JOSE Working Group M.B. Jones
Internet-Draft Microsoft
Intended status: Standards Track J. Bradley
Expires: November 29, 2013 Ping Identity
N. Sakimura
NRI
May 28, 2013

JSON Web Signature (JWS)
draft-ietf-jose-json-web-signature-11

Abstract

JSON Web Signature (JWS) is a means of representing 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. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification.

Status of This Memo

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This Internet-Draft will expire on November 29, 2013.

Copyright Notice

Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1. Introduction

JSON Web Signature (JWS) is a means of representing content secured with digital signatures or Message Authentication Codes (MACs) using JavaScript Object Notation (JSON) [RFC4627] based data structures. The JWS cryptographic mechanisms provide integrity protection for arbitrary sequences of octets.

Two closely related representations 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. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) [JWE] specification.

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].

2. Terminology

JSON Web Signature (JWS)
A data structure representing a digitally signed or MACed message. The structure represents three values: the JWS Header, the JWS Payload, and the JWS Signature.
JSON Text Object
A UTF-8 [RFC3629] encoded text string representing a JSON object; the syntax of JSON objects is defined in Section 2.2 of [RFC4627].
JWS Header
A JSON Text Object (or JSON Text Objects, when using the JWS JSON Serialization) that describes the digital signature or MAC operation applied to create the JWS Signature value. The members of the JWS Header object(s) are Header Parameters.
JWS Payload
The sequence of octets to be secured -- a.k.a., the message. The payload can contain an arbitrary sequence of octets.
JWS Signature
A sequence of octets containing the cryptographic material that ensures the integrity of the JWS Protected Header and the JWS Payload. The JWS Signature value is a digital signature or MAC value calculated over the JWS Signing Input using the parameters specified in the JWS Header.
JWS Protected Header
A JSON Text Object that contains the portion of the JWS Header that is integrity protected. For the JWS Compact Serialization, this comprises the entire JWS Header. For the JWS JSON Serialization, this is one component of the JWS Header.
Header Parameter
A name/value pair that is member of the JWS Header.
Header Parameter Name
The name of a member of the JWS Header.
Header Parameter Value
The value of a member of the JWS Header.
Base64url Encoding
The URL- and filename-safe Base64 encoding described in RFC 4648 [RFC4648], Section 5, with the (non URL-safe) '=' padding characters omitted, as permitted by Section 3.2. (See Appendix C for notes on implementing base64url encoding without padding.)
Encoded JWS Header
Base64url encoding of the JWS Protected Header.
Encoded JWS Payload
Base64url encoding of the JWS Payload.
Encoded JWS Signature
Base64url encoding of the JWS Signature.
JWS Signing Input
The concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload.
JWS Compact Serialization
A representation of the JWS as the concatenation of the Encoded JWS Header, the Encoded JWS Payload, and the Encoded JWS Signature in that order, with the three strings being separated by two period ('.') characters. This representation is compact and URL-safe.
JWS JSON Serialization
A representation of the JWS as a JSON structure containing JWS Header, Encoded JWS Payload, and Encoded JWS Signature values. Unlike the JWS Compact Serialization, the JWS JSON Serialization enables multiple digital signatures and/or MACs to be applied to the same content. This representation is neither compact nor URL-safe.
Collision Resistant Namespace
A namespace that allows names to be allocated in a manner such that they are highly unlikely to collide with other names. For instance, collision resistance can be achieved through administrative delegation of portions of the namespace or through use of collision-resistant name allocation functions. Examples of Collision Resistant Namespaces include: Domain Names, Object Identifiers (OIDs) as defined in the ITU-T X.660 and X.670 Recommendation series, and Universally Unique IDentifiers (UUIDs) [RFC4122]. When using 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.
StringOrURI
A JSON string value, with the additional requirement that while arbitrary string values MAY be used, any value containing a ":" character MUST be a URI [RFC3986]. StringOrURI values are compared as case-sensitive strings with no transformations or canonicalizations applied.

3. JSON Web Signature (JWS) Overview

JWS represents digitally signed or MACed content using JSON data structures and base64url encoding. Three values are represented in a JWS: the JWS Header, the JWS Payload, and the JWS Signature. In the Compact Serialization, the three values are base64url-encoded for transmission, and represented as the concatenation of the encoded strings in that order, with the three strings being separated by two period ('.') characters. A JSON Serialization for this information is also defined in Section 8.

The JWS Header describes the signature or MAC method and parameters employed. The JWS Payload is the message content to be secured. The JWS Signature ensures the integrity of both the JWS Protected Header and the JWS Payload.

3.1. Example JWS

The following example JWS Header declares that the encoded object is a JSON Web Token (JWT) [JWT] and the JWS Header and the JWS Payload are secured using the HMAC SHA-256 algorithm:

  {"typ":"JWT",
   "alg":"HS256"}

Base64url encoding the octets of the UTF-8 representation of the JWS Header yields this Encoded JWS Header value:

  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9

The following is an example of a JSON object that can be used as a 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}

Base64url encoding the octets of the UTF-8 representation of the JSON object yields the following Encoded JWS Payload (with line breaks for display purposes only):

  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

Computing the HMAC of the octets of the ASCII [USASCII] representation of the JWS Signing Input (the concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload) with the HMAC SHA-256 algorithm using the key specified in Appendix A.1 and base64url encoding the result yields this Encoded 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

This computation is illustrated in more detail in Appendix A.1. See Appendix A for additional examples.

4. JWS Header

The members of the JSON object(s) represented by the JWS Header describe the digital signature or MAC applied to the Encoded JWS Header and the Encoded JWS Payload and optionally additional properties of the JWS. The Header Parameter Names within the JWS Header MUST be unique; JWSs with duplicate Header Parameter Names MUST be rejected.

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 other header parameters MUST be ignored when not understood.

