One document matched: draft-jones-json-web-encryption-00.xml
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<rfc category="std" docName="draft-jones-json-web-encryption-00"
ipr="trust200902">
<front>
<title abbrev="JWE">JSON Web Encryption (JWE)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="Eric Rescorla" initials="E." surname="Rescorla">
<organization>RTFM, Inc.</organization>
<address>
<email>ekr@rtfm.com</email>
</address>
</author>
<author fullname="Joe Hildebrand" initials="J." surname="Hildebrand">
<organization>Cisco Systems, Inc.</organization>
<address>
<email>jhildebr@cisco.com</email>
</address>
</author>
<date day="6" month="September" year="2011" />
<area>Security</area>
<keyword>RFC</keyword>
<keyword>Request for Comments</keyword>
<keyword>I-D</keyword>
<keyword>Internet-Draft</keyword>
<keyword>Assertion</keyword>
<keyword>Simple Web Token</keyword>
<keyword>Security Token</keyword>
<keyword>SWT</keyword>
<keyword>JavaScript Object Notation</keyword>
<keyword>JSON</keyword>
<keyword>JSON Web Token</keyword>
<keyword>JWT</keyword>
<keyword>JSON Web Signature</keyword>
<keyword>JWS</keyword>
<keyword>JSON Web Encryption</keyword>
<keyword>JWE</keyword>
<keyword>JSON Web Key</keyword>
<keyword>JWK</keyword>
<abstract>
<t>
TBD - THIS SPECIFICATION IS CURRENTLY UNDER DEVELOPMENT AND INCOMPLETE
</t>
<t>
JSON Web Encryption (JWE) is a means of representing encrypted
content using JSON data structures. Related signature
capabilities are described in the separate JSON Web Signature
(JWS) specification.
</t>
</abstract>
<note title="Requirements Language">
<t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described
in <xref target="RFC2119">RFC 2119</xref>.
</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>
TBD - THIS SPECIFICATION IS CURRENTLY UNDER DEVELOPMENT AND INCOMPLETE
</t>
<t>
JSON Web Encryption (JWE) is a compact encryption format
intended for space constrained environments such as HTTP
Authorization headers and URI query parameters. It provides a
wrapper for encrypted content using JSON <xref
target="RFC4627">RFC 4627</xref> data structures. The JWE
encryption mechanisms are independent of the type of content
being encrypted. A related signature capability is described
in a separate JSON Web Signature (JWS) <xref target="JWS" />
specification.
</t>
</section>
<section title="Terminology">
<t>
<list style="hanging">
<t hangText="JSON Web Encryption (JWE)">
A data structure representing an encrypted version of a
Plaintext. The structure consists of three parts: the JWE
Header, the JWE Encrypted Key, and the JWE Ciphertext.
</t>
<t hangText="Plaintext">
The bytes to be encrypted - a.k.a., the message.
</t>
<t hangText="Ciphertext">
The encrypted version of the Plaintext.
</t>
<t hangText="Content Encryption Key (CEK)">
A symmetric key generated to encrypt the Plaintext for the
recipient to produce the Ciphertext, which is encrypted to
the recipient as the JWE Encrypted Key.
</t>
<t hangText="JWE Header">
A string containing a JSON object that describes the
encryption operations applied to create the JWE Encrypted
Key and the JWE Ciphertext.
</t>
<t hangText="JWE Ciphertext">
A byte array containing the Ciphertext.
</t>
<t hangText="JWE Encrypted Key">
The Content Encryption Key (CEK) 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.
</t>
<t hangText="Encoded JWE Header">
Base64url encoding of the UTF-8 <xref target="RFC3629">RFC
3629</xref> representation of the JWE Header.
</t>
<t hangText="Encoded JWE Ciphertext">
Base64url encoding of the JWE Ciphertext.
</t>
<t hangText="Encoded JWE Encrypted Key">
Base64url encoding of the JWE Encrypted Key.
</t>
<t hangText="Header Parameter Names">
The names of the members within the JWE Header.
</t>
<t hangText="Header Parameter Values">
The values of the members within the JWE Header.
</t>
<t hangText="Base64url Encoding">
For the purposes of this specification, this term always
refers to the URL- and filename-safe Base64 encoding
described in <xref target="RFC4648">RFC 4648</xref>,
Section 5, with the '=' padding characters omitted, as
permitted by Section 3.2. (See Appendix C of <xref
target="JWS" /> for notes on implementing base64url
encoding without padding.)
</t>
</list>
</t>
</section>
<section title="JSON Web Encryption (JWE) Overview">
<t>
TBD - THIS SPECIFICATION IS CURRENTLY UNDER DEVELOPMENT AND INCOMPLETE
</t>
<t>
JWE provides a wrapper for encrypted content using JSON data
structures and base64url encoding. The representation
consists of three parts: the JWT Header, the JWE Encrypted
Key, and the JWE Ciphertext. The three parts are
base64url-encoded for transmission, and typically represented
as the concatenation of the encoded strings in that order,
with the three strings being separated by period ('.')
characters, as is done when used in JSON Web Tokens (JWTs)
<xref target="JWT" />.
