One document matched: draft-ietf-jose-json-web-signature-02.xml
<?xml version="1.0" encoding="US-ASCII"?>
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<rfc category="std" ipr="trust200902" docName="draft-ietf-jose-json-web-signature-02">
<front>
<title>JSON Web Signature (JWS)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization abbrev="Ping Identity">Ping Identity</organization>
<address>
<email>ve7jtb@ve7jtb.com</email>
</address>
</author>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization abbrev="NRI">Nomura Research Institute</organization>
<address>
<email>n-sakimura@nri.co.jp</email>
</address>
</author>
<date day="12" month="May" year="2012" />
<area>Security</area>
<workgroup>JOSE Working Group</workgroup>
<keyword>RFC</keyword>
<keyword>Request for Comments</keyword>
<keyword>I-D</keyword>
<keyword>Internet-Draft</keyword>
<keyword>JavaScript Object Notation</keyword>
<keyword>JSON</keyword>
<keyword>JSON Web Token</keyword>
<keyword>JWT</keyword>
<keyword>JSON Web Signature</keyword>
<keyword>JWS</keyword>
<keyword>JSON Web Encryption</keyword>
<keyword>JWE</keyword>
<keyword>JSON Web Key</keyword>
<keyword>JWK</keyword>
<keyword>JSON Web Algorithms</keyword>
<keyword>JWA</keyword>
<abstract>
<t>
JSON Web Signature (JWS) is a means of
representing content secured with digital signatures or
Message Authentication Codes (MACs)
using JSON data structures.
Cryptographic algorithms and identifiers used with this
specification are enumerated in the separate
JSON Web Algorithms (JWA) specification.
Related encryption capabilities are described in the separate
JSON Web Encryption (JWE) specification.
</t>
</abstract>
<note title="Requirements Language">
<t>
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 <xref target="RFC2119">RFC 2119</xref>.
</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>
JSON Web Signature (JWS) is a compact format for
representing content secured with digital signatures or
Message Authentication Codes (MACs)
intended for space constrained environments such as HTTP
Authorization headers and URI query parameters. It represents
this content using JSON <xref target="RFC4627" /> data
structures. The JWS digital signature and MAC mechanisms are independent of
the type of content being secured, allowing arbitrary content
to be secured.
Cryptographic algorithms and identifiers used with this
specification are enumerated in the separate
JSON Web Algorithms (JWA) <xref target="JWA" /> specification.
Related encryption capabilities are described in the separate
JSON Web Encryption (JWE) <xref target="JWE" /> specification.
</t>
</section>
<section title="Terminology">
<t>
<list style="hanging">
<t hangText="JSON Web Signature (JWS)">
A data structure cryptographically securing a JWS Header
and a JWS Payload with a JWS Signature value.
</t>
<t hangText="JWS Header">
A string representing a JSON object that describes the
digital signature or MAC operation applied to
create the JWS Signature value.
</t>
<t hangText="JWS Payload">
The bytes to be secured - a.k.a., the message.
The payload can contain an arbitrary sequence of bytes.
</t>
<t hangText="JWS Signature">
A byte array containing the cryptographic
material that secures the contents of the JWS Header
and the JWS Payload.
</t>
<t hangText="Encoded JWS Header">
Base64url encoding of the bytes of the
UTF-8 <xref target="RFC3629">RFC 3629</xref>
representation of the JWS Header.
</t>
<t hangText="Encoded JWS Payload">
Base64url encoding of the JWS Payload.
</t>
<t hangText="Encoded JWS Signature">
Base64url encoding of the JWS Signature.
</t>
<t hangText="JWS Secured Input">
The concatenation of the Encoded JWS Header, a period ('.')
character, and the Encoded JWS Payload.
</t>
<t hangText="Header Parameter Names">
The names of the members within the JSON object
represented in a JWS Header.
</t>
<t hangText="Header Parameter Values">
The values of the members within the JSON object
represented in a JWS Header.
</t>
<t hangText="JWS Compact Serialization">
A representation of the JWS as the concatenation of the
Encoded JWS Header, the Encoded JWS Payload, and the
Encoded JWS Signature in that order, with the three
strings being separated by period ('.') characters.
</t>
<t hangText="Base64url Encoding">
For the purposes of this specification, this term always
refers to the URL- and filename-safe Base64 encoding
described in <xref target="RFC4648">RFC 4648</xref>,
Section 5, with the (non URL-safe) '=' padding characters
omitted, as permitted by Section 3.2. (See <xref
target="base64urlnotes" /> for notes on implementing
base64url encoding without padding.)
</t>
<t hangText="StringOrURI">
A JSON string value, with the additional requirement that
while arbitrary string values MAY be used, any value
containing a ":" character MUST be a URI as defined in
<xref target="RFC3986">RFC 3986</xref>.
</t>
</list>
</t>
</section>
<section title="JSON Web Signature (JWS) Overview">
<t>
JWS represents digitally signed or MACed content using JSON data
structures and base64url encoding. The representation
consists of three parts: the JWS Header, the JWS Payload,
and the JWS Signature.
