corresponding to the key used to digitally sign the JWS 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 recipient MUST validate the certificate chain according to [RFC5280] and reject the signature if any validation failure occurs. Use of this Header Parameter is OPTIONAL.
See Appendix B for an example x5c value.
The x5t (X.509 Certificate SHA-1 Thumbprint) Header Parameter is a base64url encoded SHA-1 thumbprint (a.k.a. digest) of the DER encoding of the X.509 certificate [RFC5280] corresponding to the key used to digitally sign the JWS. Use of this Header Parameter 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 Header Parameters be defined for that purpose. For example, it is suggested that a new x5t#S256 (X.509 Certificate Thumbprint using SHA-256) Header Parameter could be defined by registering it in the IANA JSON Web Signature and Encryption Header Parameters registry defined in Section 9.1.
The typ (type) Header Parameter is used to declare the MIME Media Type [IANA.MediaTypes] of this complete JWS object in contexts where this is useful to the application. This parameter has no effect upon the JWS processing. Use of this Header Parameter is OPTIONAL.
Per [RFC2045], all media type values, subtype values, and parameter names are case-insensitive. However, parameter values are case-sensitive unless otherwise specified for the specific parameter.
To keep messages compact in common situations, it is RECOMMENDED that senders omit an "application/" prefix of a media type value in a typ Header Parameter when no other '/' appears in the media type value. A recipient using the media type value MUST treat it as if "application/" were prepended to any typ value not containing a '/'. For instance, a typ value of example SHOULD be used to represent the application/example media type; whereas, the media type application/example;part="1/2" cannot be shortened to example;part="1/2".
The typ value JOSE can be used by applications to indicate that this object is a JWS or JWE using the JWS Compact Serialization or the JWE Compact Serialization. The typ value JOSE+JSON can be used by applications to indicate that this object is a JWS or JWE using the JWS JSON Serialization or the JWE JSON Serialization. Other type values can also be used by applications.
The cty (content type) Header Parameter is used to declare the MIME Media Type [IANA.MediaTypes] of the secured content (the payload) in contexts where this is useful to the application. This parameter has no effect upon the JWS processing. Use of this Header Parameter is OPTIONAL.
Per [RFC2045], all media type values, subtype values, and parameter names are case-insensitive. However, parameter values are case-sensitive unless otherwise specified for the specific parameter.
To keep messages compact in common situations, it is RECOMMENDED that senders omit an "application/" prefix of a media type value in a cty Header Parameter when no other '/' appears in the media type value. A recipient using the media type value MUST treat it as if "application/" were prepended to any cty value not containing a '/'. For instance, a cty value of example SHOULD be used to represent the application/example media type; whereas, the media type application/example;part="1/2" cannot be shortened to example;part="1/2".
The crit (critical) Header Parameter indicates that extensions to the initial RFC versions of [[ this specification ]] and [JWA] are being used that MUST be understood and processed. Its value is an array listing the Header Parameter names present in the JWS Header that use those extensions. If any of the listed extension Header Parameters are not understood and supported by the receiver, it MUST reject the JWS. Senders must not include Header Parameter names defined by the initial RFC versions of [[ this specification ]] or [JWA] for use with JWS, duplicate names, or names that do not occur as Header Parameter names within the JWS Header in the crit list. Senders MUST not use the empty list [] as the crit value. Recipients MAY reject the JWS if the critical list contains any Header Parameter names defined by the initial RFC versions of [[ this specification ]] or [JWA] for use with JWS, or any other constraints on its use are violated. This Header Parameter MUST be integrity protected, and therefore MUST occur only within the JWS Protected Header, when used. Use of this Header Parameter is OPTIONAL. This Header Parameter MUST be understood and processed by implementations.
An example use, along with a hypothetical exp (expiration-time) field is:
{"alg":"ES256",
"crit":["exp"],
"exp":1363284000
}
Additional Header Parameter names can be defined by those using JWSs. However, in order to prevent collisions, any new Header Parameter name should either be registered in the IANA JSON Web Signature and Encryption Header Parameters registry defined in Section 9.1 or be a Public Name: a value that contains a Collision-Resistant Name. In each case, the definer of the name or value needs to take reasonable precautions to make sure they are in control of the part of the namespace they use to define the Header Parameter name.
New Header Parameters should be introduced sparingly, as they can result in non-interoperable JWSs.
A producer and consumer of a JWS may agree to use Header Parameter names that are Private Names: names that are not Registered Header Parameter names Section 4.1 or Public Header Parameter names Section 4.2. Unlike Public Header Parameter names, Private Header Parameter names are subject to collision and should be used with caution.
To create a JWS, one MUST perform these steps. The order of the steps is not significant in cases where there are no dependencies between the inputs and outputs of the steps.
When validating a JWS, the following steps MUST be taken. The order of the steps is not significant in cases where there are no dependencies between the inputs and outputs of the steps. If any of the listed steps fails, then the signature or MAC cannot be validated.
