JSON Web Signature (JWS)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jp
Security
JOSE Working GroupRFCRequest for CommentsI-DInternet-DraftJavaScript Object NotationJSONJSON Web TokenJWTJSON Web SignatureJWSJSON Web EncryptionJWEJSON Web KeyJWKJSON Web AlgorithmsJWA
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.
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.
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) specification.
Related encryption capabilities are described in the separate
JSON Web Encryption (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 .
A data structure representing a digitally signed or MACed message.
The structure represents three values:
the JWS Header,
the JWS Payload, and
the JWS Signature.
A UTF-8
encoded text string representing a JSON object;
the syntax of JSON objects is defined in
Section 2.2 of .
A JSON Text Object
(or JSON Text Objects, when using the JWS JSON Serialization)
that describes the
digital signature or MAC operation applied to
create the JWS Signature value.
The members of the JWS Header object(s) are Header Parameters.
The sequence of octets to be secured -- a.k.a., the message.
The payload can contain an arbitrary sequence of octets.
A sequence of octets containing the cryptographic material that
ensures the integrity of
the JWS Protected Header
and the JWS Payload.
The JWS Signature value is a digital signature or MAC value
calculated over the JWS Signing Input using the parameters
specified in the JWS Header.
A JSON Text Object that contains the portion of the
JWS Header that is integrity protected.
For the JWS Compact Serialization, this comprises the entire JWS Header.
For the JWS JSON Serialization, this is one component of the JWS Header.
A name/value pair that is member of the JWS Header.
The name of a member of the JWS Header.
The value of a member of the JWS Header.
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 for notes on implementing
base64url encoding without padding.)
Base64url encoding of the JWS Protected Header.
Base64url encoding of the JWS Payload.
Base64url encoding of the JWS Signature.
The concatenation of the Encoded JWS Header, a period ('.')
character, and the Encoded JWS Payload.
A representation of the JWS as the concatenation of
the Encoded JWS Header,
the Encoded JWS Payload, and
the Encoded JWS Signature
in that order, with the three strings being separated
by two period ('.') characters.
This representation is compact and URL-safe.
A representation of the JWS as a JSON structure containing
JWS Header,
Encoded JWS Payload, and
Encoded JWS Signature values.
Unlike the JWS Compact Serialization,
the JWS JSON Serialization
enables multiple digital signatures and/or MACs to
be applied to the same content.
This representation is neither compact nor URL-safe.
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
.
StringOrURI values are compared as case-sensitive strings
with no transformations or canonicalizations applied.
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
.
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)
and the JWS Header and the JWS Payload are
secured using the HMAC SHA-256 algorithm:
Base64url encoding the octets of the UTF-8 representation of
the JWS Header yields this Encoded JWS Header value:
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.)
Base64url encoding the octets of the UTF-8 representation of the JSON
object yields the following Encoded JWS Payload
(with line breaks for display purposes only):
Computing the HMAC of the octets of the ASCII
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
and base64url encoding the result
yields this Encoded JWS Signature value:
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):
This computation is illustrated in more detail in .
See for additional examples.
The members of the JSON object(s) represented by the JWS Header describe the
digital signature or MAC applied to the
Encoded JWS Header and the Encoded JWS Payload and optionally
additional properties of the JWS.
The Header Parameter Names within the JWS Header MUST be unique;
JWSs with duplicate Header Parameter Names MUST be rejected.
Implementations are required to understand
the specific header parameters defined by this specification
that are designated as "MUST be understood"
and process them in the manner defined in this specification.
All other header parameters defined by this specification that
are not so designated MUST be ignored when not understood.
Unless listed as a critical header parameter, per ,
all other header parameters MUST be ignored when not understood.
There are three classes of Header Parameter Names:
Reserved Header Parameter Names, Public Header Parameter Names,
and Private Header Parameter Names.
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
.
As indicated by the common registry, JWSs and JWEs share a
common header parameter space; when a parameter is used by
both specifications, its usage must be compatible
between the specifications.
The alg (algorithm) header
parameter identifies the cryptographic algorithm used to
secure the JWS.
The algorithm specified by the alg value
MUST be supported by the implementation
and there MUST be a key for use with that algorithm associated with the
party that digitally signed or MACed the content
or the JWS MUST be rejected.
alg values SHOULD either be
registered in the IANA
JSON Web Signature and Encryption Algorithms registry
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
;
the initial contents of this registry are the values defined in
Section 3.1 of the
JSON Web Algorithms (JWA) specification.
The jku (JWK Set URL)
header parameter is a URI 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) .
The protocol used to acquire the resource MUST provide
integrity protection; an HTTP GET request to retrieve the
certificate MUST use TLS ;
the identity of the server MUST be validated, as per
Section 3.1 of HTTP Over TLS .
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 .
Use of this header parameter is OPTIONAL.
The x5u (X.509 URL) header
parameter is a URI that refers to a resource for
the X.509 public key certificate or certificate chain
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 in PEM encoded form
.
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 ;
the identity of the server MUST be validated, as per
Section 3.1 of HTTP Over TLS .
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
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 .
The x5c (X.509 Certificate Chain)
header parameter contains the X.509 public key
certificate or certificate chain
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
( Section 4 -- not base64url encoded)
DER 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 and reject the JWS if any
validation failure occurs.