In the Compact Serialization, the three parts are
base64url-encoded for transmission, and represented
as the concatenation of the encoded strings in that order,
with the three strings being separated by period ('.')
characters.
(A JSON Serialization for this information is defined in the separate
JSON Web Signature JSON Serialization (JWS-JS) <xref target="JWS-JS" />
specification.)
</t>
<t>
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 Header and the JWS Payload.
</t>
<section title="Example JWS" anchor="ExampleJWS">
<t>
The following example JWS Header declares that the
encoded object is a JSON Web Token (JWT) <xref target="JWT" />
and the JWS Header and the JWS Payload are
secured using the HMAC SHA-256 algorithm:
</t>
<figure><artwork><![CDATA[{"typ":"JWT",
"alg":"HS256"}]]></artwork></figure>
<t>
Base64url encoding the bytes of the UTF-8 representation of
the JWS Header yields this Encoded JWS Header value:
</t>
<figure><artwork><![CDATA[eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9]]></artwork></figure>
<t>
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.)
</t>
<figure><artwork><![CDATA[{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}]]></artwork></figure>
<t>
Base64url encoding the bytes of the UTF-8 representation of the JSON
object yields the following Encoded JWS Payload
(with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ]]></artwork></figure>
<t>
Computing the HMAC of the bytes of the UTF-8 representation of the JWS Secured Input
(the concatenation of the Encoded JWS Header, a period ('.')
character, and the Encoded JWS Payload)
(which is the same as the ASCII representation)
with the HMAC SHA-256 algorithm
using the key specified in <xref target="HMACSHA256Example" />
and base64url encoding the result
yields this Encoded JWS Signature value:
</t>
<figure><artwork><![CDATA[dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk]]></artwork></figure>
<t>
Concatenating these parts in the order
Header.Payload.Signature with period characters between the
parts yields this complete JWS representation
(with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk]]></artwork></figure>
<t>
This computation is illustrated in more detail in <xref
target="HMACSHA256Example"></xref>.
</t>
</section>
</section>
<section title="JWS Header">
<t>
The members of the JSON object 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 this object MUST be unique;
JWSs with duplicate Header Parameter Names MUST be rejected.
Implementations MUST understand the entire contents of the
header; otherwise, the JWS MUST be rejected.
</t>
<t>
There are three classes of Header Parameter Names:
Reserved Header Parameter Names, Public Header Parameter Names,
and Private Header Parameter Names.
</t>
<section title="Reserved Header Parameter Names" anchor="ReservedHeaderParameterName">
<t>
The following header parameter names are reserved
with meanings as defined below. All
the names are short because a core goal of JWSs is for the
representations to be compact.
</t>
<t>
Additional reserved header parameter names MAY be defined
via the IANA
JSON Web Signature and Encryption Header Parameters registry
<xref target="JWA" />.
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.
</t>
<section title='"alg" (Algorithm) Header Parameter'>
<t>
The <spanx style="verb">alg</spanx> (algorithm) header
parameter identifies the cryptographic algorithm used to
secure the JWS.
A list of defined <spanx style="verb">alg</spanx> values for use with
JWS is presented in Section 3.1 of the
JSON Web Algorithms (JWA) <xref target="JWA" /> specification.
The processing of the <spanx style="verb">alg</spanx>
header parameter requires that the value MUST
be one that is both supported and for which there exists a
key for use with that algorithm associated with the
party that digitally signed or MACed the content.
The <spanx style="verb">alg</spanx> value is case sensitive.
Its value MUST be a string containing a StringOrURI value.
This header parameter is REQUIRED.
</t>
<t>
<spanx style="verb">alg</spanx> values SHOULD either be
defined in the IANA
JSON Web Signature and Encryption Algorithms registry
<xref target="JWA" /> or be
a URI that contains a collision resistant namespace.
</t>
</section>
<section title='"jku" (JWK Set URL) Header Parameter'>
<t>
The <spanx style="verb">jku</spanx> (JWK Set URL)
header parameter is an absolute URL 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)
as defined in the JSON Web Key (JWK) <xref target="JWK" /> specification.
The protocol used to acquire the resource MUST provide
integrity protection; an HTTP GET request to retrieve the
certificate MUST use TLS <xref target="RFC2818">RFC
2818</xref> <xref target="RFC5246">RFC 5246</xref>;
the identity of the server MUST be validated, as per
Section 3.1 of HTTP Over TLS <xref target='RFC2818' />.
This header parameter is OPTIONAL.
</t>
</section>
<section title='"jwk" (JSON Web Key) Header Parameter'>
<t>
The <spanx style="verb">jwk</spanx> (JSON Web Key)
header parameter is a public key that corresponds to the
key used to digitally sign the JWS.
This key is represented as a JSON Web Key <xref target="JWK" />.
This header parameter is OPTIONAL.
</t>
</section>
<section title='"x5u" (X.509 URL) Header Parameter'>
<t>
The <spanx style="verb">x5u</spanx> (X.509 URL) header
parameter is an absolute URL 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
<xref target="RFC5280">RFC 5280</xref> in PEM encoded form
<xref target="RFC1421">RFC 1421</xref>.