There are three classes of Header Parameter Names: Reserved Header Parameter Names, Public Header Parameter Names, and Private Header Parameter Names.

4.1. Reserved Header Parameter Names

The following Header Parameter Names are reserved with meanings as defined below. All the names are short because a core goal of this specification is for the resulting representations using the JWS Compact Serialization to be compact.

Additional reserved Header Parameter Names can be defined via the IANA JSON Web Signature and Encryption Header Parameters registry Section 10.1. 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.

4.1.1. "alg" (Algorithm) Header Parameter

The alg (algorithm) header parameter identifies the cryptographic algorithm used to secure the JWS. The algorithm specified by the alg value MUST be supported by the implementation and there MUST be a key for use with that algorithm associated with the party that digitally signed or MACed the content or the JWS MUST be rejected. alg values SHOULD either be registered in the IANA JSON Web Signature and Encryption Algorithms registry [JWA] or be a value that contains a Collision Resistant Namespace. The alg value is a case sensitive string containing a StringOrURI value. Use of this header parameter is REQUIRED. This header parameter MUST be understood by implementations.

A list of defined alg values can be found in the IANA JSON Web Signature and Encryption Algorithms registry [JWA]; the initial contents of this registry are the values defined in Section 3.1 of the JSON Web Algorithms (JWA) [JWA] specification.

4.1.2. "jku" (JWK Set URL) Header Parameter

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 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.

4.1.3. "jwk" (JSON Web Key) Header Parameter

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.

4.1.4. "x5u" (X.509 URL) Header Parameter

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.

4.1.5. "x5t" (X.509 Certificate Thumbprint) Header Parameter

The x5t (X.509 Certificate 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 Section 10.1.

4.1.6. "x5c" (X.509 Certificate Chain) Header Parameter

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 verify the certificate chain according to [RFC5280] and reject the JWS if any validation failure occurs. Use of this header parameter is OPTIONAL.

See Appendix B for an example x5c value.

4.1.7. "kid" (Key ID) Header Parameter

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. Should the recipient be unable to locate a key corresponding to the kid value, they SHOULD treat that condition as an error. The interpretation 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 can be used to match a JWK kid parameter value.

4.1.8. "typ" (Type) Header Parameter

The typ (type) header parameter is used to declare the type of this object. The type value JWS is used to indicate that this object is a JWS using the JWS Compact Serialization. The type value JWS+JSON is used to indicate that this object is a JWS using the JWS JSON Serialization. Other type values MAY be used, and if not understood, SHOULD be ignored. The typ value is a case sensitive string. Use of this header parameter is OPTIONAL.

MIME Media Type [RFC2046] values MAY be used as typ values.

typ values SHOULD either be registered in the IANA JSON Web Signature and Encryption Type Values registry Section 10.2 or be a value that contains a Collision Resistant Namespace.

4.1.9. "cty" (Content Type) Header Parameter

The cty (content type) header parameter is used to declare the type of the secured content (the Payload). For example, the JSON Web Token (JWT) [JWT] specification uses the cty value JWT to indicate that the Payload is a JSON Web Token (JWT). Content type values that are not understood SHOULD be ignored. The cty value is a case sensitive string. Use of this header parameter is OPTIONAL.

The values used for the cty header parameter come from the same value space as the typ header parameter, with the same rules applying.

4.1.10. "crit" (Critical) Header Parameter

The crit (critical) header parameter indicates that extensions to [[ this specification ]] are being used that MUST be understood and processed. Its value is an array listing the header parameter names defined by those extensions that are used in the JWS Header. 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 [[ this specification ]], 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 [[ this specification ]] or any other constraints on its use are violated. This header parameter MUST be integrity protected, and therefore MUST occur only with the JWS Protected Header, when used. Use of this header parameter is OPTIONAL. This header parameter MUST be understood by implementations.

An example use, along with a hypothetical exp (expiration-time) field is:

  {"alg":"ES256",
   "crit":["exp"],
   "exp":1363284000
  }

4.2. Public Header Parameter Names

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 Section 10.1 or be a Public Name: a value that contains a Collision Resistant Namespace. 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.

4.3. Private Header Parameter Names

A producer and consumer of a JWS may agree to use Header Parameter Names that are Private Names: names that are not Reserved Names Section 4.1 or Public Names Section 4.2. Unlike Public Names, Private Names are subject to collision and should be used with caution.

5. Producing and Consuming JWSs

5.1. Message Signing or MACing

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.

  1. Create the content to be used as the JWS Payload.
  2. Base64url encode the octets of the JWS Payload. This encoding becomes the Encoded JWS Payload.
  3. Create a JWS Header containing the desired set of header parameters. Note that white space is explicitly allowed in the representation and no canonicalization need be performed before encoding.
  4. Base64url encode the octets of the UTF-8 representation of the JWS Protected Header to create the Encoded JWS Header. If the JWS Protected Header is not present (which can only happen when using the JWS JSON Serialization), let the Encoded JWS Header be the empty string.
  5. Compute the JWS Signature in the manner defined for the particular algorithm being used over the JWS Signing Input (the concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload). The alg (algorithm) header parameter MUST be present in the JWS Header, with the algorithm value accurately representing the algorithm used to construct the JWS Signature.
  6. Base64url encode the representation of the JWS Signature to create the Encoded JWS Signature.
  7. The three encoded parts are result values used in both the JWS Compact Serialization and the JWS JSON Serialization representations.
  8. If the JWS JSON Serialization is being used, repeat this process for each digital signature or MAC value being applied.
  9. Create the desired serialized output. The JWS Compact Serialization of this result is the concatenation of the Encoded JWS Header, the Encoded JWS Payload, and the Encoded JWS Signature in that order, with the three strings being separated by two period ('.') characters. The JWS JSON Serialization is described in Section 8.

5.2. Message Signature or MAC Validation

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 JWS MUST be rejected.