It is an application decision which signatures, MACs, or plaintext values must successfully validate for the JWS to be accepted. In some cases, all must successfully validate or the JWS will be rejected. In other cases, only a specific signature, MAC, or plaintext value needs to be successfully validated. However, in all cases, at least one signature, MAC, or plaintext value MUST successfully validate or the JWS MUST be rejected.
Processing a JWS inevitably requires comparing known strings to members and values in a JSON object. For example, in checking what the algorithm is, the Unicode string alg will be checked against the member names in the JWS Header to see if there is a matching Header Parameter name. The same process is then used to determine if the value of the alg Header Parameter represents a supported algorithm.
Since the only string comparison operations that are performed are equality and inequality, the same rules can be used for comparing both member names and member values against known strings. The JSON rules for doing member name comparison are described in Section 8.3 of [I-D.ietf-json-rfc4627bis].
Also, see the JSON security considerations in Section 10.2 and the Unicode security considerations in Section 10.3.
It is necessary for the recipient of a JWS to be able to determine the key that was employed for the digital signature or MAC operation. The key employed can be identified using the Header Parameter methods described in Section 4.1 or can be identified using methods that are outside the scope of this specification. Specifically, the Header Parameters jku, jwk, kid, x5u, x5c, and x5t can be used to identify the key used. These Header Parameters MUST be integrity protected if the information that they convey is to be utilized in a trust decision.
The sender SHOULD include sufficient information in the Header Parameters to identify the key used, unless the application uses another means or convention to determine the key used. Validation of the signature or MAC fails when the algorithm used requires a key (which is true of all algorithms except for none) and the key used cannot be determined.
The means of exchanging any shared symmetric keys used is outside the scope of this specification.
Also, see Appendix D for notes on possible key selection algorithms.
JWS objects use one of two serializations, the JWS Compact Serialization or the JWS JSON Serialization. Applications using this specification need to specify what serialization and serialization features are used for that application. For instance, applications might specify that only the JWS JSON Serialization is used, that only JWS JSON Serialization support for a single signature or MAC value is used, or that support for multiple signatures and/or MAC values is used. JWS implementations only need to implement the features needed for the applications they are designed to support.
The JWS Compact Serialization represents digitally signed or MACed content as a compact URL-safe string. This string is BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) || '.' || BASE64URL(JWS Signature). Only one signature/MAC is supported by the JWS Compact Serialization and it provides no syntax to represent a JWS Unprotected Header value.
The JWS JSON Serialization represents digitally signed or MACed content as a JSON object. Content using the JWS JSON Serialization can be secured with more than one digital signature and/or MAC operation. This representation is neither optimized for compactness nor URL-safe.
The following members are defined for use in top-level JSON objects used for the JWS JSON Serialization:
The following members are defined for use in the JSON objects that are elements of the signatures array:
Of these members of the two JSON objects defined above, only the payload, signatures, and signature members MUST be present. At least one of the protected and header members MUST be present for each signature/MAC computation so that an alg Header Parameter value is conveyed.
Additional members can be present in both the JSON objects defined above; if not understood by implementations encountering them, they MUST be ignored.
The Header Parameter values used when creating or validating individual signature or MAC values are the union of the two sets of Header Parameter values that may be present: (1) the JWS Protected Header values represented in the protected member of the signature/MAC's array element, and (2) the JWS Unprotected Header values in the header member of the signature/MAC's array element. The union of these sets of Header Parameters comprises the JWS Header. The Header Parameter names in the two locations MUST be disjoint.
The contents of the JWS Payload and JWS Signature values are exactly as defined in the rest of this specification. They are interpreted and validated in the same manner, with each corresponding JWS Signature and set of Header Parameter values being created and validated together.
Each JWS Signature value is computed on the JWS Signing Input using the parameters of the corresponding JWS Header value in the same manner as for the JWS Compact Serialization. This has the desirable property that each JWS Signature value represented in the signatures array is identical to the value that would have been computed for the same parameter in the JWS Compact Serialization, provided that the JWS Protected Header value for that signature/MAC computation (which represents the integrity-protected Header Parameter values) matches that used in the JWS Compact Serialization.
In summary, the syntax of a JWS using the JWS JSON Serialization is as follows:
{
"payload":"<payload contents>",
"signatures":[
{"protected":"<integrity-protected header 1 contents>",
"header":<non-integrity-protected header 1 contents>,
"signature":"<signature 1 contents>"},
...
{"protected":"<integrity-protected header N contents>",
"header":<non-integrity-protected header N contents>,
"signature":"<signature N contents>"}]
}
See Appendix A.6 for an example of computing a JWS using the JWS JSON Serialization.
Implementations MUST support TLS. Which version(s) ought to be implemented will vary over time, and depend on the widespread deployment and known security vulnerabilities at the time of implementation. At the time of this writing, TLS version 1.2 [RFC5246] is the most recent version, but has very limited actual deployment, and might not be readily available in implementation toolkits. TLS version 1.0 [RFC2246] is the most widely deployed version, and will give the broadest interoperability.