The certificate containing the public key of the entity
that digitally signed 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 <xref target="RFC2818">RFC
2818</xref> <xref target="RFC5246">RFC 5246</xref>;
the identity of the server MUST be validated, as per
Section 3.1 of HTTP Over TLS <xref target='RFC2818' />.
This header parameter is OPTIONAL.
</t>
</section>
<section title='"x5t" (X.509 Certificate Thumbprint) Header Parameter'>
<t>
The <spanx style="verb">x5t</spanx> (X.509 Certificate Thumbprint)
header parameter provides 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.
This header parameter is OPTIONAL.
</t>
<t>
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 <spanx style="verb">x5t#S256</spanx> (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 <xref target="JWA" />.
</t>
</section>
<section title='"x5c" (X.509 Certificate Chain) Header Parameter'>
<t>
The <spanx style="verb">x5c</spanx> (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 an
array of certificate values. Each value is a
base64-encoded (not base64url encoded) DER/BER PKIX
certificate value.
The certificate containing the public key of the entity
that digitally signed 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 <xref target="RFC5280"/> and reject the JWS if any
validation failure occurs.
This header parameter is OPTIONAL.
</t>
</section>
<section title='"kid" (Key ID) Header Parameter'>
<t>
The <spanx style="verb">kid</spanx> (key ID) header
parameter is a hint indicating which key was used to
secure the JWS.
This allows originators to explicitly signal a change of
key to recipients.
Should the recipient be unable to locate a key
corresponding to the <spanx style="verb">kid</spanx>
value, they SHOULD treat that condition as an error.
The interpretation of the contents of the
<spanx style="verb">kid</spanx> parameter is unspecified.
Its value MUST be a string.
This header parameter is OPTIONAL.
</t>
</section>
<section title='"typ" (Type) Header Parameter'>
<t>
The <spanx style="verb">typ</spanx> (type) header
parameter is used to declare the type of the secured
content.
The type value <spanx style="verb">JWS</spanx> MAY be used
to indicate that the secured content is a JWS.
The <spanx style="verb">typ</spanx> value is case sensitive.
Its value MUST be a string.
This header parameter is OPTIONAL.
</t>
<t>
MIME Media Type <xref target="RFC2045">RFC 2045</xref>
values MAY be used as <spanx style="verb">typ</spanx> values.
</t>
<t>
<spanx style="verb">typ</spanx> values SHOULD either be
defined in the IANA
JSON Web Signature and Encryption "typ" Values registry
<xref target="JWA" /> or be
a URI that contains a collision resistant namespace.
</t>
</section>
</section>
<section title="Public Header Parameter Names" anchor="PublicHeaderParameterName">
<t>
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 defined in the IANA
JSON Web Signature and Encryption Header Parameters registry
<xref target="JWA" /> or be
a URI 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.
</t>
<t>
New header parameters should be introduced sparingly, as
they can result in non-interoperable JWSs.
</t>
</section>
<section title="Private Header Parameter Names" anchor="PrivateHeaderParameterName">
<t>
A producer and consumer of a JWS may agree to any header
parameter name that is not a Reserved Name <xref
target="ReservedHeaderParameterName"></xref> or a Public
Name <xref
target="PublicHeaderParameterName"></xref>. Unlike Public
Names, these private names are subject to collision and
should be used with caution.
</t>
</section>
</section>
<section title="Rules for Creating and Validating a JWS">
<t>
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.
<list style="numbers">
<t>
Create the content to be used as the JWS Payload.
</t>
<t>
Base64url encode the bytes of the JWS Payload. This
encoding becomes the Encoded JWS Payload.
</t>
<t>
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.
</t>
<t>
Base64url encode the bytes of the UTF-8 representation of
the JWS Header to create the Encoded JWS Header.
</t>
<t>
Compute the JWS Signature in the manner defined for
the particular algorithm being used. The JWS Secured Input
is always the concatenation of the Encoded JWS Header,
a period ('.') character, and the Encoded JWS Payload.
The <spanx style="verb">alg</spanx> (algorithm) header parameter MUST be
present in the JSON Header, with the algorithm value
accurately representing the algorithm used to construct
the JWS Signature.
</t>
<t>
Base64url encode the representation of the JWS Signature
to create the Encoded JWS Signature.
</t>
<t>
The three encoded parts, taken together, are the result.
The 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 period ('.')
characters.
</t>
</list>
</t>
<t>
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.
</t>
<t>
<list style="numbers">
<t>
Parse the three parts of the input (which are separated by
period characters when using the JWS Compact
Serialization) into the Encoded JWS Header, the Encoded
JWS Payload, and the Encoded JWS Signature.
</t>
<t>
The Encoded JWS Header MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
</t>
<t>
The resulting JWS Header MUST be completely valid
JSON syntax conforming to <xref target="RFC4627">RFC
4627</xref>.