  1. Parse the serialized input to determine the values of the JWS Header, the Encoded JWS Payload, and the Encoded JWS Signature. When using the JWS Compact Serialization, the Encoded JWS Header, the Encoded JWS Payload, and the Encoded JWS Signature are represented as text strings in that order, separated by two period ('.') characters. The JWS JSON Serialization is described in Section 8.
  2. The Encoded JWS Header MUST be successfully base64url decoded following the restriction given in this specification that no padding characters have been used.
  3. Let the JWS Protected Header value be the result of base64url decoding the Encoded JWS Header.
  4. The resulting JWS Protected Header MUST be a completely valid JSON object conforming to RFC 4627 [RFC4627].
  5. If using the JWS Compact Serialization, let the JWS Header be the JWS Protected Header; otherwise, when using the JWS JSON Serialization, let the JWS Header be the union of the members of the JWS Protected Header, the members of the unprotected value, and the members of the corresponding header value, all of which must be completely valid JSON objects.
  6. The resulting JWS Header MUST NOT contain duplicate Header Parameter Names. When using the JWS JSON Serialization, this restriction includes that the same Header Parameter Name also MUST NOT occur in distinct JSON Text Object values that together comprise the JWS Header.
  7. The resulting JWS Header MUST be validated to only include parameters and values whose syntax and semantics are both understood and supported or that are specified as being ignored when not understood.
  8. The Encoded JWS Payload MUST be successfully base64url decoded following the restriction given in this specification that no padding characters have been used.
  9. The Encoded JWS Signature MUST be successfully base64url decoded following the restriction given in this specification that no padding characters have been used.
  10. The JWS Signature MUST be successfully validated against the JWS Signing Input (the concatenation of the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload) in the manner defined for the algorithm being used, which MUST be accurately represented by the value of the alg (algorithm) header parameter, which MUST be present.
  11. If the JWS JSON Serialization is being used, repeat this process for each digital signature or MAC value contained in the representation.

5.3. String Comparison Rules

Processing a JWS inevitably requires comparing known strings to values in JSON objects. For example, in checking what the algorithm is, the Unicode string encoding alg will be checked against the member names in the JWS Header to see if there is a matching Header Parameter Name. A similar process occurs when determining if the value of the alg header parameter represents a supported algorithm.

Comparisons between JSON strings and other Unicode strings MUST be performed as specified below:

  1. Remove any JSON escaping from the input JSON string and convert the string into a sequence of Unicode code points.
  2. Likewise, convert the string to be compared against into a sequence of Unicode code points.
  3. Unicode Normalization [USA15] MUST NOT be applied at any point to either the JSON string or to the string it is to be compared against.
  4. Comparisons between the two strings MUST be performed as a Unicode code point to code point equality comparison. (Note that values that originally used different Unicode encodings (UTF-8, UTF-16, etc.) may result in the same code point values.)

Also, see the JSON security considerations in Section 11.2 and the Unicode security considerations in Section 11.3.

6. Cryptographic Algorithms

JWS uses cryptographic algorithms to digitally sign or MAC the JWS Protected Header and the JWS Payload. The JSON Web Algorithms (JWA) [JWA] specification describes a set of cryptographic algorithms and identifiers to be used with this specification. Specifically, Section 3.1 specifies a set of alg (algorithm) header parameter values intended for use this specification. It also describes the semantics and operations that are specific to these algorithms.

7. Key Identification

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, x5u, x5t, x5c, and kid can be used to identify the key used. 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. Recipients MUST reject the input when the algorithm used requires a key (which is true of all algorithms except for none) and the key used cannot be determined.

8. JWS JSON Serialization

The JWS JSON Serialization represents digitally signed or MACed content as a JSON object. Unlike the JWS Compact Serialization, content using the JWS JSON Serialization can be secured with more than one digital signature and/or MAC value.

The representation is closely related to that used in the JWS Compact Serialization, with the following differences for the JWS JSON Serialization:

The syntax of a JWS using the JWS JSON Serialization is as follows:

  {"protected":<integrity-protected shared header contents>",
   "unprotected":<non-integrity-protected shared header contents>",
   "payload":"<payload contents>"
   "signatures":[
    {"header":"<per-signature unprotected header 1 contents>",
     "signature":"<signature 1 contents>"},
    ...
    {"header":"<per-signature unprotected header N contents>",
     "signature":"<signature N contents>"}],
  }

Of these members, only the payload, signatures, and signature members MUST be present. At least one of the header, protected, and unprotected members MUST be present so that an alg header parameter value is conveyed for each signature/MAC computation.

The contents of the Encoded JWS Payload and Encoded 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 Encoded JWS Signature and set of header parameter values being created and validated together. The JWS Header values used are the union of the header parameters in the protected, unprotected, and corresponding header members, as described earlier.

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 Encoded JWS Signature value 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 Encoded JWS Header value (which represents the integrity-protected header parameter values) matches that used in the JWS Compact Serialization.

See Appendix A.6 for an example of computing a JWS using the JWS JSON Serialization.

9. Implementation Considerations

The JWS Compact Serialization is mandatory to implement. Implementation of the JWS JSON Serialization is OPTIONAL.

10. IANA Considerations

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

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

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

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

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

10.1. JSON Web Signature and Encryption Header Parameters Registry

This specification establishes the IANA JSON Web Signature and Encryption Header Parameters registry for reserved JWS and JWE Header Parameter Names. The registry records the reserved Header Parameter Name and a reference to the specification that defines it. The same Header Parameter Name MAY 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.

10.1.1. Registration Template

Header Parameter Name:

The name requested (e.g., "example"). This name is case sensitive. Names that match other registered names in a case insensitive manner SHOULD NOT be accepted.
Header Parameter Usage Location(s):

The header parameter usage locations, which should be one or more of the values JWS or JWE.
Change Controller:

For Standards Track RFCs, state "IETF". 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.