Use of this header parameter is OPTIONAL.
See 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 is used to declare the type of this object.
The type value JWS is used
to indicate that this object is a JWS using the JWS Compact Serialization.
The type value JWS+JSON is used
to indicate that this object is a JWS using the JWS JSON Serialization.
Other type values MAY be used, and if not understood, SHOULD be ignored.
The typ value is a case sensitive string.
Use of this header parameter is OPTIONAL.
MIME Media Type
values MAY be used as typ values.
typ values SHOULD either be
registered in the IANA
JSON Web Signature and Encryption Type Values registry
or be
a value that contains a Collision Resistant Namespace.
The cty (content type) header
parameter is used to declare the type of the secured
content (the Payload).
For example, the JSON Web Token (JWT)
specification uses the cty value
JWT
to indicate that the Payload is a JSON Web Token (JWT).
Content type values that are not understood SHOULD be ignored.
The cty value is a case sensitive string.
Use of this header parameter is OPTIONAL.
The values used for the cty
header parameter come from the same value space as the
typ header parameter,
with the same rules applying.
The crit (critical) header parameter
indicates that extensions to [[ this specification ]] are being used
that MUST be understood and processed.
Its value is an array listing the header parameter names defined
by those extensions that are used in the JWS Header.
If any of the listed extension header parameters are not
understood and supported by the receiver, it MUST reject the JWS.
Senders MUST NOT include header parameter names defined by
[[ this specification ]], duplicate names, or
names that do not occur as header parameter names within the JWS Header
in the crit list.
Senders MUST not use the empty list []
as the crit value.
Recipients MAY reject the JWS if the critical list
contains any header parameter names defined by [[ this specification ]]
or any other constraints on its use are violated.
This header parameter MUST be integrity protected, and therefore
MUST occur only with the JWS Protected Header, when used.
Use of this header parameter is OPTIONAL.
This header parameter MUST be understood by implementations.
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
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
or Public Names .
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.
Create the content to be used as the JWS Payload.
Base64url encode the octets of the JWS Payload. This
encoding becomes the Encoded JWS Payload.
Create a JWS Header containing the desired set of header
parameters. Note that white space is explicitly allowed
in the representation and no canonicalization need be performed
before encoding.
Base64url encode the octets of the UTF-8 representation of
the JWS Protected Header to create the Encoded JWS Header.
If the JWS Protected Header is not present
(which can only happen when using the JWS JSON Serialization),
let the Encoded JWS Header be the empty string.
Compute the JWS Signature in the manner defined for
the particular algorithm being used over the JWS Signing Input
(the concatenation of the Encoded JWS Header,
a period ('.') character, and the Encoded JWS Payload).
The alg (algorithm) header parameter MUST be
present in the JWS Header, with the algorithm value
accurately representing the algorithm used to construct
the JWS Signature.
Base64url encode the representation of the JWS Signature
to create the Encoded JWS Signature.
The three encoded parts are result values used in both the
JWS Compact Serialization and the JWS JSON Serialization representations.
If the JWS JSON Serialization is being used, repeat this process
for each digital signature or MAC value being applied.
Create the desired serialized output.
The JWS Compact Serialization of this result is the
concatenation of
the Encoded JWS Header,
the Encoded JWS Payload, and
the Encoded JWS Signature
in that order, with the three strings
being separated by two period ('.') characters.
The JWS JSON Serialization is described in .
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.
Parse the serialized input to determine the values of
the JWS Header,
the Encoded JWS Payload, and
the Encoded JWS Signature.
When using the JWS Compact Serialization,
the Encoded JWS Header,
the Encoded JWS Payload, and
the Encoded JWS Signature
are represented as text strings in that order,
separated by two period ('.') characters.
The JWS JSON Serialization
is described in .
The Encoded JWS Header MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
Let the JWS Protected Header value be the result of
base64url decoding the Encoded JWS Header.
The resulting JWS Protected Header MUST be a completely valid
JSON object conforming to RFC 4627.
If using the JWS Compact Serialization, let the JWS Header be the
JWS Protected Header;
otherwise, when using the JWS JSON Serialization,
let the JWS Header be the union of the members of the JWS Protected Header,
the members of the unprotected value, and
the members of the corresponding header value,
all of which must be completely valid JSON objects.
The resulting JWS Header MUST NOT contain duplicate
Header Parameter Names.
When using the JWS JSON Serialization, this restriction includes
that the same Header Parameter Name also MUST NOT occur in
distinct JSON Text Object values that together comprise the JWS Header.
The resulting JWS Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported
or that are specified as being ignored when not understood.
The Encoded JWS Payload MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
The Encoded JWS Signature MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
The JWS Signature MUST be successfully validated
against the JWS Signing Input (the concatenation of the
Encoded JWS Header, a period ('.') character, and the
Encoded JWS Payload)
in the manner defined for the algorithm being used, which
MUST be accurately represented by the value of the alg (algorithm)
header parameter, which MUST be present.
If the JWS JSON Serialization is being used, repeat this process
for each digital signature or MAC value contained in the representation.
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:
Remove any JSON escaping from the input JSON string and
convert the string into a sequence of Unicode code points.