To protect against information disclosure and tampering, confidentiality protection MUST be applied using TLS with a ciphersuite that provides confidentiality and integrity protection.
Whenever TLS is used, a TLS server certificate check MUST be performed, per RFC 6125 [RFC6125].
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).
This specification establishes the IANA JSON Web Signature and Encryption Header Parameters registry for JWS and JWE Header Parameter names. The registry records the Header Parameter name and a reference to the specification that defines it. The same Header Parameter name can be registered multiple times, provided that the parameter usage is compatible between the specifications. Different registrations of the same Header Parameter name will typically use different Header Parameter Usage Location(s) values.
This specification registers the Header Parameter names defined in Section 4.1 in this registry.
This specification registers the application/jose Media Type [RFC2046] in the MIME Media Types registry [IANA.MediaTypes], which can be used to indicate that the content is a JWS or JWE object using the JWS Compact Serialization or the JWE Compact Serialization and the application/jose+json Media Type in the MIME Media Types registry, which can be used to indicate that the content is a JWS or JWE object using the JWS JSON Serialization or the JWE JSON Serialization.
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 concerns are listed here.
All the security considerations in XML DSIG 2.0 [W3C.CR-xmldsig-core2-20120124], also apply to this specification, other than those that are XML specific. Likewise, many of the best practices documented in XML Signature Best Practices [W3C.WD-xmldsig-bestpractices-20110809] also apply to this specification, other than those that are XML specific.
Keys are only as strong as the amount of entropy used to generate them. A minimum of 128 bits of entropy should be used for all keys, and depending upon the application context, more may be required. In particular, it may be difficult to generate sufficiently random values in some browsers and application environments.
Creators of JWSs should not allow third parties to insert arbitrary content into the message without adding entropy not controlled by the third party.
When utilizing TLS to retrieve information, the authority providing the resource MUST be authenticated and the information retrieved MUST be free from modification.
When cryptographic algorithms are implemented in such a way that successful operations take a different amount of time than unsuccessful operations, attackers may be able to use the time difference to obtain information about the keys employed. Therefore, such timing differences must be avoided.
A SHA-1 hash is used when computing x5t (x.509 certificate thumbprint) values, for compatibility reasons. Should an effective means of producing SHA-1 hash collisions be developed, and should an attacker wish to interfere with the use of a known certificate on a given system, this could be accomplished by creating another certificate whose SHA-1 hash value is the same and adding it to the certificate store used by the intended victim. A prerequisite to this attack succeeding is the attacker having write access to the intended victim's certificate store.
If, in the future, certificate thumbprints need to be computed using hash functions other than SHA-1, it is suggested that additional related Header Parameters be defined for that purpose. For example, it is suggested that a new x5t#S256 (X.509 Certificate Thumbprint using SHA-256) Header Parameter could be defined and used.
Strict JSON validation is a security requirement. If malformed JSON is received, then the intent of the sender is impossible to reliably discern. Ambiguous and potentially exploitable situations could arise if the JSON parser used does not reject malformed JSON syntax.
Section 4 of the JSON Data Interchange Format specification [I-D.ietf-json-rfc4627bis] states "The names within an object SHOULD be unique", whereas this specification states that "Header Parameter names within this object MUST be unique; recipients MUST either reject JWSs with duplicate Header Parameter 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]". Thus, this specification requires that the Section 4 "SHOULD" be treated as a "MUST" by senders and that it be either treated as a "MUST" or in the manner specified in ECMAScript 5.1 by receivers. Ambiguous and potentially exploitable situations could arise if the JSON parser used does not enforce the uniqueness of member names or returns an unpredictable value for duplicate member names.
Some JSON parsers might not reject input that contains extra significant characters after a valid input. For instance, the input {"tag":"value"}ABCD contains a valid JSON object followed by the extra characters ABCD. Such input MUST be rejected in its entirety.
Header Parameter names and algorithm names are Unicode strings. For security reasons, the representations of these names must be compared verbatim after performing any escape processing (as per Section 8.3 of [I-D.ietf-json-rfc4627bis]). This means, for instance, that these JSON strings must compare as being equal ("sig", "\u0073ig"), whereas these must all compare as being not equal to the first set or to each other ("SIG", "Sig", "si\u0047").
JSON strings can contain characters outside the Unicode Basic Multilingual Plane. For instance, the G clef character (U+1D11E) may be represented in a JSON string as "\uD834\uDD1E". Ideally, JWS implementations SHOULD ensure that characters outside the Basic Multilingual Plane are preserved and compared correctly; alternatively, if this is not possible due to these characters exercising limitations present in the underlying JSON implementation, then input containing them MUST be rejected.
| [RFC4122] | Leach, P., Mealling, M. and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005. |
| [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. |
| [JWT] | Jones, M.B., Bradley, J. and N. Sakimura, "JSON Web Token (JWT)", Internet-Draft draft-ietf-oauth-json-web-token, January 2014. |
| [MagicSignatures] | Panzer (editor), J., Laurie, B. and D. Balfanz, "Magic Signatures", January 2011. |
| [JSS] | Bradley, J. and N. Sakimura (editor), "JSON Simple Sign", September 2010. |
| [CanvasApp] | Facebook, , "Canvas Applications", 2010. |
| [JWE] | Jones, M.B., Rescorla, E. and J. Hildebrand, "JSON Web Encryption (JWE)", Internet-Draft draft-ietf-jose-json-web-encryption, January 2014. |
This section provides several examples of JWSs. While the first three examples all represent JSON Web Tokens (JWTs) [JWT], the payload can be any octet sequence, as shown in Appendix A.4.
