JSON Web Encryption (JWE)Microsoftmbj@microsoft.comhttp://self-issued.info/Cisco Systems, Inc.jhildebr@cisco.com
Security
JOSE Working GroupRFCRequest for CommentsI-DInternet-DraftJavaScript Object NotationJSONJSON Object Signing and EncryptionJOSEJSON Web SignatureJWSJSON Web EncryptionJWEJSON Web KeyJWKJSON Web AlgorithmsJWA
JSON Web Encryption (JWE) represents encrypted content
using JSON-based data structures.
Cryptographic algorithms and identifiers for use with this
specification are described in the separate
JSON Web Algorithms (JWA) specification
and IANA registries defined by that specification.
Related digital signature and Message Authentication Code (MAC)
capabilities are described
in the separate JSON Web Signature (JWS) specification.
JSON Web Encryption (JWE) represents encrypted content
using JSON-based data structures .
The JWE cryptographic mechanisms encrypt and provide integrity protection for
an arbitrary sequence of octets.
Two closely related serializations for JWEs are defined.
The JWE Compact Serialization is a compact, URL-safe representation
intended for space constrained environments such as HTTP
Authorization headers and URI query parameters.
The JWE JSON Serialization represents JWEs as JSON objects and
enables the same content to be encrypted to multiple parties.
Both share the same cryptographic underpinnings.
Cryptographic algorithms and identifiers for use with this
specification are described in the separate
JSON Web Algorithms (JWA) specification
and IANA registries defined by that specification.
Related digital signature and MAC capabilities are described
in the separate JSON Web Signature (JWS)
specification.
Names defined by this specification are short because a core goal is
for the resulting representations to be compact.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "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" .
The interpretation should only be applied when the terms appear in all capital letters.
BASE64URL(OCTETS) denotes the base64url encoding of OCTETS,
per Section 2 of .
UTF8(STRING) denotes the octets of the
UTF-8 representation of STRING,
where STRING is a sequence of zero or more Unicode characters.
ASCII(STRING) denotes the octets of the
ASCII representation of STRING,
where STRING is a sequence of zero or more ASCII characters.
The concatenation of two values A and B
is denoted as A || B.
The terms
"JSON Web Signature (JWS)",
"Base64url Encoding",
"Collision-Resistant Name",
"Header Parameter",
"JOSE Header",
and "StringOrURI" are defined by
the JWS specification .
The terms
"Ciphertext",
"Digital Signature", "Initialization Vector (IV)",
"Message Authentication Code (MAC)",
and "Plaintext" are defined by
the "Internet Security Glossary, Version 2".
These terms are defined by this specification:
A data structure representing an encrypted and integrity-protected message.
An AEAD algorithm is one that encrypts the plaintext,
allows Additional Authenticated Data to be specified,
and provides an integrated content integrity check
over the ciphertext and Additional Authenticated Data.
AEAD algorithms accept two inputs, the plaintext and the
Additional Authenticated Data value, and produce two outputs,
the ciphertext and the Authentication Tag value.
AES Galois/Counter Mode (GCM) is one such algorithm.
An input to an AEAD operation that
is integrity protected but not encrypted.
An output of an AEAD operation that
ensures the integrity of
the ciphertext
and the Additional Authenticated Data.
Note that some algorithms may not use an Authentication Tag,
in which case this value is the empty octet sequence.
A symmetric key for the AEAD algorithm
used to encrypt the plaintext
to produce the ciphertext and the Authentication Tag.
Encrypted Content Encryption Key value.
Note that for some algorithms, the JWE Encrypted Key
value is specified as being the empty octet sequence.
Initialization Vector value used
when encrypting the plaintext.
Note that some algorithms may not use an Initialization Vector,
in which case this value is the empty octet sequence.
Additional value to be integrity protected by
the authenticated encryption operation.
This can only be present when using the JWE JSON Serialization.
(Note that this can also be achieved when using either
the JWE Compact Serialization or the JWE JSON Serialization
by including the AAD value as an integrity-protected Header Parameter value,
but at the cost of the value being double base64url encoded.)