</t>
<t>
JWE utilizes encryption to ensure the confidentiality of the
contents of the Plaintext. JWE does not add a content
integrity check if not provided by the underlying encryption
algorithm. If such a check is needed, an algorithm providing
it such as AES-GCM <xref target="NIST-800-38D" /> can be used,
or alternatively, it can be provided through composition by
encrypting a representation of the signed content.
</t>
<section title="Example JWE" anchor="ExampleJWE">
<t>
The following example JWE Header object declares that:
<list style="symbols">
<t>
the Content Encryption Key is encrypted to the recipient
using the RSA-PKCS1_1.5 algorithm to produce the JWE
Encrypted Key,
</t>
<t>
the Plaintext is encrypted using the AES-256-GCM
algorithm to produce the JWE Ciphertext,
</t>
<t>
the specified 64-bit Initialization Vector with the
based64url encoding <spanx
style="verb">__79_Pv6-fg</spanx> was used,
</t>
<t>
the thumbprint of the X.509 certificate that corresponds
to the key used to encrypt the JWE has the base64url
encoding <spanx
style="verb">7noOPq-hJ1_hCnvWh6IeYI2w9Q0</spanx>.
</t>
</list>
</t>
<artwork><![CDATA[{"alg":"RSA1_5",
"enc":"A256GCM",
"iv":"__79_Pv6-fg",
"x5t":"7noOPq-hJ1_hCnvWh6IeYI2w9Q0"}]]></artwork>
<t>
Base64url encoding the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
</t>
<artwork><![CDATA[TBD]]></artwork>
<t>
TBD finish this example by showing generation of a Content
Encryption Key (CEK), using the CEK to encrypt the Plaintext
to produce the Ciphertext (and base64url encoding it), and
using the recipient's key to encrypt the CEK to produce the
JWE Encrypted Key (and base64url encoding it).
</t>
</section>
</section>
<section title="JWE Header">
<t>
The members of the JWE Header describe the encryption applied
to the Plaintext. Implementations MUST understand the
entire contents of the header; otherwise, the JWE MUST be
rejected for processing.
</t>
<t>
The member names within the JWE Header are referred to as
Header Parameter Names. These names MUST be unique. The
corresponding values are referred to as Header Parameter
Values.
</t>
<section title="Reserved Header Parameter Names" anchor="ReservedHeaderParameterName">
<t>
The following header parameter names are reserved. All the
names are short because a core goal of JWE is for the
representations to be compact.
</t>
<t>
TBD Describe the relationship between the JWS and JWE header
parameters - especially the <spanx style="verb">alg</spanx>
parameter, which can contain either signature algorithms
(from JWS) or encryption algorithms (from JWE), and the key
reference parameters <spanx style="verb">jku</spanx>, <spanx
style="verb">kid</spanx>, <spanx style="verb">x5u</spanx>,
and <spanx style="verb">x5t</spanx>.
</t>
<texttable title="Reserved Header Parameter Definitions" anchor="HeaderParameterTable">
<ttcol align="left">Header Parameter Name</ttcol>
<ttcol align="left">JSON Value Type</ttcol>
<ttcol align="left">Header Parameter Syntax</ttcol>
<ttcol align="left">Header Parameter Semantics</ttcol>
<c>alg</c>
<c>string</c>
<c>StringOrURI</c>
<c>
The <spanx style="verb">alg</spanx> (algorithm) header
parameter identifies the cryptographic algorithm used to
secure the JWE Encrypted Key. A list of reserved <spanx
style="verb">alg</spanx> values is presented in <xref
target="AlgTable"></xref>.
The processing of the <spanx style="verb">alg</spanx>
(algorithm) header parameter requires that the value of
the <spanx style="verb">alg</spanx> header parameter MUST
be one that is both supported and for which there exists a
key for use with that algorithm associated with the
intended recipient. The <spanx style="verb">alg</spanx>
value is case sensitive.
This header parameter is REQUIRED.
</c>
<c>enc</c>
<c>string</c>
<c>StringOrURI</c>
<c>
The <spanx style="verb">enc</spanx> (encryption
method) header parameter identifies the symmetric
encryption algorithm used to secure the Ciphertext. A
list of reserved <spanx style="verb">enc</spanx> values is
presented in <xref target="EncTable"></xref>. The
processing of the <spanx style="verb">enc</spanx>
(encryption method) header parameter requires that the
value of the <spanx style="verb">enc</spanx> header
parameter MUST be one that is supported. The <spanx
style="verb">enc</spanx> value is case sensitive. This
header parameter is REQUIRED.
