OAuth Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track J. Bradley
Expires: January 15, 2014 Ping Identity
N. Sakimura
NRI
July 14, 2013
JSON Web Token (JWT)
draft-ietf-oauth-json-web-token-10
Abstract
JSON Web Token (JWT) is a compact URL-safe means of representing
claims to be transferred between two parties. The claims in a JWT
are encoded as a JavaScript Object Notation (JSON) object that is
used as the payload of a JSON Web Signature (JWS) structure or as the
plaintext of a JSON Web Encryption (JWE) structure, enabling the
claims to be digitally signed or MACed and/or encrypted.
The suggested pronunciation of JWT is the same as the English word
"jot".
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 15, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
Jones, et al. Expires January 15, 2014 [Page 1]
Internet-Draft JSON Web Token (JWT) July 2013
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. JSON Web Token (JWT) Overview . . . . . . . . . . . . . . . . 6
3.1. Example JWT . . . . . . . . . . . . . . . . . . . . . . . 6
4. JWT Claims . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Reserved Claim Names . . . . . . . . . . . . . . . . . . . 8
4.1.1. "iss" (Issuer) Claim . . . . . . . . . . . . . . . . . 8
4.1.2. "sub" (Subject) Claim . . . . . . . . . . . . . . . . 8
4.1.3. "aud" (Audience) Claim . . . . . . . . . . . . . . . . 8
4.1.4. "exp" (Expiration Time) Claim . . . . . . . . . . . . 9
4.1.5. "nbf" (Not Before) Claim . . . . . . . . . . . . . . . 9
4.1.6. "iat" (Issued At) Claim . . . . . . . . . . . . . . . 9
4.1.7. "jti" (JWT ID) Claim . . . . . . . . . . . . . . . . . 9
4.1.8. "typ" (Type) Claim . . . . . . . . . . . . . . . . . . 9
4.2. Public Claim Names . . . . . . . . . . . . . . . . . . . . 10
4.3. Private Claim Names . . . . . . . . . . . . . . . . . . . 10
5. JWT Header . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. "typ" (Type) Header Parameter . . . . . . . . . . . . . . 10
5.2. "cty" (Content Type) Header Parameter . . . . . . . . . . 11
5.3. Replicating Claims as Header Parameters . . . . . . . . . 11
6. Plaintext JWTs . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Example Plaintext JWT . . . . . . . . . . . . . . . . . . 12
7. Rules for Creating and Validating a JWT . . . . . . . . . . . 12
7.1. String Comparison Rules . . . . . . . . . . . . . . . . . 14
8. Cryptographic Algorithms . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9.1. JSON Web Token Claims Registry . . . . . . . . . . . . . . 15
9.1.1. Registration Template . . . . . . . . . . . . . . . . 16
9.1.2. Initial Registry Contents . . . . . . . . . . . . . . 16
9.2. Sub-Namespace Registration of
urn:ietf:params:oauth:token-type:jwt . . . . . . . . . . . 17
9.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 17
9.3. JSON Web Signature and Encryption Type Values
Registration . . . . . . . . . . . . . . . . . . . . . . . 17
9.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 17
9.4. Media Type Registration . . . . . . . . . . . . . . . . . 17
Jones, et al. Expires January 15, 2014 [Page 2]
Internet-Draft JSON Web Token (JWT) July 2013
9.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 17
9.5. Registration of JWE Header Parameter Names . . . . . . . . 18
9.5.1. Registry Contents . . . . . . . . . . . . . . . . . . 18
10. Security Considerations . . . . . . . . . . . . . . . . . . . 18
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Example Encrypted JWT . . . . . . . . . . . . . . . . 21
Appendix B. Relationship of JWTs to SAML Assertions . . . . . . . 22
Appendix C. Relationship of JWTs to Simple Web Tokens (SWTs) . . 22
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 23
Appendix E. Document History . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26
Jones, et al. Expires January 15, 2014 [Page 3]
Internet-Draft JSON Web Token (JWT) July 2013
1. Introduction
JSON Web Token (JWT) is a compact claims representation format
intended for space constrained environments such as HTTP
Authorization headers and URI query parameters. JWTs encode claims
to be transmitted as a JavaScript Object Notation (JSON) [RFC4627]
object that is used as the payload of a JSON Web Signature (JWS)
[JWS] structure or as the plaintext of a JSON Web Encryption (JWE)
[JWE] structure, enabling the claims to be digitally signed or MACed
and/or encrypted. JWTs are always represented using the JWS Compact
Serialization or the JWE Compact Serialization.
The suggested pronunciation of JWT is the same as the English word
"jot".
