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<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<table summary="layout" width="66%" border="0" cellpadding="0" cellspacing="0"><tr><td><table summary="layout" width="100%" border="0" cellpadding="2" cellspacing="1">
<tr><td class="header">JOSE Working Group</td><td class="header">M. Jones</td></tr>
<tr><td class="header">Internet-Draft</td><td class="header">Microsoft</td></tr>
<tr><td class="header">Intended status: Standards Track</td><td class="header">October 14, 2012</td></tr>
<tr><td class="header">Expires: April 17, 2013</td><td class="header"> </td></tr>
</table></td></tr></table>
<h1><br />JSON Web Algorithms (JWA)<br />draft-ietf-jose-json-web-algorithms-06</h1>
<h3>Abstract</h3>
<p>
The JSON Web Algorithms (JWA) specification enumerates
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS),
JSON Web Encryption (JWE), and
JSON Web Key (JWK) specifications.
</p>
<h3>Status of this Memo</h3>
<p>
This Internet-Draft is submitted in full
conformance with the provisions of BCP 78 and BCP 79.</p>
<p>
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current
Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.</p>
<p>
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any time.
It is inappropriate to use Internet-Drafts as reference material or to cite
them other than as “work in progress.”</p>
<p>
This Internet-Draft will expire on April 17, 2013.</p>
<h3>Copyright Notice</h3>
<p>
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.</p>
<p>
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.</p>
<a name="toc"></a><br /><hr />
<h3>Table of Contents</h3>
<p class="toc">
<a href="#anchor1">1.</a>
Introduction<br />
<a href="#anchor2">1.1.</a>
Notational Conventions<br />
<a href="#anchor3">2.</a>
Terminology<br />
<a href="#anchor4">2.1.</a>
Terms Incorporated from the JWS Specification<br />
<a href="#anchor5">2.2.</a>
Terms Incorporated from the JWE Specification<br />
<a href="#anchor6">2.3.</a>
Terms Incorporated from the JWK Specification<br />
<a href="#anchor7">2.4.</a>
Defined Terms<br />
<a href="#SigningAlgs">3.</a>
Cryptographic Algorithms for JWS<br />
<a href="#JWSAlgValues">3.1.</a>
"alg" (Algorithm) Header Parameter Values for JWS<br />
<a href="#DefiningHMAC">3.2.</a>
MAC with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512<br />
<a href="#DefiningRSA">3.3.</a>
Digital Signature with RSA SHA-256, RSA SHA-384, or RSA SHA-512<br />
<a href="#DefiningECDSA">3.4.</a>
Digital Signature with ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA P-521 SHA-512<br />
<a href="#anchor8">3.5.</a>
Using the Algorithm "none"<br />
<a href="#MoreSigAlgs">3.6.</a>
Additional Digital Signature/MAC Algorithms and Parameters<br />
<a href="#EncryptingAlgs">4.</a>
Cryptographic Algorithms for JWE<br />
<a href="#JWEAlgValues">4.1.</a>
"alg" (Algorithm) Header Parameter Values for JWE<br />
<a href="#JWEEncValues">4.2.</a>
"enc" (Encryption Method) Header Parameter Values for JWE<br />
<a href="#KeyEncryptionRSA15">4.3.</a>
Key Encryption with RSAES-PKCS1-V1_5<br />
<a href="#KeyEncryptionRSAOAEP">4.4.</a>
Key Encryption with RSAES OAEP<br />
<a href="#KeyEncryptionAESKW">4.5.</a>
Key Encryption with AES Key Wrap<br />
<a href="#DirectEncryption">4.6.</a>
Direct Encryption with a Shared Symmetric Key<br />
<a href="#ECDHES">4.7.</a>
Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES)<br />
<a href="#KeyDerivECDHES">4.7.1.</a>
Key Derivation for "ECDH-ES"<br />
<a href="#AESCBC">4.8.</a>
Composite Plaintext Encryption Algorithms "A128CBC+HS256" and "A256CBC+HS512"<br />
<a href="#KeyDerivCBC">4.8.1.</a>
Key Derivation for "A128CBC+HS256" and "A256CBC+HS512"<br />
<a href="#PlaintextEncryptionCBC">4.8.2.</a>
Encryption Calculation for "A128CBC+HS256" and "A256CBC+HS512"<br />
<a href="#IntHMAC">4.8.3.</a>
Integrity Calculation for "A128CBC+HS256" and "A256CBC+HS512"<br />
<a href="#PlaintextEncryptionGCM">4.9.</a>
Plaintext Encryption with AES GCM<br />
<a href="#MoreEncAlgs">4.10.</a>
Additional Encryption Algorithms and Parameters<br />
<a href="#JWKAlgs">5.</a>
Cryptographic Algorithms for JWK<br />
<a href="#JWKAlgValues">5.1.</a>
"alg" (Algorithm Family) Parameter Values for JWK<br />
<a href="#JWKEC">5.2.</a>
JWK Parameters for Elliptic Curve Keys<br />
<a href="#crvDef">5.2.1.</a>
"crv" (Curve) Parameter<br />
<a href="#xDef">5.2.2.</a>
"x" (X Coordinate) Parameter<br />
<a href="#yDef">5.2.3.</a>
"y" (Y Coordinate) Parameter<br />
<a href="#JWKRSA">5.3.</a>
JWK Parameters for RSA Keys<br />
<a href="#modDef">5.3.1.</a>
"mod" (Modulus) Parameter<br />
<a href="#xpoDef">5.3.2.</a>
"xpo" (Exponent) Parameter<br />
<a href="#MoreKeyAlgs">5.4.</a>
Additional Key Algorithm Families and Parameters<br />
<a href="#IANA">6.</a>
IANA Considerations<br />
<a href="#JWSJWEAlgsReg">6.1.</a>
JSON Web Signature and Encryption Algorithms Registry<br />
<a href="#anchor9">6.1.1.</a>
Registration Template<br />
<a href="#anchor10">6.1.2.</a>
Initial Registry Contents<br />
<a href="#KeyAlgRegistry">6.2.</a>
JSON Web Key Algorithm Families Registry<br />
<a href="#anchor11">6.2.1.</a>
Registration Template<br />
<a href="#anchor12">6.2.2.</a>
Initial Registry Contents<br />
<a href="#anchor13">6.3.</a>
JSON Web Key Parameters Registration<br />
<a href="#anchor14">6.3.1.</a>
Registry Contents<br />
<a href="#Security">7.</a>
Security Considerations<br />
<a href="#rfc.references1">8.</a>
References<br />
<a href="#rfc.references1">8.1.</a>
Normative References<br />
<a href="#rfc.references2">8.2.</a>
Informative References<br />
<a href="#SigAlgXref">Appendix A.</a>
Digital Signature/MAC Algorithm Identifier Cross-Reference<br />
<a href="#EncAlgXref">Appendix B.</a>
Encryption Algorithm Identifier Cross-Reference<br />
<a href="#Acknowledgements">Appendix C.</a>
Acknowledgements<br />
<a href="#TBD">Appendix D.</a>
Open Issues<br />
<a href="#anchor17">Appendix E.</a>
Document History<br />
<a href="#rfc.authors">§</a>
Author's Address<br />
</p>
<br clear="all" />
<a name="anchor1"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.1"></a><h3>1.
Introduction</h3>
<p>
The JSON Web Algorithms (JWA) specification enumerates
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS) <a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a>,
JSON Web Encryption (JWE) <a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>, and
JSON Web Key (JWK) <a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a> specifications.
All these specifications utilize
JavaScript Object Notation (JSON) <a class='info' href='#RFC4627'>[RFC4627]<span> (</span><span class='info'>Crockford, D., “The application/json Media Type for JavaScript Object Notation (JSON),” July 2006.</span><span>)</span></a>
based data structures.
This specification also describes the semantics and operations
that are specific to these algorithms and algorithm families.
</p>
<p>
Enumerating the algorithms and identifiers for them in this
specification, rather than in the JWS, JWE, and JWK
specifications, is intended to allow them to remain unchanged
in the face of changes in the set of required, recommended,
optional, and deprecated algorithms over time.
</p>
<a name="anchor2"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.1.1"></a><h3>1.1.
Notational Conventions</h3>
<p>
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 class='info' href='#RFC2119'>[RFC2119]<span> (</span><span class='info'>Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.</span><span>)</span></a>.
</p>
<a name="anchor3"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2"></a><h3>2.
Terminology</h3>
<a name="anchor4"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2.1"></a><h3>2.1.
Terms Incorporated from the JWS Specification</h3>
<p>
These terms defined by the
JSON Web Signature (JWS) <a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a>
specification are incorporated into this specification:
</p>
<p>
</p>
<blockquote class="text"><dl>
<dt>JSON Web Signature (JWS)</dt>
<dd>
A data structure cryptographically securing a JWS Header
and a JWS Payload with a JWS Signature value.
</dd>
<dt>JWS Header</dt>
<dd>
A string representing a
JavaScript Object Notation (JSON) <a class='info' href='#RFC4627'>[RFC4627]<span> (</span><span class='info'>Crockford, D., “The application/json Media Type for JavaScript Object Notation (JSON),” July 2006.</span><span>)</span></a>
object that describes the
digital signature or MAC operation applied to
create the JWS Signature value.
</dd>
<dt>JWS Payload</dt>
<dd>
The bytes to be secured - a.k.a., the message.
The payload can contain an arbitrary sequence of bytes.
</dd>
<dt>JWS Signature</dt>
<dd>
A byte array containing the cryptographic
material that secures the contents of the JWS Header
and the JWS Payload.
</dd>
<dt>Base64url Encoding</dt>
<dd>
The URL- and filename-safe Base64 encoding
described in <a class='info' href='#RFC4648'>RFC 4648<span> (</span><span class='info'>Josefsson, S., “The Base16, Base32, and Base64 Data Encodings,” October 2006.</span><span>)</span></a> [RFC4648],
Section 5, with the (non URL-safe) '=' padding characters
omitted, as permitted by Section 3.2. (See Appendix C of
<a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a> for notes on implementing base64url
encoding without padding.)
</dd>
<dt>Encoded JWS Header</dt>
<dd>
Base64url encoding of the bytes of the
UTF-8 <a class='info' href='#RFC3629'>[RFC3629]<span> (</span><span class='info'>Yergeau, F., “UTF-8, a transformation format of ISO 10646,” November 2003.</span><span>)</span></a>
representation of the JWS Header.
</dd>
<dt>Encoded JWS Payload</dt>
<dd>
Base64url encoding of the JWS Payload.
</dd>
<dt>Encoded JWS Signature</dt>
<dd>
Base64url encoding of the JWS Signature.
</dd>
<dt>JWS Secured Input</dt>
<dd>
The concatenation of the Encoded JWS Header, a period ('.')
character, and the Encoded JWS Payload.
</dd>
<dt>Collision Resistant Namespace</dt>
<dd>
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)
<a class='info' href='#RFC4122'>[RFC4122]<span> (</span><span class='info'>Leach, P., Mealling, M., and R. Salz, “A Universally Unique IDentifier (UUID) URN Namespace,” July 2005.</span><span>)</span></a>.
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.
</dd>
</dl></blockquote><p>
</p>
<a name="anchor5"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2.2"></a><h3>2.2.
Terms Incorporated from the JWE Specification</h3>
<p>
These terms defined by the
JSON Web Encryption (JWE) <a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>
specification are incorporated into this specification:
</p>
<p>
</p>
<blockquote class="text"><dl>
<dt>JSON Web Encryption (JWE)</dt>
<dd>
A data structure representing an encrypted version of a
Plaintext. The structure consists of four parts: the JWE
Header, the JWE Encrypted Key, the JWE Ciphertext, and
the JWE Integrity Value.
</dd>
<dt>Plaintext</dt>
<dd>
The bytes to be encrypted - a.k.a., the message.
The plaintext can contain an arbitrary sequence of bytes.
</dd>
<dt>Ciphertext</dt>
<dd>
The encrypted version of the Plaintext.
</dd>
<dt>Content Encryption Key (CEK)</dt>
<dd>
A symmetric key used to encrypt the Plaintext for the
recipient to produce the Ciphertext.