Ciphertext value resulting from
authenticated encryption of the plaintext with Additional Authenticated Data.
Authentication Tag value resulting from
authenticated encryption of the plaintext with Additional Authenticated Data.
JSON object that contains the Header Parameters that
are integrity protected by the authenticated encryption operation.
These parameters apply to all recipients of the JWE.
For the JWE Compact Serialization, this comprises the entire JOSE Header.
For the JWE JSON Serialization, this is one component of the JOSE Header.
JSON object that contains the Header Parameters that
apply to all recipients of the JWE
that are not integrity protected.
This can only be present when using the JWE JSON Serialization.
JSON object that contains Header Parameters that
apply to a single recipient of the JWE.
These Header Parameter values are not integrity protected.
This can only be present when using the JWE JSON Serialization.
A representation of the JWE as a compact, URL-safe string.
A representation of the JWE as a JSON object.
The JWE JSON Serialization
enables the same content to be encrypted to multiple parties.
This representation is neither optimized for compactness nor URL safe.
A method of determining the Content Encryption Key value to
use. Each algorithm used for determining the CEK value uses a
specific Key Management Mode.
Key Management Modes employed by this specification are
Key Encryption,
Key Wrapping,
Direct Key Agreement,
Key Agreement with Key Wrapping, and
Direct Encryption.
A Key Management Mode in which the CEK value
is encrypted to the intended recipient using an asymmetric encryption algorithm.
A Key Management Mode in which the CEK value
is encrypted to the intended recipient using a symmetric key wrapping algorithm.
A Key Management Mode in which a key agreement algorithm is used to agree upon
the CEK value.
A Key Management Mode in which a key agreement algorithm is used to agree upon
a symmetric key used to encrypt the CEK value
to the intended recipient using a symmetric key wrapping algorithm.
A Key Management Mode in which the CEK value
used is the secret symmetric key value shared between the parties.
JWE represents encrypted content using JSON data
structures and base64url encoding.
These JSON data structures MAY contain whitespace and/or line breaks
before or after any JSON values or structural characters,
in accordance with Section 2 of RFC 7159.
A JWE represents these logical values
(each of which is defined in ):
JOSE HeaderJWE Encrypted KeyJWE Initialization VectorJWE AADJWE CiphertextJWE Authentication Tag
For a JWE,
the JOSE Header members are the union of the members of these values
(each of which is defined in ):
JWE Protected HeaderJWE Shared Unprotected HeaderJWE Per-Recipient Unprotected Header
JWE utilizes authenticated encryption to ensure the confidentiality
and integrity of the plaintext
and the integrity of the JWE Protected Header and the JWE AAD.
This document defines two serializations for JWEs:
a compact, URL-safe serialization called the JWE Compact Serialization
and a JSON serialization called the JWE JSON Serialization.
In both serializations, the
JWE Protected Header,
JWE Encrypted Key,
JWE Initialization Vector,
JWE Ciphertext, and
JWE Authentication Tag
are base64url encoded,
since JSON lacks a way to directly represent arbitrary octet sequences.
When present, the JWE AAD is also base64url encoded.
In the JWE Compact Serialization, no JWE Shared Unprotected Header or
JWE Per-Recipient Unprotected Header are used.
In this case, the JOSE Header and the JWE Protected Header are the same.
In the JWE Compact Serialization, a JWE is represented as the
concatenation:
BASE64URL(UTF8(JWE Protected Header)) || '.' ||BASE64URL(JWE Encrypted Key) || '.' ||BASE64URL(JWE Initialization Vector) || '.' ||BASE64URL(JWE Ciphertext) || '.' ||BASE64URL(JWE Authentication Tag)
See for more information
about the JWE Compact Serialization.
In the JWE JSON Serialization, one or more of the JWE Protected Header,
JWE Shared Unprotected Header, and
JWE Per-Recipient Unprotected Header MUST be present.
In this case, the members of the JOSE Header are the union of
the members of the JWE Protected Header,
JWE Shared Unprotected Header, and
JWE Per-Recipient Unprotected Header
values that are present.