10.1.2. Initial Registry Contents

This specification registers the Header Parameter Names defined in Section 4.1 in this registry.

10.2. JSON Web Signature and Encryption Type Values Registry

This specification establishes the IANA JSON Web Signature and Encryption Type Values registry for values of the JWS and JWE typ (type) header parameter. It is RECOMMENDED that all registered typ values also include a MIME Media Type [RFC2046] value that the registered value is a short name for. The registry records the typ value, the MIME type value that it is an abbreviation for (if any), and a reference to the specification that defines it.

MIME Media Type [RFC2046] values MUST NOT be directly registered as new typ values; rather, new typ values MAY be registered as short names for MIME types.

10.2.1. Registration Template

"typ" Header Parameter Value:

The name requested (e.g., "example"). This name is case sensitive. Names that match other registered names in a case insensitive manner SHOULD NOT be accepted.
Abbreviation for MIME Type:

The MIME type that this name is an abbreviation for (e.g., "application/example").
Change Controller:

For Standards Track RFCs, state "IETF". 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.

10.2.2. Initial Registry Contents

This specification registers the JWS and JWS+JSON type values in this registry:

10.3. Media Type Registration

10.3.1. Registry Contents

This specification registers the application/jws and application/jws+json Media Types [RFC2046] in the MIME Media Type registry [RFC4288] to indicate, respectively, that the content is a JWS using the JWS Compact Serialization or a JWS using the JWS JSON Serialization.

11. Security Considerations

11.1. Cryptographic 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 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.

11.2. JSON Security Considerations

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 2.2 of the JavaScript Object Notation (JSON) specification [RFC4627] states "The names within an object SHOULD be unique", whereas this specification states that "Header Parameter Names within this object MUST be unique; JWSs with duplicate Header Parameter Names MUST be rejected". Thus, this specification requires that the Section 2.2 "SHOULD" be treated as a "MUST". Ambiguous and potentially exploitable situations could arise if the JSON parser used does not enforce the uniqueness of 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.

11.3. Unicode Comparison Security Considerations

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 RFC 4627 [RFC4627], Section 2.5). 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.

12. References

12.1. Normative References

[RFC1421] Linn, J., "Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures", RFC 1421, February 1993.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", RFC 4288, December 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.
[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.
[ITU.X690.1994] 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.
[W3C.WD-xmldsig-bestpractices-20110809] Datta, P. and F. Hirsch, "XML Signature Best Practices", World Wide Web Consortium WD WD-xmldsig-bestpractices-20110809, August 2011.
[USA15] Davis, M., Whistler, K. and M. Deurst, "Unicode Normalization Forms", Unicode Standard Annex 15, 09 2009.
[JWK] Jones, M.B., "JSON Web Key (JWK)", Internet-Draft draft-ietf-jose-json-web-key, May 2013.
[JWA] Jones, M.B., "JSON Web Algorithms (JWA)", Internet-Draft draft-ietf-jose-json-web-algorithms, May 2013.
[USASCII] American National Standards Institute, "Coded Character Set -- 7-bit American Standard Code for Information Interchange", ANSI X3.4, 1986.

12.2. Informative References

[RFC4122] Leach, P., Mealling, M. and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005.
[W3C.CR-xmldsig-core2-20120124] Datta, P., Hirsch, F., Eastlake, D., Cantor, S., Roessler, T., Reagle, J., Yiu, K. and D. Solo, "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, May 2013.
[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, May 2013.

Appendix A. JWS Examples

This section provides several examples of JWSs. While these examples all represent JSON Web Tokens (JWTs) [JWT], the payload can be any base64url encoded content.

A.1. Example JWS using HMAC SHA-256

A.1.1. Encoding

The following example JWS 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 following octet sequence contains the UTF-8 representation of the JWS Header:

[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]

Base64url encoding these octets yields this Encoded JWS Header 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]

Base64url encoding the above yields the Encoded JWS Payload value (with line breaks for display purposes only):

  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

Concatenating the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload yields this JWS Signing Input value (with line breaks for display purposes only):

  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

The ASCII representation of the JWS Signing Input 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 key represented by the following octet sequence:

[3, 35, 53, 75, 43, 15, 165, 188, 131, 126, 6, 101, 119, 123, 166, 143, 90, 179, 40, 230, 240, 84, 201, 40, 169, 15, 132, 178, 210, 80, 46, 191, 211, 251, 90, 146, 210, 6, 71, 239, 150, 138, 180, 195, 119, 98, 61, 34, 61, 46, 33, 114, 5, 46, 79, 8, 192, 205, 154, 245, 103, 208, 128, 163]

Running the HMAC SHA-256 algorithm on the octets of the ASCII representation of the JWS Signing Input with this key yields the following 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]

Base64url encoding the above HMAC output yields the Encoded 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

A.1.2. Decoding

Decoding the JWS requires base64url decoding the Encoded JWS Header, Encoded JWS Payload, and Encoded JWS Signature to produce the JWS Header, JWS Payload, and JWS Signature octet sequences. The octet sequence containing the UTF-8 representation of the JWS Header is decoded into the JWS Header string.

A.1.3. Validating

Next we validate the decoded results. Since the alg parameter in the header is "HS256", we validate the HMAC SHA-256 value contained in the JWS Signature. If any of the validation steps fail, the JWS MUST be rejected.

First, we validate that the JWS Header string is legal JSON.

To validate the HMAC value, we repeat the previous process of using the correct key and the ASCII representation of 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.

A.2. Example JWS using RSASSA-PKCS-v1_5 SHA-256

A.2.1. Encoding

The JWS 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 Header used is:

  {"alg":"RS256"}

The following octet sequence contains the UTF-8 representation of the JWS Header:

[123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]

Base64url encoding these octets yields this Encoded JWS Header value:

  eyJhbGciOiJSUzI1NiJ9

The JWS Payload used in this example, which follows, is the same as in the previous example. Since the Encoded JWS Payload will therefore be the same, its computation is not repeated here.

