JSON Web Token (JWT)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jp
Security
OAuth Working GroupRFCRequest for CommentsI-DInternet-DraftAssertionClaimSimple Web TokenSecurity TokenSWTJavaScript Object NotationJSONJSON Web TokenJWTJSON Web SignatureJWSJSON Web EncryptionJWEJSON Web KeyJWKJSON Web AlgorithmsJWA
JSON Web Token (JWT) is a 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 digitally signed or MACed using JSON
Web Signature (JWS) and/or encrypted using JSON Web Encryption
(JWE).
The suggested pronunciation of JWT is the same as the English
word "jot".
JSON Web Token (JWT) is a compact token 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)
object that is base64url encoded
and digitally signed or MACed and/or encrypted. Signing and MACing is
performed using JSON Web Signature (JWS) .
Encryption is performed using
JSON Web Encryption (JWE) .
The suggested pronunciation of JWT is the same as the English
word "jot".
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 .
A string consisting of multiple parts, the first being the
Encoded JWT Header, plus additional parts depending upon
the contents of the header, with the parts being separated
by period ('.') characters, and each part containing
base64url encoded content.
A string representing a JSON 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.
The name of a member of the JSON object representing a
JWT Header.
The value of a member of the JSON object representing a
JWT Header.
A string representing a JSON object that
contains the claims conveyed by the JWT.
When the JWT is digitally signed or MACed, the bytes of the UTF-8 representation of the
JWT Claims Set are base64url encoded to create the Encoded JWS Payload.
When the JWT is encrypted, the bytes of the UTF-8 representation of the
JWT Claims Set are used as the JWE Plaintext.
The name of a member of the JSON object representing a
JWT Claims Set.
The value of a member of the JSON object representing a
JWT Claims Set.
Base64url encoding of the bytes of the
UTF-8
representation of the JWT Header.
For the purposes of this specification, this term always
refers to the URL- and filename-safe Base64 encoding
described in RFC 4648,
Section 5, with the (non URL-safe) '=' padding characters
omitted, as permitted by Section 3.2. (See Appendix C of
for notes on implementing base64url
encoding without padding.)
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)
.
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.
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
.
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 for details
regarding date/times in general and UTC in particular.
JWTs represent a set of claims as a JSON object that is
base64url encoded and digitally signed or MACed and/or
encrypted. The JWT Claims Set represents this JSON object.
As per RFC 4627
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 bytes of the UTF-8 representation of the JWT Claims Set
are digitally signed or MACed in the manner described in JSON Web Signature (JWS)
and/or encrypted in the manner described
in JSON Web Encryption (JWE) .
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 claims are digitally signed or MACed.
If the JWT Header is a JWE Header, the claims are encrypted.
A JWT is represented as a JWS or JWE. The number of parts is
dependent upon the representation of the resulting JWS or JWE.
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:
Base64url encoding the bytes of the UTF-8 representation of
the JWT Header yields this Encoded JWS Header value,
which is used as the Encoded JWT Header:
The following is an example of a JWT Claims Set:
Base64url encoding the bytes of the UTF-8 representation of
the JSON Claims Set yields this Encoded JWS Payload
(with line breaks for display purposes only):
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 ,
yields this Encoded JWS Signature:
Concatenating these parts in this order
with period characters between the
parts yields this complete JWT (with line breaks for
display purposes only):
This computation is illustrated in more detail in , Appendix A.1.
The JWT Claims Set represents a JSON object whose members
are the claims conveyed by the JWT.
The Claim Names within this object MUST be unique;
JWTs with duplicate Claim Names MUST be rejected.
Note however, that the set of claims that a
JWT must contain to be considered valid is context-dependent
and is outside the scope of this specification. When used in
a security-related context, implementations MUST understand
and support all of the claims present; otherwise, the JWT MUST
be rejected for processing.
There are three classes of JWT Claim Names: Reserved Claim
Names, Public Claim Names, and Private Claim Names.
The following claim names are reserved. None of the claims
defined below are intended to be mandatory, 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 tokens to be compact.
Additional reserved claim names MAY be defined via the
IANA JSON Web Token Claims registry .
The exp (expiration time)
claim identifies the expiration time on or after which the
token 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.
This claim is OPTIONAL.
The nbf (not before) claim
identifies the time before which the token 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.
This claim is OPTIONAL.
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 token.
Its value MUST be a number containing an IntDate value.
This claim is OPTIONAL.
The iss (issuer) claim
identifies the principal that issued the JWT. The
processing of this claim is generally application
specific.
The iss value is case sensitive.
Its value MUST be a string containing a StringOrURI value.