</c>
<c>iv</c>
<c>string</c>
<c>String</c>
<c>
Initialization Vector (<spanx style="verb">iv</spanx>)
value for algorithms requiring it, represented as a
base64url encoded string.
This header parameter is OPTIONAL.
</c>
<c>epk</c>
<c>string</c>
<c>String</c>
<c>
Ephemeral Public Key (<spanx style="verb">epk</spanx>)
value created by the originator for the use in ECDH-ES
<xref target="RFC6090">RFC 6090</xref>
encryption. This key is represented in the same manner as
a JSON Web Key <xref target="JWK" /> JWK Key Object value,
containing <spanx style="verb">curve</spanx>, <spanx
style="verb">x</spanx>, and <spanx style="verb">y</spanx>
members. The inclusion of the JWK Key Object <spanx
style="verb">algorithm</spanx> member is OPTIONAL.
This header parameter is OPTIONAL.
</c>
<c>zip</c>
<c>string</c>
<c>String</c>
<c>
Compression algorithm (<spanx style="verb">zip</spanx>)
applied to the Plaintext before encryption, if any. This
specification defines the value <spanx
style="verb">GZIP</spanx> to refer to the <xref
target="RFC1952">GZIP</xref> algorithm. If no <spanx
style="verb">zip</spanx> parameter is present, or its
value is <spanx style="verb">none</spanx>, no compression
is applied to the Plaintext before encryption. The <spanx
style="verb">zip</spanx> value is case sensitive. This
header parameter is OPTIONAL.
</c>
<c>jku</c>
<c>string</c>
<c>URL</c>
<c>
The <spanx style="verb">jku</spanx> (JSON Key URL) header
parameter is a URL that points to a JSON-encoded set of
public keys, one of which corresponds to the key that was
used to encrypt the JWE. The keys MUST
be encoded as per the JSON Web Key (JWK) <xref
target="JWK" /> specification. This header parameter is
OPTIONAL.
</c>
<c>kid</c>
<c>string</c>
<c>String</c>
<c>
The <spanx style="verb">kid</spanx> (key ID) header
parameter is a hint indicating which key was used to
encrypt the JWE. This
allows originators to explicitly signal a change of key to
recipients. Omitting this parameter is equivalent to
setting it to an empty string. The interpretation of the
contents of the <spanx style="verb">kid</spanx> parameter
is unspecified.
This header parameter is OPTIONAL.
</c>
<c>x5u</c>
<c>string</c>
<c>URL</c>
<c>
The <spanx style="verb">x5u</spanx> (X.509 URL) header
parameter is a URL utilizing TLS (as defined in <xref
target="RFC5785">RFC 5785</xref>) that points to an X.509
public key certificate or certificate chain that that
corresponds to the key that was used to encrypt the JWE.
This certificate or
certificate chain MUST use the PEM encoding (per <xref
target="RFC1421">RFC 1421</xref>) and MUST conform to <xref
target="RFC5280">RFC 5280</xref>.
This header parameter is OPTIONAL.
</c>
<c>x5t</c>
<c>string</c>
<c>String</c>
<c>
The <spanx style="verb">x5t</spanx> (x.509 certificate
thumbprint) header parameter provides a base64url encoded
SHA-1 thumbprint (a.k.a. digest) of the DER encoding of
the X.509 certificate that corresponds to the key that was
used to encrypt the JWE.
This header parameter is OPTIONAL.
</c>
<c>typ</c>
<c>string</c>
<c>String</c>
<c>
The <spanx style="verb">typ</spanx> (type) header
parameter is used to declare the type of the encrypted
content.
The <spanx style="verb">typ</spanx> value is case sensitive.
This header parameter is OPTIONAL.
</c>
</texttable>
<t>
Additional reserved header parameter names MAY be defined
via the IANA JSON Web Encryption Header Parameters registry,
as per <xref target="IANA" />. The syntax values used above
are defined as follows:
</t>
<texttable title="Header Parameter Syntax Definitions" anchor="SyntaxDefinitions">
<ttcol align="left">Syntax Name</ttcol>
<ttcol align="left">Syntax Definition</ttcol>
<c>String</c>
<c>
Any string value MAY be used.
</c>
<c>StringOrURI</c>
<c>
Any string value MAY be used but a value containing a ":"
character MUST be a URI as defined in <xref
target="RFC3986">RFC 3986</xref>.
</c>
</texttable>
</section>
<section title="Public Header Parameter Names" anchor="PublicHeaderParameterName">
<t>
Additional header parameter names can be defined by those
using JWE. However, in order to prevent collisions, any new
header parameter name or algorithm value SHOULD either be
defined in the IANA JSON Web Encryption Header Parameters
registry or be defined as a URI that contains a collision
resistant namespace. In each case, the definer of the name
or value MUST take reasonable precautions to make sure they
are in control of the part of the namespace they use to
define the header parameter name.