The following example JWS Protected Header declares that the data structure is a JSON Web Token (JWT) [JWT] and the JWS Signing Input is secured using the HMAC SHA-256 algorithm.
{"typ":"JWT",
"alg":"HS256"}
The octets representing UTF8(JWS Protected Header) in this case are:
[123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32, 34, 97, 108, 103, 34, 58, 34, 72, 83, 50, 53, 54, 34, 125]
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
The JWS Payload used in this example is the octets of the UTF-8 representation of the JSON object below. (Note that the payload can be any base64url encoded octet sequence, and need not be a base64url encoded JSON object.)
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
The following octet sequence, which is the UTF-8 representation of the JSON object above, is the JWS Payload:
[123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10, 32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56, 48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97, 109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111, 111, 116, 34, 58, 116, 114, 117, 101, 125]
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value (with line breaks for display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) gives this string (with line breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
The resulting JWS Signing Input value, which is the ASCII representation of above string, is the following octet sequence:
[101, 121, 74, 48, 101, 88, 65, 105, 79, 105, 74, 75, 86, 49, 81, 105, 76, 65, 48, 75, 73, 67, 74, 104, 98, 71, 99, 105, 79, 105, 74, 73, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
HMACs are generated using keys. This example uses the symmetric key represented in JSON Web Key [JWK] format below (with line breaks for display purposes only):
{"kty":"oct",
"k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75
aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
}
Running the HMAC SHA-256 algorithm on the JWS Signing Input with this key yields this JWS Signature octet sequence:
[116, 24, 223, 180, 151, 153, 224, 37, 79, 250, 96, 125, 216, 173, 187, 186, 22, 212, 37, 77, 105, 214, 191, 240, 91, 88, 5, 88, 83, 132, 141, 121]
Encoding this JWS Signature as BASE64URL(JWS Signature) gives this value:
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
Concatenating these values in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS representation using the JWS Compact Serialization (with line breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ . dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
Since the alg Header Parameter is HS256, we validate the HMAC SHA-256 value contained in the JWS Signature.
To validate the HMAC value, we repeat the previous process of using the correct key and the JWS Signing Input as input to the HMAC SHA-256 function and then taking the output and determining if it matches the JWS Signature. If it matches exactly, the HMAC has been validated.
The JWS Protected Header in this example is different from the previous example in two ways: First, because a different algorithm is being used, the alg value is different. Second, for illustration purposes only, the optional typ parameter is not used. (This difference is not related to the algorithm employed.) The JWS Protected Header used is:
{"alg":"RS256"}
The octets representing UTF8(JWS Protected Header) in this case are:
[123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJSUzI1NiJ9
The JWS Payload used in this example, which follows, is the same as in the previous example. Since the BASE64URL(JWS Payload) value will therefore be the same, its computation is not repeated here.
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) gives this string (with line breaks for display purposes only):
eyJhbGciOiJSUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
The resulting JWS Signing Input value, which is the ASCII representation of above string, is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
This example uses the RSA key represented in JSON Web Key [JWK] format below (with line breaks for display purposes only):
{"kty":"RSA",
"n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ",
"e":"AQAB",
"d":"Eq5xpGnNCivDflJsRQBXHx1hdR1k6Ulwe2JZD50LpXyWPEAeP88vLNO97I
jlA7_GQ5sLKMgvfTeXZx9SE-7YwVol2NXOoAJe46sui395IW_GO-pWJ1O0
BkTGoVEn2bKVRUCgu-GjBVaYLU6f3l9kJfFNS3E0QbVdxzubSu3Mkqzjkn
439X0M_V51gfpRLI9JYanrC4D4qAdGcopV_0ZHHzQlBjudU2QvXt4ehNYT
CBr6XCLQUShb1juUO1ZdiYoFaFQT5Tw8bGUl_x_jTj3ccPDVZFD9pIuhLh
BOneufuBiB4cS98l2SR_RQyGWSeWjnczT0QU91p1DhOVRuOopznQ"
}
The RSA private key is then passed to the RSA signing function, which also takes the hash type, SHA-256, and the JWS Signing Input as inputs. The result of the digital signature is an octet sequence, which represents a big endian integer. In this example, it is:
[112, 46, 33, 137, 67, 232, 143, 209, 30, 181, 216, 45, 191, 120, 69, 243, 65, 6, 174, 27, 129, 255, 247, 115, 17, 22, 173, 209, 113, 125, 131, 101, 109, 66, 10, 253, 60, 150, 238, 221, 115, 162, 102, 62, 81, 102, 104, 123, 0, 11, 135, 34, 110, 1, 135, 237, 16, 115, 249, 69, 229, 130, 173, 252, 239, 22, 216, 90, 121, 142, 232, 198, 109, 219, 61, 184, 151, 91, 23, 208, 148, 2, 190, 237, 213, 217, 217, 112, 7, 16, 141, 178, 129, 96, 213, 248, 4, 12, 167, 68, 87, 98, 184, 31, 190, 127, 249, 217, 46, 10, 231, 111, 36, 242, 91, 51, 187, 230, 244, 74, 230, 30, 177, 4, 10, 203, 32, 4, 77, 62, 249, 18, 142, 212, 1, 48, 121, 91, 212, 189, 59, 65, 238, 202, 208, 102, 171, 101, 25, 129, 253, 228, 141, 247, 127, 55, 45, 195, 139, 159, 175, 221, 59, 239, 177, 139, 93, 163, 204, 60, 46, 176, 47, 158, 58, 65, 214, 18, 202, 173, 21, 145, 18, 115, 160, 95, 35, 185, 232, 56, 250, 175, 132, 157, 105, 132, 41, 239, 90, 30, 136, 121, 130, 54, 195, 212, 14, 96, 69, 34, 165, 68, 200, 242, 122, 122, 45, 184, 6, 99, 209, 108, 247, 202, 234, 86, 222, 64, 92, 178, 33, 90, 69, 178, 194, 85, 102, 181, 90, 193, 167, 72, 160, 112, 223, 200, 163, 42, 70, 149, 67, 208, 25, 238, 251, 71]
Encoding the signature as BASE64URL(JWS Signature) produces this value (with line breaks for display purposes only):
cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7 AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4 BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K 0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB p0igcN_IoypGlUPQGe77Rw
Concatenating these values in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS representation using the JWS Compact Serialization (with line breaks for display purposes only):
eyJhbGciOiJSUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ . cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7 AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4 BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K 0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB p0igcN_IoypGlUPQGe77Rw
Since the alg Header Parameter is RS256, we validate the RSASSA-PKCS-v1_5 SHA-256 digital signature contained in the JWS Signature.
Validating the JWS Signature is a little different from the previous example. We pass (n, e), JWS Signature, and the JWS Signing Input to an RSASSA-PKCS-v1_5 signature verifier that has been configured to use the SHA-256 hash function.
The JWS Protected Header for this example differs from the previous example because a different algorithm is being used. The JWS Protected Header used is:
{"alg":"ES256"}
The octets representing UTF8(JWS Protected Header) in this case are:
[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJFUzI1NiJ9
The JWS Payload used in this example, which follows, is the same as in the previous examples. Since the BASE64URL(JWS Payload) value will therefore be the same, its computation is not repeated here.
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) gives this string (with line breaks for display purposes only):
eyJhbGciOiJFUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
The resulting JWS Signing Input value, which is the ASCII representation of above string, is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
This example uses the elliptic curve key represented in JSON Web Key [JWK] format below:
{"kty":"EC",
"crv":"P-256",
"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",
"d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"
}
The ECDSA private part d is then passed to an ECDSA signing function, which also takes the curve type, P-256, the hash type, SHA-256, and the JWS Signing Input as inputs. The result of the digital signature is the EC point (R, S), where R and S are unsigned integers. In this example, the R and S values, given as octet sequences representing big endian integers are:
| Result Name | Value |
|---|---|
| R | [14, 209, 33, 83, 121, 99, 108, 72, 60, 47, 127, 21, 88, 7, 212, 2, 163, 178, 40, 3, 58, 249, 124, 126, 23, 129, 154, 195, 22, 158, 166, 101] |
| S | [197, 10, 7, 211, 140, 60, 112, 229, 216, 241, 45, 175, 8, 74, 84, 128, 166, 101, 144, 197, 242, 147, 80, 154, 143, 63, 127, 138, 131, 163, 84, 213] |
The JWS Signature is the value R || S. Encoding the signature as BASE64URL(JWS Signature) produces this value (with line breaks for display purposes only):
DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA pmWQxfKTUJqPP3-Kg6NU1Q
Concatenating these values in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS representation using the JWS Compact Serialization (with line breaks for display purposes only):
eyJhbGciOiJFUzI1NiJ9 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ . DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA pmWQxfKTUJqPP3-Kg6NU1Q
Since the alg Header Parameter is ES256, we validate the ECDSA P-256 SHA-256 digital signature contained in the JWS Signature.
Validating the JWS Signature is a little different from the first example. We need to split the 64 member octet sequence of the JWS Signature into two 32 octet sequences, the first R and the second S. We then pass (x, y), (R, S) and the JWS Signing Input to an ECDSA signature verifier that has been configured to use the P-256 curve with the SHA-256 hash function.