</dd>
<dt>Content Integrity Key (CIK)</dt>
<dd>
A key used with a MAC function to ensure the integrity
of the Ciphertext and the parameters used to create it.
</dd>
<dt>Content Master Key (CMK)</dt>
<dd>
A key from which the CEK and CIK are derived.
When key wrapping or key encryption are employed, the CMK
is randomly generated and encrypted to the recipient as
the JWE Encrypted Key.
When key agreement is employed, the CMK is the result of
the key agreement algorithm.
</dd>
<dt>JWE Header</dt>
<dd>
A string representing a JSON object that describes the
encryption operations applied to create the JWE Encrypted
Key, the JWE Ciphertext, and the JWE Integrity Value.
</dd>
<dt>JWE Encrypted Key</dt>
<dd>
When key wrapping or key encryption are employed,
the Content Master Key (CMK) is encrypted with the
intended recipient's key and the resulting encrypted
content is recorded as a byte array, which is referred to
as the JWE Encrypted Key.
Otherwise, when key agreement is employed,
the JWE Encrypted Key is the empty byte array.
</dd>
<dt>JWE Ciphertext</dt>
<dd>
A byte array containing the Ciphertext.
</dd>
<dt>JWE Integrity Value</dt>
<dd>
A byte array containing a MAC value that ensures the
integrity of the Ciphertext and the parameters used to
create it.
</dd>
<dt>Encoded JWE Header</dt>
<dd>
Base64url encoding of the bytes of the
UTF-8 <a class='info' href='#RFC3629'>[RFC3629]<span> (</span><span class='info'>Yergeau, F., “UTF-8, a transformation format of ISO 10646,” November 2003.</span><span>)</span></a>
representation of the JWE Header.
</dd>
<dt>Encoded JWE Encrypted Key</dt>
<dd>
Base64url encoding of the JWE Encrypted Key.
</dd>
<dt>Encoded JWE Ciphertext</dt>
<dd>
Base64url encoding of the JWE Ciphertext.
</dd>
<dt>Encoded JWE Integrity Value</dt>
<dd>
Base64url encoding of the JWE Integrity Value.
</dd>
<dt>AEAD Algorithm</dt>
<dd>
An Authenticated Encryption with Associated Data (AEAD)
<a class='info' href='#RFC5116'>[RFC5116]<span> (</span><span class='info'>McGrew, D., “An Interface and Algorithms for Authenticated Encryption,” January 2008.</span><span>)</span></a> encryption algorithm is one that
provides an integrated content integrity check. AES
Galois/Counter Mode (GCM) is one such algorithm.
</dd>
</dl></blockquote><p>
</p>
<a name="anchor6"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2.3"></a><h3>2.3.
Terms Incorporated from the JWK Specification</h3>
<p>
These terms defined by the
JSON Web Key (JWK) <a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a>
specification are incorporated into this specification:
</p>
<p>
</p>
<blockquote class="text"><dl>
<dt>JSON Web Key (JWK)</dt>
<dd>
A JSON data structure that represents a public key.
</dd>
<dt>JSON Web Key Set (JWK Set)</dt>
<dd>
A JSON object that contains an array of JWKs as a member.
</dd>
</dl></blockquote><p>
</p>
<a name="anchor7"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2.4"></a><h3>2.4.
Defined Terms</h3>
<p>
These terms are defined for use by this specification:
</p>
<p>
</p>
<blockquote class="text"><dl>
<dt>Header Parameter Name</dt>
<dd>
The name of a member of the JSON object representing a
JWS Header or JWE Header.
</dd>
<dt>Header Parameter Value</dt>
<dd>
The value of a member of the JSON object representing a
JWS Header or JWE Header.
</dd>
</dl></blockquote><p>
</p>
<a name="SigningAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3"></a><h3>3.
Cryptographic Algorithms for JWS</h3>
<p>
JWS uses cryptographic algorithms to digitally sign or
create a Message Authentication Codes (MAC) of the contents
of the JWS Header and the JWS Payload. The
use of the following algorithms for producing JWSs is defined in
this section.
</p>
<a name="JWSAlgValues"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.1"></a><h3>3.1.
"alg" (Algorithm) Header Parameter Values for JWS</h3>
<p>
The table below is the set of
<tt>alg</tt> (algorithm) header
parameter values defined by this specification for use with JWS, each of which
is explained in more detail in the following sections:
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left">
<tr><th align="left">alg Parameter Value</th><th align="left">Digital Signature or MAC Algorithm</th><th align="left">Implementation Requirements</th></tr>
<tr>
<td align="left">HS256</td>
<td align="left">HMAC using SHA-256 hash algorithm</td>
<td align="left">REQUIRED</td>
</tr>
<tr>
<td align="left">HS384</td>
<td align="left">HMAC using SHA-384 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">HS512</td>
<td align="left">HMAC using SHA-512 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">RS256</td>
<td align="left">RSASSA using SHA-256 hash algorithm</td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">RS384</td>
<td align="left">RSASSA using SHA-384 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">RS512</td>
<td align="left">RSASSA using SHA-512 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">ES256</td>
<td align="left">ECDSA using P-256 curve and SHA-256 hash algorithm</td>
<td align="left">RECOMMENDED+</td>
</tr>
<tr>
<td align="left">ES384</td>
<td align="left">ECDSA using P-384 curve and SHA-384 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">ES512</td>
<td align="left">ECDSA using P-521 curve and SHA-512 hash algorithm</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">none</td>
<td align="left">No digital signature or MAC value included</td>
<td align="left">REQUIRED</td>
</tr>
</table>
<br clear="all" />
<p>
All the names are short because a core goal of JWS is
for the representations to be compact. However, there is no
a priori length restriction on <tt>alg</tt> values.
</p>
<p>
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
</p>
<p>
See <a class='info' href='#SigAlgXref'>Appendix A<span> (</span><span class='info'>Digital Signature/MAC Algorithm Identifier Cross-Reference</span><span>)</span></a> for a table cross-referencing the
digital signature and MAC <tt>alg</tt> (algorithm)
values used in this specification
with the equivalent identifiers used by other
standards and software packages.
</p>
<a name="DefiningHMAC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.2"></a><h3>3.2.
MAC with HMAC SHA-256, HMAC SHA-384, or HMAC SHA-512</h3>
<p>
Hash-based Message Authentication Codes (HMACs) enable one to
use a secret plus a cryptographic hash function to generate a
Message Authentication Code (MAC). This can be used to
demonstrate that the MAC matches the hashed content, in this
case the JWS Secured Input, which therefore demonstrates that
whoever generated the MAC was in possession of the secret.
The means of exchanging the shared key is outside the scope
of this specification.
</p>
<p>
The algorithm for implementing and validating HMACs is
provided in <a class='info' href='#RFC2104'>RFC 2104<span> (</span><span class='info'>Krawczyk, H., Bellare, M., and R. Canetti, “HMAC: Keyed-Hashing for Message Authentication,” February 1997.</span><span>)</span></a> [RFC2104]. This
section defines the use of the HMAC SHA-256, HMAC SHA-384,
and HMAC SHA-512 functions <a class='info' href='#SHS'>[SHS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Secure Hash Standard (SHS),” October 2008.</span><span>)</span></a>. The
<tt>alg</tt> (algorithm) header parameter values
<tt>HS256</tt>, <tt>HS384</tt>, and <tt>HS512</tt> are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded HMAC value using the respective hash function.
</p>
<p>
A key of the same size as the hash output (for instance, 256
bits for <tt>HS256</tt>) or larger MUST
be used with this algorithm.
</p>
<p>
The HMAC SHA-256 MAC is generated per RFC 2104,
using SHA-256 as the hash algorithm "H",
using the bytes of the ASCII <a class='info' href='#USASCII'>[USASCII]<span> (</span><span class='info'>American National Standards Institute, “Coded Character Set -- 7-bit American Standard Code for Information Interchange,” 1986.</span><span>)</span></a> representation
of the JWS Secured Input as the "text" value,
and using the shared key.
The HMAC output value is the JWS Signature.
The JWS signature is base64url encoded to produce the Encoded JWS Signature.
</p>
<p>
The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC value per RFC 2104,
using SHA-256 as the hash algorithm "H",
using the bytes of the ASCII representation
of the received JWS Secured input as the "text" value,
and using the shared key.
This computed HMAC value is then compared to the result of
base64url decoding the received Encoded JWS signature.
Alternatively, the computed HMAC value can be base64url encoded
and compared to the received Encoded JWS Signature,
as this comparison produces the same result as comparing
the unencoded values.
In either case, if the values match, the HMAC has been validated.
If the validation fails, the JWS MUST be rejected.
</p>
<p>
Securing content with the HMAC SHA-384 and HMAC SHA-512
algorithms is performed identically to the procedure for
HMAC SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger minimum key sizes and result values:
384 bits each for HMAC SHA-384 and 512 bits each for HMAC SHA-512.
</p>
<a name="DefiningRSA"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.3"></a><h3>3.3.
Digital Signature with RSA SHA-256, RSA SHA-384, or RSA SHA-512</h3>
<p>
This section defines the use of the RSASSA-PKCS1-V1_5
digital signature algorithm as defined in
Section 8.2 of <a class='info' href='#RFC3447'>RFC 3447<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a> [RFC3447],
(commonly known as PKCS #1),
using SHA-256, SHA-384, or SHA-512 <a class='info' href='#SHS'>[SHS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Secure Hash Standard (SHS),” October 2008.</span><span>)</span></a>
as the hash functions.
The <tt>alg</tt> (algorithm) header
parameter values <tt>RS256</tt>, <tt>RS384</tt>, and <tt>RS512</tt> are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded RSA digital signature using the respective hash function.
</p>
<p>
A key of size 2048 bits or larger MUST be used with these algorithms.
</p>
<p>
The RSA SHA-256 digital signature is generated as follows:
</p>
<ol class="text">
<li>
Generate a digital signature of the bytes of the ASCII representation
of the JWS Secured Input
using RSASSA-PKCS1-V1_5-SIGN
and the SHA-256 hash function with the desired private
key. The output will be a byte array.
</li>
<li>
Base64url encode the resulting byte array.
</li>
</ol><p>
The output is the Encoded JWS Signature for that JWS.
</p>
<p>
The RSA SHA-256 digital signature for a JWS is validated as follows:
</p>
<ol class="text">
<li>
Take the Encoded JWS Signature and base64url decode it into
a byte array. If decoding fails, the JWS MUST
be rejected.
</li>
<li>
Submit the bytes of the ASCII representation of the JWS Secured Input
and the public key corresponding to the private key used
by the signer to the RSASSA-PKCS1-V1_5-VERIFY algorithm
using SHA-256 as the hash function.
</li>
<li>
If the validation fails, the JWS MUST be rejected.
</li>
</ol><p>
</p>
<p>
Signing with the RSA SHA-384 and RSA SHA-512
algorithms is performed identically to the procedure for
RSA SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger result values:
384 bits for RSA SHA-384 and 512 bits for RSA SHA-512.
</p>
<a name="DefiningECDSA"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.4"></a><h3>3.4.
Digital Signature with ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA P-521 SHA-512</h3>
<p>
The Elliptic Curve Digital Signature Algorithm (ECDSA) <a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a>
provides for the use of Elliptic Curve cryptography, which is
able to provide equivalent security to RSA cryptography but
using shorter key sizes and with greater processing
speed. This means that ECDSA digital signatures will be substantially
smaller in terms of length than equivalently strong RSA
digital signatures.
</p>
<p>
This specification defines the use of ECDSA with the P-256
curve and the SHA-256 cryptographic hash function, ECDSA
with the P-384 curve and the SHA-384 hash function, and
ECDSA with the P-521 curve and the SHA-512 hash
function. The P-256, P-384, and P-521 curves are
defined in <a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a>. The <tt>alg</tt> (algorithm) header parameter values <tt>ES256</tt>, <tt>ES384</tt>, and <tt>ES512</tt> are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA
P-521 SHA-512 digital signature, respectively.