Likewise, convert the string to be compared against into
a sequence 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.
(Note that values that originally used different Unicode encodings
(UTF-8, UTF-16, etc.) may result in the same code point values.)
Also, see the JSON security considerations in and
the Unicode security considerations in .
JWS uses cryptographic algorithms to digitally sign or MAC
the JWS Protected Header and the JWS Payload.
The JSON Web Algorithms (JWA)
specification describes a set of cryptographic algorithms and
identifiers to be used with this specification.
Specifically, Section 3.1 specifies a set of
alg (algorithm) header parameter values
intended for use this specification.
It also describes the semantics and operations that are
specific to these algorithms.
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 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.
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:
Values in the JWS JSON Serialization are represented as members of
a JSON object, rather than as base64url encoded strings
separated by period ('.') characters.
(However binary values and values that are integrity protected
are still base64url encoded.)
The Encoded JWS Header value, if non-empty, is stored in the
protected member.
The Encoded JWS Payload value is stored in the
payload member.
There can be multiple signature and/or MAC values, rather than just one.
A JSON array in the signatures member
is used to hold values that are specific to a particular
signature or MAC computation, with one array element
per signature/MAC represented.
These array elements are JSON objects.
Each Encoded JWS Signature value is stored in the
signature member of a JSON object
that is an element of the signatures array.
Some header parameter values, such as the alg
value and parameters used for selecting keys, can also differ for different
signature/MAC computations.
Per-signature/MAC header parameter values are stored in the
header members of the same JSON objects
that are elements of the signatures array.
Some header parameters, including the alg
parameter, can be shared among all signature/MAC computations.
These header parameters are stored in either of two
top-level member(s) of the JSON object:
the protected member and
the unprotected member.
The values of these members are JSON Text Objects containing
Header Parameters.
Not all header parameters are integrity protected.
The shared header parameters in the protected
member are integrity protected, and are base64url encoded.
The per-signature/MAC header parameters in the
header array element members
and the shared header parameters in the
unprotected member are not integrity protected.
These JSON Text Objects containing header parameters that are
not integrity protected are not base64url encoded.
The header parameter values used when creating or validating
individual signature or MAC values are
the union of the three sets of header parameter values that may be present:
(1) the per-signature/MAC values in the header
member of the signature/MAC's array element,
(2) the shared integrity-protected values in the
protected member, and
(3) the shared non-integrity-protected values in the
unprotected member.
The union of these sets of header parameters comprises the JWS Header.
The header parameter names in the three locations MUST be disjoint.
Of these members, only the
payload,
signatures,
and signature
members MUST be present.
At least one of the
header,
protected,
and unprotected
members MUST be present so that an alg
header parameter value is conveyed for each signature/MAC computation.
The contents of the
Encoded JWS Payload and
Encoded JWS Signature
values are exactly as defined in the rest of this specification.
They are interpreted and validated in the same manner,
with each corresponding
Encoded JWS Signature and
set of header parameter values
being created and validated together.
The JWS Header values used are the union of the header parameters in the
protected,
unprotected, and
corresponding header members,
as described earlier.
Each JWS Signature value is computed on the
JWS Signing Input using the
parameters of the corresponding JWS Header value
in the same manner as for the JWS Compact Serialization.
This has the desirable property that each
Encoded JWS Signature value
in the signatures array
is identical to the value
that would have been computed for the same parameter
in the JWS Compact Serialization,
provided that the Encoded JWS Header value
(which represents the integrity-protected header parameter values)
matches that used in
the JWS Compact Serialization.
See for an example
of computing a JWS using the JWS JSON Serialization.
The JWS Compact Serialization is mandatory to implement.
Implementation of the JWS JSON Serialization is OPTIONAL.
The following registration procedure is used for all the
registries established by this specification.
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: 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.
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.
The header parameter usage locations, which should be one or more of the values
JWS or
JWE.
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.
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.
This specification registers the Header Parameter Names defined in
in this registry.
Header Parameter Name: alg
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: jku
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: jwk
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification document(s): of [[ this document ]]
Header Parameter Name: x5u
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: x5t
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: x5c
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: kid
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: typ
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: cty
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
Header Parameter Name: crit
Header Parameter Usage Location(s): JWS
Change Controller: IETF
Specification Document(s): of [[ this document ]]
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
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
values MUST NOT be directly registered as new
typ values; rather, new
typ values MAY be registered
as short names for MIME types.
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.
The MIME type that this name is an abbreviation for (e.g., "application/example").
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.
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.
This specification registers the JWS
and JWS+JSON
type values in this registry:
"typ" Header Parameter Value: JWS
Abbreviation for MIME type: application/jws
Change Controller: IETF
Specification Document(s): of [[ this document ]]
"typ" Header Parameter Value: JWS+JSON
Abbreviation for MIME type: application/jws+json
Change Controller: IETF
Specification Document(s): of [[ this document ]]
This specification registers the
application/jws and
application/jws+json
Media Types
in the MIME Media Type registry
to indicate, respectively, that the content is
a JWS using the JWS Compact Serialization or
a JWS using the JWS JSON Serialization.