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 Token (JWT) A string representing a set of claims as a JSON
object that is encoded in a JWS or JWE, enabling the claims to be
digitally signed or MACed and/or encrypted.
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 of [JWS] for notes on implementing base64url
encoding without padding.)
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].
JWT Header A JSON Text Object that describes the cryptographic
operations applied to the JWT. When the JWT is digitally signed
or MACed, the JWT Header is a JWS Header. When the JWT is
encrypted, the JWT Header is a JWE Header.
Header Parameter Name The name of a member of the JWT Header.
Jones, et al. Expires January 15, 2014 [Page 4]
Internet-Draft JSON Web Token (JWT) July 2013
Header Parameter Value The value of a member of the JWT Header.
JWT Claims Set A JSON Text Object that contains the Claims conveyed
by the JWT.
Claim A piece of information asserted about a subject. A Claim is
represented as a name/value pair consisting of a Claim Name and a
Claim Value.
Claim Name The name portion of a Claim representation. A Claim Name
is always a string.
Claim Value The value portion of a Claim representation. A Claim
Value can be any JSON value.
Encoded JWT Header Base64url encoding of the JWT Header.
Nested JWT A JWT in which nested signing and/or encryption are
employed. In nested JWTs, a JWT is used as the payload or
plaintext value of an enclosing JWS or JWE structure,
respectively.
Plaintext JWT A JWT whose Claims are not integrity protected or
encrypted.
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.
IntDate A JSON numeric value representing the number of seconds from
1970-01-01T0:0:0Z UTC until the specified UTC date/time. See RFC
3339 [RFC3339] for details regarding date/times in general and UTC
in particular.
Jones, et al. Expires January 15, 2014 [Page 5]
Internet-Draft JSON Web Token (JWT) July 2013
3. JSON Web Token (JWT) Overview
JWTs represent a set of claims as a JSON object that is encoded in a
JWS and/or JWE structure. This JSON object is the JWT Claims Set. As
per RFC 4627 [RFC4627] Section 2.2, the JSON object consists of zero
or more name/value pairs (or members), where the names are strings
and the values are arbitrary JSON values. These members are the
claims represented by the JWT.
The member names within the JWT Claims Set are referred to as Claim
Names. The corresponding values are referred to as Claim Values.
The contents of the JWT Header describe the cryptographic operations
applied to the JWT Claims Set. If the JWT Header is a JWS Header, the
JWT is represented as a JWS, and the claims are digitally signed or
MACed, with the JWT Claims Set being the JWS Payload. If the JWT
Header is a JWE Header, the JWT is represented as a JWE, and the
claims are encrypted, with the JWT Claims Set being the input
Plaintext. A JWT may be enclosed in another JWE or JWS structure to
create a Nested JWT, enabling nested signing and encryption to be
performed.
A JWT is represented as a sequence of URL-safe parts separated by
period ('.') characters. Each part contains a base64url encoded
value. The number of parts in the JWT is dependent upon the
representation of the resulting JWS or JWE object using the JWS
Compact Serialization or the JWE Compact Serialization.
3.1. Example JWT
The following example JWT Header declares that the encoded object is
a JSON Web Token (JWT) and the JWT is MACed using the HMAC SHA-256
algorithm:
{"typ":"JWT",
"alg":"HS256"}
Base64url encoding the octets of the UTF-8 representation of the JWT
Header yields this Encoded JWS Header value, which is used as the
Encoded JWT Header:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
The following is an example of a JWT Claims Set:
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Jones, et al. Expires January 15, 2014 [Page 6]
Internet-Draft JSON Web Token (JWT) July 2013
The following octet sequence, which is the UTF-8 representation of
the JWT Claims Set 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):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly
9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
Signing the Encoded JWS Header and Encoded JWS Payload with the HMAC
SHA-256 algorithm and base64url encoding the signature in the manner
specified in [JWS], yields this Encoded JWS Signature:
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
Concatenating these parts in this order with period ('.') characters
between the parts yields this complete JWT (with line breaks for
display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
This computation is illustrated in more detail in Appendix A.1 of
[JWS]. See Appendix A for an example of an encrypted JWT.
4. JWT Claims
The JWT Claims Set represents a JSON object whose members are the
claims conveyed by the JWT. The Claim Names within a JWT Claims Set
MUST be unique; recipients MUST either reject JWTs with duplicate
Claim 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].
The set of claims that a JWT must contain to be considered valid is
context-dependent and is outside the scope of this specification.
Specific applications of JWTs will require implementations to
Jones, et al. Expires January 15, 2014 [Page 7]
Internet-Draft JSON Web Token (JWT) July 2013
understand and process some claims in particular ways. However, in
the absence of such requirements, all claims that are not understood
by implementations SHOULD be ignored.