</p>
<p>
The ECDSA P-256 SHA-256 digital signature is generated as follows:
</p>
<ol class="text">
<li>
Generate a digital signature of the bytes of the ASCII representation
of the JWS Secured Input
using ECDSA P-256 SHA-256 with
the desired private key. The output will be the pair
(R, S), where R and S are 256 bit unsigned integers.
</li>
<li>
Turn R and S into byte arrays in big endian order,
with each array being be 32 bytes long.
The array representations MUST not be shortened
to omit any leading zero bytes contained in the values.
</li>
<li>
Concatenate the two byte arrays in the order R and then S.
(Note that many ECDSA implementations will directly produce
this concatenation as their output.)
</li>
<li>
Base64url encode the resulting 64 byte array.
</li>
</ol><p>
The output is the Encoded JWS Signature for the JWS.
</p>
<p>
The ECDSA P-256 SHA-256 digital signature for a JWS is validated as follows:
</p>
<ol class="text">
<li>
Take the Encoded JWS Signature and base64url decode it into
a byte array. If decoding fails, the JWS MUST
be rejected.
</li>
<li>
The output of the base64url decoding MUST be a 64 byte
array.
If decoding does not result in a 64 byte array, the JWS MUST be rejected.
</li>
<li>
Split the 64 byte array into two 32 byte arrays. The first
array will be R and the second S
(with both being in big endian byte order).
</li>
<li>
Submit the bytes of the ASCII representation of the JWS Secured Input
R, S and the public key (x, y) to the ECDSA P-256
SHA-256 validator.
</li>
<li>
If the validation fails, the JWS MUST be rejected.
</li>
</ol><p>
Note that ECDSA digital
signature contains a value referred to as K, which is a random
number generated for each digital signature instance. This
means that two ECDSA digital signatures using exactly the same
input parameters will output different signature values because
their K values will be different. A consequence of this is
that one cannot validate an ECDSA signature by recomputing
the signature and comparing the results.
</p>
<p>
Signing with the ECDSA P-384 SHA-384 and ECDSA P-521 SHA-512
algorithms is performed identically to the procedure for
ECDSA P-256 SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger result values.
For ECDSA P-384 SHA-384, R and S will be 384 bits each,
resulting in a 96 byte array.
For ECDSA P-521 SHA-512, R and S will be 521 bits each,
resulting in a 132 byte array.
</p>
<a name="anchor8"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.5"></a><h3>3.5.
Using the Algorithm "none"</h3>
<p>
JWSs MAY also be created that do not provide integrity protection.
Such a JWS is called a "Plaintext JWS".
Plaintext JWSs MUST use the <tt>alg</tt>
value <tt>none</tt>, and are formatted
identically to other JWSs, but with an empty JWS Signature
value.
</p>
<a name="MoreSigAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3.6"></a><h3>3.6.
Additional Digital Signature/MAC Algorithms and Parameters</h3>
<p>
Additional algorithms MAY be used to protect JWSs with
corresponding <tt>alg</tt> (algorithm)
header parameter values being defined to refer to them.
New <tt>alg</tt> header parameter values SHOULD
either be registered in the IANA JSON Web Signature and Encryption Algorithms
registry <a class='info' href='#JWSJWEAlgsReg'>Section 6.1<span> (</span><span class='info'>JSON Web Signature and Encryption Algorithms Registry</span><span>)</span></a> or be
a URI that contains a Collision Resistant Namespace.
In particular, it is permissible to use the algorithm identifiers defined in
<a class='info' href='#RFC3275'>XML DSIG<span> (</span><span class='info'>Eastlake, D., Reagle, J., and D. Solo, “(Extensible Markup Language) XML-Signature Syntax and Processing,” March 2002.</span><span>)</span></a> [RFC3275],
<a class='info' href='#W3C.CR-xmldsig-core2-20120124'>XML DSIG 2.0<span> (</span><span class='info'>Roessler, T., Yiu, K., Solo, D., Reagle, J., Datta, P., Eastlake, D., Hirsch, F., and S. Cantor, “XML Signature Syntax and Processing Version 2.0,” January 2012.</span><span>)</span></a> [W3C.CR‑xmldsig‑core2‑20120124],
and related specifications as
<tt>alg</tt> values.
</p>
<p>
As indicated by the common registry, JWSs and JWEs share a
common <tt>alg</tt> value space.
The values used by the two specifications MUST be distinct,
as the <tt>alg</tt> value MAY be used
to determine whether the object is a JWS or JWE.
</p>
<p>
Likewise, additional reserved header parameter names MAY be defined
via the IANA
JSON Web Signature and Encryption Header Parameters registry
<a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a>.
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.
</p>
<a name="EncryptingAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4"></a><h3>4.
Cryptographic Algorithms for JWE</h3>
<p>
JWE uses cryptographic algorithms to encrypt the Content
Master Key (CMK) and the Plaintext. This section
specifies a set of specific algorithms for these purposes.
</p>
<a name="JWEAlgValues"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.1"></a><h3>4.1.
"alg" (Algorithm) Header Parameter Values for JWE</h3>
<p>
The table below is the set of <tt>alg</tt> (algorithm) header parameter values
that are defined by this specification for use with JWE.
These algorithms are used to encrypt the CMK, producing the
JWE Encrypted Key, or to use key agreement to agree upon the CMK.
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left">
<tr><th align="left">alg Parameter Value</th><th align="left">Key Encryption or Agreement Algorithm</th><th align="left">Implementation Requirements</th></tr>
<tr>
<td align="left">RSA1_5</td>
<td align="left">RSAES-PKCS1-V1_5 <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a></td>
<td align="left">REQUIRED</td>
</tr>
<tr>
<td align="left">RSA-OAEP</td>
<td align="left">RSAES using Optimal Asymmetric Encryption Padding (OAEP)
<a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>, with the
default parameters specified by RFC 3447 in Section A.2.1</td>
<td align="left">OPTIONAL</td>
</tr>
<tr>
<td align="left">A128KW</td>
<td align="left">Advanced Encryption Standard (AES) Key Wrap Algorithm
<a class='info' href='#RFC3394'>[RFC3394]<span> (</span><span class='info'>Schaad, J. and R. Housley, “Advanced Encryption Standard (AES) Key Wrap Algorithm,” September 2002.</span><span>)</span></a>
using 128 bit keys </td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">A256KW</td>
<td align="left">AES Key Wrap Algorithm
using 256 bit keys</td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">dir</td>
<td align="left">Direct use of a shared symmetric key as the Content Master Key (CMK)
for the block encryption step
(rather than using the symmetric key to wrap the CMK)</td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">ECDH-ES</td>
<td align="left">Elliptic Curve Diffie-Hellman Ephemeral Static
<a class='info' href='#RFC6090'>[RFC6090]<span> (</span><span class='info'>McGrew, D., Igoe, K., and M. Salter, “Fundamental Elliptic Curve Cryptography Algorithms,” February 2011.</span><span>)</span></a> key agreement using the
Concat KDF, as defined in Section 5.8.1 of <a class='info' href='#NIST.800-56A'>[NIST.800‑56A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised),” March 2007.</span><span>)</span></a>,
with the agreed-upon key being used directly as the Content Master Key (CMK)
(rather than being used to wrap the CMK),
as specified in <a class='info' href='#ECDHES'>Section 4.7<span> (</span><span class='info'>Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES)</span><span>)</span></a>
</td>
<td align="left">RECOMMENDED+</td>
</tr>
<tr>
<td align="left">ECDH-ES+A128KW</td>
<td align="left">Elliptic Curve Diffie-Hellman Ephemeral Static key agreement
per <tt>ECDH-ES</tt> and <a class='info' href='#ECDHES'>Section 4.7<span> (</span><span class='info'>Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES)</span><span>)</span></a>,
but where the agreed-upon key is used to wrap the Content Master Key (CMK)
with the <tt>A128KW</tt> function
(rather than being used directly as the CMK)</td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">ECDH-ES+A256KW</td>
<td align="left">Elliptic Curve Diffie-Hellman Ephemeral Static key agreement
per <tt>ECDH-ES</tt> and <a class='info' href='#ECDHES'>Section 4.7<span> (</span><span class='info'>Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES)</span><span>)</span></a>,
but where the agreed-upon key is used to wrap the Content Master Key (CMK)
with the <tt>A256KW</tt> function
(rather than being used directly as the CMK)</td>
<td align="left">RECOMMENDED</td>
</tr>
</table>
<br clear="all" />
<p>
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
</p>
<a name="JWEEncValues"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.2"></a><h3>4.2.
"enc" (Encryption Method) Header Parameter Values for JWE</h3>
<p>
The table below is the set of
<tt>enc</tt> (encryption method) header parameter values that
are defined by this specification for use with JWE. These algorithms are used
to encrypt the Plaintext, which produces the Ciphertext.
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left">
<tr><th align="left">enc Parameter Value</th><th align="left">Block Encryption Algorithm</th><th align="left">Implementation Requirements</th></tr>
<tr>
<td align="left">A128CBC+HS256</td>
<td align="left">Composite AEAD algorithm using Advanced Encryption Standard (AES)
in Cipher Block Chaining (CBC) mode with PKCS #5 padding
<a class='info' href='#AES'>[AES]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.</span><span>)</span></a> <a class='info' href='#NIST.800-38A'>[NIST.800‑38A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation,” December 2001.</span><span>)</span></a>
with an integrity calculation using HMAC SHA-256,
using a 256 bit CMK
as specified in <a class='info' href='#AESCBC'>Section 4.8<span> (</span><span class='info'>Composite Plaintext Encryption Algorithms "A128CBC+HS256" and "A256CBC+HS512"</span><span>)</span></a>
</td>
<td align="left">REQUIRED</td>
</tr>
<tr>
<td align="left">A256CBC+HS512</td>
<td align="left">Composite AEAD algorithm using AES in CBC mode with PKCS #5 padding
with an integrity calculation using HMAC SHA-512,
using a 512 bit CMK
as specified in <a class='info' href='#AESCBC'>Section 4.8<span> (</span><span class='info'>Composite Plaintext Encryption Algorithms "A128CBC+HS256" and "A256CBC+HS512"</span><span>)</span></a>
</td>
<td align="left">REQUIRED</td>
</tr>
<tr>
<td align="left">A128GCM</td>
<td align="left">AES in Galois/Counter Mode (GCM)
<a class='info' href='#AES'>[AES]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.</span><span>)</span></a> <a class='info' href='#NIST.800-38D'>[NIST.800‑38D]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.</span><span>)</span></a>
using 128 bit keys</td>
<td align="left">RECOMMENDED</td>
</tr>
<tr>
<td align="left">A256GCM</td>
<td align="left">AES GCM
using 256 bit keys</td>
<td align="left">RECOMMENDED</td>
</tr>
</table>
<br clear="all" />
<p>
All the names are short because a core goal of JWE is
for the representations to be compact. However, there is no
a priori length restriction on <tt>alg</tt> values.
</p>
<p>
See <a class='info' href='#EncAlgXref'>Appendix B<span> (</span><span class='info'>Encryption Algorithm Identifier Cross-Reference</span><span>)</span></a> for a table cross-referencing the
encryption <tt>alg</tt> (algorithm) and
<tt>enc</tt> (encryption method)
values used in this specification
with the equivalent identifiers used by other
standards and software packages.
</p>
<a name="KeyEncryptionRSA15"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.3"></a><h3>4.3.
Key Encryption with RSAES-PKCS1-V1_5</h3>
<p>
This section defines the specifics of encrypting a JWE CMK with
RSAES-PKCS1-V1_5 <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>.
The <tt>alg</tt> header parameter value
<tt>RSA1_5</tt> is used in this case.
</p>
<p>
A key of size 2048 bits or larger MUST be used with this algorithm.
</p>
<a name="KeyEncryptionRSAOAEP"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.4"></a><h3>4.4.
Key Encryption with RSAES OAEP</h3>
<p>
This section defines the specifics of encrypting a JWE CMK with
RSAES using Optimal Asymmetric Encryption Padding (OAEP)
<a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>, with the
default parameters specified by RFC 3447 in Section A.2.1.