</t>
<t>
New header parameters should be introduced sparingly, as
they can result in non-interoperable JWEs.
</t>
</section>
<section title="Private Header Parameter Names" anchor="PrivateHeaderParameterName">
<t>
A producer and consumer of a JWE may agree to any header
parameter name that is not a Reserved Name <xref
target="ReservedHeaderParameterName"></xref> or a Public
Name <xref
target="PublicHeaderParameterName"></xref>. Unlike Public
Names, these private names are subject to collision and
should be used with caution.
</t>
<t>
New header parameters should be introduced sparingly, as
they can result in non-interoperable JWEs.
</t>
</section>
</section>
<section anchor="sec.encryption" title="Message Encryption">
<t>The message encryption process is as follows:</t>
<t><list style="numbers">
<t>
Generate a random Content Encryption Key (CEK). The CEK
MUST have a length at least equal to that of the required
encryption keys and MUST be generated randomly. See <xref
target="RFC4086">RFC 4086</xref> for considerations on
generating random values.
</t>
<t>
Encrypt the CEK for the recipient (see <xref
target="sec.encrypt_cek"/>).
</t>
<t>
Generate a random IV (if required for the algorithm).
</t>
<t>
Compress the Plaintext if a <spanx
style="verb">zip</spanx> parameter was included.
</t>
<t>
Serialize the (compressed) Plaintext into a bitstring M.
</t>
<t>
Encrypt M using the CEK and IV to form the bitstring C.
</t>
<t>
Set the Encoded JWE Ciphertext equal to the base64url encoded
representation of C.
</t>
<t>
Create the JWE Header containing the encryption
parameters used.
</t>
<t>
Base64url encoded the UTF-8 representation of the JWE
Header to create the Encoded JWE Header.
</t>
<t>
The three encoded parts, taken together, are the result of
the encryption.
</t>
</list></t>
</section>
<section anchor="sec.decryption" title="Message Decryption">
<t>The message decryption process is the reverse of the encryption
process. If any of these steps fails, the JWE MUST be rejected.</t>
<t>
<list style="numbers">
<t>
The Encoded JWE Header, the Encoded JWE Encrypted Key, and
the Encoded JWE Ciphertext MUST successfully base64url
decoded following the restriction that no padding
characters have been used.
</t>
<t>
The resulting JWE Header MUST be completely valid
JSON syntax conforming to <xref target="RFC4627">RFC
4627</xref>.
</t>
<t>
The resulting JWE Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported.
</t>
<t>
Verify that the JWE Header appears to reference a key
known to the recipient.
</t>
<t>
Decrypt the JWE Encrypted Key to produce the CEK.
</t>
<t>
Decrypt the binary representation of the JWE Ciphertext
using the CEK.
</t>
<t>
Uncompress the result of the previous step, if a <spanx
style="verb">zip</spanx> parameter was included.
</t>
<t>
Output the result.
</t>
</list>
</t>
</section>
<section anchor="sec.encrypt_cek" title="CEK Encryption">
<t>
JWE supports two forms of CEK encryption:
</t>
<t>
<list style="symbols">
<t>
Asymmetric encryption under the recipient's public key.
</t>
<t>
Symmetric encryption under a shared key.
</t>
</list>
</t>
<section anchor="sec.asymmetric_encryption"
title="Asymmetric Encryption">
<t>
In the asymmetric encryption mode, the CEK is encrypted
under the recipient's public key. The asymmetric encryption
modes defined for use with this in this specification are
listed in in <xref target="AlgTable"></xref>.
</t>
</section>
<section anchor="sec.symmetric_encryption"
title="Symmetric Encryption">
<t>
In the symmetric encryption mode, the CEK is encrypted under
a symmetric key shared between the sender and receiver.
<!-- All such modes MUST provide integrity for the CEK. -->
The symmetric encryption modes defined for use with this in
this specification are listed in in <xref target="AlgTable"></xref>.
For GCM, the random 64-bit IV is prepended to the ciphertext.
</t>
</section>
</section>
<section anchor="sec.msg-composition" title="Composition">
<t>
This document does not specify a combination signed and
encrypted mode. However, because the contents of a message can
be arbitrary, and encryption and data origin authentication
can be provided by recursively encapsulating multiple JWE and
JWS messages. In general, senders SHOULD sign the message and
then encrypt the result (thus encrypting the signature). This
prevents attacks in which the signature is stripped, leaving
just an encrypted message, as well as providing privacy for
the signer.
</t>
</section>
<section title="Encrypting JWEs with Cryptographic Algorithms" anchor="Encrypting">
<t>
JWE uses cryptographic algorithms to encrypt the Content
Encryption Key (CEK) and the Plaintext. This section
specifies a set of specific algorithms for these purposes.