</t>
<t>
The resulting JWS Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported.
</t>
<t>
The Encoded JWS Payload MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
</t>
<t>
The Encoded JWS Signature MUST be successfully base64url
decoded following the restriction given in this specification that
no padding characters have been used.
</t>
<t>
The JWS Signature MUST be successfully validated
against the JWS Secured 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 <spanx style="verb">alg</spanx> (algorithm)
header parameter, which MUST be present.
</t>
</list>
</t>
<t>
Processing a JWS inevitably requires comparing known strings
to values in the header. For example, in checking what the
algorithm is, the Unicode string encoding <spanx style="verb">alg</spanx> 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 <spanx style="verb">alg</spanx> header parameter represents a supported
algorithm.
</t>
<t>
Comparisons between JSON strings and other Unicode strings
MUST be performed as specified below:
<list style="numbers">
<t>
Remove any JSON applied escaping to produce an array of
Unicode code points.
</t>
<t>
<xref target="USA15">Unicode Normalization</xref> MUST NOT
be applied at any point to either the JSON string or to
the string it is to be compared against.
</t>
<t>
Comparisons between the two strings MUST be performed as a
Unicode code point to code point equality comparison.
</t>
</list>
</t>
</section>
<section title="Securing JWSs with Cryptographic Algorithms" anchor="Signing">
<t>
JWS uses cryptographic algorithms to digitally sign or MAC
the contents of the JWS Header and the JWS Payload.
The JSON Web Algorithms (JWA) <xref target="JWA" />
specification enumerates a set of cryptographic algorithms and
identifiers to be used with this specification.
Specifically, Section 3.1 enumerates a set of
<spanx style="verb">alg</spanx> (algorithm) header parameter values
intended for use this specification.
It also describes the semantics and operations that are
specific to these algorithms and algorithm families.
</t>
<t>
Public keys employed for digital signing can be identified using the
Header Parameter methods described in <xref
target="ReservedHeaderParameterName" /> or can be distributed
using methods that are outside the scope of this
specification.
</t>
</section>
<section title="IANA Considerations" anchor="IANA">
<section title="Registration of application/jws MIME Media Type" anchor="JWSMIMEType">
<t>
This specification registers the <spanx
style="verb">application/jws</spanx> MIME Media Type
<xref target="RFC2045">RFC 2045</xref>.
<list style="hanging">
<t hangText='Type name:'>
<vspace />
application
</t>
<t hangText='Subtype name:'>
<vspace />
jws
</t>
<t hangText='Required parameters:'>
<vspace />
n/a
</t>
<t hangText='Optional parameters:'>
<vspace />
n/a
</t>
<t hangText='Encoding considerations:'>
<vspace />
n/a
</t>
<t hangText='Security considerations:'>
<vspace />
See the Security Considerations section of this document
</t>
<t hangText='Interoperability considerations:'>
<vspace />
n/a
</t>
<t hangText='Published specification:'>
<vspace />
[[ this document ]]
</t>
<t hangText='Applications that use this media type:'>
<vspace />
OpenID Connect
</t>
<t hangText='Additional information:'>
<vspace />
Magic number(s): n/a
<vspace />
File extension(s): n/a
<vspace />
Macintosh file type code(s): n/a
</t>
<t hangText='Person & email address to contact for further information:'>
<vspace />
Michael B. Jones
<vspace />
mbj@microsoft.com
</t>
<t hangText='Intended usage:'>
<vspace />
COMMON
</t>
<t hangText='Restrictions on usage:'>
<vspace />
none
</t>
<t hangText='Author:'>
<vspace />
Michael B. Jones
<vspace />
mbj@microsoft.com
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
</list>
</t>
</section>
<section title='Registration of "JWS" Type Value' anchor="JWSTypReg">
<t>
This specification registers the following <spanx style="verb">typ</spanx>
header parameter value in the
JSON Web Signature and Encryption "typ" Values registry established by the
JSON Web Algorithms (JWA) <xref target="JWA" /> specification:
<list style='hanging'>
<t hangText='"typ" header parameter value:'>
<vspace />
"JWS"
</t>
<t hangText='Abbreviation for MIME type:'>
<vspace />
application/jws
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
<t hangText='Description:'>
<vspace />
[[ this document ]]
</t>
</list>
</t>
</section>
</section>
<section title="Security Considerations" anchor="Security">
<section title="Cryptographic Security Considerations">
<t>
All the security considerations in
<xref target="W3C.CR-xmldsig-core2-20120124">XML DSIG 2.0</xref>,
also apply to this specification, other than those that are XML specific.
Likewise, many of the best practices documented in
<xref target="W3C.WD-xmldsig-bestpractices-20110809">XML Signature Best Practices</xref>
also apply to this specification,
other than those that are XML specific.
</t>
<t>
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.
</t>
<t>
When utilizing TLS to retrieve information, the authority
providing the resource MUST be authenticated and the
information retrieved MUST be free from modification.
</t>
<t>
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.
</t>
<t>
TBD: We need to also put in text about: Importance
of keeping secrets secret. Rotating keys. Strengths and
weaknesses of the different algorithms.