The <tt>alg</tt> header parameter value
<tt>RSA-OAEP</tt> is used in this case.
</p>
<p>
A key of size 2048 bits or larger MUST be used with this algorithm.
</p>
<a name="KeyEncryptionAESKW"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.5"></a><h3>4.5.
Key Encryption with AES Key Wrap</h3>
<p>
This section defines the specifics of encrypting a JWE CMK with
the Advanced Encryption Standard (AES) Key Wrap Algorithm
<a class='info' href='#RFC3394'>[RFC3394]<span> (</span><span class='info'>Schaad, J. and R. Housley, “Advanced Encryption Standard (AES) Key Wrap Algorithm,” September 2002.</span><span>)</span></a>
using 128 or 256 bit keys.
The <tt>alg</tt> header parameter values
<tt>A128KW</tt> or <tt>A256KW</tt>
are used in this case.
</p>
<a name="DirectEncryption"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.6"></a><h3>4.6.
Direct Encryption with a Shared Symmetric Key</h3>
<p>
This section defines the specifics of directly performing symmetric key
encryption without performing a key wrapping step. In this case,
the shared symmetric key is used directly as the Content Master Key (CMK)
value for the <tt>enc</tt> algorithm.
An empty byte array is used as the JWE Encrypted Key value.
The <tt>alg</tt> header parameter value
<tt>dir</tt>
is used in this case.
</p>
<a name="ECDHES"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.7"></a><h3>4.7.
Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static (ECDH-ES)</h3>
<p>
This section defines the specifics of key agreement with
Elliptic Curve Diffie-Hellman Ephemeral Static <a class='info' href='#RFC6090'>[RFC6090]<span> (</span><span class='info'>McGrew, D., Igoe, K., and M. Salter, “Fundamental Elliptic Curve Cryptography Algorithms,” February 2011.</span><span>)</span></a>,
and using the
Concat KDF, as defined in Section 5.8.1 of <a class='info' href='#NIST.800-56A'>[NIST.800‑56A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised),” March 2007.</span><span>)</span></a>.
The key agreement result can be used in one of two ways:
(1) directly as the Content Master Key (CMK) for the
<tt>enc</tt> algorithm, or
(2) as a symmetric key used to wrap the CMK with either the
<tt>A128KW</tt> or <tt>A256KW</tt>
algorithms.
The <tt>alg</tt> header parameter values
<tt>ECDH-ES</tt>,
<tt>ECDH-ES+A128KW</tt>, and
<tt>ECDH-ES+A256KW</tt>
are respectively used in this case.
</p>
<p>
In the direct case, the output of the Concat KDF MUST be a key of the
same length as that used by the
<tt>enc</tt> algorithm;
in this case, the empty byte array is used as the JWE Encrypted Key value.
In the key wrap case, the output of the Concat KDF MUST be a key of the
length needed for the specified key wrap algorithm,
either 128 or 256 bits respectively.
</p>
<p>
A new <tt>epk</tt> (ephemeral public key)
value MUST be generated for each key agreement transaction.
</p>
<a name="KeyDerivECDHES"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.7.1"></a><h3>4.7.1.
Key Derivation for "ECDH-ES"</h3>
<p>
The key derivation process derives the agreed upon key from the
ECDH-ES output.
</p>
<p>
Key derivation is performed using the Concat KDF, as
defined in Section 5.8.1 of <a class='info' href='#NIST.800-56A'>[NIST.800‑56A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised),” March 2007.</span><span>)</span></a>, where the Digest
Method is SHA-256.
The Concat KDF parameters are set as follows:
</p>
<blockquote class="text"><dl>
<dt>keydatalen</dt>
<dd>
This is set to the number of bits in the desired output key.
For <tt>ECDH-ES</tt>, this is length of the key
used by the <tt>enc</tt> algorithm.
For <tt>ECDH-ES+A128KW</tt>, and
<tt>ECDH-ES+A256KW</tt>, this is
128 and 256, respectively.
</dd>
<dt>AlgorithmID</dt>
<dd>
This is set to the concatenation of keydatalen represented as a
32 bit big endian integer and
the bytes of the UTF-8 representation of the
<tt>alg</tt> header parameter value.
</dd>
<dt>PartyUInfo</dt>
<dd>
If an <tt>apu</tt> (agreement PartyUInfo)
header parameter is present, this is set to the result of
base64url decoding the <tt>apu</tt> value;
otherwise, it is set to the empty byte string.
</dd>
<dt>PartyVInfo</dt>
<dd>
If an <tt>apv</tt> (agreement PartyVInfo)
header parameter is present, this is set to the result of
base64url decoding the <tt>apv</tt> value;
otherwise, it is set to the empty byte string.
</dd>
<dt>SuppPubInfo</dt>
<dd>
This is set to the empty byte string.
</dd>
<dt>SuppPrivInfo</dt>
<dd>
This is set to the empty byte string.
</dd>
</dl></blockquote><p>
</p>
<p>
For all three <tt>alg</tt> values,
the digest function used is SHA-256.
</p>
<a name="AESCBC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.8"></a><h3>4.8.
Composite Plaintext Encryption Algorithms "A128CBC+HS256" and "A256CBC+HS512"</h3>
<p>
This section defines two composite <tt>enc</tt>
algorithms that perform plaintext encryption using non-AEAD
algorithms and add an integrity check calculation, so that
the resulting composite algorithms are AEAD.
These composite algorithms derive a Content Encryption Key (CEK) and a
Content Integrity Key (CIK) from a Content Master Key,
per <a class='info' href='#KeyDerivCBC'>Section 4.8.1<span> (</span><span class='info'>Key Derivation for "A128CBC+HS256" and "A256CBC+HS512"</span><span>)</span></a>.
They perform block encryption with AES CBC,
per <a class='info' href='#PlaintextEncryptionCBC'>Section 4.8.2<span> (</span><span class='info'>Encryption Calculation for "A128CBC+HS256" and "A256CBC+HS512"</span><span>)</span></a>.
Finally, they add an integrity check using HMAC SHA-2 algorithms of
matching strength, per <a class='info' href='#IntHMAC'>Section 4.8.3<span> (</span><span class='info'>Integrity Calculation for "A128CBC+HS256" and "A256CBC+HS512"</span><span>)</span></a>.
</p>
<p>
A 256 bit Content Master Key (CMK) value is used with the
<tt>A128CBC+HS256</tt> algorithm.
A 512 bit Content Master Key (CMK) value is used with the
<tt>A256CBC+HS512</tt> algorithm.
</p>
<a name="KeyDerivCBC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.8.1"></a><h3>4.8.1.
Key Derivation for "A128CBC+HS256" and "A256CBC+HS512"</h3>
<p>
The key derivation process derives CEK and CIK values from the CMK.
This section defines the specifics of deriving keys for the
<tt>enc</tt> algorithms
<tt>A128CBC+HS256</tt> and
<tt>A256CBC+HS512</tt>.
</p>
<p>
Key derivation is performed using the Concat KDF, as
defined in Section 5.8.1 of <a class='info' href='#NIST.800-56A'>[NIST.800‑56A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised),” March 2007.</span><span>)</span></a>, where the Digest
Method is SHA-256 or SHA-512, respectively.
The Concat KDF parameters are set as follows:
</p>
<blockquote class="text"><dl>
<dt>keydatalen</dt>
<dd>
This is set to the number of bits in the desired output key.
</dd>
<dt>AlgorithmID</dt>
<dd>
This is set to the concatenation of keydatalen represented as a
32 bit big endian integer and
the bytes of the UTF-8 representation of the
<tt>enc</tt> header parameter value.
</dd>
<dt>PartyUInfo</dt>
<dd>
If an <tt>epu</tt> (encryption PartyUInfo)
header parameter is present, this is set to the result of
base64url decoding the <tt>epu</tt> value;
otherwise, it is set to the empty byte string.
</dd>
<dt>PartyVInfo</dt>
<dd>
If an <tt>epv</tt> (encryption PartyVInfo)
header parameter is present, this is set to the result of
base64url decoding the <tt>epv</tt> value;
otherwise, it is set to the empty byte string.
</dd>
<dt>SuppPubInfo</dt>
<dd>
This is set to the bytes of one of the ASCII strings
"Encryption" ([69, 110, 99, 114, 121, 112, 116, 105, 111, 110]) or
"Integrity" ([73, 110, 116, 101, 103, 114, 105, 116, 121]) respectively,
depending upon whether the CEK or CIK is being generated.
</dd>
<dt>SuppPrivInfo</dt>
<dd>
This is set to the empty byte string.
</dd>
</dl></blockquote><p>
</p>
<p>
To compute the CEK from the CMK, the ASCII label "Encryption"
is used for the SuppPubInfo value.
For <tt>A128CBC+HS256</tt>, the keydatalen is 128 and
the digest function used is SHA-256.
For <tt>A256CBC+HS512</tt>, the keydatalen is 256 and
the digest function used is SHA-512.
</p>
<p>
To compute the CIK from the CMK, the ASCII label "Integrity"
is used for the SuppPubInfo value.
For <tt>A128CBC+HS256</tt>, the keydatalen is 256 and
the digest function used is SHA-256.
For <tt>A256CBC+HS512</tt>, the keydatalen is 512 and
the digest function used is SHA-512.
</p>
<p>
Example derivation computations are shown in Appendices A.4 and A.5 of
<a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>.
</p>
<a name="PlaintextEncryptionCBC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.8.2"></a><h3>4.8.2.
Encryption Calculation for "A128CBC+HS256" and "A256CBC+HS512"</h3>
<p>
This section defines the specifics of encrypting the JWE Plaintext with
Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with PKCS #5 padding
<a class='info' href='#AES'>[AES]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.</span><span>)</span></a> <a class='info' href='#NIST.800-38A'>[NIST.800‑38A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation,” December 2001.</span><span>)</span></a>
using 128 or 256 bit keys.
The <tt>enc</tt> header parameter values
<tt>A128CBC+HS256</tt> or
<tt>A256CBC+HS512</tt>
are respectively used in this case.
</p>
<p>
The CEK is used as the encryption key.
</p>
<p>
Use of an initialization vector of size 128 bits is
REQUIRED with these algorithms.
</p>
<p>
An example encryption calculation is shown in
Appendix A.2 of <a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>.
</p>
<a name="IntHMAC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.8.3"></a><h3>4.8.3.
Integrity Calculation for "A128CBC+HS256" and "A256CBC+HS512"</h3>
<p>
This section defines the specifics of computing the JWE Integrity Value for the
<tt>enc</tt> algorithms
<tt>A128CBC+HS256</tt> and
<tt>A256CBC+HS512</tt>.
This value is computed as a MAC of the JWE parameters to
be secured.
</p>
<p>
The MAC input value is the bytes of the ASCII
representation of the concatenation of
the Encoded JWE Header, a period ('.') character,
the Encoded JWE Encrypted Key, a second period character ('.'),
the Encoded JWE Initialization Vector, a third period ('.') character, and
the Encoded JWE Ciphertext.
</p>
<p>
The CIK is used as the MAC key.
</p>
<p>
For <tt>A128CBC+HS256</tt>, HMAC SHA-256
is used as the MAC algorithm.
For <tt>A256CBC+HS512</tt>, HMAC SHA-512
is used as the MAC algorithm.
</p>
<p>
The resulting MAC value is used as the JWE Integrity Value.
The same integrity calculation is performed during decryption.
During decryption, the computed integrity value must match
the received JWE integrity value.
</p>
<p>
An example integrity value calculation is shown in
Appendix A.2 of <a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>.
</p>
<a name="PlaintextEncryptionGCM"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.9"></a><h3>4.9.
Plaintext Encryption with AES GCM</h3>
<p>
This section defines the specifics of encrypting the JWE Plaintext with
Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM)
<a class='info' href='#AES'>[AES]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.</span><span>)</span></a> <a class='info' href='#NIST.800-38D'>[NIST.800‑38D]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.</span><span>)</span></a>
using 128 or 256 bit keys.