</t>
<t>
The table below <xref target="AlgTable" /> is the set of
<spanx style="verb">alg</spanx> header parameter values that
are reserved by this specification. These algorithms are used
to encrypt the CEK, which produces the JWE Encrypted Key.
</t>
<texttable title="JWE Reserved alg Parameter Values" anchor="AlgTable">
<ttcol align="left">alg Parameter Value</ttcol>
<ttcol align="left">Encryption Algorithm</ttcol>
<c>RSA1_5</c>
<c>RSA using RSA-PKCS1-1.5 padding, as defined in <xref
target="RFC3447">RFC 3447</xref></c>
<c>RSA-OAEP</c>
<c>RSA using Optimal Asymmetric Encryption Padding (OAEP), as
defined in <xref target="RFC3447">RFC 3447</xref></c>
<c>ECDH-ES</c>
<c>Elliptic Curve Diffie-Hellman Ephemeral Secret, as defined
in <xref target="RFC6090">RFC 6090</xref>, and using the
Concat KDF, as defined in <xref target="NIST-800-56A" /></c>
<c>A128KW</c>
<c>Advanced Encryption Standard (AES) Key Wrap Algorithm using
128 bit keys, as defined in <xref target="RFC3394">RFC
3394</xref></c>
<c>A256KW</c>
<c>Advanced Encryption Standard (AES) Key Wrap Algorithm using
256 bit keys, as defined in <xref target="RFC3394">RFC
3394</xref></c>
<c>A128GCM</c>
<c>Advanced Encryption Standard (AES) using 128 bit keys in
Galois/Counter Mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38D" /></c>
<c>A256GCM</c>
<c>Advanced Encryption Standard (AES) using 256 bit keys in
Galois/Counter Mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38D" /></c>
</texttable>
<t>
The table below <xref target="EncTable" /> is the set of
<spanx style="verb">enc</spanx> header parameter values that
are reserved by this specification. These algorithms are used
to encrypt the Plaintext, which produces the Ciphertext.
</t>
<texttable title="JWE Reserved enc Parameter Values" anchor="EncTable">
<ttcol align="left">enc Parameter Value</ttcol>
<ttcol align="left">Symmetric Encryption Algorithm</ttcol>
<c>A128CBC</c>
<c>Advanced Encryption Standard (AES) using 128 bit keys in
Cipher Block Chaining mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38A" /></c>
<c>A256CBC</c>
<c>Advanced Encryption Standard (AES) using 256 bit keys in
Cipher Block Chaining mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38A" /></c>
<c>A128GCM</c>
<c>Advanced Encryption Standard (AES) using 128 bit keys in
Galois/Counter Mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38D" /></c>
<c>A256GCM</c>
<c>Advanced Encryption Standard (AES) using 256 bit keys in
Galois/Counter Mode, as defined in <xref target="FIPS-197" />
and <xref target="NIST-800-38D" /></c>
</texttable>
<t>
Of these algorithms, only RSA-PKCS1-1.5 with 2048 bit keys,
AES-128-CBC, and AES-256-CBC MUST be implemented by conforming
implementations. It is RECOMMENDED that implementations also
support ECDH-ES with 256 bit keys, AES-128-GCM, and
AES-256-GCM. Support for other algorithms and key sizes is
OPTIONAL.
</t>
<section title="Encrypting a JWE with TBD" anchor="EncryptingWithTBD">
<t>
TBD - Descriptions of the particulars of each specified
algorithm go here
</t>
</section>
<section title="Additional Algorithms" anchor="MoreAlgs">
<t>
Additional algorithms MAY be used to protect JWEs with
corresponding <spanx style="verb">alg</spanx> and <spanx
style="verb">enc</spanx> header parameter values being
defined to refer to them. New <spanx
style="verb">alg</spanx> and <spanx style="verb">enc</spanx>
header parameter values SHOULD either be defined in the IANA
JSON Web Encryption Algorithms registry or be a URI that
contains a collision resistant namespace. In particular,
the use of algorithm identifiers defined in <xref
target="W3C.REC-xmlenc-core-20021210" />, <xref
target="W3C.CR-xmlenc-core1-20110303" />, and related
specifications is permitted.
</t>
</section>
</section>
<section title="IANA Considerations" anchor="IANA">
<t>
This specification calls for:
<list style="symbols">
<t>
A new IANA registry entitled "JSON Web Encryption Header
Parameters" for reserved header parameter names is defined
in <xref target="ReservedHeaderParameterName"></xref>.
Inclusion in the registry is RFC Required in the <xref
target="RFC5226">RFC 5226</xref> sense for reserved JWE
header parameter names that are intended to be
interoperable between implementations. The registry will
just record the reserved header parameter name and a
pointer to the RFC that defines it. This specification
defines inclusion of the header parameter names defined in
<xref target="HeaderParameterTable"></xref>.