In the JWE JSON Serialization, a JWE is represented as a JSON object
containing some or all of these eight members:
protected, with the value BASE64URL(UTF8(JWE Protected Header))unprotected, with the value JWE Shared Unprotected Headerheader, with the value JWE Per-Recipient Unprotected Headerencrypted_key, with the value BASE64URL(JWE Encrypted Key)iv, with the value BASE64URL(JWE Initialization Vector)ciphertext, with the value BASE64URL(JWE Ciphertext)tag, with the value BASE64URL(JWE Authentication Tag)aad, with the value BASE64URL(JWE AAD)
The six base64url-encoded result strings
and the two unprotected JSON object values
are represented as members within a JSON object.
The inclusion of some of these values is OPTIONAL.
The JWE JSON Serialization can also
encrypt the plaintext to multiple recipients.
See for more information
about the JWE JSON Serialization.
This example encrypts the plaintext
"The true sign of intelligence is not knowledge but imagination."
to the recipient.
The following example JWE Protected Header declares that:
The Content Encryption Key is encrypted to the recipient
using the RSAES-OAEP algorithm to produce
the JWE Encrypted Key.
Authenticated encryption is performed on the plaintext
using the AES GCM
algorithm with a 256-bit key
to produce the ciphertext and the Authentication Tag.
Encoding this JWE Protected Header as
BASE64URL(UTF8(JWE Protected Header)) gives this value:
The remaining steps to finish creating this JWE are:
Generate a random Content Encryption Key (CEK).
Encrypt the CEK with the recipient's public key using the RSAES-OAEP
algorithm to produce the JWE Encrypted Key.
Base64url-encode the JWE Encrypted Key.
Generate a random JWE Initialization Vector.
Base64url-encode the JWE Initialization Vector.
Let the Additional Authenticated Data encryption parameter be
ASCII(BASE64URL(UTF8(JWE Protected Header))).
Perform authenticated encryption on the plaintext
with the AES GCM algorithm
using the CEK as the encryption key,
the JWE Initialization Vector,
and the Additional Authenticated Data value,
requesting a 128-bit Authentication Tag output.
Base64url-encode the ciphertext.
Base64url-encode the Authentication Tag.
Assemble the final representation:
The Compact Serialization of this result is the string
BASE64URL(UTF8(JWE Protected Header))
|| '.' || BASE64URL(JWE Encrypted Key)
|| '.' || BASE64URL(JWE Initialization Vector)
|| '.' || BASE64URL(JWE Ciphertext)
|| '.' || BASE64URL(JWE Authentication Tag).
The final result in this example
(with line breaks for display purposes only) is:
See for the complete details of computing this JWE.
See for additional examples,
including examples using the JWE JSON Serialization
in Sections
and .
For a JWE,
the members of the JSON object(s) representing the JOSE Header
describe the encryption applied to the plaintext and optionally
additional properties of the JWE.
The Header Parameter names within the JOSE Header MUST be unique,
just as described in Section 4 of .
The rules about handling Header Parameters that are not understood
by the implementation are also the same.
The classes of Header Parameter names are likewise the same.
The following Header Parameter names for use in JWEs are registered
in the IANA
"JSON Web Signature and Encryption Header Parameters" registry
established by
,
with meanings as defined below.
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.
This parameter has the same meaning, syntax, and processing rules as the
alg Header Parameter defined in
Section 4.1.1 of , except that
the Header Parameter identifies the cryptographic algorithm used to
encrypt or determine the value of the CEK.
The encrypted content is not usable if the alg
value does not represent a supported algorithm, or if the recipient does
not have a key that can be used with that algorithm.
A list of defined alg values
for this use can be found
in the IANA "JSON Web Signature and Encryption Algorithms" registry
established by
;
the initial contents of this registry are the values defined in
Section 4.1 of
.
The enc (encryption algorithm)
Header Parameter identifies the content encryption algorithm
used to perform authenticated encryption on the plaintext
to produce the ciphertext and the Authentication Tag.