Type name: application
Subtype name: jws
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: JWS 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 Persona, Salesforce, Google, numerous others that use signed JWTs
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
Type name: application
Subtype name: jws+json
Required parameters: n/a
Optional parameters: n/a
Encoding considerations:
application/jws+json values are represented as a JSON Object;
UTF-8 encoding SHOULD be employed for the JSON object.
Security considerations: See the Security Considerations section of [[ this document ]]
Interoperability considerations: n/a
Published specification: [[ this document ]]
Applications that use this media type:
TBD
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 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,
also apply to this specification, other than those that are XML specific.
Likewise, many of the best practices documented in
XML Signature Best Practices
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 states "The names
within an object SHOULD be unique", whereas this specification states that
"Header Parameter Names within this object MUST be unique;
JWSs with duplicate Header Parameter Names MUST be rejected".
Thus, this specification requires that the Section 2.2 "SHOULD"
be treated as a "MUST".
Ambiguous and potentially exploitable situations could arise
if the JSON parser used does not enforce the uniqueness of member names.
Some JSON parsers might not reject input that contains extra
significant characters after a valid input. For instance,
the input {"tag":"value"}ABCD
contains a valid JSON object followed by
the extra characters ABCD.
Such input MUST be rejected in its entirety.
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, 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.
Unicode Normalization Formsmarkdavis@google.comken@unicode.orgJSON Web Key (JWK)Microsoftmbj@microsoft.comhttp://self-issued.info/JSON Web Algorithms (JWA)Microsoftmbj@microsoft.comhttp://self-issued.info/Coded Character Set -- 7-bit American Standard Code for Information InterchangeAmerican National Standards InstituteJSON Web Token (JWT)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jpMagic SignaturesJSON Simple SignindependentNomura Research InstituteCanvas ApplicationsJSON Web Encryption (JWE)Microsoftmbj@microsoft.comhttp://self-issued.info/RTFM, Inc.ekr@rtfm.comCisco Systems, Inc.jhildebr@cisco.com
This section provides several examples of JWSs. While these
examples all represent JSON Web Tokens (JWTs) , the payload can be any base64url encoded
content.
The following example JWS Header declares that the
data structure is a JSON Web Token (JWT)
and the JWS Signing Input is secured using
the HMAC SHA-256 algorithm.
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:
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.)
The following octet sequence, which is the UTF-8 representation
of the JSON object above, is the JWS Payload:
[123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10, 32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56, 48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97, 109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111, 111, 116, 34, 58, 116, 114, 117, 101, 125]
Base64url encoding the above yields the Encoded JWS Payload value
(with line breaks for display purposes only):
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):
The ASCII representation of the JWS Signing Input
is the following octet sequence:
[101, 121, 74, 48, 101, 88, 65, 105, 79, 105, 74, 75, 86, 49, 81, 105, 76, 65, 48, 75, 73, 67, 74, 104, 98, 71, 99, 105, 79, 105, 74, 73, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
HMACs are generated using keys. This example uses the key
represented by the following octet sequence:
[3, 35, 53, 75, 43, 15, 165, 188, 131, 126, 6, 101, 119, 123, 166, 143, 90, 179, 40, 230, 240, 84, 201, 40, 169, 15, 132, 178, 210, 80, 46, 191, 211, 251, 90, 146, 210, 6, 71, 239, 150, 138, 180, 195, 119, 98, 61, 34, 61, 46, 33, 114, 5, 46, 79, 8, 192, 205, 154, 245, 103, 208, 128, 163]
Running the HMAC SHA-256 algorithm on the octets of the ASCII representation
of the JWS Signing Input
with this key yields the following octet sequence:
[116, 24, 223, 180, 151, 153, 224, 37, 79, 250, 96, 125, 216, 173, 187, 186, 22, 212, 37, 77, 105, 214, 191, 240, 91, 88, 5, 88, 83, 132, 141, 121]
Base64url encoding the above HMAC output yields the
Encoded JWS Signature value:
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):
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:
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:
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.