  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}

Concatenating the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload yields this JWS Signing Input value (with line breaks for display purposes only):

  eyJhbGciOiJSUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

The ASCII representation of the JWS Signing Input 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]

The RSA key consists of a public part (Modulus, Exponent), and a Private Exponent. The values of the RSA key used in this example, presented as the octet sequences representing big endian integers are:

Parameter Name Value
Modulus [161, 248, 22, 10, 226, 227, 201, 180, 101, 206, 141, 45, 101, 98, 99, 54, 43, 146, 125, 190, 41, 225, 240, 36, 119, 252, 22, 37, 204, 144, 161, 54, 227, 139, 217, 52, 151, 197, 182, 234, 99, 221, 119, 17, 230, 124, 116, 41, 249, 86, 176, 251, 138, 143, 8, 154, 220, 75, 105, 137, 60, 193, 51, 63, 83, 237, 208, 25, 184, 119, 132, 37, 47, 236, 145, 79, 228, 133, 119, 105, 89, 75, 234, 66, 128, 211, 44, 15, 85, 191, 98, 148, 79, 19, 3, 150, 188, 110, 155, 223, 110, 189, 210, 189, 163, 103, 142, 236, 160, 198, 104, 247, 1, 179, 141, 191, 251, 56, 200, 52, 44, 226, 254, 109, 39, 250, 222, 74, 90, 72, 116, 151, 157, 212, 185, 207, 154, 222, 196, 199, 91, 5, 133, 44, 44, 15, 94, 248, 165, 193, 117, 3, 146, 249, 68, 232, 237, 100, 193, 16, 198, 182, 71, 96, 154, 164, 120, 58, 235, 156, 108, 154, 215, 85, 49, 48, 80, 99, 139, 131, 102, 92, 111, 111, 122, 130, 163, 150, 112, 42, 31, 100, 27, 130, 211, 235, 242, 57, 34, 25, 73, 31, 182, 134, 135, 44, 87, 22, 245, 10, 248, 53, 141, 154, 139, 157, 23, 195, 64, 114, 143, 127, 135, 216, 154, 24, 216, 252, 171, 103, 173, 132, 89, 12, 46, 207, 117, 147, 57, 54, 60, 7, 3, 77, 111, 96, 111, 158, 33, 224, 84, 86, 202, 229, 233, 161]
Exponent [1, 0, 1]
Private Exponent [18, 174, 113, 164, 105, 205, 10, 43, 195, 126, 82, 108, 69, 0, 87, 31, 29, 97, 117, 29, 100, 233, 73, 112, 123, 98, 89, 15, 157, 11, 165, 124, 150, 60, 64, 30, 63, 207, 47, 44, 211, 189, 236, 136, 229, 3, 191, 198, 67, 155, 11, 40, 200, 47, 125, 55, 151, 103, 31, 82, 19, 238, 216, 193, 90, 37, 216, 213, 206, 160, 2, 94, 227, 171, 46, 139, 127, 121, 33, 111, 198, 59, 234, 86, 39, 83, 180, 6, 68, 198, 161, 81, 39, 217, 178, 149, 69, 64, 160, 187, 225, 163, 5, 86, 152, 45, 78, 159, 222, 95, 100, 37, 241, 77, 75, 113, 52, 65, 181, 93, 199, 59, 155, 74, 237, 204, 146, 172, 227, 146, 126, 55, 245, 125, 12, 253, 94, 117, 129, 250, 81, 44, 143, 73, 97, 169, 235, 11, 128, 248, 168, 7, 70, 114, 138, 85, 255, 70, 71, 31, 52, 37, 6, 59, 157, 83, 100, 47, 94, 222, 30, 132, 214, 19, 8, 26, 250, 92, 34, 208, 81, 40, 91, 214, 59, 148, 59, 86, 93, 137, 138, 5, 104, 84, 19, 229, 60, 60, 108, 101, 37, 255, 31, 227, 78, 61, 220, 112, 240, 213, 100, 80, 253, 164, 139, 161, 46, 16, 78, 157, 235, 159, 184, 24, 129, 225, 196, 189, 242, 93, 146, 71, 244, 80, 200, 101, 146, 121, 104, 231, 115, 52, 244, 65, 79, 117, 167, 80, 225, 57, 84, 110, 58, 138, 115, 157]

The RSA private key (Modulus, Private Exponent) is then passed to the RSA signing function, which also takes the hash type, SHA-256, and the octets of the ASCII representation of 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]

Base64url encoding the digital signature produces this value for the Encoded JWS Signature (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

A.2.2. Decoding

Decoding the JWS requires base64url decoding the Encoded JWS Header, Encoded JWS Payload, and Encoded JWS Signature to produce the JWS Header, JWS Payload, and JWS Signature octet sequences. The octet sequence containing the UTF-8 representation of the JWS Header is decoded into the JWS Header string.

A.2.3. Validating

Since the alg parameter in the header is "RS256", we validate the RSASSA-PKCS-v1_5 SHA-256 digital signature contained in the JWS Signature. If any of the validation steps fail, the JWS MUST be rejected.

First, we validate that the JWS Header string is legal JSON.

Validating the JWS Signature is a little different from the previous example. First, we base64url decode the Encoded JWS Signature to produce a digital signature S to check. We then pass (n, e), S and the octets of the ASCII representation of the JWS Signing Input to an RSASSA-PKCS-v1_5 signature verifier that has been configured to use the SHA-256 hash function.