</t>
<t>
A new IANA registry entitled "JSON Web Encryption
Algorithms" for reserved values used with the <spanx
style="verb">alg</spanx> and <spanx
style="verb">enc</spanx> header parameter values, as
defined in <xref target="MoreAlgs"></xref>. Inclusion in
the registry is RFC Required in the <xref
target="RFC5226">RFC 5226</xref> sense. The registry will
record the <spanx style="verb">alg</spanx> or <spanx
style="verb">enc</spanx> value and a pointer to the RFC
that defines it. This specification defines inclusion of
the algorithm values defined in <xref
target="AlgTable"></xref> and <xref
target="EncTable"></xref>.
</t>
</list>
</t>
</section>
<section title="Security Considerations" anchor="Security">
<t>
TBD: Lots of work to do here. We need to remember to look into
any issues relating to security and JSON parsing. One wonders
just how secure most JSON parsing libraries are. Were they
ever hardened for security scenarios? If not, what kind of
holes does that open up? Also, we need to walk through the
JSON standard and see what kind of issues we have especially
around comparison of names. For instance, comparisons of
header parameter names and other parameters must occur after
they are unescaped. Need to also put in text about: Importance
of keeping secrets secret. Rotating keys. Strengths and
weaknesses of the different algorithms.
</t>
<t>
TBD: Need to put in text about why strict JSON validation is
necessary. Basically, that if malformed JSON is received then
the intent of the sender is impossible to reliably discern.
</t>
<t>
[[ TBD: we need a section on generating randomness in browsers
- it's easy to screw up ]]
</t>
<section title="Unicode Comparison Security Issues">
<t>
Header parameter names in JWEs are Unicode strings. For
security reasons, the representations of these names must be
compared verbatim after performing any escape processing (as
per <xref target="RFC4627">RFC 4627</xref>, Section 2.5).
</t>
<t>
This means, for instance, that these JSON strings must
compare as being equal ("enc", "\u0065nc"), whereas these
must all compare as being not equal to the first set or to
each other ("ENC", "Enc", "en\u0043").
</t>
<t>
JSON strings MAY contain characters outside the Unicode
Basic Multilingual Plane. For instance, the G clef
character (U+1D11E) may be represented in a JSON string as
"\uD834\uDD1E". Ideally, JWE implementations SHOULD ensure
that characters outside the Basic Multilingual Plane are
preserved and compared correctly; alternatively, if this is
not possible due to these characters exercising limitations
present in the underlying JSON implementation, then input
containing them MUST be rejected.
</t>
</section>
</section>
<section title="Open Issues and Things To Be Done (TBD)" anchor="TBD">
<t>
The following items remain to be done in this draft (and related drafts):
<list style="symbols">
<t>
Describe the relationship between the JWE, JWS, and JWT
header parameters. In particular, point out that the set of
"alg" values defined by each must be compatible and
non-overlapping.
</t>
<t>
Consider whether we want to define composite
signing/encryption operations (as was the consensus to do
at IIW, as documented at http://self-issued.info/?p=378).
</t>
<t>
Consider whether reusing the JWS <spanx
style="verb">jku</spanx>, <spanx style="verb">kid</spanx>,
<spanx style="verb">x5u</spanx>, and <spanx
style="verb">x5t</spanx> parameters is the right thing to
do, particularly as it effectively precludes specifying
composite operations.
</t>
<t>
Consider whether to add parameters for directly including
keys in the header, either as JWK Key Objects, or X.509
cert values, or both.
</t>
<t>
Consider whether to add version numbers.
</t>
<t>
Consider which of the open issues from the JWS and JWT specs
also apply here.
</t>
<t>
Finish the Security Considerations section.
</t>
<t>
Write a note in the Security Considerations section about
how <spanx style="verb">x5t</spanx> (x.509 certificate
thumbprint) should be deprecated because of known problems
with SHA-1.
</t>
<t>
Should StringOrURI use IRIs rather than RFC 3986 URIs?
</t>
<t>
Provide a more robust description of the use of the IV.
The current statement "For GCM, the random 64-bit IV is
prepended to the ciphertext" in the Symmetric Encryption
section is almost certainly out of place.
</t>
<t>
It would be good to say somewhere, in normative language,
that eventually the algorithms and/or key sizes currently
specified will no longer be considered sufficiently secure
and will be removed. Therefore, implementers MUST be
prepared for this eventuality.