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):
The ASCII representation of the JWS Signing Input
is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
The RSA key consists of a public part (Modulus, Exponent), and a
Private Exponent. The values of the RSA key used in
this example, presented as the octet sequences representing
big endian integers are:
Parameter NameValueModulus
[161, 248, 22, 10, 226, 227, 201, 180, 101, 206, 141, 45, 101, 98, 99, 54, 43, 146, 125, 190, 41, 225, 240, 36, 119, 252, 22, 37, 204, 144, 161, 54, 227, 139, 217, 52, 151, 197, 182, 234, 99, 221, 119, 17, 230, 124, 116, 41, 249, 86, 176, 251, 138, 143, 8, 154, 220, 75, 105, 137, 60, 193, 51, 63, 83, 237, 208, 25, 184, 119, 132, 37, 47, 236, 145, 79, 228, 133, 119, 105, 89, 75, 234, 66, 128, 211, 44, 15, 85, 191, 98, 148, 79, 19, 3, 150, 188, 110, 155, 223, 110, 189, 210, 189, 163, 103, 142, 236, 160, 198, 104, 247, 1, 179, 141, 191, 251, 56, 200, 52, 44, 226, 254, 109, 39, 250, 222, 74, 90, 72, 116, 151, 157, 212, 185, 207, 154, 222, 196, 199, 91, 5, 133, 44, 44, 15, 94, 248, 165, 193, 117, 3, 146, 249, 68, 232, 237, 100, 193, 16, 198, 182, 71, 96, 154, 164, 120, 58, 235, 156, 108, 154, 215, 85, 49, 48, 80, 99, 139, 131, 102, 92, 111, 111, 122, 130, 163, 150, 112, 42, 31, 100, 27, 130, 211, 235, 242, 57, 34, 25, 73, 31, 182, 134, 135, 44, 87, 22, 245, 10, 248, 53, 141, 154, 139, 157, 23, 195, 64, 114, 143, 127, 135, 216, 154, 24, 216, 252, 171, 103, 173, 132, 89, 12, 46, 207, 117, 147, 57, 54, 60, 7, 3, 77, 111, 96, 111, 158, 33, 224, 84, 86, 202, 229, 233, 161]
Exponent
[1, 0, 1]
Private Exponent
[18, 174, 113, 164, 105, 205, 10, 43, 195, 126, 82, 108, 69, 0, 87, 31, 29, 97, 117, 29, 100, 233, 73, 112, 123, 98, 89, 15, 157, 11, 165, 124, 150, 60, 64, 30, 63, 207, 47, 44, 211, 189, 236, 136, 229, 3, 191, 198, 67, 155, 11, 40, 200, 47, 125, 55, 151, 103, 31, 82, 19, 238, 216, 193, 90, 37, 216, 213, 206, 160, 2, 94, 227, 171, 46, 139, 127, 121, 33, 111, 198, 59, 234, 86, 39, 83, 180, 6, 68, 198, 161, 81, 39, 217, 178, 149, 69, 64, 160, 187, 225, 163, 5, 86, 152, 45, 78, 159, 222, 95, 100, 37, 241, 77, 75, 113, 52, 65, 181, 93, 199, 59, 155, 74, 237, 204, 146, 172, 227, 146, 126, 55, 245, 125, 12, 253, 94, 117, 129, 250, 81, 44, 143, 73, 97, 169, 235, 11, 128, 248, 168, 7, 70, 114, 138, 85, 255, 70, 71, 31, 52, 37, 6, 59, 157, 83, 100, 47, 94, 222, 30, 132, 214, 19, 8, 26, 250, 92, 34, 208, 81, 40, 91, 214, 59, 148, 59, 86, 93, 137, 138, 5, 104, 84, 19, 229, 60, 60, 108, 101, 37, 255, 31, 227, 78, 61, 220, 112, 240, 213, 100, 80, 253, 164, 139, 161, 46, 16, 78, 157, 235, 159, 184, 24, 129, 225, 196, 189, 242, 93, 146, 71, 244, 80, 200, 101, 146, 121, 104, 231, 115, 52, 244, 65, 79, 117, 167, 80, 225, 57, 84, 110, 58, 138, 115, 157]
The RSA private key (Modulus, Private Exponent) is then passed to the RSA
signing function, which also takes the hash type, SHA-256,
and the octets of the ASCII representation of the JWS Signing Input
as inputs. The result of the digital signature is an octet sequence,
which represents a big endian integer. In this example, it
is:
[112, 46, 33, 137, 67, 232, 143, 209, 30, 181, 216, 45, 191, 120, 69, 243, 65, 6, 174, 27, 129, 255, 247, 115, 17, 22, 173, 209, 113, 125, 131, 101, 109, 66, 10, 253, 60, 150, 238, 221, 115, 162, 102, 62, 81, 102, 104, 123, 0, 11, 135, 34, 110, 1, 135, 237, 16, 115, 249, 69, 229, 130, 173, 252, 239, 22, 216, 90, 121, 142, 232, 198, 109, 219, 61, 184, 151, 91, 23, 208, 148, 2, 190, 237, 213, 217, 217, 112, 7, 16, 141, 178, 129, 96, 213, 248, 4, 12, 167, 68, 87, 98, 184, 31, 190, 127, 249, 217, 46, 10, 231, 111, 36, 242, 91, 51, 187, 230, 244, 74, 230, 30, 177, 4, 10, 203, 32, 4, 77, 62, 249, 18, 142, 212, 1, 48, 121, 91, 212, 189, 59, 65, 238, 202, 208, 102, 171, 101, 25, 129, 253, 228, 141, 247, 127, 55, 45, 195, 139, 159, 175, 221, 59, 239, 177, 139, 93, 163, 204, 60, 46, 176, 47, 158, 58, 65, 214, 18, 202, 173, 21, 145, 18, 115, 160, 95, 35, 185, 232, 56, 250, 175, 132, 157, 105, 132, 41, 239, 90, 30, 136, 121, 130, 54, 195, 212, 14, 96, 69, 34, 165, 68, 200, 242, 122, 122, 45, 184, 6, 99, 209, 108, 247, 202, 234, 86, 222, 64, 92, 178, 33, 90, 69, 178, 194, 85, 102, 181, 90, 193, 167, 72, 160, 112, 223, 200, 163, 42, 70, 149, 67, 208, 25, 238, 251, 71]
Base64url encoding the digital signature produces this value for
the Encoded JWS Signature
(with line breaks for display purposes only):
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):
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:
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:
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.