</t>
<t>
TBD: Write security considerations about the implications of
using a SHA-1 hash (for compatibility reasons) for the
<spanx style="verb">x5t</spanx> (x.509 certificate
thumbprint).
</t>
<t>
TBD: We need a section on generating randomness in browsers;
it's easy to screw up.
</t>
</section>
<section title="JSON Security Considerations">
<t>
TBD: We need to look into
any issues relating to security and JSON parsing. One wonders
just how secure most JSON parsing libraries are. Were they
ever hardened for security scenarios? If not, what kind of
holes does that open up?
We need to put in text about why strict JSON validation is
necessary - basically, that if malformed JSON is received then
the intent of the sender is impossible to reliably discern.
</t>
</section>
<section title="Unicode Comparison Security Considerations">
<t>
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 <xref target="RFC4627">RFC 4627</xref>, 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").
</t>
<t>
JSON strings MAY 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.
</t>
</section>
</section>
<section title="Open Issues and Things To Be Done (TBD)" anchor="TBD">
<t>
The following items remain to be done in this draft:
<list style="symbols">
<t>
Add an example in which the payload is not a base64url
encoded JSON object.
</t>
<t>
Finish the Security Considerations section.
</t>
</list>
</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.1421.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2045.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2818.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.3629.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.3986.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.4627.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.4648.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5246.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5280.xml' ?>
<reference anchor="USA15">
<front>
<title>Unicode Normalization Forms</title>
<author fullname="Mark Davis" initials="M." surname="Davis">
<address>
<email>markdavis@google.com</email>
</address>
</author>
<author fullname="Ken Whistler" initials="K." surname="Whistler">
<address>
<email>ken@unicode.org</email>
</address>
</author>
<author fullname="Martin Dürst" initials="M."
surname="Dürst"></author>
<date day="03" month="09" year="2009" />
</front>
<seriesInfo name="Unicode Standard Annex" value="15" />
</reference>
<reference anchor="JWK">
<front>
<title>JSON Web Key (JWK)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<date day="12" month="May" year="2012" />
</front>
<format target="http://tools.ietf.org/html/draft-ietf-jose-json-web-key" type="HTML" />
</reference>
<reference anchor="JWA">
<front>
<title>JSON Web Algorithms (JWA)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<date day="12" month="May" year="2012" />
</front>
<format target="http://tools.ietf.org/html/draft-ietf-jose-json-web-algorithms" type="HTML" />
</reference>
</references>
<references title="Informative References">
<?rfc include="http://xml.resource.org/public/rfc/bibxml4/reference.W3C.CR-xmldsig-core2-20120124.xml" ?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml4/reference.W3C.WD-xmldsig-bestpractices-20110809.xml" ?>
<reference anchor="JWT">
<front>
<title>JSON Web Token (JWT)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="Dirk Balfanz" initials="D." surname="Balfanz">
<organization>Google</organization>
<address>
<email>balfanz@google.com</email>
</address>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization abbrev="Ping Identity">Ping Identity</organization>
<address>
<email>ve7jtb@ve7jtb.com</email>
</address>
</author>
<author fullname="Yaron Y. Goland" initials="Y.Y." surname="Goland">
<organization>Microsoft</organization>
<address>
<email>yarong@microsoft.com</email>
</address>
</author>
<author fullname="John Panzer" initials="J." surname="Panzer">
<organization>Google</organization>
<address>
<email>jpanzer@google.com</email>
</address>
</author>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization abbrev="NRI">Nomura Research Institute</organization>
<address>
<email>n-sakimura@nri.co.jp</email>
</address>
</author>
<author fullname="Paul Tarjan" initials="P." surname="Tarjan">
<organization>Facebook</organization>
<address>
<email>pt@fb.com</email>
</address>
</author>
<date day="12" month="May" year="2012" />
</front>
<format target="http://tools.ietf.org/html/draft-jones-json-web-token" type="HTML" />
</reference>
<reference anchor="JWS-JS">
<front>
<title>JSON Web Signature JSON Serialization (JWS-JS)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization>independent</organization>
<address>
<email>ve7jtb@ve7jtb.com</email>
</address>
</author>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization abbrev="NRI">Nomura Research Institute</organization>
<address>
<email>n-sakimura@nri.co.jp</email>
</address>
</author>
<date day="12" month="March" year="2012" />
</front>
<format target="http://tools.ietf.org/html/draft-jones-json-web-signature-json-serialization" type="HTML" />
</reference>
<reference anchor="MagicSignatures">
<front>
<title>Magic Signatures</title>
<author fullname="John Panzer (editor)" initials="J." surname="Panzer (editor)"></author>
<author fullname="Ben Laurie" initials="B." surname="Laurie"></author>
<author fullname="Dirk Balfanz" initials="D." surname="Balfanz"></author>
<date day="7" month="January" year="2011" />
</front>
<format target="http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html" type="HTML" />
</reference>
<reference anchor="JSS">
<front>
<title>JSON Simple Sign</title>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization>independent</organization>
</author>
<author fullname="Nat Sakimura (editor)" initials="N. " surname="Sakimura (editor)">
<organization abbrev="NRI">Nomura Research Institute</organization>
</author>
<date month="September" year="2010" />
</front>
<format target="http://jsonenc.info/jss/1.0/" type="HTML" />
</reference>
<reference anchor="CanvasApp">
<front>
<title>Canvas Applications</title>
<author fullname="Facebook" surname="Facebook"></author>
<date year="2010" />
</front>
<format target="http://developers.facebook.com/docs/authentication/canvas" type="HTML" />
</reference>
<reference anchor="JWE">
<front>
<title>JSON Web Encryption (JWE)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="Eric Rescorla" initials="E." surname="Rescorla">
<organization abbrev="RTFM">RTFM, Inc.</organization>
<address>
<email>ekr@rtfm.com</email>
</address>
</author>
<author fullname="Joe Hildebrand" initials="J." surname="Hildebrand">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<email>jhildebr@cisco.com</email>
</address>
</author>
<date day="12" month="May" year="2012" />
</front>
<format target="http://tools.ietf.org/html/draft-ietf-jose-json-web-encryption" type="HTML" />
</reference>
</references>
<section title="JWS Examples" anchor="JWSExamples">
<t>
This section provides several examples of JWSs. While these
examples all represent JSON Web Tokens (JWTs) <xref
target="JWT" />, the payload can be any base64url encoded
content.