This claim is OPTIONAL.
The aud (audience) claim
identifies the audience that the JWT is intended for. The
principal intended to process the JWT MUST be identified
with the value of the audience claim. If the principal
processing the claim does not identify itself with the
identifier in the aud claim
value then the JWT MUST be rejected. The interpretation
of the audience value is generally
application specific.
The aud value is case sensitive.
Its value MUST be a string containing a StringOrURI value.
This claim is OPTIONAL.
The prn (principal) claim
identifies the subject of the JWT. The processing of this
claim is generally application specific.
The prn value is case sensitive.
Its value MUST be a string containing a StringOrURI value.
This claim is OPTIONAL.
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 case sensitive.
Its value MUST be a string.
This claim is OPTIONAL.
The typ (type) claim is used
to declare a type for the contents of this JWT Claims Set.
The typ value is case sensitive.
Its value MUST be a string.
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.
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 or be
a URI that contains a Collision Resistant Namespace.
A producer and consumer of a JWT may agree to any claim
name that is not a Reserved Name or a Public Name . Unlike Public Names,
these private names are subject to collision and should be
used with caution.
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;
JWTs with duplicate Header Parameter Names MUST be rejected.
The corresponding values are referred to as Header Parameter Values.
Implementations MUST understand the entire contents of the
header; otherwise, the JWT MUST be rejected for processing.
JWS Header Parameters are defined by .
JWE Header Parameters are defined by .
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.
The typ (type) header parameter
is used to declare the type of this object.
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 case sensitive.
Its value MUST be a string.
This header parameter is OPTIONAL.
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.
To support use cases where the JWT content is secured by a
means other than a signature and/or encryption contained
within the token (such as a signature on a data structure
containing the token), 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) ; it is a
JWS with an empty JWS Signature value.
The following example JWT Header declares that the
encoded object is a Plaintext JWT:
Base64url encoding the bytes of the UTF-8 representation of
the JWT Header yields this Encoded JWT Header:
The following is an example of a JWT Claims Set:
Base64url encoding the bytes of the UTF-8 representation of
the JSON Claims Set yields this Encoded JWS Payload
(with line breaks for display purposes only):
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):
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.
Create a JWT Claims Set containing the desired claims.
Note that white space is explicitly allowed in the
representation and no canonicalization is performed before
encoding.
Let the Message be the bytes of the UTF-8 representation
of the JWT Claims Set.
Create a JWT Header containing the desired set of header
parameters. The JWT
MUST conform to either the or specifications.
Note that white
space is explicitly allowed in the representation and no
canonicalization is performed before encoding.
Base64url encode the bytes of the UTF-8 representation of
the JWT Header. Let this be the Encoded JWT Header.
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
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 for creating a JWE MUST be followed.
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.
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 token MUST be
rejected for processing.
The JWT MUST contain at least one period character.
Let the Encoded JWT Header be the portion of the JWT
before the first period character.
The Encoded JWT Header MUST be successfully base64url
decoded following the restriction given in this
specification that no padding characters have been used.
The resulting JWT Header MUST be completely valid JSON syntax
conforming to RFC 4627.
The resulting JWT Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported.
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.
Depending upon whether the JWT is a JWS or JWE,
there are two cases:
If the JWT is a JWS, all steps specified in 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 for validating a JWE MUST be followed.
Let the Message be the JWE Plaintext.
If the JWT Header contains a cty (content type)
value of "JWT",
then the Message contains 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.
Otherwise, let the JWT Claims Set be the Message.
The JWT Claims Set MUST be completely valid
JSON syntax conforming to RFC
4627.
When used in a security-related context, the
JWT Claims Set MUST be validated to only include claims
whose syntax and semantics are both understood and
supported.
Processing a JWT inevitably requires comparing known strings
to values in the token. 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. 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:
Remove any JSON applied escaping to produce an array of
Unicode code points.
Unicode Normalization MUST NOT
be applied at any point to either the JSON string or to
the string it is to be compared against.
Comparisons between the two strings MUST be performed as a
Unicode code point to code point equality comparison.
JWTs use JSON Web Signature (JWS) and
JSON Web Encryption (JWE) to sign and/or
encrypt the contents of the JWT.
Of the JWS signing algorithms, only HMAC SHA-256 and none MUST be
implemented by conforming JWT implementations. It is
RECOMMENDED that implementations also support the RSA SHA-256
and ECDSA P-256 SHA-256 algorithms. Support for other
algorithms and key sizes is OPTIONAL.