There are three classes of JWT Claim Names: Reserved Claim Names,
Public Claim Names, and Private Claim Names.
4.1. Reserved Claim Names
The following Claim Names are reserved. None of the claims defined
below are intended to be mandatory to use, but rather, provide a
starting point for a set of useful, interoperable claims. All the
names are short because a core goal of JWTs is for the representation
to be compact. Additional reserved Claim Names can be defined via
the IANA JSON Web Token Claims registry Section 9.1.
4.1.1. "iss" (Issuer) Claim
The "iss" (issuer) claim identifies the principal that issued the
JWT. The processing of this claim is generally application specific.
The "iss" value is a case sensitive string containing a StringOrURI
value. Use of this claim is OPTIONAL.
4.1.2. "sub" (Subject) Claim
The "sub" (subject) claim identifies the principal that is the
subject of the JWT. The Claims in a JWT are normally statements
about the subject. The processing of this claim is generally
application specific. The "sub" value is a case sensitive string
containing a StringOrURI value. Use of this claim is OPTIONAL.
4.1.3. "aud" (Audience) Claim
The "aud" (audience) claim identifies the audiences that the JWT is
intended for. Each principal intended to process the JWT MUST
identify itself with a value in audience claim. If the principal
processing the claim does not identify itself with a value in the
"aud" claim, then the JWT MUST be rejected. In the general case, the
"aud" value is an array of case sensitive strings, each containing a
StringOrURI value. In the special case when the JWT has one
audience, the "aud" value MAY be a single case sensitive string
containing a StringOrURI value. The interpretation of audience
values is generally application specific. Use of this claim is
OPTIONAL.
Jones, et al. Expires January 15, 2014 [Page 8]
Internet-Draft JSON Web Token (JWT) July 2013
4.1.4. "exp" (Expiration Time) Claim
The "exp" (expiration time) claim identifies the expiration time on
or after which the JWT MUST NOT be accepted for processing. The
processing of the "exp" claim requires that the current date/time
MUST be before the expiration date/time listed in the "exp" claim.
Implementers MAY provide for some small leeway, usually no more than
a few minutes, to account for clock skew. Its value MUST be a number
containing an IntDate value. Use of this claim is OPTIONAL.
4.1.5. "nbf" (Not Before) Claim
The "nbf" (not before) claim identifies the time before which the JWT
MUST NOT be accepted for processing. The processing of the "nbf"
claim requires that the current date/time MUST be after or equal to
the not-before date/time listed in the "nbf" claim. Implementers MAY
provide for some small leeway, usually no more than a few minutes, to
account for clock skew. Its value MUST be a number containing an
IntDate value. Use of this claim is OPTIONAL.
4.1.6. "iat" (Issued At) Claim
The "iat" (issued at) claim identifies the time at which the JWT was
issued. This claim can be used to determine the age of the JWT. Its
value MUST be a number containing an IntDate value. Use of this
claim is OPTIONAL.
4.1.7. "jti" (JWT ID) Claim
The "jti" (JWT ID) claim provides a unique identifier for the JWT.
The identifier value MUST be assigned in a manner that ensures that
there is a negligible probability that the same value will be
accidentally assigned to a different data object. The "jti" claim
can be used to prevent the JWT from being replayed. The "jti" value
is a case sensitive string. Use of this claim is OPTIONAL.
4.1.8. "typ" (Type) Claim
The "typ" (type) claim MAY be used to declare a type for the contents
of this JWT Claims Set in an application-specific manner in contexts
where this is useful to the application. The "typ" value is a case
sensitive string. Use of this claim is OPTIONAL.
The values used for the "typ" claim come from the same value space as
the "typ" header parameter, with the same rules applying.
Jones, et al. Expires January 15, 2014 [Page 9]
Internet-Draft JSON Web Token (JWT) July 2013
4.2. Public Claim Names
Claim Names can be defined at will by those using JWTs. However, in
order to prevent collisions, any new Claim Name SHOULD either be
registered in the IANA JSON Web Token Claims registry Section 9.1 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 Claim Name.
4.3. Private Claim Names
A producer and consumer of a JWT MAY agree to use Claim 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. JWT Header
The members of the JSON object represented by the JWT Header describe
the cryptographic operations applied to the JWT and optionally,
additional properties of the JWT. The member names within the JWT
Header are referred to as Header Parameter Names. These names MUST
be unique; recipients MUST either reject JWTs 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]. The corresponding values are
referred to as Header Parameter Values.
JWS Header Parameters are defined by [JWS]. JWE Header Parameters
are defined by [JWE]. This specification further specifies the use
of the following header parameter in both the cases where the JWT is
a JWS and where it is a JWE.