</t>
</list>
</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC1421;
&RFC1952;
&RFC2119;
&RFC3447;
&RFC3629;
&RFC3986;
&RFC4086;
&RFC4627;
&RFC4648;
&RFC5226;
&RFC5280;
&RFC5785;
&RFC6090;
<reference anchor="FIPS-197">
<front>
<title>Advanced Encryption Standard (AES)</title>
<author>
<organization>National Institute of Standards and Technology (NIST)
</organization>
</author>
<date month="November" year="2001" />
</front>
<seriesInfo name="FIPS" value="PUB 197" />
</reference>
<reference anchor="NIST-800-38A">
<front>
<title>Recommendation for Block Cipher Modes of Operation</title>
<author>
<organization>National Institute of Standards and Technology (NIST)
</organization>
</author>
<date month="December" year="2001" />
</front>
<seriesInfo name="NIST" value="PUB 800-38A" />
</reference>
<reference anchor="NIST-800-38D">
<front>
<title>Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC</title>
<author>
<organization>National Institute of Standards and Technology (NIST)
</organization>
</author>
<date month="December" year="2001" />
</front>
<seriesInfo name="NIST" value="PUB 800-38D" />
</reference>
<reference anchor="NIST-800-56A">
<front>
<title>Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised)</title>
<author>
<organization>National Institute of Standards and Technology (NIST)
</organization>
</author>
<date month="March" year="2007" />
</front>
<seriesInfo name="NIST" value="PUB 800-56A" />
</reference>
<reference anchor="JWT">
<front>
<title>JSON Web Token (JWT)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="Dirk Balfanz" initials="D." surname="Balfanz">
<organization>Google</organization>
<address>
<email>balfanz@google.com</email>
</address>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization>independent</organization>
<address>
<email>ve7jtb@ve7jtb.com</email>
</address>
</author>
<author fullname="Yaron Y. Goland" initials="Y.Y." surname="Goland">
<organization>Microsoft</organization>
<address>
<email>yarong@microsoft.com</email>
</address>
</author>
<author fullname="John Panzer" initials="J." surname="Panzer">
<organization>Google</organization>
<address>
<email>jpanzer@google.com</email>
</address>
</author>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization>Nomura Research Institute</organization>
<address>
<email>n-sakimura@nri.co.jp</email>
</address>
</author>
<author fullname="Paul Tarjan" initials="P." surname="Tarjan">
<organization>Facebook</organization>
<address>
<email>pt@fb.com</email>
</address>
</author>
<date day="11" month="July" year="2011" />
</front>
<format target="http://self-issued.info/docs/draft-jones-json-web-token.html" type="HTML" />
</reference>
<reference anchor="JWS">
<front>
<title>JSON Web Signature (JWS)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname="Dirk Balfanz" initials="D." surname="Balfanz">
<organization>Google</organization>
<address>
<email>balfanz@google.com</email>
</address>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization>independent</organization>
<address>
<email>ve7jtb@ve7jtb.com</email>
</address>
</author>
<author fullname="Yaron Y. Goland" initials="Y.Y." surname="Goland">
<organization>Microsoft</organization>
<address>
<email>yarong@microsoft.com</email>
</address>
</author>
<author fullname="John Panzer" initials="J." surname="Panzer">
<organization>Google</organization>
<address>
<email>jpanzer@google.com</email>
</address>
</author>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization>Nomura Research Institute</organization>
<address>
<email>n-sakimura@nri.co.jp</email>
</address>
</author>
<author fullname="Paul Tarjan" initials="P." surname="Tarjan">
<organization>Facebook</organization>
<address>
<email>pt@fb.com</email>
</address>
</author>
<date day="29" month="April" year="2011" />
</front>
<format target="http://self-issued.info/docs/draft-jones-json-web-signature.html" type="HTML" />
</reference>
<reference anchor="JWK">
<front>
<title>JSON Web Key (JWK)</title>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<date day="29" month="April" year="2011" />
</front>
<format target="http://self-issued.info/docs/draft-jones-json-web-key.html" type="HTML" />
</reference>
</references>
<references title="Informative References">
&RFC3275;
&RFC3394;
&RFC5652;
&W3C.REC-xmlenc-core-20021210;
&W3C.CR-xmlenc-core1-20110303;
&jsms;
<reference anchor="JSS">
<front>
<title>JSON Simple Sign</title>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization>independent</organization>
</author>
<author fullname="Nat Sakimura (editor)" initials="N. " surname="Sakimura (editor)">
<organization>Nomura Research Institute</organization>
</author>
<date month="September" year="2010" />
</front>
<format target="http://jsonenc.info/jss/1.0/" type="HTML" />
</reference>
<reference anchor="JCA">
<front>
<title>Java Cryptography Architecture</title>
<author fullname="Oracle" surname="Oracle">
</author>
<date year="2011" />
</front>
<format target="http://download.java.net/jdk7/docs/technotes/guides/security/SunProviders.html" type="HTML" />
</reference>
</references>
<section title="JWE Examples" anchor="JWEExamples">
<t>
This section provides several examples of JWEs.