A.3. Example JWS using ECDSA P-256 SHA-256

A.3.1. Encoding

The JWS Header for this example differs from the previous example because a different algorithm is being used. The JWS Header used is:

  {"alg":"ES256"}

The following octet sequence contains the UTF-8 representation of the JWS Header:

[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]

Base64url encoding these octets yields this Encoded JWS Header value:

  eyJhbGciOiJFUzI1NiJ9

The JWS Payload used in this example, which follows, is the same as in the previous examples. Since the Encoded JWS Payload will therefore be the same, its computation is not repeated here.

  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}

Concatenating the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload yields this JWS Signing Input value (with line breaks for display purposes only):

  eyJhbGciOiJFUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

The ASCII representation of the JWS Signing Input 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]

The ECDSA key consists of a public part, the EC point (x, y), and a private part d. The values of the ECDSA key used in this example, presented as the octet sequences representing three 256 bit big endian integers are:

Parameter Name Value
x [127, 205, 206, 39, 112, 246, 196, 93, 65, 131, 203, 238, 111, 219, 75, 123, 88, 7, 51, 53, 123, 233, 239, 19, 186, 207, 110, 60, 123, 209, 84, 69]
y [199, 241, 68, 205, 27, 189, 155, 126, 135, 44, 223, 237, 185, 238, 185, 244, 179, 105, 93, 110, 169, 11, 36, 173, 138, 70, 35, 40, 133, 136, 229, 173]
d [142, 155, 16, 158, 113, 144, 152, 191, 152, 4, 135, 223, 31, 93, 119, 233, 203, 41, 96, 110, 190, 210, 38, 59, 95, 87, 194, 19, 223, 132, 244, 178]

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 octets of the ASCII representation of 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]

Concatenating the S array to the end of the R array and base64url encoding the result produces this value for the Encoded JWS Signature (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

A.3.2. Decoding

Decoding the JWS requires base64url decoding the Encoded JWS Header, Encoded JWS Payload, and Encoded JWS Signature to produce the JWS Header, JWS Payload, and JWS Signature octet sequences. The octet sequence containing the UTF-8 representation of the JWS Header is decoded into the JWS Header string.

A.3.3. Validating

Since the alg parameter in the header is "ES256", we validate the ECDSA P-256 SHA-256 digital signature contained in the JWS Signature. If any of the validation steps fail, the JWS MUST be rejected.

First, we validate that the JWS Header string is legal JSON.

Validating the JWS Signature is a little different from the first example. First, we base64url decode the Encoded JWS Signature as in the previous examples but we then need to split the 64 member octet sequence that must result into two 32 octet sequences, the first R and the second S. We then pass (x, y), (R, S) and the octets of the ASCII representation of 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.

As explained in Section 3.4 of the JSON Web Algorithms (JWA) [JWA] specification, the use of the K value in ECDSA means that we cannot validate the correctness of the digital signature in the same way we validated the correctness of the HMAC. Instead, implementations MUST use an ECDSA validator to validate the digital signature.

A.4. Example JWS using ECDSA P-521 SHA-512

A.4.1. Encoding

The JWS Header for this example differs from the previous example because a different ECDSA curve and hash function are used. The JWS Header used is:

  {"alg":"ES512"}

The following octet sequence contains the UTF-8 representation of the JWS Header:

[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 53, 49, 50, 34, 125]

Base64url encoding these octets yields this Encoded JWS Header 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]

Base64url encoding these octets yields the Encoded JWS Payload value:

  UGF5bG9hZA

Concatenating the Encoded JWS Header, a period ('.') character, and the Encoded JWS Payload yields this JWS Signing Input value:

  eyJhbGciOiJFUzUxMiJ9.UGF5bG9hZA

The ASCII representation of the JWS Signing Input 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]

The ECDSA key consists of a public part, the EC point (x, y), and a private part d. The values of the ECDSA key used in this example, presented as the octet sequences representing three 521 bit big endian integers are:

Parameter Name Value
x [1, 233, 41, 5, 15, 18, 79, 198, 188, 85, 199, 213, 57, 51, 101, 223, 157, 239, 74, 176, 194, 44, 178, 87, 152, 249, 52, 235, 4, 227, 198, 186, 227, 112, 26, 87, 167, 145, 14, 157, 129, 191, 54, 49, 89, 232, 235, 203, 21, 93, 99, 73, 244, 189, 182, 204, 248, 169, 76, 92, 89, 199, 170, 193, 1, 164]
y [0, 52, 166, 68, 14, 55, 103, 80, 210, 55, 31, 209, 189, 194, 200, 243, 183, 29, 47, 78, 229, 234, 52, 50, 200, 21, 204, 163, 21, 96, 254, 93, 147, 135, 236, 119, 75, 85, 131, 134, 48, 229, 203, 191, 90, 140, 190, 10, 145, 221, 0, 100, 198, 153, 154, 31, 110, 110, 103, 250, 221, 237, 228, 200, 200, 246]
d [1, 142, 105, 111, 176, 52, 80, 88, 129, 221, 17, 11, 72, 62, 184, 125, 50, 206, 73, 95, 227, 107, 55, 69, 237, 242, 216, 202, 228, 240, 242, 83, 159, 70, 21, 160, 233, 142, 171, 82, 179, 192, 197, 234, 196, 206, 7, 81, 133, 168, 231, 187, 71, 222, 172, 29, 29, 231, 123, 204, 246, 97, 53, 230, 61, 130]

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 octets of the ASCII representation of 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]

Concatenating the S array to the end of the R array and base64url encoding the result produces this value for the Encoded JWS Signature (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
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
  AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq
  wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp
  EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn

A.4.2. Decoding

Decoding the JWS requires base64url decoding the Encoded JWS Header, Encoded JWS Payload, and Encoded JWS Signature to produce the JWS Header, JWS Payload, and JWS Signature octet sequences. The octet sequence containing the UTF-8 representation of the JWS Header is decoded into the JWS Header string.