5.1. "typ" (Type) Header Parameter
The "typ" (type) header parameter MAY be used to declare the type of
this JWT in an application-specific manner in contexts where this is
useful to the application. This parameter has no effect upon the JWT
processing. If present, it is RECOMMENDED that its value be either
"JWT" or "urn:ietf:params:oauth:token-type:jwt" to indicate that this
object is a JWT. The "typ" value is a case sensitive string. Use of
this header parameter is OPTIONAL.
Jones, et al. Expires January 15, 2014 [Page 10]
Internet-Draft JSON Web Token (JWT) July 2013
5.2. "cty" (Content Type) Header Parameter
The "cty" (content type) header parameter is used to declare
structural information about the JWT. Its value MUST be a string.
In the normal case where nested signing or encryption operations are
not employed, the use of this header parameter is NOT RECOMMENDED.
In the case that nested signing or encryption is employed, the use of
this header parameter is REQUIRED; in this case, the value MUST be
"JWT", to indicate that a Nested JWT is carried in this JWT.
The values used for the "cty" header parameter come from the same
value space as the "typ" header parameter, with the same rules
applying.
5.3. Replicating Claims as Header Parameters
In some applications using encrypted JWTs, it is useful to have an
unencrypted representation of some Claims. This might be used, for
instance, in application processing rules to determine whether and
how to process the JWT before it is decrypted.
This specification allows Claims present in the JWT Claims Set to be
replicated as Header Parameters in a JWT that is a JWE, as needed by
the application. If such replicated Claims are present, the
application receiving them SHOULD verify that their values are
identical. It is the responsibility of the application to ensure
that only claims that are safe to be transmitted in an unencrypted
manner are replicated as Header Parameter values in the JWT.
This specification reserves the "iss" (issuer) and "aud" (audience)
Header Parameter Names for the purpose of providing unencrypted
replicas of these Claims in encrypted JWTs for applications that need
them. Other specifications MAY similarly reserve other names that
are reserved Claim Names as Header Parameter Names, as needed.
6. Plaintext JWTs
To support use cases where the JWT content is secured by a means
other than a signature and/or encryption contained within the JWT
(such as a signature on a data structure containing the JWT), JWTs
MAY also be created without a signature or encryption. A plaintext
JWT is a JWS using the "none" JWS "alg" header parameter value
defined in JSON Web Algorithms (JWA) [JWA]; it is a JWS with the
empty string for its JWS Signature value.
Jones, et al. Expires January 15, 2014 [Page 11]
Internet-Draft JSON Web Token (JWT) July 2013
6.1. Example Plaintext JWT
The following example JWT Header declares that the encoded object is
a Plaintext JWT:
{"alg":"none"}
Base64url encoding the octets of the UTF-8 representation of the JWT
Header yields this Encoded JWT Header:
eyJhbGciOiJub25lIn0
The following is an example of a JWT Claims Set:
{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}
Base64url encoding the octets of the UTF-8 representation of the JWT
Claims Set yields this Encoded JWS Payload (with line breaks for
display purposes only):
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
The Encoded JWS Signature is the empty string.
Concatenating these parts in this order with period ('.') characters
between the parts yields this complete JWT (with line breaks for
display purposes only):
eyJhbGciOiJub25lIn0
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
7. Rules for Creating and Validating a JWT
To create a JWT, 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 a JWT Claims Set containing the desired claims. Note that
white space is explicitly allowed in the representation and no
canonicalization need be performed before encoding.
Jones, et al. Expires January 15, 2014 [Page 12]
Internet-Draft JSON Web Token (JWT) July 2013
2. Let the Message be the octets of the UTF-8 representation of the
JWT Claims Set.
3. Create a JWT Header containing the desired set of header
parameters. The JWT MUST conform to either the [JWS] or [JWE]
specifications. 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
JWT Header. Let this be the Encoded JWT Header.
5. Depending upon whether the JWT is a JWS or JWE, there are two
cases:
* If the JWT is a JWS, create a JWS using the JWT Header as the
JWS Header and the Message as the JWS Payload; all steps
specified in [JWS] for creating a JWS MUST be followed.
* Else, if the JWT is a JWE, create a JWE using the JWT Header
as the JWE Header and the Message as the JWE Plaintext; all
steps specified in [JWE] for creating a JWE MUST be followed.
6. If a nested signing or encryption operation will be performed,
let the Message be the JWS or JWE, and return to Step 3, using a
"cty" (content type) value of "JWT" in the new JWT Header created
in that step.
7. Otherwise, let the resulting JWT be the JWS or JWE.
When validating a JWT 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 JWT MUST be rejected for processing.