This algorithm MUST be an AEAD algorithm with a specified key length.
The encrypted content is not usable if the enc
value does not represent a supported algorithm.
enc values should either be
registered in the IANA
"JSON Web Signature and Encryption Algorithms" registry
established by
or be
a value that contains a Collision-Resistant Name.
The enc value is a case-sensitive ASCII string
containing a StringOrURI value.
This Header Parameter MUST be present
and MUST be understood and processed by implementations.
A list of defined enc values
for this use can be found
in the IANA "JSON Web Signature and Encryption Algorithms" registry
established by
;
the initial contents of this registry are the values defined in
Section 5.1 of
.
The zip (compression algorithm)
applied to the plaintext before encryption, if any.
The zip value defined by this specification is:
DEF
- Compression with the DEFLATE algorithm
Other values MAY be used.
Compression algorithm values can be registered in the IANA
"JSON Web Encryption Compression Algorithms" registry
established by
.
The zip value is a case-sensitive string.
If no zip parameter is present,
no compression is applied to the plaintext before encryption.
When used, this Header Parameter MUST be integrity protected;
therefore, it MUST occur only within the JWE Protected Header.
Use of this Header Parameter is OPTIONAL.
This Header Parameter MUST be understood and processed by implementations.
This parameter has the same meaning, syntax, and processing rules as the
jku Header Parameter defined in
Section 4.1.2 of , except that
the JWK Set resource contains
the public key to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
This parameter has the same meaning, syntax, and processing rules as the
jwk Header Parameter defined in
Section 4.1.3 of , except that
the key is
the public key to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
This parameter has the same meaning, syntax, and processing rules as the
kid Header Parameter defined in
Section 4.1.4 of , except that
the key hint references
the public key to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
This parameter allows originators to explicitly signal a change of
key to JWE recipients.
This parameter has the same meaning, syntax, and processing rules as the
x5u Header Parameter defined in
Section 4.1.5 of , except that
the X.509 public key certificate or certificate chain
contains the public key
to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
This parameter has the same meaning, syntax, and processing rules as the
x5c Header Parameter defined in
Section 4.1.6 of , except that
the X.509 public key certificate or certificate chain
contains the public key
to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
See Appendix B of for an example
x5c value.
This parameter has the same meaning, syntax, and processing rules as the
x5t Header Parameter defined in
Section 4.1.7 of , except that
the certificate referenced by the thumbprint contains
the public key to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
Note that certificate thumbprints are also sometimes known as certificate fingerprints.
This parameter has the same meaning, syntax, and processing rules as the
x5t#S256 Header Parameter defined in
Section 4.1.8 of , except that
the certificate referenced by the thumbprint contains
the public key to which the JWE was encrypted;
this can be used to determine the private key needed to decrypt the JWE.
Note that certificate thumbprints are also sometimes known as certificate fingerprints.
This parameter has the same meaning, syntax, and processing rules as the
typ Header Parameter defined in
Section 4.1.9 of , except that
the type is that of this complete JWE.
This parameter has the same meaning, syntax, and processing rules as the
cty Header Parameter defined in
Section 4.1.10 of , except that
the type is that of the secured content (the plaintext).
This parameter has the same meaning, syntax, and processing rules as the
crit Header Parameter defined in
Section 4.1.11 of , except that
Header Parameters for a JWE are being referred to,
rather than Header Parameters for a JWS.
Additional Header Parameter names can be defined by those
using JWEs. However, in order to prevent collisions, any new
Header Parameter name should either be registered in the IANA
"JSON Web Signature and Encryption Header Parameters" registry
established by
or be a Public Name:
a value that contains a Collision-Resistant Name.
In each case, the definer of the name
or value needs to take reasonable precautions to make sure they
are in control of the part of the namespace they use to
define the Header Parameter name.
New Header Parameters should be introduced sparingly, as
they can result in non-interoperable JWEs.
A producer and consumer of a JWE may agree to use Header Parameter names
that are Private Names: names that are
not Registered Header Parameter names ()
or Public Header Parameter names ().