</t>
<section title="JWS using HMAC SHA-256" anchor="HMACSHA256Example">
<section title="Encoding">
<t>
The following example JWS Header declares that the
data structure is a JSON Web Token (JWT) <xref target="JWT" />
and the JWS Secured Input is secured using
the HMAC SHA-256 algorithm.
</t>
<figure><artwork><![CDATA[{"typ":"JWT",
"alg":"HS256"}]]></artwork></figure>
<t>
The following byte array contains the UTF-8 representation of
the JWS Header:
</t>
<t>
[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]
</t>
<t>
Base64url encoding these bytes yields this
Encoded JWS Header value:
</t>
<figure><artwork><![CDATA[eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9]]></artwork></figure>
<t>
The JWS Payload used in this example
is the bytes of the UTF-8 representation of the JSON object below.
(Note that the payload can be any base64url
encoded sequence of bytes, and need not be a base64url encoded JSON
object.)
</t>
<figure><artwork><![CDATA[{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}]]></artwork></figure>
<t>
The following byte array, which is the UTF-8 representation
of the JSON object above, is the JWS Payload:
</t>
<t>
[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]
</t>
<t>
Base64url encoding the above yields the Encoded JWS Payload value
(with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ]]></artwork></figure>
<t>
Concatenating the Encoded JWS Header, a period character,
and the Encoded JWS Payload yields this JWS Secured Input
value (with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ]]></artwork></figure>
<t>
The UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)
is the following byte array:
</t>
<t>
[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]
</t>
<t>
HMACs are generated using keys. This example uses the key
represented by the following byte array:
</t>
<t>
[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]
</t>
<t>
Running the HMAC SHA-256 algorithm on the bytes of the UTF-8 representation
of the JWS Secured Input
(which is the same as the ASCII representation)
with this key yields the following byte array:
</t>
<t>
[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]
</t>
<t>
Base64url encoding the above HMAC output yields the
Encoded JWS Signature value:
</t>
<figure><artwork><![CDATA[dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk]]></artwork></figure>
</section>
<section title="Decoding">
<t>
Decoding the JWS first requires removing the base64url
encoding from the Encoded JWS Header, the Encoded JWS Payload,
and the Encoded JWS Signature. We base64url decode
the inputs and
turn them into the corresponding byte arrays. We
decode the Encoded JWS Header byte array containing
the UTF-8 representation of the JWS Header
into the JWS Header string.
</t>
</section>
<section title="Validating">
<t>
Next we validate the decoded results. Since the <spanx style="verb">alg</spanx>
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.
</t>
<t>
First, we validate that the JWS Header
string is legal JSON.
</t>
<t>
To validate the HMAC value, we repeat the previous process
of using the correct key and the UTF-8 representation of
the JWS Secured Input
(which is the same as the ASCII representation)
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.
</t>
</section>
</section>
<section title="JWS using RSA SHA-256" anchor="RSASHA256Example">
<section title="Encoding">
<t>
The JWS Header in this example is different
from the previous example in two ways: First, because a
different algorithm is being used, the <spanx style="verb">alg</spanx> 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:
</t>
<figure><artwork><![CDATA[{"alg":"RS256"}]]></artwork></figure>
<t>
The following byte array contains the UTF-8 representation of
the JWS Header:
</t>
<t>
[123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]
</t>
<t>
Base64url encoding these bytes yields this
Encoded JWS Header value:
</t>
<figure><artwork><![CDATA[eyJhbGciOiJSUzI1NiJ9]]></artwork></figure>
<t>
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.