The <tt>enc</tt> header parameter values
<tt>A128GCM</tt> or <tt>A256GCM</tt>
are used in this case.
</p>
<p>
The CMK is used as the encryption key.
</p>
<p>
Use of an initialization vector of size 96 bits is
REQUIRED with this algorithm.
</p>
<p>
The "additional authenticated data" parameter is used to
secure the header and key values.
The "additional authenticated data" value used is the bytes of the ASCII
representation of the concatenation of
the Encoded JWE Header, a period ('.') character,
the Encoded JWE Encrypted Key, a second period character ('.'), and
the Encoded JWE Initialization Vector.
This same "additional authenticated data" value is used when decrypting as well.
</p>
<p>
The requested size of the "authentication tag" output MUST be
128 bits, regardless of the key size.
</p>
<p>
As GCM is an AEAD algorithm, the JWE Integrity Value is set
to be the "authentication tag" value produced by the encryption.
During decryption, the received JWE integrity value is used as the
"authentication tag" value.
</p>
<a name="MoreEncAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.10"></a><h3>4.10.
Additional Encryption Algorithms and Parameters</h3>
<p>
Additional algorithms MAY be used to protect JWEs with
corresponding <tt>alg</tt> (algorithm) and
<tt>enc</tt> (encryption method)
header parameter values being
defined to refer to them. New
<tt>alg</tt> and
<tt>enc</tt>
header parameter values SHOULD
either be registered in the IANA JSON Web Signature and Encryption Algorithms
registry <a class='info' href='#JWSJWEAlgsReg'>Section 6.1<span> (</span><span class='info'>JSON Web Signature and Encryption Algorithms Registry</span><span>)</span></a> or be
a URI that contains a Collision Resistant Namespace.
In particular, it is permissible to use the algorithm identifiers defined in
<a class='info' href='#W3C.REC-xmlenc-core-20021210'>XML Encryption<span> (</span><span class='info'>Eastlake, D. and J. Reagle, “XML Encryption Syntax and Processing,” December 2002.</span><span>)</span></a> [W3C.REC‑xmlenc‑core‑20021210],
<a class='info' href='#W3C.CR-xmlenc-core1-20120313'>XML Encryption 1.1<span> (</span><span class='info'>Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler, “XML Encryption Syntax and Processing Version 1.1,” March 2012.</span><span>)</span></a> [W3C.CR‑xmlenc‑core1‑20120313],
and related specifications as
<tt>alg</tt> and
<tt>enc</tt> values.
</p>
<p>
As indicated by the common registry, JWSs and JWEs share a
common <tt>alg</tt> value space.
The values used by the two specifications MUST be distinct,
as the <tt>alg</tt> value MAY be used
to determine whether the object is a JWS or JWE.
</p>
<p>
Likewise, additional reserved header parameter names MAY be defined
via the IANA JSON Web Signature and Encryption Header Parameters registry
<a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a>.
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.
</p>
<a name="JWKAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5"></a><h3>5.
Cryptographic Algorithms for JWK</h3>
<p>
A JSON Web Key (JWK) <a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a> is a
JavaScript Object Notation (JSON) <a class='info' href='#RFC4627'>[RFC4627]<span> (</span><span class='info'>Crockford, D., “The application/json Media Type for JavaScript Object Notation (JSON),” July 2006.</span><span>)</span></a>
data structure that represents a public key. A JSON Web Key Set
(JWK Set) is a JSON data structure for representing a set of JWKs.
This section specifies a set of algorithm families to be used
for those public keys and the algorithm family specific
parameters for representing those keys.
</p>
<a name="JWKAlgValues"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.1"></a><h3>5.1.
"alg" (Algorithm Family) Parameter Values for JWK</h3>
<p>
The table below is the set of
<tt>alg</tt> (algorithm family) parameter
values that are defined by this specification for use in JWKs.
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left">
<tr><th align="left">alg Parameter Value</th><th align="left">Algorithm Family</th><th align="left">Implementation Requirements</th></tr>
<tr>
<td align="left">EC</td>
<td align="left">Elliptic Curve <a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a> key family</td>
<td align="left">RECOMMENDED+</td>
</tr>
<tr>
<td align="left">RSA</td>
<td align="left">RSA <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a> key family</td>
<td align="left">REQUIRED</td>
</tr>
</table>
<br clear="all" />
<p>
All the names are short because a core goal of JWK is
for the representations to be compact. However, there is no
a priori length restriction on <tt>alg</tt> values.
</p>
<p>
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
</p>
<a name="JWKEC"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.2"></a><h3>5.2.
JWK Parameters for Elliptic Curve Keys</h3>
<p>
JWKs can represent Elliptic Curve <a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a> keys. In
this case, the <tt>alg</tt>
member value MUST be <tt>EC</tt>.
Furthermore, these additional members MUST be present:
</p>
<a name="crvDef"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.2.1"></a><h3>5.2.1.
"crv" (Curve) Parameter</h3>
<p>
The <tt>crv</tt> (curve) member identifies
the cryptographic curve used with the key. Curve values
from <a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a> used by this specification are:
</p>
<ul class="text">
<li><tt>P-256</tt>
</li>
<li><tt>P-384</tt>
</li>
<li><tt>P-521</tt>
</li>
</ul><p>
Additional <tt>crv</tt> values MAY be used, provided
they are understood by implementations using that Elliptic Curve key.
The <tt>crv</tt> value is a case sensitive string.
</p>
<a name="xDef"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.2.2"></a><h3>5.2.2.
"x" (X Coordinate) Parameter</h3>
<p>
The <tt>x</tt> (x coordinate) member contains the
x coordinate for the elliptic curve point. It is
represented as the base64url encoding of the
coordinate's big endian representation as a byte array.
The array representation MUST not be shortened
to omit any leading zero bytes contained in the value.
For instance, when representing 521 bit integers,
the byte array to be base64url encoded MUST contain 66 bytes,
including any leading zero bytes.
</p>
<a name="yDef"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.2.3"></a><h3>5.2.3.
"y" (Y Coordinate) Parameter</h3>
<p>
The <tt>y</tt> (y coordinate) member contains the
y coordinate for the elliptic curve point. It is
represented as the base64url encoding of the
coordinate's big endian representation as a byte array.
The array representation MUST not be shortened
to omit any leading zero bytes contained in the value.
For instance, when representing 521 bit integers,
the byte array to be base64url encoded MUST contain 66 bytes,
including any leading zero bytes.
</p>
<a name="JWKRSA"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.3"></a><h3>5.3.
JWK Parameters for RSA Keys</h3>
<p>
JWKs can represent RSA <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a> keys. In
this case, the <tt>alg</tt>
member value MUST be <tt>RSA</tt>.
Furthermore, these additional members MUST be present:
</p>
<a name="modDef"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.3.1"></a><h3>5.3.1.
"mod" (Modulus) Parameter</h3>
<p>
The <tt>mod</tt> (modulus) member contains
the modulus value for the RSA public key. It is
represented as the base64url encoding of the value's
unsigned big endian representation as a byte array.
The array representation MUST not be shortened
to omit any leading zero bytes.
For instance, when representing 2048 bit integers,
the byte array to be base64url encoded MUST contain 256 bytes,
including any leading zero bytes.
</p>
<a name="xpoDef"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.3.2"></a><h3>5.3.2.
"xpo" (Exponent) Parameter</h3>
<p>
The <tt>xpo</tt> (exponent) member contains
the exponent value for the RSA public key. It is
represented as the base64url encoding of the value's
unsigned big endian representation as a byte array.
The array representation MUST utilize the minimum
number of bytes to represent the value.
For instance, when representing the value 65537,
the byte array to be base64url encoded MUST consist of the
three bytes [1, 0, 1].
</p>
<a name="MoreKeyAlgs"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.5.4"></a><h3>5.4.
Additional Key Algorithm Families and Parameters</h3>
<p>
Public keys using additional algorithm families MAY be
represented using JWK data structures with corresponding
<tt>alg</tt> (algorithm family) parameter
values being defined to refer to them.
New <tt>alg</tt> parameter values SHOULD
either be registered in the
IANA JSON Web Key Algorithm Families registry <a class='info' href='#KeyAlgRegistry'>Section 6.2<span> (</span><span class='info'>JSON Web Key Algorithm Families Registry</span><span>)</span></a> or be
a URI that contains a Collision Resistant Namespace.
</p>
<p>
Likewise, parameters for representing keys for additional
algorithm families or additional key properties
SHOULD either be registered in the
IANA JSON Web Key Parameters registry <a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a> or be
a URI that contains a Collision Resistant Namespace.
</p>
<a name="IANA"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6"></a><h3>6.
IANA Considerations</h3>
<p>
The following registration procedure is used for all the
registries established by this specification.
</p>
<p>
Values are registered with a Specification Required
<a class='info' href='#RFC5226'>[RFC5226]<span> (</span><span class='info'>Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.</span><span>)</span></a> 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.
</p>
<p>
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. ]]
</p>
<p>
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.
</p>
<p>
IANA must only accept registry updates from the Designated Expert(s), and should direct
all requests for registration to the review mailing list.
</p>
<a name="JWSJWEAlgsReg"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.1"></a><h3>6.1.
JSON Web Signature and Encryption Algorithms Registry</h3>
<p>
This specification establishes the
IANA JSON Web Signature and Encryption Algorithms registry
for values of the JWS and JWE
<tt>alg</tt> (algorithm) and
<tt>enc</tt> (encryption method)
header parameters.
The registry records the algorithm name,
the algorithm usage locations from the set
<tt>alg</tt> and
<tt>enc</tt>,
implementation requirements,
and a reference to the specification that defines it.
The same algorithm name may be registered multiple times,
provided that the sets of usage locations are disjoint.
The implementation requirements of an algorithm may be changed
over time by the Designated Experts(s) as the
cryptographic landscape evolves, for instance,
to change the status of an algorithm to DEPRECATED, or
to change the status of an algorithm from OPTIONAL
to RECOMMENDED or REQUIRED.
</p>
<a name="anchor9"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.1.1"></a><h3>6.1.1.
Registration Template</h3>
<p>
</p>
<blockquote class="text"><dl>
<dt>Algorithm Name:</dt>
<dd>
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.
</dd>
<dt>Algorithm Usage Location(s):</dt>
<dd>
The algorithm usage, which must be one or more of the values
<tt>alg</tt> or
<tt>enc</tt>.
</dd>
<dt>Implementation Requirements:</dt>
<dd>
The algorithm implementation requirements, which must be one the words
REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.
Optionally, the word may be followed by a "+" or "-".
The use of "+" indicates that the requirement strength is likely
to be increased in a future version of the specification.
The use of "-" indicates that the requirement strength is likely
to be decreased in a future version of the specification.
</dd>
<dt>Change Controller:</dt>
<dd>
For standards-track RFCs, state "IETF". For others, give the name of the
responsible party. Other details (e.g., postal address, e-mail address, home page
URI) may also be included.
</dd>
<dt>Specification Document(s):</dt>
<dd>
Reference to the document that specifies the parameter, preferably including a URI that
can be used to retrieve a copy of the document. An indication of the relevant
sections may also be included, but is not required.
</dd>
</dl></blockquote><p>
</p>
<a name="anchor10"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.1.2"></a><h3>6.1.2.
Initial Registry Contents</h3>
<p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>HS256</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a>
of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>HS384</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a>
of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>HS512</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a>
of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>RS256</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>RS384</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>RS512</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ES256</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED+
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ES384</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ES512</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>none</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWSAlgValues'>Section 3.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWS</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>RSA1_5</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>RSA-OAEP</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: OPTIONAL
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A128KW</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A256KW</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>dir</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ECDH-ES</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED+
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ECDH-ES+A128KW</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>ECDH-ES+A256KW</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>alg</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEAlgValues'>Section 4.1<span> (</span><span class='info'>"alg" (Algorithm) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A128CBC+HS256</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>enc</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEEncValues'>Section 4.2<span> (</span><span class='info'>"enc" (Encryption Method) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A256CBC+HS512</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>enc</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEEncValues'>Section 4.2<span> (</span><span class='info'>"enc" (Encryption Method) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A128GCM</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>enc</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEEncValues'>Section 4.2<span> (</span><span class='info'>"enc" (Encryption Method) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Algorithm Name: <tt>A256GCM</tt>
</li>
<li>
Algorithm Usage Location(s): <tt>enc</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWEEncValues'>Section 4.2<span> (</span><span class='info'>"enc" (Encryption Method) Header Parameter Values for JWE</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<a name="KeyAlgRegistry"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.2"></a><h3>6.2.