The JWS Protected Header for this example differs from the previous example because different ECDSA curves and hash functions are used. The JWS Protected Header used is:
{"alg":"ES512"}
The octets representing UTF8(JWS Protected Header) in this case are:
[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 53, 49, 50, 34, 125]
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJFUzUxMiJ9
The JWS Payload used in this example, is the ASCII string "Payload". The representation of this string is the octet sequence:
[80, 97, 121, 108, 111, 97, 100]
Encoding this JWS Payload as BASE64URL(JWS Payload) gives this value:
UGF5bG9hZA
Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) gives this string (with line breaks for display purposes only):
eyJhbGciOiJFUzUxMiJ9.UGF5bG9hZA
The resulting JWS Signing Input value, which is the ASCII representation of above string, is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 85, 120, 77, 105, 74, 57, 46, 85, 71, 70, 53, 98, 71, 57, 104, 90, 65]
This example uses the elliptic curve key represented in JSON Web Key [JWK] format below (with line breaks for display purposes only):
{"kty":"EC",
"crv":"P-521",
"x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_
NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk",
"y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDl
y79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2",
"d":"AY5pb7A0UFiB3RELSD64fTLOSV_jazdF7fLYyuTw8lOfRhWg6Y6rUrPA
xerEzgdRhajnu0ferB0d53vM9mE15j2C"
}
The ECDSA private part d is then passed to an ECDSA signing function, which also takes the curve type, P-521, the hash type, SHA-512, and the JWS Signing Input as inputs. The result of the digital signature is the EC point (R, S), where R and S are unsigned integers. In this example, the R and S values, given as octet sequences representing big endian integers are:
| Result Name | Value |
|---|---|
| R | [1, 220, 12, 129, 231, 171, 194, 209, 232, 135, 233, 117, 247, 105, 122, 210, 26, 125, 192, 1, 217, 21, 82, 91, 45, 240, 255, 83, 19, 34, 239, 71, 48, 157, 147, 152, 105, 18, 53, 108, 163, 214, 68, 231, 62, 153, 150, 106, 194, 164, 246, 72, 143, 138, 24, 50, 129, 223, 133, 206, 209, 172, 63, 237, 119, 109] |
| S | [0, 111, 6, 105, 44, 5, 41, 208, 128, 61, 152, 40, 92, 61, 152, 4, 150, 66, 60, 69, 247, 196, 170, 81, 193, 199, 78, 59, 194, 169, 16, 124, 9, 143, 42, 142, 131, 48, 206, 238, 34, 175, 83, 203, 220, 159, 3, 107, 155, 22, 27, 73, 111, 68, 68, 21, 238, 144, 229, 232, 148, 188, 222, 59, 242, 103] |
The JWS Signature is the value R || S. Encoding the signature as BASE64URL(JWS Signature) produces this value (with line breaks for display purposes only):
AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn
Concatenating these values in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS representation using the JWS Compact Serialization (with line breaks for display purposes only):
eyJhbGciOiJFUzUxMiJ9 . UGF5bG9hZA . AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn
Since the alg Header Parameter is ES512, we validate the ECDSA P-521 SHA-512 digital signature contained in the JWS Signature.
Validating the JWS Signature is similar to the previous example. We need to split the 132 member octet sequence of the JWS Signature into two 66 octet sequences, the first R and the second S. We then pass (x, y), (R, S) and the JWS Signing Input to an ECDSA signature verifier that has been configured to use the P-521 curve with the SHA-512 hash function.
The following example JWS Protected Header declares that the encoded object is a Plaintext JWS:
{"alg":"none"}
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJub25lIn0
The JWS Payload used in this example, which follows, is the same as in the previous examples. Since the BASE64URL(JWS Payload) value will therefore be the same, its computation is not repeated here.
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
The JWS Signature is the empty octet string and BASE64URL(JWS Signature) is the empty string.
Concatenating these parts in the order Header.Payload.Signature with period ('.') characters between the parts yields this complete JWS (with line breaks for display purposes only):
eyJhbGciOiJub25lIn0 . eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ .
This section contains an example using the JWS JSON Serialization. This example demonstrates the capability for conveying multiple digital signatures and/or MACs for the same payload.
The JWS Payload used in this example is the same as that used in the examples in Appendix A.2 and Appendix A.3 (with line breaks for display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
Two digital signatures are used in this example: the first using RSASSA-PKCS-v1_5 SHA-256 and the second using ECDSA P-256 SHA-256. For the first, the JWS Protected Header and key are the same as in Appendix A.2, resulting in the same JWS Signature value; therefore, its computation is not repeated here. For the second, the JWS Protected Header and key are the same as in Appendix A.3, resulting in the same JWS Signature value; therefore, its computation is not repeated here.