Unlike Public Header Parameter names,
Private Header Parameter names are subject to collision and
should be used with caution.
The message encryption process is as follows.
The order of the steps is not significant in cases where
there are no dependencies between the inputs and outputs of the steps.
Determine the Key Management Mode employed by the algorithm
used to determine the Content Encryption Key value.
(This is the algorithm recorded in the
alg (algorithm)
Header Parameter of the resulting JWE.)
When Key Wrapping, Key Encryption,
or Key Agreement with Key Wrapping are employed,
generate a random CEK value.
See RFC 4086 for
considerations on generating random values.
The CEK MUST have a length equal to that
required for the content encryption algorithm.
When Direct Key Agreement or Key Agreement with Key Wrapping
are employed, use the key agreement algorithm
to compute the value of the agreed upon key.
When Direct Key Agreement is employed,
let the CEK be the agreed upon key.
When Key Agreement with Key Wrapping is employed,
the agreed upon key will be used to wrap the CEK.
When Key Wrapping, Key Encryption,
or Key Agreement with Key Wrapping are employed,
encrypt the CEK to the recipient and let the result be the
JWE Encrypted Key.
When Direct Key Agreement or Direct Encryption are employed,
let the JWE Encrypted Key be the empty octet sequence.
When Direct Encryption is employed,
let the CEK be the shared symmetric key.
Compute the encoded key value BASE64URL(JWE Encrypted Key).
If the JWE JSON Serialization is being used, repeat this process
(steps 1-7)
for each recipient.
Generate a random JWE Initialization Vector of the correct size
for the content encryption algorithm (if required for the algorithm);
otherwise, let the JWE Initialization Vector be the empty octet sequence.
Compute the encoded Initialization Vector value
BASE64URL(JWE Initialization Vector).
If a zip parameter was included,
compress the plaintext using the specified compression algorithm
and let M be the octet sequence representing the compressed plaintext;
otherwise, let M be the octet sequence representing the plaintext.
Create the JSON object(s) containing the desired set of Header Parameters,
which together comprise the JOSE Header: one or more of the JWE Protected
Header, the JWE Shared Unprotected
Header, and the JWE Per-Recipient Unprotected Header.
Compute the Encoded Protected Header value
BASE64URL(UTF8(JWE Protected Header)).
If the JWE Protected Header is not present
(which can only happen when using the JWE JSON Serialization
and no protected member is present),
let this value be the empty string.
Let the Additional Authenticated Data encryption parameter be
ASCII(Encoded Protected Header).
However, if a JWE AAD value is present
(which can only be the case when using the JWE JSON Serialization),
instead let the Additional Authenticated Data encryption parameter be
ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
Encrypt M using the CEK, the JWE Initialization Vector, and
the Additional Authenticated Data value
using the specified content encryption algorithm
to create the JWE Ciphertext value and the JWE Authentication Tag
(which is the Authentication Tag output from the encryption operation).
Compute the encoded ciphertext value BASE64URL(JWE Ciphertext).
Compute the encoded Authentication Tag value
BASE64URL(JWE Authentication Tag).
If a JWE AAD value is present,
compute the encoded AAD value BASE64URL(JWE AAD).
Create the desired serialized output.
The Compact Serialization of this result is the string
BASE64URL(UTF8(JWE Protected Header))
|| '.' || BASE64URL(JWE Encrypted Key)
|| '.' || BASE64URL(JWE Initialization Vector)
|| '.' || BASE64URL(JWE Ciphertext)
|| '.' || BASE64URL(JWE Authentication Tag).
The JWE JSON Serialization is described in .
The message decryption process is the reverse of the
encryption process.
The order of the steps is not significant in cases where
there are no dependencies between the inputs and outputs of the steps.
If any of these steps fail, the encrypted content cannot be validated.
When there are multiple recipients,
it is an application decision which of the recipients' encrypted content
must successfully validate for the JWE to be accepted.