JSON Web Key Algorithm Families Registry</h3>
<p>
This specification establishes the
IANA JSON Web Key Algorithm Families registry
for values of the JWK
<tt>alg</tt> (algorithm family) parameter.
The registry records the <tt>alg</tt> value
and a reference to the specification that defines it.
This specification registers the values defined in
<a class='info' href='#JWKAlgValues'>Section 5.1<span> (</span><span class='info'>"alg" (Algorithm Family) Parameter Values for JWK</span><span>)</span></a>.
</p>
<a name="anchor11"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.2.1"></a><h3>6.2.1.
Registration Template</h3>
<p>
</p>
<blockquote class="text"><dl>
<dt>"alg" Parameter Value:</dt>
<dd>
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.
</dd>
<dt>Change Controller:</dt>
<dd>
For standards-track RFCs, state "IETF". For others, give the name of the
responsible party. Other details (e.g., postal address, e-mail address, home page
URI) may also be included.
</dd>
<dt>Implementation Requirements:</dt>
<dd>
The algorithm implementation requirements, which must be one the words
REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.
Optionally, the word may be followed by a "+" or "-".
The use of "+" indicates that the requirement strength is likely
to be increased in a future version of the specification.
The use of "-" indicates that the requirement strength is likely
to be decreased in a future version of the specification.
</dd>
<dt>Specification Document(s):</dt>
<dd>
Reference to the document that specifies the parameter, preferably including a URI that
can be used to retrieve a copy of the document. An indication of the relevant
sections may also be included, but is not required.
</dd>
</dl></blockquote><p>
</p>
<a name="anchor12"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.2.2"></a><h3>6.2.2.
Initial Registry Contents</h3>
<p>
</p>
<ul class="text">
<li>
"alg" Parameter Value: <tt>EC</tt>
</li>
<li>
Implementation Requirements: RECOMMENDED+
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWKAlgValues'>Section 5.1<span> (</span><span class='info'>"alg" (Algorithm Family) Parameter Values for JWK</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
"alg" Parameter Value: <tt>RSA</tt>
</li>
<li>
Implementation Requirements: REQUIRED
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#JWKAlgValues'>Section 5.1<span> (</span><span class='info'>"alg" (Algorithm Family) Parameter Values for JWK</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<a name="anchor13"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.3"></a><h3>6.3.
JSON Web Key Parameters Registration</h3>
<p>
This specification registers the parameter names defined in
<a class='info' href='#JWKEC'>Section 5.2<span> (</span><span class='info'>JWK Parameters for Elliptic Curve Keys</span><span>)</span></a> and <a class='info' href='#JWKRSA'>Section 5.3<span> (</span><span class='info'>JWK Parameters for RSA Keys</span><span>)</span></a> in the
IANA JSON Web Key Parameters registry <a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a>.
</p>
<a name="anchor14"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.6.3.1"></a><h3>6.3.1.
Registry Contents</h3>
<p>
</p>
<ul class="text">
<li>
Parameter Name: <tt>crv</tt>
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#crvDef'>Section 5.2.1<span> (</span><span class='info'>"crv" (Curve) Parameter</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Parameter Name: <tt>x</tt>
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#xDef'>Section 5.2.2<span> (</span><span class='info'>"x" (X Coordinate) Parameter</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Parameter Name: <tt>y</tt>
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#yDef'>Section 5.2.3<span> (</span><span class='info'>"y" (Y Coordinate) Parameter</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Parameter Name: <tt>mod</tt>
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#modDef'>Section 5.3.1<span> (</span><span class='info'>"mod" (Modulus) Parameter</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<ul class="text">
<li>
Parameter Name: <tt>xpo</tt>
</li>
<li>
Change Controller: IETF
</li>
<li>
Specification Document(s): <a class='info' href='#xpoDef'>Section 5.3.2<span> (</span><span class='info'>"xpo" (Exponent) Parameter</span><span>)</span></a> of [[ this document ]]
</li>
</ul><p>
</p>
<a name="Security"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.7"></a><h3>7.
Security Considerations</h3>
<p>
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 key, preventing various attacks, and helping the
user avoid mistakes such as inadvertently encrypting a message for
the wrong recipient. The entire list of security considerations is
beyond the scope of this document, but some significant concerns are
listed here.
</p>
<p>
The security considerations in
<a class='info' href='#AES'>[AES]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.</span><span>)</span></a>,
<a class='info' href='#DSS'>[DSS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Digital Signature Standard (DSS),” June 2009.</span><span>)</span></a>,
<a class='info' href='#JWE'>[JWE]<span> (</span><span class='info'>Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” October 2012.</span><span>)</span></a>,
<a class='info' href='#JWK'>[JWK]<span> (</span><span class='info'>Jones, M., “JSON Web Key (JWK),” October 2012.</span><span>)</span></a>,
<a class='info' href='#JWS'>[JWS]<span> (</span><span class='info'>Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” October 2012.</span><span>)</span></a>,
<a class='info' href='#NIST.800-38A'>[NIST.800‑38A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation,” December 2001.</span><span>)</span></a>,
<a class='info' href='#NIST.800-38D'>[NIST.800‑38D]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.</span><span>)</span></a>,
<a class='info' href='#NIST.800-56A'>[NIST.800‑56A]<span> (</span><span class='info'>National Institute of Standards and Technology (NIST), “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised),” March 2007.</span><span>)</span></a>,
<a class='info' href='#RFC2104'>[RFC2104]<span> (</span><span class='info'>Krawczyk, H., Bellare, M., and R. Canetti, “HMAC: Keyed-Hashing for Message Authentication,” February 1997.</span><span>)</span></a>,
<a class='info' href='#RFC3394'>[RFC3394]<span> (</span><span class='info'>Schaad, J. and R. Housley, “Advanced Encryption Standard (AES) Key Wrap Algorithm,” September 2002.</span><span>)</span></a>,
<a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>,
<a class='info' href='#RFC5116'>[RFC5116]<span> (</span><span class='info'>McGrew, D., “An Interface and Algorithms for Authenticated Encryption,” January 2008.</span><span>)</span></a>,
<a class='info' href='#RFC6090'>[RFC6090]<span> (</span><span class='info'>McGrew, D., Igoe, K., and M. Salter, “Fundamental Elliptic Curve Cryptography Algorithms,” February 2011.</span><span>)</span></a>, and
<a class='info' href='#SHS'>[SHS]<span> (</span><span class='info'>National Institute of Standards and Technology, “Secure Hash Standard (SHS),” October 2008.</span><span>)</span></a> apply to this specification.
</p>
<p>
Eventually the algorithms and/or key sizes currently described
in this specification will no longer be considered
sufficiently secure and will be removed. Therefore,
implementers and deployments must be prepared for this
eventuality.
</p>
<p>
Algorithms of matching strength should be used together whenever possible.
For instance, when AES Key Wrap is used with a given key size,
using the same key size for AES GCM is recommended.
</p>
<p>
While Section 8 of RFC 3447 <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>
explicitly calls for people not to adopt RSASSA-PKCS1 for new
applications and instead requests that people transition to
RSASSA-PSS, this specification does include RSASSA-PKCS1, for
interoperability reasons, because it commonly implemented.
</p>
<p>
Keys used with RSAES-PKCS1-v1_5 must follow the constraints in
Section 7.2 of RFC 3447 <a class='info' href='#RFC3447'>[RFC3447]<span> (</span><span class='info'>Jonsson, J. and B. Kaliski, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1,” February 2003.</span><span>)</span></a>. In particular, keys with
a low public key exponent value must not be used.
</p>
<p>
Plaintext JWSs (JWSs that use the <tt>alg</tt>
value <tt>none</tt>) provide no integrity protection.
Thus, they must only be used in contexts where the payload is secured by
means other than a digital signature or MAC value, or need not be secured.
</p>
<p>
Receiving agents that validate signatures and sending agents that
encrypt messages need to be cautious of cryptographic processing
usage when validating signatures and encrypting messages using keys
larger than those mandated in this specification. An attacker could
send certificates with keys that would result in excessive
cryptographic processing, for example, keys larger than those
mandated in this specification, which could swamp the processing
element. Agents that use such keys without first validating the
certificate to a trust anchor are advised to have some sort of
cryptographic resource management system to prevent such attacks.
</p>
<a name="rfc.references"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.8"></a><h3>8.