The JWS Protected Header value used for the first signature is:
{"alg":"RS256"}
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJSUzI1NiJ9
The JWS Protected Header value used for the second signature is:
{"alg":"ES256"}
Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected Header)) gives this value:
eyJhbGciOiJFUzI1NiJ9
Key ID values are supplied for both keys using per-signature Header Parameters. The two values used to represent these Key IDs are:
{"kid":"2010-12-29"}
and
{"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}
Combining the protected and unprotected header values supplied, the JWS Header values used for the first and second signatures respectively are:
{"alg":"RS256",
"kid":"2010-12-29"}
and
{"alg":"ES256",
"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}
The complete JSON Web Signature JSON Serialization for these values is as follows (with line breaks for display purposes only):
{"payload":
"eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
"signatures":[
{"protected":"eyJhbGciOiJSUzI1NiJ9",
"header":
{"kid":"2010-12-29"},
"signature":
"cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZ
mh7AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjb
KBYNX4BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHl
b1L07Qe7K0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZES
c6BfI7noOPqvhJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AX
LIhWkWywlVmtVrBp0igcN_IoypGlUPQGe77Rw"},
{"protected":"eyJhbGciOiJFUzI1NiJ9",
"header":
{"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
"signature":
"DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
lSApmWQxfKTUJqPP3-Kg6NU1Q"}]
}
The JSON array below is an example of a certificate chain that could be used as the value of an x5c (X.509 Certificate Chain) Header Parameter, per Section 4.1.6. Note that since these strings contain base64 encoded (not base64url encoded) values, they are allowed to contain white space and line breaks.
["MIIE3jCCA8agAwIBAgICAwEwDQYJKoZIhvcNAQEFBQAwYzELMAkGA1UEBhMCVVM
xITAfBgNVBAoTGFRoZSBHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR2
8gRGFkZHkgQ2xhc3MgMiBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTAeFw0wNjExM
TYwMTU0MzdaFw0yNjExMTYwMTU0MzdaMIHKMQswCQYDVQQGEwJVUzEQMA4GA1UE
CBMHQXJpem9uYTETMBEGA1UEBxMKU2NvdHRzZGFsZTEaMBgGA1UEChMRR29EYWR
keS5jb20sIEluYy4xMzAxBgNVBAsTKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYW
RkeS5jb20vcmVwb3NpdG9yeTEwMC4GA1UEAxMnR28gRGFkZHkgU2VjdXJlIENlc
nRpZmljYXRpb24gQXV0aG9yaXR5MREwDwYDVQQFEwgwNzk2OTI4NzCCASIwDQYJ
KoZIhvcNAQEBBQADggEPADCCAQoCggEBAMQt1RWMnCZM7DI161+4WQFapmGBWTt
wY6vj3D3HKrjJM9N55DrtPDAjhI6zMBS2sofDPZVUBJ7fmd0LJR4h3mUpfjWoqV
Tr9vcyOdQmVZWt7/v+WIbXnvQAjYwqDL1CBM6nPwT27oDyqu9SoWlm2r4arV3aL
GbqGmu75RpRSgAvSMeYddi5Kcju+GZtCpyz8/x4fKL4o/K1w/O5epHBp+YlLpyo
7RJlbmr2EkRTcDCVw5wrWCs9CHRK8r5RsL+H0EwnWGu1NcWdrxcx+AuP7q2BNgW
JCJjPOq8lh8BJ6qf9Z/dFjpfMFDniNoW1fho3/Rb2cRGadDAW/hOUoz+EDU8CAw
EAAaOCATIwggEuMB0GA1UdDgQWBBT9rGEyk2xF1uLuhV+auud2mWjM5zAfBgNVH
SMEGDAWgBTSxLDSkdRMEXGzYcs9of7dqGrU4zASBgNVHRMBAf8ECDAGAQH/AgEA
MDMGCCsGAQUFBwEBBCcwJTAjBggrBgEFBQcwAYYXaHR0cDovL29jc3AuZ29kYWR
keS5jb20wRgYDVR0fBD8wPTA7oDmgN4Y1aHR0cDovL2NlcnRpZmljYXRlcy5nb2
RhZGR5LmNvbS9yZXBvc2l0b3J5L2dkcm9vdC5jcmwwSwYDVR0gBEQwQjBABgRVH
SAAMDgwNgYIKwYBBQUHAgEWKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYWRkeS5j
b20vcmVwb3NpdG9yeTAOBgNVHQ8BAf8EBAMCAQYwDQYJKoZIhvcNAQEFBQADggE
BANKGwOy9+aG2Z+5mC6IGOgRQjhVyrEp0lVPLN8tESe8HkGsz2ZbwlFalEzAFPI
UyIXvJxwqoJKSQ3kbTJSMUA2fCENZvD117esyfxVgqwcSeIaha86ykRvOe5GPLL
5CkKSkB2XIsKd83ASe8T+5o0yGPwLPk9Qnt0hCqU7S+8MxZC9Y7lhyVJEnfzuz9
p0iRFEUOOjZv2kWzRaJBydTXRE4+uXR21aITVSzGh6O1mawGhId/dQb8vxRMDsx
uxN89txJx9OjxUUAiKEngHUuHqDTMBqLdElrRhjZkAzVvb3du6/KFUJheqwNTrZ
EjYx8WnM25sgVjOuH0aBsXBTWVU+4=",
"MIIE+zCCBGSgAwIBAgICAQ0wDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1Z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",
"MIIC5zCCAlACAQEwDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1ZhbGlDZXJ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"]
This appendix describes how to implement base64url encoding and decoding functions without padding based upon standard base64 encoding and decoding functions that do use padding.
