| JOSE Working Group | M.B. Jones |
| Internet-Draft | Microsoft |
| Intended status: Standards Track | J. Bradley |
| Expires: January 16, 2014 | Ping Identity |
| N. Sakimura | |
| NRI | |
| July 15, 2013 |
JSON Web Signature (JWS)
draft-ietf-jose-json-web-signature-13
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.
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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.
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].
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 7.2.
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.
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}
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 JWS Payload yields this 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.
The members of the JSON object(s) representing 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; 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: Reserved Header Parameter Names, Public Header Parameter Names, and Private 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 8.1. 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.
The alg (algorithm) header parameter identifies a cryptographic algorithm used to secure the JWS. The recipient MUST reject the JWS 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 [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.
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 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 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 8.1.
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.
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.
The typ (type) header parameter MAY be used to declare the type of this complete JWS object in an application-specific manner in contexts where this is useful to the application. This parameter has no effect upon the JWS processing. The type value JOSE MAY be used to indicate that this object is a JWS or JWE using the JWS Compact Serialization or the JWE Compact Serialization. The type value JOSE+JSON MAY be used to indicate that this object is a JWS or JWE using the JWS JSON Serialization or the JWE 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 8.2 or be a value that contains a Collision Resistant Namespace.
The cty (content type) header parameter MAY be used to declare the type of the secured content (the payload) in an application-specific manner in contexts where this is useful to the application. This parameter has no effect upon the JWS processing. 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.
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 ]] or by [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 [[ this specification ]] or by [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 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
}
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 8.1 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.
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.
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 JWS MUST be rejected.
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:
Also, see the JSON security considerations in Section 9.2 and the Unicode security considerations in Section 9.3.
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, 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.
JWS objects use one of two serializations, the JWS Compact Serialization or the JWS JSON Serialization. The JWS Compact Serialization is mandatory to implement. Implementation of the JWS JSON Serialization is OPTIONAL.
The JWS Compact Serialization represents digitally signed or MACed content as a compact URL-safe string. This string 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. Only one signature/MAC is supported by the JWS Compact 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:
{
"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>"}],
}
Of these members, 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.
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 corresponding protected and 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 for that signature/MAC computation (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.
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.
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.
This specification registers the Header Parameter Names defined in Section 4.1 in this 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.
This specification registers the JOSE and JOSE+JSON type values in this registry:
This specification registers the application/jose Media Type [RFC2046] in the MIME Media Type registry [RFC4288], 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 Type 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 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; 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 2.2 "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 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.
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].
| [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, July 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, July 2013. |
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.
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 JWS Payload yields this 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 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 octets of the ASCII representation of the JWS Signing Input with this key yields this 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 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
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.
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.
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]
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 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
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.
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.
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]
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 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
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.
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.
The JWS Header for this example differs from the previous example because different ECDSA curves and hash functions 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 this 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]
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 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
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.
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.
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 .
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 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"}
Base64url encoding these octets yields this Encoded JWS Header value:
eyJhbGciOiJSUzI1NiJ9
The JWS Protected Header value used for the second signature is:
{"alg":"ES256"}
Base64url encoding these octets yields this Encoded JWS Header 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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",
"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
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 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.
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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