References</h3>
<a name="rfc.references1"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<h3>8.1. Normative References</h3>
<table width="99%" border="0">
<tr><td class="author-text" valign="top"><a name="AES">[AES]</a></td>
<td class="author-text">National Institute of Standards and Technology (NIST), “<a href="http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf">Advanced Encryption Standard (AES)</a>,” FIPS PUB 197, November 2001.</td></tr>
<tr><td class="author-text" valign="top"><a name="DSS">[DSS]</a></td>
<td class="author-text">National Institute of Standards and
Technology, “<a href="http://csrc.nist.gov/publications/fips/fips186-3/fips_186-3.pdf">Digital Signature Standard (DSS)</a>,” FIPS PUB 186-3, June 2009.</td></tr>
<tr><td class="author-text" valign="top"><a name="JWE">[JWE]</a></td>
<td class="author-text"><a href="mailto:mbj@microsoft.com">Jones, M.</a>, <a href="mailto:ekr@rtfm.com">Rescorla, E.</a>, and <a href="mailto:jhildebr@cisco.com">J. Hildebrand</a>, “<a href="http://tools.ietf.org/html/draft-ietf-jose-json-web-encryption">JSON Web Encryption (JWE)</a>,” October 2012.</td></tr>
<tr><td class="author-text" valign="top"><a name="JWK">[JWK]</a></td>
<td class="author-text"><a href="mailto:mbj@microsoft.com">Jones, M.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-jose-json-web-key">JSON Web Key (JWK)</a>,” October 2012.</td></tr>
<tr><td class="author-text" valign="top"><a name="JWS">[JWS]</a></td>
<td class="author-text"><a href="mailto:mbj@microsoft.com">Jones, M.</a>, <a href="mailto:ve7jtb@ve7jtb.com">Bradley, J.</a>, and <a href="mailto:n-sakimura@nri.co.jp">N. Sakimura</a>, “<a href="http://tools.ietf.org/html/draft-ietf-jose-json-web-signature">JSON Web Signature (JWS)</a>,” October 2012.</td></tr>
<tr><td class="author-text" valign="top"><a name="NIST.800-38A">[NIST.800-38A]</a></td>
<td class="author-text">National Institute of Standards and Technology (NIST), “<a href="http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf">Recommendation for Block Cipher Modes of Operation</a>,” NIST PUB 800-38A, December 2001.</td></tr>
<tr><td class="author-text" valign="top"><a name="NIST.800-38D">[NIST.800-38D]</a></td>
<td class="author-text">National Institute of Standards and Technology (NIST), “<a href="http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf">Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC</a>,” NIST PUB 800-38D, December 2001.</td></tr>
<tr><td class="author-text" valign="top"><a name="NIST.800-56A">[NIST.800-56A]</a></td>
<td class="author-text">National Institute of Standards and Technology (NIST), “<a href="http://csrc.nist.gov/publications/nistpubs/800-56A/SP800-56A_Revision1_Mar08-2007.pdf">Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised)</a>,” NIST PUB 800-56A, March 2007.</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC2104">[RFC2104]</a></td>
<td class="author-text"><a href="mailto:hugo@watson.ibm.com">Krawczyk, H.</a>, <a href="mailto:mihir@cs.ucsd.edu">Bellare, M.</a>, and <a href="mailto:canetti@watson.ibm.com">R. Canetti</a>, “<a href="http://tools.ietf.org/html/rfc2104">HMAC: Keyed-Hashing for Message Authentication</a>,” RFC 2104, February 1997 (<a href="http://www.rfc-editor.org/rfc/rfc2104.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC2119">[RFC2119]</a></td>
<td class="author-text"><a href="mailto:sob@harvard.edu">Bradner, S.</a>, “<a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>,” BCP 14, RFC 2119, March 1997 (<a href="http://www.rfc-editor.org/rfc/rfc2119.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2119.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2119.xml">XML</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3394">[RFC3394]</a></td>
<td class="author-text">Schaad, J. and R. Housley, “<a href="http://tools.ietf.org/html/rfc3394">Advanced Encryption Standard (AES) Key Wrap Algorithm</a>,” RFC 3394, September 2002 (<a href="http://www.rfc-editor.org/rfc/rfc3394.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3447">[RFC3447]</a></td>
<td class="author-text">Jonsson, J. and B. Kaliski, “<a href="http://tools.ietf.org/html/rfc3447">Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1</a>,” RFC 3447, February 2003 (<a href="http://www.rfc-editor.org/rfc/rfc3447.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3629">[RFC3629]</a></td>
<td class="author-text">Yergeau, F., “<a href="http://tools.ietf.org/html/rfc3629">UTF-8, a transformation format of ISO 10646</a>,” STD 63, RFC 3629, November 2003 (<a href="http://www.rfc-editor.org/rfc/rfc3629.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC4627">[RFC4627]</a></td>
<td class="author-text">Crockford, D., “<a href="http://tools.ietf.org/html/rfc4627">The application/json Media Type for JavaScript Object Notation (JSON)</a>,” RFC 4627, July 2006 (<a href="http://www.rfc-editor.org/rfc/rfc4627.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC4648">[RFC4648]</a></td>
<td class="author-text">Josefsson, S., “<a href="http://tools.ietf.org/html/rfc4648">The Base16, Base32, and Base64 Data Encodings</a>,” RFC 4648, October 2006 (<a href="http://www.rfc-editor.org/rfc/rfc4648.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC5116">[RFC5116]</a></td>
<td class="author-text">McGrew, D., “<a href="http://tools.ietf.org/html/rfc5116">An Interface and Algorithms for Authenticated Encryption</a>,” RFC 5116, January 2008 (<a href="http://www.rfc-editor.org/rfc/rfc5116.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC5226">[RFC5226]</a></td>
<td class="author-text">Narten, T. and H. Alvestrand, “<a href="http://tools.ietf.org/html/rfc5226">Guidelines for Writing an IANA Considerations Section in RFCs</a>,” BCP 26, RFC 5226, May 2008 (<a href="http://www.rfc-editor.org/rfc/rfc5226.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC6090">[RFC6090]</a></td>
<td class="author-text">McGrew, D., Igoe, K., and M. Salter, “<a href="http://tools.ietf.org/html/rfc6090">Fundamental Elliptic Curve Cryptography Algorithms</a>,” RFC 6090, February 2011 (<a href="http://www.rfc-editor.org/rfc/rfc6090.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="SHS">[SHS]</a></td>
<td class="author-text">National Institute of Standards and
Technology, “<a href="http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf">Secure Hash Standard (SHS)</a>,” FIPS PUB 180-3, October 2008.</td></tr>
<tr><td class="author-text" valign="top"><a name="USASCII">[USASCII]</a></td>
<td class="author-text">American National Standards Institute, “Coded Character Set -- 7-bit American Standard Code for Information Interchange,” ANSI X3.4, 1986.</td></tr>
</table>
<a name="rfc.references2"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<h3>8.2. Informative References</h3>
<table width="99%" border="0">
<tr><td class="author-text" valign="top"><a name="CanvasApp">[CanvasApp]</a></td>
<td class="author-text">Facebook, “<a href="http://developers.facebook.com/docs/authentication/canvas">Canvas Applications</a>,” 2010.</td></tr>
<tr><td class="author-text" valign="top"><a name="I-D.rescorla-jsms">[I-D.rescorla-jsms]</a></td>
<td class="author-text">Rescorla, E. and J. Hildebrand, “<a href="http://tools.ietf.org/html/draft-rescorla-jsms-00">JavaScript Message Security Format</a>,” draft-rescorla-jsms-00 (work in progress), March 2011 (<a href="http://www.ietf.org/internet-drafts/draft-rescorla-jsms-00.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="JCA">[JCA]</a></td>
<td class="author-text">Oracle, “<a href="http://download.java.net/jdk7/docs/technotes/guides/security/SunProviders.html">Java Cryptography Architecture</a>,” 2011.</td></tr>
<tr><td class="author-text" valign="top"><a name="JSE">[JSE]</a></td>
<td class="author-text">Bradley, J. and N. Sakimura (editor), “<a href="http://jsonenc.info/enc/1.0/">JSON Simple Encryption</a>,” September 2010.</td></tr>
<tr><td class="author-text" valign="top"><a name="JSS">[JSS]</a></td>
<td class="author-text">Bradley, J. and N. Sakimura (editor), “<a href="http://jsonenc.info/jss/1.0/">JSON Simple Sign</a>,” September 2010.</td></tr>
<tr><td class="author-text" valign="top"><a name="MagicSignatures">[MagicSignatures]</a></td>
<td class="author-text">Panzer (editor), J., Laurie, B., and D. Balfanz, “<a href="http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html">Magic Signatures</a>,” January 2011.</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3275">[RFC3275]</a></td>
<td class="author-text">Eastlake, D., Reagle, J., and D. Solo, “<a href="http://tools.ietf.org/html/rfc3275">(Extensible Markup Language) XML-Signature Syntax and Processing</a>,” RFC 3275, March 2002 (<a href="http://www.rfc-editor.org/rfc/rfc3275.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC4122">[RFC4122]</a></td>
<td class="author-text"><a href="mailto:paulle@microsoft.com">Leach, P.</a>, <a href="mailto:michael@refactored-networks.com">Mealling, M.</a>, and <a href="mailto:rsalz@datapower.com">R. Salz</a>, “<a href="http://tools.ietf.org/html/rfc4122">A Universally Unique IDentifier (UUID) URN Namespace</a>,” RFC 4122, July 2005 (<a href="http://www.rfc-editor.org/rfc/rfc4122.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc4122.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc4122.xml">XML</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="W3C.CR-xmldsig-core2-20120124">[W3C.CR-xmldsig-core2-20120124]</a></td>
<td class="author-text">Roessler, T., Yiu, K., Solo, D., Reagle, J., Datta, P., Eastlake, D., Hirsch, F., and S. Cantor, “<a href="http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124">XML Signature Syntax and Processing Version 2.0</a>,” World Wide Web Consortium CR CR-xmldsig-core2-20120124, January 2012 (<a href="http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124">HTML</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="W3C.CR-xmlenc-core1-20120313">[W3C.CR-xmlenc-core1-20120313]</a></td>
<td class="author-text">Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler, “<a href="http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313">XML Encryption Syntax and Processing Version 1.1</a>,” World Wide Web Consortium CR CR-xmlenc-core1-20120313, March 2012 (<a href="http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313">HTML</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="W3C.REC-xmlenc-core-20021210">[W3C.REC-xmlenc-core-20021210]</a></td>
<td class="author-text">Eastlake, D. and J. Reagle, “<a href="http://www.w3.org/TR/2002/REC-xmlenc-core-20021210">XML Encryption Syntax and Processing</a>,” World Wide Web Consortium Recommendation REC-xmlenc-core-20021210, December 2002 (<a href="http://www.w3.org/TR/2002/REC-xmlenc-core-20021210">HTML</a>).</td></tr>
</table>
<a name="SigAlgXref"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.A"></a><h3>Appendix A.
Digital Signature/MAC Algorithm Identifier Cross-Reference</h3>
<p>
This appendix contains a table cross-referencing the
digital signature and MAC <tt>alg</tt> (algorithm)
values used in this specification
with the equivalent identifiers used by other standards and
software packages. See <a class='info' href='#RFC3275'>XML DSIG<span> (</span><span class='info'>Eastlake, D., Reagle, J., and D. Solo, “(Extensible Markup Language) XML-Signature Syntax and Processing,” March 2002.</span><span>)</span></a> [RFC3275],
<a class='info' href='#W3C.CR-xmldsig-core2-20120124'>XML DSIG 2.0<span> (</span><span class='info'>Roessler, T., Yiu, K., Solo, D., Reagle, J., Datta, P., Eastlake, D., Hirsch, F., and S. Cantor, “XML Signature Syntax and Processing Version 2.0,” January 2012.</span><span>)</span></a> [W3C.CR‑xmldsig‑core2‑20120124],
and <a class='info' href='#JCA'>Java Cryptography Architecture<span> (</span><span class='info'>Oracle, “Java Cryptography Architecture,” 2011.</span><span>)</span></a> [JCA]
for more information about the names defined by those
documents.
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left"><col align="left"><col align="left">
<tr><th align="left">Algorithm</th><th align="left">JWS</th><th align="left">XML DSIG</th><th align="left">JCA</th><th align="left">OID</th></tr>
<tr>
<td align="left">HMAC using SHA-256 hash algorithm</td>
<td align="left">HS256</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#hmac-sha256</td>
<td align="left">HmacSHA256</td>
<td align="left">1.2.840.113549.2.9</td>
</tr>
<tr>
<td align="left">HMAC using SHA-384 hash algorithm</td>
<td align="left">HS384</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#hmac-sha384</td>
<td align="left">HmacSHA384</td>
<td align="left">1.2.840.113549.2.10</td>
</tr>
<tr>
<td align="left">HMAC using SHA-512 hash algorithm</td>
<td align="left">HS512</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#hmac-sha512</td>
<td align="left">HmacSHA512</td>
<td align="left">1.2.840.113549.2.11</td>
</tr>
<tr>
<td align="left">RSASSA using SHA-256 hash algorithm</td>
<td align="left">RS256</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#rsa-sha256</td>
<td align="left">SHA256withRSA</td>
<td align="left">1.2.840.113549.1.1.11</td>
</tr>
<tr>
<td align="left">RSASSA using SHA-384 hash algorithm</td>
<td align="left">RS384</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#rsa-sha384</td>
<td align="left">SHA384withRSA</td>
<td align="left">1.2.840.113549.1.1.12</td>
</tr>
<tr>
<td align="left">RSASSA using SHA-512 hash algorithm</td>
<td align="left">RS512</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#rsa-sha512</td>
<td align="left">SHA512withRSA</td>
<td align="left">1.2.840.113549.1.1.13</td>
</tr>
<tr>
<td align="left">ECDSA using P-256 curve and SHA-256 hash algorithm</td>
<td align="left">ES256</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256</td>
<td align="left">SHA256withECDSA</td>
<td align="left">1.2.840.10045.4.3.2</td>
</tr>
<tr>
<td align="left">ECDSA using P-384 curve and SHA-384 hash algorithm</td>
<td align="left">ES384</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384</td>
<td align="left">SHA384withECDSA</td>
<td align="left">1.2.840.10045.4.3.3</td>
</tr>
<tr>
<td align="left">ECDSA using P-521 curve and SHA-512 hash algorithm</td>
<td align="left">ES512</td>
<td align="left">http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512</td>
<td align="left">SHA512withECDSA</td>
<td align="left">1.2.840.10045.4.3.4</td>
</tr>
</table>
<br clear="all" />
<a name="EncAlgXref"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.B"></a><h3>Appendix B.
Encryption Algorithm Identifier Cross-Reference</h3>
<p>
This appendix contains a table cross-referencing the <tt>alg</tt> (algorithm) and <tt>enc</tt> (encryption method)
values used in this specification with the equivalent
identifiers used by other standards and software packages.