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):
The ASCII representation of the JWS Signing Input
is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
The ECDSA key consists of a public part, the EC point (x,
y), and a private part d. The values of the ECDSA key
used in this example, presented as the octet sequences
representing three 256 bit big endian integers are:
Parameter NameValuex
[127, 205, 206, 39, 112, 246, 196, 93, 65, 131, 203, 238, 111, 219, 75, 123, 88, 7, 51, 53, 123, 233, 239, 19, 186, 207, 110, 60, 123, 209, 84, 69]
y
[199, 241, 68, 205, 27, 189, 155, 126, 135, 44, 223, 237, 185, 238, 185, 244, 179, 105, 93, 110, 169, 11, 36, 173, 138, 70, 35, 40, 133, 136, 229, 173]
d
[142, 155, 16, 158, 113, 144, 152, 191, 152, 4, 135, 223, 31, 93, 119, 233, 203, 41, 96, 110, 190, 210, 38, 59, 95, 87, 194, 19, 223, 132, 244, 178]
The ECDSA private part d is then passed to an ECDSA
signing function, which also takes the curve type, P-256,
the hash type, SHA-256, and the octets of the ASCII representation of
the JWS Signing Input
as inputs. The result of the
digital signature is the EC point (R, S), where R and S are
unsigned integers. In this example, the R and S values,
given as octet sequences representing big endian integers are:
Result NameValueR
[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):
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):
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) 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 a different ECDSA curve
and hash function are used. The JWS Header used is:
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:
The JWS Payload used in this example, is the ASCII string "Payload".
The representation of this string is the octet sequence:
[80, 97, 121, 108, 111, 97, 100]
Base64url encoding these octets yields the Encoded JWS Payload value:
Concatenating the Encoded JWS Header, a period ('.') character,
and the Encoded JWS Payload yields this JWS Signing Input
value:
The ASCII representation of the JWS Signing Input
is the following octet sequence:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 85, 120, 77, 105, 74, 57, 46, 85, 71, 70, 53, 98, 71, 57, 104, 90, 65]
The ECDSA key consists of a public part, the EC point (x,
y), and a private part d. The values of the ECDSA key
used in this example, presented as the octet sequences
representing three 521 bit big endian integers are:
Parameter NameValuex
[1, 233, 41, 5, 15, 18, 79, 198,
188, 85, 199, 213, 57, 51, 101, 223, 157, 239, 74, 176, 194, 44, 178, 87,
152, 249, 52, 235, 4, 227, 198, 186, 227, 112, 26, 87, 167, 145, 14, 157,
129, 191, 54, 49, 89, 232, 235, 203, 21, 93, 99, 73, 244, 189, 182, 204,
248, 169, 76, 92, 89, 199, 170, 193, 1, 164]
y
[0, 52, 166, 68, 14, 55,
103, 80, 210, 55, 31, 209, 189, 194, 200, 243, 183, 29, 47, 78, 229, 234,
52, 50, 200, 21, 204, 163, 21, 96, 254, 93, 147, 135, 236, 119, 75, 85,
131, 134, 48, 229, 203, 191, 90, 140, 190, 10, 145, 221, 0, 100, 198, 153,
154, 31, 110, 110, 103, 250, 221, 237, 228, 200, 200, 246]
d
[1, 142, 105, 111,
176, 52, 80, 88, 129, 221, 17, 11, 72, 62, 184, 125, 50, 206, 73, 95,
227, 107, 55, 69, 237, 242, 216, 202, 228, 240, 242, 83, 159, 70, 21, 160,
233, 142, 171, 82, 179, 192, 197, 234, 196, 206, 7, 81, 133, 168, 231, 187,
71, 222, 172, 29, 29, 231, 123, 204, 246, 97, 53, 230, 61, 130]
The ECDSA private part d is then passed to an ECDSA
signing function, which also takes the curve type, P-521,
the hash type, SHA-512, and the octets of the ASCII representation of
the JWS Signing Input
as inputs. The result of the
digital signature is the EC point (R, S), where R and S are
unsigned integers. In this example, the R and S values,
given as octet sequences representing big endian integers are:
Result NameValueR
[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):
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):
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) 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:
Base64url encoding the octets of the UTF-8 representation of
the JWS Header yields this Encoded JWS Header:
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.
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):
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
(with line breaks for display purposes only):
Two digital signatures are used in this example: both using
RSASSA-PKCS-v1_5 SHA-256.
For the first, the JWS Protected Header and key
are the same as in ,
resulting in the same JWS Signature value;
therefore, its computation is not repeated here.
For the second a different key is used, which is
provided in ;
its computation follows the same procedure as the first,
so it is not detailed here either, other than including
the resulting Encoded JWS Signature value.
The JWS Protected Header value used for both computations is:
Base64url encoding these octets yields this
Encoded JWS Header value:
Key ID values are supplied for both keys using per-signature
header parameters.