1. The JWT MUST contain at least one period ('.') character.
2. Let the Encoded JWT Header be the portion of the JWT before the
first period ('.') character.
3. The Encoded JWT Header MUST be successfully base64url decoded
following the restriction given in this specification that no
padding characters have been used.
4. The resulting JWT Header MUST be completely valid JSON syntax
conforming to RFC 4627 [RFC4627].
Jones, et al. Expires January 15, 2014 [Page 13]
Internet-Draft JSON Web Token (JWT) July 2013
5. The resulting JWT 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.
6. Determine whether the JWT is a JWS or a JWE by examining the
"alg" (algorithm) header value and optionally, the "enc"
(encryption method) header value, if present.
7. Depending upon whether the JWT is a JWS or JWE, there are two
cases:
* If the JWT is a JWS, all steps specified in [JWS] for
validating a JWS MUST be followed. Let the Message be the
result of base64url decoding the JWS Payload.
* Else, if the JWT is a JWE, all steps specified in [JWE] for
validating a JWE MUST be followed. Let the Message be the
JWE Plaintext.
8. If the JWT Header contains a "cty" (content type) value of
"JWT", then the Message is a JWT that was the subject of nested
signing or encryption operations. In this case, return to Step
1, using the Message as the JWT.
9. Otherwise, let the JWT Claims Set be the Message.
10. The JWT Claims Set MUST be completely valid JSON syntax
conforming to RFC 4627 [RFC4627].
7.1. String Comparison Rules
Processing a JWT 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 JWT Header to see if there is a matching Header
Parameter Name.
Comparisons between JSON strings and other Unicode strings MUST be
performed by comparing Unicode code points without normalization as
specified in the String Comparison Rules in Section 5.3 of [JWS].
8. Cryptographic Algorithms
JWTs use JSON Web Signature (JWS) [JWS] and JSON Web Encryption (JWE)
[JWE] to sign and/or encrypt the contents of the JWT.
Jones, et al. Expires January 15, 2014 [Page 14]
Internet-Draft JSON Web Token (JWT) July 2013
Of the JWA signing algorithms, only HMAC SHA-256 ("HS256") and "none"
MUST be implemented by conforming JWT implementations. It is
RECOMMENDED that implementations also support RSASSA-PKCS1-V1_5 with
the SHA-256 hash algorithm ("RS256") and ECDSA using the P-256 curve
and the SHA-256 hash algorithm ("ES256"). Support for other
algorithms and key sizes is OPTIONAL.
If an implementation provides encryption capabilities, of the JWA
encryption algorithms, only RSAES-PKCS1-V1_5 with 2048 bit keys
("RSA1_5"), AES Key Wrap with 128 and 256 bit keys ("A128KW" and
"A256KW"), and the composite authenticated encryption algorithm using
AES CBC and HMAC SHA-2 ("A128CBC-HS256" and "A256CBC-HS512") MUST be
implemented by conforming implementations. It is RECOMMENDED that
implementations also support using ECDH-ES to agree upon a key used
to wrap the Content Encryption Key ("ECDH-ES+A128KW" and
"ECDH-ES+A256KW") and AES in Galois/Counter Mode (GCM) with 128 bit
and 256 bit keys ("A128GCM" and "A256GCM"). Support for other
algorithms and key sizes is OPTIONAL.
9. IANA Considerations
9.1. JSON Web Token Claims Registry
This specification establishes the IANA JSON Web Token Claims
registry for reserved JWT Claim Names. The registry records the
reserved Claim Name and a reference to the specification that defines
it. This specification registers the Claim Names defined in
Section 4.1.
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: claims-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.
Jones, et al. Expires January 15, 2014 [Page 15]
Internet-Draft JSON Web Token (JWT) July 2013
IANA must only accept registry updates from the Designated Expert(s)
and should direct all requests for registration to the review mailing
list.
9.1.1. Registration Template
Claim 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.
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.
9.1.2. Initial Registry Contents
o Claim Name: "iss"
o Change Controller: IETF
o Specification Document(s): Section 4.1.1 of [[ this document ]]
o Claim Name: "sub"
o Change Controller: IETF
o Specification Document(s): Section 4.1.2 of [[ this document ]]
o Claim Name: "aud"
o Change Controller: IETF
o Specification Document(s): Section 4.1.3 of [[ this document ]]
o Claim Name: "exp"
o Change Controller: IETF
o Specification Document(s): Section 4.1.4 of [[ this document ]]
o Claim Name: "nbf"
o Change Controller: IETF
o Specification Document(s): Section 4.1.5 of [[ this document ]]
o Claim Name: "iat"
o Change Controller: IETF
Jones, et al. Expires January 15, 2014 [Page 16]
Internet-Draft JSON Web Token (JWT) July 2013
o Specification Document(s): Section 4.1.6 of [[ this document ]]
o Claim Name: "jti"
o Change Controller: IETF
o Specification Document(s): Section 4.1.7 of [[ this document ]]
o Claim Name: "typ"
o Change Controller: IETF
o Specification Document(s): Section 4.1.8 of [[ this document ]]
9.2. Sub-Namespace Registration of urn:ietf:params:oauth:token-type:jwt
9.2.1. Registry Contents
This specification registers the value "token-type:jwt" in the IANA
urn:ietf:params:oauth registry established in An IETF URN Sub-
Namespace for OAuth [RFC6755], which can be used to indicate that the
content is a JWT.