If an implementation provides encryption capabilities,
of the JWE encryption algorithms, only RSA-PKCS1-1.5 with 2048 bit keys,
AES-128-KW, AES-256-KW,
AES-128-CBC, and AES-256-CBC MUST be implemented by conforming
implementations. It is RECOMMENDED that implementations also
support ECDH-ES with 256 bit keys, AES-128-GCM, and
AES-256-GCM. Support for other algorithms and key sizes is
OPTIONAL.
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 .
Values are registered with a Specification Required
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.
IANA must only accept registry updates from the Designated Expert(s), and should direct
all requests for registration to the review mailing list.
The name requested (e.g., "example").
For standards-track RFCs, state "IETF". For others, give the name of the
responsible party. Other details (e.g., postal address, e-mail address, home page
URI) may also be included.
Reference to the document that specifies the parameter, preferably including a URI that
can be used to retrieve a copy of the document. An indication of the relevant
sections may also be included, but is not required.
Claim Name: exp
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: nbf
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: iat
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: iss
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: aud
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: prn
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: jti
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Claim Name: typ
Change Controller: IETF
Specification Document(s): of [[ this document ]]
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.
URN: urn:ietf:params:oauth:token-type:jwtCommon Name: JSON Web Token (JWT) Token TypeChange Controller: IETFSpecification Document(s): [[this document]]
This specification registers the JWT
type value in the
IANA JSON Web Signature and Encryption Type Values registry :
"typ" Header Parameter Value: JWT
Abbreviation for MIME Type: application/jwt
Change Controller: IETF
Specification Document(s): of [[ this document ]]
This specification registers the application/jwt Media Type
in the MIME Media Type registry
to indicate that the content is a JWT.
Type Name: application
Subtype Name: jwt
Required Parameters: n/a
Optional Parameters: n/a
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
Security Considerations: See the Security Considerations section of this document
Interoperability Considerations: n/a
Published Specification: [[ this document ]]
Applications that use this media type:
OpenID Connect, Mozilla Browser ID, Salesforce, Google, numerous others
Additional Information:
Magic number(s): n/a,
File extension(s): n/a,
Macintosh file type code(s): n/a
Person & email address to contact for further information:
Michael B. Jones, mbj@microsoft.com
Intended Usage: COMMON
Restrictions on Usage: none
Author: Michael B. Jones, mbj@microsoft.com
Change Controller: IETF
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 key, 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 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.
[[ to be removed by the RFC editor before publication as an RFC ]]
The following items remain to be considered or done in this draft:
Provide an example of an encrypted JWT.
Unicode Normalization Formsmarkdavis@google.comken@unicode.orgJSON Web Signature (JWS)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jpJSON Web Encryption (JWE)Microsoftmbj@microsoft.comhttp://self-issued.info/RTFM, Inc.ekr@rtfm.comCisco Systems, Inc.jhildebr@cisco.comJSON Web Algorithms (JWA)Microsoftmbj@microsoft.comhttp://self-issued.info/Simple Web Token (SWT)Magic SignaturesJSON Simple SignindependentNomura Research InstituteCanvas ApplicationsSAML 2.0 provides
a standard for creating tokens with much greater expressivity
and more security options than supported by JWTs. However, the
cost of this flexibility and expressiveness is both size and
complexity. In addition, SAML's use of XML and XML DSIG only contributes to the size
of SAML tokens.
JWTs are intended to provide a simple 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
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 tokens
do, JWTs are not intended as a full replacement for SAML
tokens, but rather as a compromise token format to be used
when space is at a premium.
Both JWTs and Simple Web Tokens SWT,
at their core, enable sets of claims to be communicated
between applications. For SWTs, both 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
HMAC SHA-256, RSA SHA-256, and ECDSA P-256 SHA-256.
The authors acknowledge that the design of JWTs was
intentionally influenced by the design and simplicity of Simple Web Tokens and ideas for JSON
tokens that Dick Hardt discussed within the OpenID community.
Solutions for signing JSON content were previously explored by
Magic Signatures, JSON Simple Sign, and Canvas Applications, all of which
influenced this draft.
Dirk Balfanz, Yaron Y. Goland, John Panzer, and Paul Tarjan
all made significant contributions to the design of this
specification.
[[ to be removed by the RFC editor before publication as an RFC ]]
-01
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.
Moved description of how to determine whether a header is
for a JWS or a JWE from the JWT spec to the JWE spec.
Changed registration requirements from RFC Required to
Specification Required with Expert Review.
Added Registration Template sections for defined registries.
Added Registry Contents sections to populate registry values.
Added "Collision Resistant Namespace" to the terminology section.
Numerous editorial improvements.
-00
Created the initial IETF draft based upon
draft-jones-json-web-token-10 with no normative
changes.