</t>
<section title="JWE Example using TBD Algorithm" anchor="TBDExample">
<section title="Encrypting">
<t>
TBD Demonstrate encryption steps with this algorithm
</t>
</section>
<section title="Decrypting">
<t>
TBD Demonstrate decryption steps with this algorithm
</t>
</section>
</section>
</section>
<section title="Algorithm Identifier Cross-Reference" anchor="algxref">
<t>
This appendix contains a table cross-referencing the <spanx
style="verb">alg</spanx> and <spanx style="verb">enc</spanx>
values used in this specification with the equivalent
identifiers used by other standards and software packages.
See <xref target="RFC3275">XML DSIG</xref> and <xref
target="JCA">Java Cryptography Architecture</xref> for more
information about the names defined by those documents.
</t>
<texttable title="Algorithm Identifier Cross-Reference" anchor="algxreftable">
<ttcol align="left">Algorithm</ttcol>
<ttcol align="left">JWE</ttcol>
<ttcol align="left">XML ENC</ttcol>
<ttcol align="left">JCA</ttcol>
<ttcol align="left">OID</ttcol>
<c>RSA using RSA-PKCS1-1.5 padding</c>
<c>RSA1_5</c>
<c>http://www.w3.org/2001/04/xmlenc#rsa-1_5</c>
<c>RSA/ECB/PKCS1Padding</c>
<!-- TBD RSA/None/PKCS1Padding or RSA/ECB/PKCS1Padding ? -->
<c>TBD</c>
<c>RSA using Optimal Asymmetric Encryption Padding (OAEP)</c>
<c>RSA-OAEP</c>
<c>http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p</c>
<c>RSA/ECB/OAEPWithSHA-1AndMGF1Padding</c>
<!-- RSA/ECB/OAEPWithSHA-1AndMGF1Padding or RSA/ECB/OAEPWithSHA-256AndMGF1Padding or RSA/NONE/OAEPWithSHA-1AndMGF1Padding or RSA/NONE/OAEPWithSHA-256AndMGF1Padding ? -->
<c>TBD</c>
<c>Elliptic Curve Diffie-Hellman Ephemeral Secret</c>
<c>ECDH-ES</c>
<c>http://www.w3.org/2009/xmlenc11#ECDH-ES</c>
<c>TBD</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) Key Wrap Algorithm <xref
target="RFC3394">RFC 3394</xref> using 128 bit keys</c>
<c>A128KW</c>
<c>http://www.w3.org/2001/04/xmlenc#kw-aes128</c>
<c>TBD</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) Key Wrap Algorithm <xref
target="RFC3394">RFC 3394</xref> using 256 bit keys</c>
<c>A256KW</c>
<c>http://www.w3.org/2001/04/xmlenc#kw-aes256</c>
<c>TBD</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) using 128 bit keys in
Cipher Block Chaining mode</c>
<c>A128CBC</c>
<c>http://www.w3.org/2001/04/xmlenc#aes128-cbc</c>
<c>AES/CBC/PKCS5Padding</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) using 256 bit keys in
Cipher Block Chaining mode</c>
<c>A256CBC</c>
<c>http://www.w3.org/2001/04/xmlenc#aes256-cbc</c>
<c>AES/CBC/PKCS5Padding</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) using 128 bit keys in
Galois/Counter Mode</c>
<c>A128GCM</c>
<c>http://www.w3.org/2009/xmlenc11#aes128-gcm</c>
<c>AES/GCM/NoPadding</c>
<c>TBD</c>
<c>Advanced Encryption Standard (AES) using 256 bit keys in
Galois/Counter Mode</c>
<c>A256GCM</c>
<c>http://www.w3.org/2009/xmlenc11#aes256-gcm</c>
<c>AES/GCM/NoPadding</c>
<c>TBD</c>
</texttable>
</section>
<section title="Acknowledgements" anchor="Acknowledgements">
<t>
Solutions for encrypting JSON content were also explored by
<xref target="JSS" /> and <xref target="I-D.rescorla-jsms"/>,
both of which significantly influenced this draft. This draft
attempts to explicitly reuse as much from <xref
target="W3C.CR-xmlenc-core1-20110303" /> and <xref
target="RFC5652">RFC 5652</xref> as possible, while utilizing
simple compact JSON-based data structures.
</t>
<t>
Special thanks are due to John Bradley and Nat Sakimura for
the discussions that helped inform the content of this
specification and to Eric Rescorla and Joe Hildebrand for
allowing the reuse of some of the text from <xref
target="I-D.rescorla-jsms"/> in this document.
</t>
</section>
<section title='Document History'>
<t>
-00
<list style='symbols'>
<t>
First encryption draft based upon consensus decisions at
IIW documented at http://self-issued.info/?p=378. The
ability to provide encryption for JSON Web Tokens (JWTs)
<xref target="JWT" /> is a primary use case.
</t>
</list>
</t>
</section>
</back>
</rfc>
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