o URN: urn:ietf:params:oauth:token-type:jwt
o Common Name: JSON Web Token (JWT) Token Type
o Change Controller: IETF
o Specification Document(s): [[this document]]
9.3. JSON Web Signature and Encryption Type Values Registration
9.3.1. Registry Contents
This specification registers the "JWT" type value in the IANA JSON
Web Signature and Encryption Type Values registry [JWS], which can be
used to indicate that the content is a JWT.
o "typ" Header Parameter Value: "JWT"
o Abbreviation for MIME Type: application/jwt
o Change Controller: IETF
o Specification Document(s): Section 5.1 of [[ this document ]]
9.4. Media Type Registration
9.4.1. Registry Contents
This specification registers the "application/jwt" Media Type
[RFC2046] in the MIME Media Type registry [RFC4288], which can be
used to indicate that the content is a JWT.
o Type Name: application
Jones, et al. Expires January 15, 2014 [Page 17]
Internet-Draft JSON Web Token (JWT) July 2013
o Subtype Name: jwt
o Required Parameters: n/a
o Optional Parameters: n/a
o Encoding considerations: JWT values are encoded as a series of
base64url encoded values (some of which may be the empty string)
separated by period ('.') characters
o Security Considerations: See the Security Considerations section
of [[ this document ]]
o Interoperability Considerations: n/a
o Published Specification: [[ this document ]]
o Applications that use this media type: OpenID Connect, Mozilla
Persona, Salesforce, Google, numerous others
o Additional Information: Magic number(s): n/a, File extension(s):
n/a, Macintosh file type code(s): n/a
o Person & email address to contact for further information: Michael
B. Jones, mbj@microsoft.com
o Intended Usage: COMMON
o Restrictions on Usage: none
o Author: Michael B. Jones, mbj@microsoft.com
o Change Controller: IETF
9.5. Registration of JWE Header Parameter Names
This specification registers specific reserved Claim Names defined in
Section 4.1 in the IANA JSON Web Signature and Encryption Header
Parameters registry [JWS] for use by Claims replicated as Header
Parameters, per Section 5.3.
9.5.1. Registry Contents
o Header Parameter Name: "iss"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.1 of [[ this document ]]
o Header Parameter Name: "aud"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.3 of [[ this document ]]
10. Security Considerations
All of the security issues faced by any cryptographic application
must be faced by a JWT/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
Jones, et al. Expires January 15, 2014 [Page 18]
Internet-Draft JSON Web Token (JWT) July 2013
security considerations is beyond the scope of this document.
All the security considerations in the JWS specification also apply
to JWT, as do the JWE security considerations when encryption is
employed. In particular, the JWS JSON Security Considerations and
Unicode Comparison Security Considerations apply equally to the JWT
Claims Set in the same manner that they do to the JWS Header.
While syntactically, the signing and encryption operations for Nested
JWTs may be applied in any order, normally senders should sign the
message and then encrypt the result (thus encrypting the signature).
This prevents attacks in which the signature is stripped, leaving
just an encrypted message, as well as providing privacy for the
signer. Furthermore, signatures over encrypted text are not
considered valid in many jurisdictions.
Note that potential concerns about security issues related to the
order of signing and encryption operations are already addressed by
the underlying JWS and JWE specifications; in particular, because JWE
only supports the use of authenticated encryption algorithms,
cryptographic concerns about the potential need to sign after
encryption that apply in many contexts do not apply to this
specification.
11. References
11.1. Normative References
[ECMAScript]
Ecma International, "ECMAScript Language Specification,
5.1 Edition", ECMA 262, June 2011.
[JWA] Jones, M., "JSON Web Algorithms (JWA)",
draft-ietf-jose-json-web-algorithms (work in progress),
July 2013.
[JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
Encryption (JWE)", draft-ietf-jose-json-web-encryption
(work in progress), July 2013.
[JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", draft-ietf-jose-json-web-signature (work
in progress), July 2013.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
Jones, et al. Expires January 15, 2014 [Page 19]
Internet-Draft JSON Web Token (JWT) July 2013
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[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.
[RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
for OAuth", RFC 6755, October 2012.
11.2. Informative References
[CanvasApp]
Facebook, "Canvas Applications", 2010.
[JSS] Bradley, J. and N. Sakimura (editor), "JSON Simple Sign",
September 2010.
[MagicSignatures]
Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic
Signatures", January 2011.
[OASIS.saml-core-2.0-os]
Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocol for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-core-
2.0-os, March 2005.
[RFC3275] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup
Jones, et al. Expires January 15, 2014 [Page 20]
Internet-Draft JSON Web Token (JWT) July 2013
Language) XML-Signature Syntax and Processing", RFC 3275,
March 2002.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
July 2005.
[SWT] Hardt, D. and Y. Goland, "Simple Web Token (SWT)",
Version 0.9.5.1, November 2009.
[W3C.CR-xml11-20021015]
Cowan, J., "Extensible Markup Language (XML) 1.1", W3C
CR CR-xml11-20021015, October 2002.
[W3C.REC-xml-c14n-20010315]
Boyer, J., "Canonical XML Version 1.0", World Wide Web
Consortium Recommendation REC-xml-c14n-20010315,
March 2001,
<http://www.w3.org/TR/2001/REC-xml-c14n-20010315>.
Appendix A. Example Encrypted JWT
This example encrypts the same claims as used in Section 3.1 to the
recipient using RSAES-PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256.
The following example JWE Header (with line breaks for display
purposes only) declares that:
o the Content Encryption Key is encrypted to the recipient using the
RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256
algorithm to produce the Ciphertext.
{"alg":"RSA1_5","enc":"A128CBC-HS256"}
Other than using the octets of the UTF-8 representation of the JWT
Claims Set from Section 3.1 as the plaintext value, the computation
of this JWT is identical to the computation of the JWE in Appendix
A.2 of [JWE], including the keys used.
The final result in this example (with line breaks for display
purposes only) is:
Jones, et al. Expires January 15, 2014 [Page 21]
Internet-Draft JSON Web Token (JWT) July 2013
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
QR1Owv2ug2WyPBnbQrRARTeEk9kDO2w8qDcjiHnSJflSdv1iNqhWXaKH4MqAkQtM
oNfABIPJaZm0HaA415sv3aeuBWnD8J-Ui7Ah6cWafs3ZwwFKDFUUsWHSK-IPKxLG
TkND09XyjORj_CHAgOPJ-Sd8ONQRnJvWn_hXV1BNMHzUjPyYwEsRhDhzjAD26ima
sOTsgruobpYGoQcXUwFDn7moXPRfDE8-NoQX7N7ZYMmpUDkR-Cx9obNGwJQ3nM52
YCitxoQVPzjbl7WBuB7AohdBoZOdZ24WlN1lVIeh8v1K4krB8xgKvRU8kgFrEn_a
1rZgN5TiysnmzTROF869lQ.
AxY8DCtDaGlsbGljb3RoZQ.
MKOle7UQrG6nSxTLX6Mqwt0orbHvAKeWnDYvpIAeZ72deHxz3roJDXQyhxx0wKaM
HDjUEOKIwrtkHthpqEanSBNYHZgmNOV7sln1Eu9g3J8.
fiK51VwhsxJ-siBMR-YFiA
Appendix B. Relationship of JWTs to SAML Assertions
SAML 2.0 [OASIS.saml-core-2.0-os] provides a standard for creating
security tokens with greater expressivity and more security options
than supported by JWTs. However, the cost of this flexibility and
expressiveness is both size and complexity. SAML's use of XML
[W3C.CR-xml11-20021015] and XML DSIG [RFC3275] contributes to the
size of SAML assertions; its use of XML and especially XML
Canonicalization [W3C.REC-xml-c14n-20010315] contributes to their
complexity.
JWTs are intended to provide a simple security token format that is
small enough to fit into HTTP headers and query arguments in URIs.
It does this by supporting a much simpler token model than SAML and
using the JSON [RFC4627] object encoding syntax. It also supports
securing tokens using Message Authentication Codes (MACs) and digital
signatures using a smaller (and less flexible) format than XML DSIG.
Therefore, while JWTs can do some of the things SAML assertions do,
JWTs are not intended as a full replacement for SAML assertions, but
rather as a token format to be used when ease of implementation or
compactness are considerations.
SAML Assertions are always statements made by an entity about a
subject. JWTs are often used in the same manner, with the entity
making the statements being represented by the "iss" (issuer) claim,
and the subject being represented by the "sub" (subject) claim.