The two values used to represent these Key IDs are:
and:
Combining the protected and per-signature header values
supplied, the JWS Header values used for the first and second
signatures respectively are:
and:
The complete JSON Web Signature JSON Serialization
for these values is as follows
(with line breaks for display purposes only):
The values of the RSA key used for the second signature in this
this example, presented as the octet sequences representing
big endian integers are:
Parameter NameValueModulus
[160, 120, 137, 109, 191, 13, 24, 29, 15, 217, 68, 35, 164, 152, 33, 179,
62, 22, 51, 134, 60, 228, 112, 172, 11, 62, 57, 16, 26, 162, 213, 250,
199, 183, 56, 103, 101, 172, 20, 178, 226, 124, 116, 135, 195, 195, 124, 91,
174, 65, 218, 196, 113, 82, 132, 161, 145, 71, 8, 117, 240, 109, 116, 40,
196, 26, 174, 135, 43, 175, 40, 166, 223, 157, 5, 188, 92, 7, 52, 219,
11, 157, 96, 99, 25, 65, 151, 108, 25, 104, 206, 147, 63, 1, 157, 154,
58, 111, 200, 251, 54, 202, 96, 220, 42, 196, 21, 252, 193, 58, 205, 44,
89, 217, 58, 164, 99, 3, 76, 195, 180, 76, 19, 103, 110, 26, 2, 122,
173, 211, 45, 218, 134, 212, 26, 198, 156, 110, 213, 139, 31, 135, 227, 43,
0, 45, 192, 39, 206, 176, 194, 154, 217, 10, 185, 227, 143, 142, 179, 117,
171, 238, 187, 88, 12, 185, 36, 110, 100, 76, 34, 39, 20, 145, 184, 44,
14, 100, 21, 77, 15, 82, 150, 53, 156, 46, 196, 231, 156, 152, 152, 85,
145, 184, 195, 213, 134, 107, 75, 10, 117, 233, 76, 215, 62, 205, 95, 170,
6, 234, 221, 139, 4, 241, 239, 203, 28, 32, 95, 192, 24, 164, 172, 132,
10, 193, 239, 45, 140, 153, 198, 140, 117, 17, 223, 12, 26, 5, 47, 223,
211, 151, 120, 15, 230, 60, 42, 51, 104, 119, 46, 41, 242, 177, 76, 33]
Exponent
[1, 0, 1]
Private Exponent
[118, 50, 242, 255, 124, 119, 87, 168, 168, 112, 223, 168, 229, 103, 13, 131,
170, 154, 205, 206, 245, 241, 74, 48, 223, 131, 48, 162, 245, 11, 182, 83,
167, 98, 4, 208, 220, 106, 25, 64, 254, 100, 175, 173, 4, 252, 108, 16,
87, 213, 184, 31, 116, 93, 84, 198, 113, 109, 2, 5, 101, 88, 41, 244,
145, 38, 26, 34, 4, 130, 91, 142, 55, 45, 192, 248, 210, 76, 152, 153,
51, 255, 242, 236, 107, 193, 13, 153, 25, 74, 66, 198, 224, 228, 254, 194,
136, 130, 168, 102, 170, 31, 253, 162, 142, 121, 170, 188, 103, 84, 57, 166,
142, 115, 220, 167, 19, 43, 110, 18, 197, 46, 56, 40, 186, 71, 188, 68,
152, 43, 159, 81, 123, 128, 103, 167, 243, 139, 188, 90, 36, 142, 151, 217,
213, 244, 149, 183, 9, 16, 149, 119, 233, 161, 201, 107, 151, 185, 157, 124,
238, 147, 50, 51, 170, 188, 190, 154, 92, 239, 46, 37, 178, 49, 74, 209,
220, 56, 19, 186, 34, 52, 152, 130, 86, 56, 237, 1, 186, 225, 244, 29,
248, 57, 21, 1, 10, 55, 176, 110, 145, 149, 4, 137, 13, 121, 236, 87,
186, 48, 218, 3, 78, 218, 2, 244, 95, 168, 218, 217, 247, 252, 81, 13,
22, 210, 219, 26, 149, 32, 217, 211, 144, 231, 104, 240, 69, 73, 237, 1,
14, 28, 161, 202, 222, 209, 156, 108, 27, 207, 126, 40, 77, 102, 93, 1]
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 .
Note that since these strings contain base64 encoded (not base64url encoded)
values, they are allowed to contain white space and line breaks.
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.
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.
Conforming implementations must reject input containing critical extensions
that are not understood or cannot be processed. The following JWS must
be rejected by all implementations, because it uses an extension
header parameter name http://example.com/UNDEFINED
that they do not understand.
Any other similar input, in which the use of the value
http://example.com/UNDEFINED is substituted for
any other header parameter name not understood by the implementation,
must also be rejected.
Solutions for signing JSON content were previously explored by
Magic Signatures, JSON Simple Sign, and Canvas Applications, 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 ]]
-11
Added Key Identification section.
For the JWS JSON Serialization, enable header parameter values
to be specified in any of three parameters:
the protected member that is
integrity protected and shared among all recipients,
the unprotected member that is
not integrity protected and shared among all recipients,
and the header member that is
not integrity protected and specific to a particular recipient.
(This does not affect the JWS Compact Serialization, in which all
header parameter values are in a single integrity protected JWE Header value.)
Removed suggested compact serialization for multiple
digital signatures and/or MACs.
Changed the MIME type name application/jws-js
to application/jws+json,
addressing issue #22.
Tightened the description of the
crit (critical) header parameter.