See
<a class='info' href='#W3C.REC-xmlenc-core-20021210'>XML Encryption<span> (</span><span class='info'>Eastlake, D. and J. Reagle, “XML Encryption Syntax and Processing,” December 2002.</span><span>)</span></a> [W3C.REC‑xmlenc‑core‑20021210],
<a class='info' href='#W3C.CR-xmlenc-core1-20120313'>XML Encryption 1.1<span> (</span><span class='info'>Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler, “XML Encryption Syntax and Processing Version 1.1,” March 2012.</span><span>)</span></a> [W3C.CR‑xmlenc‑core1‑20120313],
and <a class='info' href='#JCA'>Java Cryptography Architecture<span> (</span><span class='info'>Oracle, “Java Cryptography Architecture,” 2011.</span><span>)</span></a> [JCA] for more
information about the names defined by those documents.
</p>
<p>
For the composite algorithms <tt>A128CBC+HS256</tt> and
<tt>A256CBC+HS512</tt>, the corresponding AES CBC
algorithm identifiers are listed.
</p><table class="full" align="center" border="0" cellpadding="2" cellspacing="2">
<col align="left"><col align="left"><col align="left"><col align="left">
<tr><th align="left">Algorithm</th><th align="left">JWE</th><th align="left">XML ENC</th><th align="left">JCA</th></tr>
<tr>
<td align="left">RSAES-PKCS1-V1_5</td>
<td align="left">RSA1_5</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#rsa-1_5</td>
<td align="left">RSA/ECB/PKCS1Padding</td>
</tr>
<tr>
<td align="left">RSAES using Optimal Asymmetric Encryption Padding (OAEP)</td>
<td align="left">RSA-OAEP</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p</td>
<td align="left">RSA/ECB/OAEPWithSHA-1AndMGF1Padding</td>
</tr>
<tr>
<td align="left">Elliptic Curve Diffie-Hellman Ephemeral Static</td>
<td align="left">ECDH-ES</td>
<td align="left">http://www.w3.org/2009/xmlenc11#ECDH-ES</td>
<td align="left"> </td>
</tr>
<tr>
<td align="left">Advanced Encryption Standard (AES) Key Wrap Algorithm
using 128 bit keys</td>
<td align="left">A128KW</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#kw-aes128</td>
<td align="left"> </td>
</tr>
<tr>
<td align="left">AES Key Wrap Algorithm
using 256 bit keys</td>
<td align="left">A256KW</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#kw-aes256</td>
<td align="left"> </td>
</tr>
<tr>
<td align="left">AES in Cipher Block Chaining (CBC) mode with PKCS #5 padding
using 128 bit keys</td>
<td align="left">A128CBC+HS256</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#aes128-cbc</td>
<td align="left">AES/CBC/PKCS5Padding</td>
</tr>
<tr>
<td align="left">AES in CBC mode with PKCS #5 padding
using 256 bit keys</td>
<td align="left">A256CBC+HS512</td>
<td align="left">http://www.w3.org/2001/04/xmlenc#aes256-cbc</td>
<td align="left">AES/CBC/PKCS5Padding</td>
</tr>
<tr>
<td align="left">AES in Galois/Counter Mode (GCM)
using 128 bit keys</td>
<td align="left">A128GCM</td>
<td align="left">http://www.w3.org/2009/xmlenc11#aes128-gcm</td>
<td align="left">AES/GCM/NoPadding</td>
</tr>
<tr>
<td align="left">AES GCM
using 256 bit keys</td>
<td align="left">A256GCM</td>
<td align="left">http://www.w3.org/2009/xmlenc11#aes256-gcm</td>
<td align="left">AES/GCM/NoPadding</td>
</tr>
</table>
<br clear="all" />
<a name="Acknowledgements"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.C"></a><h3>Appendix C.
Acknowledgements</h3>
<p>
Solutions for signing and encrypting JSON content were
previously explored by <a class='info' href='#MagicSignatures'>Magic
Signatures<span> (</span><span class='info'>Panzer (editor), J., Laurie, B., and D. Balfanz, “Magic Signatures,” January 2011.</span><span>)</span></a> [MagicSignatures], <a class='info' href='#JSS'>JSON Simple Sign<span> (</span><span class='info'>Bradley, J. and N. Sakimura (editor), “JSON Simple Sign,” September 2010.</span><span>)</span></a> [JSS],
<a class='info' href='#CanvasApp'>Canvas Applications<span> (</span><span class='info'>Facebook, “Canvas Applications,” 2010.</span><span>)</span></a> [CanvasApp], <a class='info' href='#JSE'>JSON Simple Encryption<span> (</span><span class='info'>Bradley, J. and N. Sakimura (editor), “JSON Simple Encryption,” September 2010.</span><span>)</span></a> [JSE], and <a class='info' href='#I-D.rescorla-jsms'>JavaScript Message Security
Format<span> (</span><span class='info'>Rescorla, E. and J. Hildebrand, “JavaScript Message Security Format,” March 2011.</span><span>)</span></a> [I‑D.rescorla‑jsms], all of which influenced this draft. Dirk
Balfanz, John Bradley, Yaron Y. Goland, John Panzer, Nat
Sakimura, and Paul Tarjan all made significant contributions
to the design of this specification and its related
specifications.
</p>
<p>
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.
</p>
<a name="TBD"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.D"></a><h3>Appendix D.
Open Issues</h3>
<p>
[[ to be removed by the RFC editor before publication as an RFC ]]
</p>
<p>
The following items remain to be considered or done in this draft:
</p>
<ul class="text">
<li>
No known open issues.
</li>
</ul><p>
</p>
<a name="anchor17"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.E"></a><h3>Appendix E.
Document History</h3>
<p>
[[ to be removed by the RFC editor before publication as an RFC ]]
</p>
<p>
-06
</p>
<ul class="text">
<li>
Removed the <tt>int</tt> and
<tt>kdf</tt> parameters and defined the new composite
AEAD algorithms <tt>A128CBC+HS256</tt> and
<tt>A256CBC+HS512</tt> to replace the former
uses of AES CBC, which required the use of separate integrity
and key derivation functions.
</li>
<li>
Included additional values in the Concat KDF calculation -- the
desired output size and the algorithm value,
and optionally PartyUInfo and PartyVInfo values.
Added the optional header parameters
<tt>apu</tt> (agreement PartyUInfo),
<tt>apv</tt> (agreement PartyVInfo),
<tt>epu</tt> (encryption PartyUInfo), and
<tt>epv</tt> (encryption PartyVInfo).
</li>
<li>
Changed the name of the JWK RSA exponent parameter from
<tt>exp</tt> to <tt>xpo</tt>
so as to allow the potential use of the name <tt>exp</tt>
for a future extension that might define an expiration parameter for keys.
(The <tt>exp</tt> name is already used for this
purpose in the JWT specification.)
</li>
</ul><p>
</p>
<p>
-05
</p>
<ul class="text">
<li>
Support both direct encryption using a
shared or agreed upon symmetric key, and the use of a
shared or agreed upon symmetric key to key wrap the CMK.
Specifically, added the <tt>alg</tt> values
<tt>dir</tt>,
<tt>ECDH-ES+A128KW</tt>, and
<tt>ECDH-ES+A256KW</tt>
to finish filling in this set of capabilities.
</li>
<li>
Updated open issues.
</li>
</ul><p>
</p>
<p>
-04
</p>
<ul class="text">
<li>
Added text requiring that any leading zero bytes be retained in
base64url encoded key value representations for fixed-length values.
</li>
<li>
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."
</li>
<li>
Described additional open issues.
</li>
<li>
Applied editorial suggestions.
</li>
</ul><p>
</p>
<p>
-03
</p>
<ul class="text">
<li>
Always use a 128 bit "authentication tag" size for
AES GCM, regardless of the key size.
</li>
<li>
Specified that use of a 128 bit IV is REQUIRED with AES CBC.
It was previously RECOMMENDED.
</li>
<li>
Removed key size language for ECDSA algorithms, since the
key size is implied by the algorithm being used.
</li>
<li>
Stated that the <tt>int</tt> key size
must be the same as the hash output size (and not larger,
as was previously allowed) so that its size is defined for
key generation purposes.
</li>
<li>
Added the <tt>kdf</tt> (key derivation function) header parameter
to provide crypto agility for key derivation.
The default KDF remains the Concat KDF with the SHA-256 digest function.
</li>
<li>
Clarified that the <tt>mod</tt> and
<tt>exp</tt> values are unsigned.
</li>
<li>
Added Implementation Requirements columns to algorithm tables
and Implementation Requirements entries to algorithm registries.
</li>
<li>
Changed AES Key Wrap to RECOMMENDED.
</li>
<li>
Moved registries
JSON Web Signature and Encryption Header Parameters and
JSON Web Signature and Encryption Type Values
to the JWS specification.
</li>
<li>
Moved JSON Web Key Parameters registry to the JWK specification.
</li>
<li>
Changed registration requirements from RFC Required to
Specification Required with Expert Review.
</li>
<li>
Added Registration Template sections for defined registries.
</li>
<li>
Added Registry Contents sections to populate registry values.
</li>
<li>
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".
</li>
<li>
Added "Collision Resistant Namespace" to the terminology section.
</li>
<li>
Numerous editorial improvements.
</li>
</ul><p>
</p>
<p>
-02
</p>
<ul class="text">
<li>
For AES GCM,
use the "additional authenticated data" parameter
to provide integrity for the header, encrypted key, and
ciphertext and use the resulting "authentication tag"
value as the JWE Integrity Value.
</li>
<li>
Defined minimum required key sizes for algorithms
without specified key sizes.
</li>
<li>
Defined KDF output key sizes.
</li>
<li>
Specified the use of PKCS #5 padding with AES CBC.
</li>
<li>
Generalized text to allow key agreement to be employed
as an alternative to key wrapping or key encryption.
</li>
<li>
Clarified that ECDH-ES is a key agreement algorithm.
</li>
<li>
Required implementation of AES-128-KW and AES-256-KW.
</li>
<li>
Removed the use of <tt>A128GCM</tt> and
<tt>A256GCM</tt> for key wrapping.
</li>
<li>
Removed <tt>A512KW</tt> since it turns
out that it's not a standard algorithm.
</li>
<li>
Clarified the relationship between
<tt>typ</tt> header parameter values
and MIME types.
</li>
<li>
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.
</li>
<li>
Established registries:
JSON Web Signature and Encryption Header Parameters,
JSON Web Signature and Encryption Algorithms,
JSON Web Signature and Encryption "typ" Values,
JSON Web Key Parameters, and
JSON Web Key Algorithm Families.
</li>
<li>
Moved algorithm-specific definitions from JWK to JWA.
</li>
<li>
Reformatted to give each member definition its own section heading.
</li>
</ul><p>
</p>
<p>
-01
</p>
<ul class="text">
<li>
Moved definition of "alg":"none" for JWSs here from the JWT
specification since this functionality is likely to be
useful in more contexts that just for JWTs.
</li>
<li>
Added Advanced Encryption Standard (AES) Key Wrap Algorithm
using 512 bit keys (<tt>A512KW</tt>).
</li>
<li>
Added text "Alternatively, the Encoded JWS Signature MAY be base64url
decoded to produce the JWS Signature and this value can
be compared with the computed HMAC value, as this
comparison produces the same result as comparing the
encoded values".
</li>
<li>
Corrected the Magic Signatures reference.
</li>
<li>
Made other editorial improvements suggested by JOSE
working group participants.
</li>
</ul><p>
</p>
<p>
-00
</p>
<ul class="text">
<li>
Created the initial IETF draft based upon
draft-jones-json-web-signature-04 and
draft-jones-json-web-encryption-02 with no normative changes.
</li>
<li>
Changed terminology to no longer call both digital
signatures and HMACs "signatures".
</li>
</ul><p>
</p>
<a name="rfc.authors"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<h3>Author's Address</h3>
<table width="99%" border="0" cellpadding="0" cellspacing="0">
<tr><td class="author-text"> </td>
<td class="author-text">Michael B. Jones</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Microsoft</td></tr>
<tr><td class="author" align="right">Email: </td>
<td class="author-text"><a href="mailto:mbj@microsoft.com">mbj@microsoft.com</a></td></tr>
<tr><td class="author" align="right">URI: </td>
<td class="author-text"><a href="http://self-issued.info/">http://self-issued.info/</a></td></tr>
</table>
</body></html>