To be concrete, example C# code implementing these functions is shown below. Similar code could be used in other languages.
static string base64urlencode(byte [] arg)
{
string s = Convert.ToBase64String(arg); // Regular base64 encoder
s = s.Split('=')[0]; // Remove any trailing '='s
s = s.Replace('+', '-'); // 62nd char of encoding
s = s.Replace('/', '_'); // 63rd char of encoding
return s;
}
static byte [] base64urldecode(string arg)
{
string s = arg;
s = s.Replace('-', '+'); // 62nd char of encoding
s = s.Replace('_', '/'); // 63rd char of encoding
switch (s.Length % 4) // Pad with trailing '='s
{
case 0: break; // No pad chars in this case
case 2: s += "=="; break; // Two pad chars
case 3: s += "="; break; // One pad char
default: throw new System.Exception(
"Illegal base64url string!");
}
return Convert.FromBase64String(s); // Standard base64 decoder
}
As per the example code above, the number of '=' padding characters that needs to be added to the end of a base64url encoded string without padding to turn it into one with padding is a deterministic function of the length of the encoded string. Specifically, if the length mod 4 is 0, no padding is added; if the length mod 4 is 2, two '=' padding characters are added; if the length mod 4 is 3, one '=' padding character is added; if the length mod 4 is 1, the input is malformed.
An example correspondence between unencoded and encoded values follows. The octet sequence below encodes into the string below, which when decoded, reproduces the octet sequence.
3 236 255 224 193
A-z_4ME
This appendix describes a set of possible algorithms for selecting the key to be used to validate the digital signature or MAC of a JWS object or for selecting the key to be used to decrypt a JWE object. This guidance describes a family of possible algorithms, rather than a single algorithm, because in different contexts, not all the sources of keys will be used, they can be tried in different orders, and sometimes not all the collected keys will be tried; hence, different algorithms will be used in different application contexts.
These algorithms use some or all of the steps described below; the order and inclusion of the steps does not mean that they need to be performed in this order or that they are all required in all contexts. The steps below are described for illustration purposes only; specific applications can and are likely to use different algorithms. Specific applications will frequently have a much simpler method of determining the keys to use, as there may be one or two key selection methods that are profiled for the application's use. This appendix supplements the normative information on key location in Section 6.
Algorithm steps may include:
Conforming implementations must reject input containing critical extensions that are not understood or cannot be processed. The following JWS must be rejected by all implementations, because it uses an extension Header Parameter name http://example.invalid/UNDEFINED that they do not understand. Any other similar input, in which the use of the value http://example.invalid/UNDEFINED is substituted for any other Header Parameter name not understood by the implementation, must also be rejected.
The JWS Protected Header value for this JWS is:
{"alg":"none",
"crit":["http://example.invalid/UNDEFINED"],
"http://example.invalid/UNDEFINED":true
}
The complete JWS that must be rejected is as follows (with line breaks for display purposes only):
eyJhbGciOiJub25lIiwNCiAiY3JpdCI6WyJodHRwOi8vZXhhbXBsZS5jb20vVU5ERU ZJTkVEIl0sDQogImh0dHA6Ly9leGFtcGxlLmNvbS9VTkRFRklORUQiOnRydWUNCn0. RkFJTA.
In some contexts, it is useful integrity protect content that is not itself contained in a JWS object. One way to do this is create a JWS object in the normal fashion using a representation of the content as the payload, but then delete the payload representation from the JWS, and send this modified object to the recipient, rather than the JWS. When using the JWS Compact Serialization, the deletion is accomplished by replacing the second field (which contains BASE64URL(JWS Payload)) value with the empty string; when using the JWS JSON Serialization, the deletion is accomplished by deleting the payload member. This method assumes that the recipient can reconstruct the exact payload used in the JWS. To use the modified object, the recipient reconstructs the JWS by re-inserting the payload representation into the modified object, and uses the resulting JWS in the usual manner. Note that this method needs no support from JWS libraries, as applications can use this method by modifying the inputs and outputs of standard JWS libraries.
Solutions for signing JSON content were previously explored by Magic Signatures [MagicSignatures], JSON Simple Sign [JSS], and Canvas Applications [CanvasApp], all of which influenced this draft.
Thanks to Axel Nennker for his early implementation and feedback on the JWS and JWE specifications.
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, Brian Campbell, Breno de Medeiros, Dick Hardt, Joe Hildebrand, Jeff Hodges, Edmund Jay, Yaron Y. Goland, Ben Laurie, James Manger, Matt Miller, Tony Nadalin, Axel Nennker, John Panzer, Emmanuel Raviart, Eric Rescorla, 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.
[[ to be removed by the RFC Editor before publication as an RFC ]]
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