</t>
<figure><artwork><![CDATA[{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}]]></artwork></figure>
<t>
Concatenating the Encoded JWS Header, a period character,
and the Encoded JWS Payload yields this JWS Secured Input
value (with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJhbGciOiJSUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ]]></artwork></figure>
<t>
The UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)
is the following byte array:
</t>
<t>
[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]
</t>
<t>
The RSA key consists of a public part (n, e), and a
private exponent d. The values of the RSA key used in
this example, presented as the byte arrays representing
big endian integers are:
</t>
<texttable>
<ttcol align="left">Parameter Name</ttcol>
<ttcol align="left">Value</ttcol>
<c>n</c>
<c>
[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]
</c>
<c>e</c>
<c>
[1, 0, 1]
</c>
<c>d</c>
<c>
[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]
</c>
</texttable>
<t>
The RSA private key (n, d) is then passed to the RSA
signing function, which also takes the hash type, SHA-256,
and the bytes of the UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)
as inputs. The result of the digital signature is a byte array S,
which represents a big endian integer. In this example, S
is:
</t>
<texttable>
<ttcol align="left">Result Name</ttcol>
<ttcol align="left">Value</ttcol>
<c>S</c>
<c>
[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]
</c>
</texttable>
<t>
Base64url encoding the digital signature produces this value for
the Encoded JWS Signature
(with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7
AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4
BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K
0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv
hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB
p0igcN_IoypGlUPQGe77Rw]]></artwork></figure>
</section>
<section title="Decoding">
<t>
Decoding the JWS from this example requires processing the
Encoded JWS Header and Encoded JWS Payload exactly as
done in the first example.
</t>
</section>
<section title="Validating">
<t>
Since the <spanx style="verb">alg</spanx> parameter in the header is "RS256", we
validate the RSA SHA-256 digital signature contained in the JWS Signature. If any of the validation steps fail, the
JWS MUST be rejected.
</t>
<t>
First, we validate that the JWS Header
string is legal JSON.
</t>
<t>
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 bytes of the UTF-8 representation of the
JWS Secured Input
(which is the same as the ASCII representation)
to an RSA signature verifier that has
been configured to use the SHA-256 hash function.
</t>
</section>
</section>
<section title="JWS using ECDSA P-256 SHA-256" anchor="ECDSASHA256Example">
<section title="Encoding">
<t>
The JWS Header for this example differs from
the previous example because a different algorithm is
being used. The JWS Header used is:
</t>
<figure><artwork><![CDATA[{"alg":"ES256"}]]></artwork></figure>
<t>
The following byte array contains the UTF-8 representation of
the JWS Header:
</t>
<t>
[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]
</t>
<t>
Base64url encoding these bytes yields this
Encoded JWS Header value:
</t>
<figure><artwork><![CDATA[eyJhbGciOiJFUzI1NiJ9]]></artwork></figure>
<t>
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.
</t>
<figure><artwork><![CDATA[{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}]]></artwork></figure>
<t>
Concatenating the Encoded JWS Header, a period character,
and the Encoded JWS Payload yields this JWS Secured Input
value (with line breaks for display purposes only):
</t>
<figure><artwork><![CDATA[eyJhbGciOiJFUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ]]></artwork></figure>
<t>
The UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)
is the following byte array:
</t>
<t>
[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]
</t>
<t>
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 byte arrays
representing big endian integers are:
</t>
<texttable>
<ttcol align="left">Parameter Name</ttcol>
<ttcol align="left">Value</ttcol>
<c>x</c>
<c>
[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]
</c>
<c>y</c>
<c>
[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]
</c>
<c>d</c>
<c>
[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]
</c>
</texttable>
<t>
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 bytes of the UTF-8 representation of
the JWS Secured Input
(which is the same as the ASCII representation)
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 byte arrays representing big endian integers are:
</t>
<texttable>
<ttcol align="left">Result Name</ttcol>
<ttcol align="left">Value</ttcol>
<c>R</c>
<c>
[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]
</c>
<c>S</c>
<c>
[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]
</c>
</texttable>
<t>
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):
</t>
<figure><artwork><![CDATA[DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA
pmWQxfKTUJqPP3-Kg6NU1Q]]></artwork></figure>
</section>
<section title="Decoding">
<t>
Decoding the JWS from this example requires processing the
Encoded JWS Header and Encoded JWS Payload exactly as
done in the first example.
</t>
</section>
<section title="Validating">
<t>
Since the <spanx style="verb">alg</spanx> 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.
</t>
<t>
First, we validate that the JWS Header
string is legal JSON.
</t>
<t>
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 byte array that must result
into two 32 byte arrays, the first R and the second S. We
then pass (x, y), (R, S) and the bytes of the UTF-8 representation of
the JWS Secured Input
(which is the same as the ASCII representation)
to an ECDSA signature verifier that
has been configured to use the P-256 curve with the
SHA-256 hash function.
</t>
<t>
As explained in Section 3.4 of the
JSON Web Algorithms (JWA) <xref target="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.