However, with these claims being optional, other uses of the JWT
format are also permitted.
Appendix C. Relationship of JWTs to Simple Web Tokens (SWTs)
Both JWTs and Simple Web Tokens SWT [SWT], at their core, enable sets
of claims to be communicated between applications. For SWTs, both
Jones, et al. Expires January 15, 2014 [Page 22]
Internet-Draft JSON Web Token (JWT) July 2013
the claim names and claim values are strings. For JWTs, while claim
names are strings, claim values can be any JSON type. Both token
types offer cryptographic protection of their content: SWTs with HMAC
SHA-256 and JWTs with a choice of algorithms, including signature,
MAC, and encryption algorithms.
Appendix D. Acknowledgements
The authors acknowledge that the design of JWTs was intentionally
influenced by the design and simplicity of Simple Web Tokens [SWT]
and ideas for JSON tokens that Dick Hardt discussed within the OpenID
community.
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.
This specification is the work of the OAuth 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, Prateek Mishra, Tony Nadalin, Axel Nennker,
John Panzer, Emmanuel Raviart, David Recordon, Eric Rescorla, Jim
Schaad, Paul Tarjan, Hannes Tschofenig, and Sean Turner.
Hannes Tschofenig and Derek Atkins chaired the OAuth working group
and Sean Turner and Stephen Farrell served as Security area directors
during the creation of this specification.
Appendix E. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-10
o Allowed Claims to be replicated as Header Parameters in encrypted
JWTs as needed by applications that require an unencrypted
representation of specific Claims.
-09
o Clarified that the "typ" header parameter is used in an
application-specific manner and has no effect upon the JWT
Jones, et al. Expires January 15, 2014 [Page 23]
Internet-Draft JSON Web Token (JWT) July 2013
processing.
o Stated that recipients MUST either reject JWTs with duplicate
Header Parameter Names or with duplicate Claim Names or use a JSON
parser that returns only the lexically last duplicate member name.
-08
o Tracked a change to how JWEs are computed (which only affected the
example encrypted JWT value).
-07
o Defined that the default action for claims that are not understood
is to ignore them unless otherwise specified by applications.
o Changed from using the term "byte" to "octet" when referring to 8
bit values.
o Tracked encryption computation changes in the JWE specification.
-06
o Changed the name of the "prn" claim to "sub" (subject) both to
more closely align with SAML name usage and to use a more
intuitive name.
o Allow JWTs to have multiple audiences.
o Applied editorial improvements suggested by Jeff Hodges, Prateek
Mishra, and Hannes Tschofenig. Many of these simplified the
terminology used.
o Explained why Nested JWTs should be signed and then encrypted.
o Clarified statements of the form "This claim is OPTIONAL" to "Use
of this claim is OPTIONAL".
o Referenced String Comparison Rules in JWS.
o Added seriesInfo information to Internet Draft references.
-05
o Updated values for example AES CBC calculations.
-04
Jones, et al. Expires January 15, 2014 [Page 24]
Internet-Draft JSON Web Token (JWT) July 2013
o Promoted Initialization Vector from being a header parameter to
being a top-level JWE element. This saves approximately 16 bytes
in the compact serialization, which is a significant savings for
some use cases. Promoting the Initialization Vector out of the
header also avoids repeating this shared value in the JSON
serialization.
o Applied changes made by the RFC Editor to RFC 6749's registry
language to this specification.
o Reference RFC 6755 -- An IETF URN Sub-Namespace for OAuth.
-03
o Added statement that "StringOrURI values are compared as case-
sensitive strings with no transformations or canonicalizations
applied".
o Indented artwork elements to better distinguish them from the body
text.
-02
o Added an example of an encrypted JWT.
o Added this language to Registration Templates: "This name is case
sensitive. Names that match other registered names in a case
insensitive manner SHOULD NOT be accepted."
o Applied editorial suggestions.
-01
o Added the "cty" (content type) header parameter for declaring type
information about the secured content, as opposed to the "typ"
(type) header parameter, which declares type information about
this object. This significantly simplified nested JWTs.
o Moved description of how to determine whether a header is for a
JWS or a JWE from the JWT spec to the JWE spec.
o Changed registration requirements from RFC Required to
Specification Required with Expert Review.
o Added Registration Template sections for defined registries.
o Added Registry Contents sections to populate registry values.
Jones, et al. Expires January 15, 2014 [Page 25]
Internet-Draft JSON Web Token (JWT) July 2013
o Added "Collision Resistant Namespace" to the terminology section.
o Numerous editorial improvements.
-00
o Created the initial IETF draft based upon
draft-jones-json-web-token-10 with no normative changes.
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
Jones, et al. Expires January 15, 2014 [Page 26]