Added a negative test case for the
crit header parameter
-10
Added an appendix suggesting a possible compact serialization
for JWSs with multiple digital signatures and/or MACs.
-09
Added JWS JSON Serialization, as specified by
draft-jones-jose-jws-json-serialization-04.
Registered application/jws-js MIME type
and JWS-JS typ header parameter value.
Defined that the default action for header parameters that
are not understood is to ignore them unless specifically
designated as "MUST be understood" or included in the new
crit (critical) header parameter list.
This addressed issue #6.
Changed term "JWS Secured Input" to "JWS Signing Input".
Changed from using the term "byte" to "octet" when referring to 8 bit values.
Changed member name from recipients to
signatures in the JWS JSON Serialization.
Added complete values using the JWS Compact Serialization
for all examples.
-08
Applied editorial improvements suggested by
Jeff Hodges and Hannes Tschofenig.
Many of these simplified the terminology used.
Clarified statements of the form "This header parameter is OPTIONAL"
to "Use of this header parameter is OPTIONAL".
Added a Header Parameter Usage Location(s) field to the
IANA JSON Web Signature and Encryption Header Parameters registry.
Added seriesInfo information to Internet Draft references.
-07
Updated references.
-06
Changed x5c (X.509 Certificate Chain)
representation from being a single string to being an array of strings,
each containing a single base64 encoded DER certificate value,
representing elements of the certificate chain.
Applied changes made by the RFC Editor to RFC 6749's registry language
to this specification.
-05
Added statement that
"StringOrURI values are compared as case-sensitive strings
with no transformations or canonicalizations applied".
Indented artwork elements to better distinguish them from the body text.
-04
Completed JSON Security Considerations section, including
considerations about rejecting input with duplicate member names.
Completed security considerations on the use of a SHA-1 hash when computing
x5t (x.509 certificate thumbprint) values.
Refer to the registries as the primary sources of defined
values and then secondarily reference the sections
defining the initial contents of the registries.
Normatively reference
XML DSIG 2.0
for its security considerations.
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."
Reference draft-jones-jose-jws-json-serialization
instead of draft-jones-json-web-signature-json-serialization.
Described additional open issues.
Applied editorial suggestions.
-03
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.
Added "Collision Resistant Namespace" to the terminology section.
Reference ITU.X690.1994 for DER encoding.
Added an example JWS using ECDSA P-521 SHA-512. This has particular
illustrative value because of the use of the 521 bit integers
in the key and signature values.
This is also an example in which the payload is not a base64url
encoded JSON object.
Added an example x5c value.
No longer say "the UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)". Just call it
"the ASCII representation of the JWS Secured Input".
Added Registration Template sections for defined registries.
Added Registry Contents sections to populate registry values.
Changed name of the JSON Web Signature and Encryption "typ" Values registry
to be the JSON Web Signature and Encryption Type Values registry, since
it is used for more than just values of the
typ parameter.
Moved registries
JSON Web Signature and Encryption Header Parameters and
JSON Web Signature and Encryption Type Values
to the JWS specification.
Numerous editorial improvements.
-02
Clarified that it is an error when a kid
value is included and no matching key is found.
Removed assumption that kid (key ID)
can only refer to an asymmetric key.
Clarified that JWSs with duplicate Header Parameter Names
MUST be rejected.
Clarified the relationship between
typ header parameter values
and MIME types.
Registered application/jws MIME type and "JWS" typ header parameter value.
Simplified JWK terminology to get replace the "JWK Key Object" and
"JWK Container Object" terms with simply "JSON Web Key (JWK)"
and "JSON Web Key Set (JWK Set)" and to eliminate potential
confusion between single keys and sets of keys.
As part of this change, the Header Parameter Name for a
public key value was changed from
jpk (JSON Public Key) to
jwk (JSON Web Key).
Added suggestion on defining additional header parameters
such as x5t#S256 in the future
for certificate thumbprints using hash algorithms other
than SHA-1.
Specify RFC 2818 server identity validation, rather than
RFC 6125 (paralleling the same decision in the OAuth specs).
Generalized language to refer to Message Authentication Codes (MACs)
rather than Hash-based Message Authentication Codes (HMACs)
unless in a context specific to HMAC algorithms.
Reformatted to give each header parameter its own section heading.
-01
Moved definition of Plaintext JWSs (using "alg":"none")
here from the JWT specification since this functionality is
likely to be useful in more contexts that just for JWTs.
Added jpk and x5c header parameters for including
JWK public keys and X.509 certificate chains directly in
the header.
Clarified that this specification is defining the JWS
Compact Serialization. Referenced the new JWS-JS spec,
which defines the JWS JSON Serialization.
Added text "New header parameters should be introduced
sparingly since an implementation that does not understand
a parameter MUST reject the JWS".
Clarified that the order of the creation and validation
steps is not significant in cases where there are no
dependencies between the inputs and outputs of the steps.
Changed "no canonicalization is performed" to "no
canonicalization need be performed".
Corrected the Magic Signatures reference.
Made other editorial improvements suggested by JOSE
working group participants.
-00
Created the initial IETF draft based upon
draft-jones-json-web-signature-04 with no normative
changes.
Changed terminology to no longer call both digital
signatures and HMACs "signatures".