</t>
</section>
</section>
<section title="Example Plaintext JWS" anchor="ExamplePlaintextJWS">
<t>
The following example JWS Header declares that the
encoded object is a Plaintext JWS:
</t>
<figure><artwork><![CDATA[{"alg":"none"}]]></artwork></figure>
<t>
Base64url encoding the bytes of the UTF-8 representation of
the JWS Header yields this Encoded JWS Header:
</t>
<figure><artwork><![CDATA[eyJhbGciOiJub25lIn0]]></artwork></figure>
<t>
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.
</t>
<figure><artwork><![CDATA[{"iss":"joe",
"exp":1300819380,
"http://example.com/is_root":true}]]></artwork></figure>
<t>
The Encoded JWS Signature is the empty string.
</t>
<t>
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):
</t>
<figure><artwork><![CDATA[eyJhbGciOiJub25lIn0
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
]]></artwork></figure>
</section>
</section>
<section title="Notes on implementing base64url encoding without padding" anchor="base64urlnotes">
<t>
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.
</t>
<t>
To be concrete, example C# code implementing these functions
is shown below. Similar code could be used in other
languages.
</t>
<figure><artwork><![CDATA[static string base64urlencode(byte [] arg)
{
string s = Convert.ToBase64String(arg); // Standard base64 encoder
s = s.Split('=')[0]; // Remove any trailing '='s
s = s.Replace('+', '-'); // 62nd char of encoding
s = s.Replace('/', '_'); // 63rd char of encoding
return s;
}
static byte [] base64urldecode(string arg)
{
string s = arg;
s = s.Replace('-', '+'); // 62nd char of encoding
s = s.Replace('_', '/'); // 63rd char of encoding
switch (s.Length % 4) // Pad with trailing '='s
{
case 0: break; // No pad chars in this case
case 2: s += "=="; break; // Two pad chars
case 3: s += "="; break; // One pad char
default: throw new System.Exception(
"Illegal base64url string!");
}
return Convert.FromBase64String(s); // Standard base64 decoder
}]]></artwork></figure>
<t>
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.
</t>
<t>
An example correspondence between unencoded and encoded values
follows. The byte sequence below encodes into the string
below, which when decoded, reproduces the byte sequence.
</t>
<figure><artwork>3 236 255 224 193</artwork></figure>
<figure><artwork>A-z_4ME</artwork></figure>
</section>
<section title="Acknowledgements" anchor="Acknowledgements">
<t>
Solutions for signing JSON content were previously explored by
<xref target="MagicSignatures">Magic Signatures</xref>, <xref
target="JSS">JSON Simple Sign</xref>, and <xref
target="CanvasApp">Canvas Applications</xref>, 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.
</t>
</section>
<section title='Document History'>
<t>
-02
<list style='symbols'>
<t>
Clarified that it is an error when a <spanx style="verb">kid</spanx>
value is included and no matching key is found.
</t>
<t>
Removed assumption that <spanx style="verb">kid</spanx> (key ID)
can only refer to an asymmetric key.
</t>
<t>
Clarified that JWSs with duplicate Header Parameter Names
MUST be rejected.
</t>
<t>
Clarified the relationship between
<spanx style="verb">typ</spanx> header parameter values
and MIME types.
</t>
<t>
Registered application/jws MIME type and "JWS" typ header parameter value.
</t>
<t>
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
<spanx style="verb">jpk</spanx> (JSON Public Key) to
<spanx style="verb">jwk</spanx> (JSON Web Key).
</t>
<t>
Added suggestion on defining additional header parameters
such as <spanx style="verb">x5t#S256</spanx> in the future
for certificate thumbprints using hash algorithms other
than SHA-1.
</t>
<t>
Specify RFC 2818 server identity validation, rather than
RFC 6125 (paralleling the same decision in the OAuth specs).
</t>
<t>
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.
</t>
<t>
Reformatted to give each header parameter its own section heading.
</t>
</list>
</t>
<t>
-01
<list style='symbols'>
<t>
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.
</t>
<t>
Added <spanx style="verb">jpk</spanx> and <spanx
style="verb">x5c</spanx> header parameters for including
JWK public keys and X.509 certificate chains directly in
the header.
</t>
<t>
Clarified that this specification is defining the JWS
Compact Serialization. Referenced the new JWS-JS spec,
which defines the JWS JSON Serialization.
</t>
<t>
Added text "New header parameters should be introduced
sparingly since an implementation that does not understand
a parameter MUST reject the JWS".
</t>
<t>
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.
</t>
<t>
Changed "no canonicalization is performed" to "no
canonicalization need be performed".
</t>
<t>
Corrected the Magic Signatures reference.
</t>
<t>
Made other editorial improvements suggested by JOSE
working group participants.
</t>
</list>
</t>
<t>
-00
<list style='symbols'>
<t>
Created the initial IETF draft based upon
draft-jones-json-web-signature-04 with no normative
changes.
</t>
<t>
Changed terminology to no longer call both digital
signatures and HMACs "signatures".
</t>
</list>
</t>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-23 09:03:49 |