A.4.3. Validating

Since the alg parameter in the header is "ES512", we validate the ECDSA P-521 SHA-512 digital signature contained in the JWS Signature. If any of the validation steps fail, the JWS MUST be rejected.

First, we validate that the JWS Header string is legal JSON.

Validating the JWS Signature is similar to the previous example. First, we base64url decode the Encoded JWS Signature as in the previous examples but we then need to split the 132 member octet sequence that must result into two 66 octet sequences, the first R and the second S. We then pass (x, y), (R, S) and the octets of the ASCII representation of 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.

As explained in Section 3.4 of the JSON Web Algorithms (JWA) [JWA] specification, the use of the K value in ECDSA means that we cannot validate the correctness of the digital signature in the same way we validated the correctness of the HMAC. Instead, implementations MUST use an ECDSA validator to validate the digital signature.

A.5. Example Plaintext JWS

The following example JWS Header declares that the encoded object is a Plaintext JWS:

  {"alg":"none"}

Base64url encoding the octets of the UTF-8 representation of the JWS Header yields this Encoded JWS Header:

  eyJhbGciOiJub25lIn0

The JWS Payload used in this example, which follows, is the same as in the previous examples. Since the Encoded JWS Payload will therefore be the same, its computation is not repeated here.

  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}

The Encoded 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
  .

A.6. Example JWS Using JWS JSON Serialization

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 Encoded JWS Payload used in this example is the same as that used in the examples in Appendix A.2 (with line breaks for display purposes only):

  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

Two digital signatures are used in this example: both using RSASSA-PKCS-v1_5 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 a different key is used, which is provided in Appendix A.6.5; its computation follows the same procedure as the first, so it is not detailed here either, other than including the resulting Encoded JWS Signature value.

A.6.1. JWS Protected Header

The JWS Protected Header value used for both computations is:

  {"alg":"RS256"}

Base64url encoding these octets yields this Encoded JWS Header value:

  eyJhbGciOiJSUzI1NiJ9

A.6.2. JWS Per-Signature Unprotected Headers

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"}

A.6.3. Complete JWS Header Values

Combining the protected and per-signature header values supplied, the JWS Header values used for the first and second signatures respectively are:

  {"alg":"RS256",
   "kid":"2010-12-29"}

and:

  {"alg":"RS256",
   "kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}

A.6.4. Complete JWS JSON Serialization Representation

The complete JSON Web Signature JSON Serialization for these values is as follows (with line breaks for display purposes only):

  {"protected":"eyJhbGciOiJSUzI1NiJ9",
   "payload":
    "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
     tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
   "signatures":[
    {"header":
      {"kid":"2010-12-29"},
     "signature":
      "cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZ
       mh7AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjb
       KBYNX4BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHl
       b1L07Qe7K0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZES
       c6BfI7noOPqvhJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AX
       LIhWkWywlVmtVrBp0igcN_IoypGlUPQGe77Rw"},
    {"header":
      {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
     "signature":
      "m2nhGPQGjPEDIotJnzcnlhUZnXeg0xzLVbh6NZzthY8yU3klJYaENE1aLAUtL
       cq-TmEeYIr30ruGH2kNFqW4-oc7LcTQu9-7ItRhfi0kKeN1zNAAUemfNYXaXA
       1JayiiCl7m9ylhLKIsvdXhFvV7XDSbUMnVoO9Yu5_ROKOJMkeU6ywR8DDcHmu
       B2KcLMfpHn1FqnUnojxwfOg1Eqyb_ppeDTm9t_h8FoQgHqRpNgsTTvxI9vSPE
       ZrWTkSf_D4ci6p06DM_nE6FbptYF3ENHF8NpGgncv_D_h9AIrZU5-6ee2HB24
       jtN9qOHw2pkVrvhtxdsSJdeG6uJqiFs0ArwQQ"}]
  }

A.6.5. RSA Key Used for Second Signature

The values of the RSA key used for the second signature in this this example, presented as the octet sequences representing big endian integers are:

Parameter Name Value
Modulus [160, 120, 137, 109, 191, 13, 24, 29, 15, 217, 68, 35, 164, 152, 33, 179, 62, 22, 51, 134, 60, 228, 112, 172, 11, 62, 57, 16, 26, 162, 213, 250, 199, 183, 56, 103, 101, 172, 20, 178, 226, 124, 116, 135, 195, 195, 124, 91, 174, 65, 218, 196, 113, 82, 132, 161, 145, 71, 8, 117, 240, 109, 116, 40, 196, 26, 174, 135, 43, 175, 40, 166, 223, 157, 5, 188, 92, 7, 52, 219, 11, 157, 96, 99, 25, 65, 151, 108, 25, 104, 206, 147, 63, 1, 157, 154, 58, 111, 200, 251, 54, 202, 96, 220, 42, 196, 21, 252, 193, 58, 205, 44, 89, 217, 58, 164, 99, 3, 76, 195, 180, 76, 19, 103, 110, 26, 2, 122, 173, 211, 45, 218, 134, 212, 26, 198, 156, 110, 213, 139, 31, 135, 227, 43, 0, 45, 192, 39, 206, 176, 194, 154, 217, 10, 185, 227, 143, 142, 179, 117, 171, 238, 187, 88, 12, 185, 36, 110, 100, 76, 34, 39, 20, 145, 184, 44, 14, 100, 21, 77, 15, 82, 150, 53, 156, 46, 196, 231, 156, 152, 152, 85, 145, 184, 195, 213, 134, 107, 75, 10, 117, 233, 76, 215, 62, 205, 95, 170, 6, 234, 221, 139, 4, 241, 239, 203, 28, 32, 95, 192, 24, 164, 172, 132, 10, 193, 239, 45, 140, 153, 198, 140, 117, 17, 223, 12, 26, 5, 47, 223, 211, 151, 120, 15, 230, 60, 42, 51, 104, 119, 46, 41, 242, 177, 76, 33]
Exponent [1, 0, 1]
Private Exponent [118, 50, 242, 255, 124, 119, 87, 168, 168, 112, 223, 168, 229, 103, 13, 131, 170, 154, 205, 206, 245, 241, 74, 48, 223, 131, 48, 162, 245, 11, 182, 83, 167, 98, 4, 208, 220, 106, 25, 64, 254, 100, 175, 173, 4, 252, 108, 16, 87, 213, 184, 31, 116, 93, 84, 198, 113, 109, 2, 5, 101, 88, 41, 244, 145, 38, 26, 34, 4, 130, 91, 142, 55, 45, 192, 248, 210, 76, 152, 153, 51, 255, 242, 236, 107, 193, 13, 153, 25, 74, 66, 198, 224, 228, 254, 194, 136, 130, 168, 102, 170, 31, 253, 162, 142, 121, 170, 188, 103, 84, 57, 166, 142, 115, 220, 167, 19, 43, 110, 18, 197, 46, 56, 40, 186, 71, 188, 68, 152, 43, 159, 81, 123, 128, 103, 167, 243, 139, 188, 90, 36, 142, 151, 217, 213, 244, 149, 183, 9, 16, 149, 119, 233, 161, 201, 107, 151, 185, 157, 124, 238, 147, 50, 51, 170, 188, 190, 154, 92, 239, 46, 37, 178, 49, 74, 209, 220, 56, 19, 186, 34, 52, 152, 130, 86, 56, 237, 1, 186, 225, 244, 29, 248, 57, 21, 1, 10, 55, 176, 110, 145, 149, 4, 137, 13, 121, 236, 87, 186, 48, 218, 3, 78, 218, 2, 244, 95, 168, 218, 217, 247, 252, 81, 13, 22, 210, 219, 26, 149, 32, 217, 211, 144, 231, 104, 240, 69, 73, 237, 1, 14, 28, 161, 202, 222, 209, 156, 108, 27, 207, 126, 40, 77, 102, 93, 1]

Appendix B. "x5c" (X.509 Certificate Chain) Example

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
    hbGlDZXJ0IFZhbGlkYXRpb24gTmV0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIE
    luYy4xNTAzBgNVBAsTLFZhbGlDZXJ0IENsYXNzIDIgUG9saWN5IFZhbGlkYXRpb
    24gQXV0aG9yaXR5MSEwHwYDVQQDExhodHRwOi8vd3d3LnZhbGljZXJ0LmNvbS8x
    IDAeBgkqhkiG9w0BCQEWEWluZm9AdmFsaWNlcnQuY29tMB4XDTA0MDYyOTE3MDY
    yMFoXDTI0MDYyOTE3MDYyMFowYzELMAkGA1UEBhMCVVMxITAfBgNVBAoTGFRoZS
    BHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR28gRGFkZHkgQ2xhc3MgM
    iBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTCCASAwDQYJKoZIhvcNAQEBBQADggEN
    ADCCAQgCggEBAN6d1+pXGEmhW+vXX0iG6r7d/+TvZxz0ZWizV3GgXne77ZtJ6XC
    APVYYYwhv2vLM0D9/AlQiVBDYsoHUwHU9S3/Hd8M+eKsaA7Ugay9qK7HFiH7Eux
    6wwdhFJ2+qN1j3hybX2C32qRe3H3I2TqYXP2WYktsqbl2i/ojgC95/5Y0V4evLO
    tXiEqITLdiOr18SPaAIBQi2XKVlOARFmR6jYGB0xUGlcmIbYsUfb18aQr4CUWWo
    riMYavx4A6lNf4DD+qta/KFApMoZFv6yyO9ecw3ud72a9nmYvLEHZ6IVDd2gWMZ
    Eewo+YihfukEHU1jPEX44dMX4/7VpkI+EdOqXG68CAQOjggHhMIIB3TAdBgNVHQ
    4EFgQU0sSw0pHUTBFxs2HLPaH+3ahq1OMwgdIGA1UdIwSByjCBx6GBwaSBvjCBu
    zEkMCIGA1UEBxMbVmFsaUNlcnQgVmFsaWRhdGlvbiBOZXR3b3JrMRcwFQYDVQQK
    Ew5WYWxpQ2VydCwgSW5jLjE1MDMGA1UECxMsVmFsaUNlcnQgQ2xhc3MgMiBQb2x
    pY3kgVmFsaWRhdGlvbiBBdXRob3JpdHkxITAfBgNVBAMTGGh0dHA6Ly93d3cudm
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Appendix C. Notes on implementing base64url encoding without padding

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

Appendix D. Negative Test Case for "crit" Header Parameter

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.com/UNDEFINED that they do not understand. Any other similar input, in which the use of the value http://example.com/UNDEFINED is substituted for any other header parameter name not understood by the implementation, must also be rejected.

The JWS Header value for this JWS is:

  {"alg":"none",
   "crit":["http://example.com/UNDEFINED"],
   "http://example.com/UNDEFINED":true
  }

The complete JWS that must be rejected is as follows (with line breaks for display purposes only):

  eyJhbGciOiJub25lIiwNCiAiY3JpdCI6WyJodHRwOi8vZXhhbXBsZS5jb20vVU5ERU
  ZJTkVEIl0sDQogImh0dHA6Ly9leGFtcGxlLmNvbS9VTkRFRklORUQiOnRydWUNCn0.
  RkFJTA.

Appendix E. Acknowledgements

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.

Appendix F. Document History

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

-11

-10

-09

-08

-07

-06

-05

-04

-03

-02

-01

-00

Authors' Addresses

Michael B. Jones Microsoft EMail: mbj@microsoft.com URI: http://self-issued.info/
John Bradley Ping Identity EMail: ve7jtb@ve7jtb.com
Nat Sakimura Nomura Research Institute EMail: n-sakimura@nri.co.jp