In some cases, encrypted content for all recipients must successfully validate
or the JWE will be considered invalid.
In other cases, only the encrypted content for a single recipient
needs to be successfully validated.
However, in all cases, the encrypted content for at least one recipient
MUST successfully validate or the JWE MUST be considered invalid.
Parse the JWE representation to extract the serialized values
for the components of the JWE.
When using the JWE Compact Serialization,
these components are
the base64url-encoded representations of
the JWE Protected Header,
the JWE Encrypted Key,
the JWE Initialization Vector,
the JWE Ciphertext, and
the JWE Authentication Tag,
and when using the JWE JSON Serialization,
these components also include the base64url-encoded representation of
the JWE AAD and the unencoded
JWE Shared Unprotected Header and
JWE Per-Recipient Unprotected Header values.
When using the JWE Compact Serialization,
the JWE Protected Header,
the JWE Encrypted Key,
the JWE Initialization Vector,
the JWE Ciphertext, and
the JWE Authentication Tag
are represented as base64url-encoded values in that order,
with each value being separated from the next by a single period ('.') character,
resulting in exactly four delimiting period characters being used.
The JWE JSON Serialization
is described in .
Base64url decode the encoded representations of
the JWE Protected Header,
the JWE Encrypted Key,
the JWE Initialization Vector,
the JWE Ciphertext,
the JWE Authentication Tag, and
the JWE AAD,
following the restriction that no line breaks, whitespace, or other additional characters have been used.
Verify that the octet sequence resulting from decoding the encoded JWE Protected Header
is a UTF-8-encoded representation of
a completely valid JSON object
conforming to RFC 7159;
let the JWE Protected Header be this JSON object.
If using the JWE Compact Serialization, let the JOSE Header be the
JWE Protected Header.
Otherwise, when using the JWE JSON Serialization,
let the JOSE Header be the union of
the members of the JWE Protected Header,
the JWE Shared Unprotected Header and
the corresponding JWE Per-Recipient Unprotected Header,
all of which must be completely valid JSON objects.
During this step,
verify that the resulting JOSE Header does not contain duplicate
Header Parameter names.
When using the JWE JSON Serialization, this restriction includes
that the same Header Parameter name also MUST NOT occur in
distinct JSON object values that together comprise the JOSE Header.
Verify that the implementation understands and can process
all fields that it is required to support,
whether required by this specification,
by the algorithms being used,
or by the crit Header Parameter value,
and that the values of those parameters are also understood and supported.
Determine the Key Management Mode employed by the algorithm
specified by the
alg (algorithm) Header Parameter.
Verify that the JWE uses a key known to the recipient.
When Direct Key Agreement or Key Agreement with Key Wrapping
are employed, use the key agreement algorithm
to compute the value of the agreed upon key.
When Direct Key Agreement is employed,
let the CEK be the agreed upon key.
When Key Agreement with Key Wrapping is employed,
the agreed upon key will be used to decrypt the JWE Encrypted Key.
When Key Wrapping, Key Encryption,
or Key Agreement with Key Wrapping are employed,
decrypt the JWE Encrypted Key to produce the CEK.
The CEK MUST have a length equal to that
required for the content encryption algorithm.
Note that when there are multiple recipients,
each recipient will only be able to decrypt JWE Encrypted Key values
that were encrypted to a key in that recipient's possession.
It is therefore normal to only be able to decrypt one of the
per-recipient JWE Encrypted Key values to obtain the CEK value.
Also, see for security considerations
on mitigating timing attacks.
When Direct Key Agreement or Direct Encryption are employed,
verify that the JWE Encrypted Key value is an empty octet sequence.
When Direct Encryption is employed,
let the CEK be the shared symmetric key.
Record whether the CEK could be successfully determined for this recipient or not.
If the JWE JSON Serialization is being used, repeat this process
(steps 4-12)
for each recipient contained in the representation.
Compute the Encoded Protected Header value
BASE64URL(UTF8(JWE Protected Header)).
If the JWE Protected Header is not present
(which can only happen when using the JWE JSON Serialization
and no protected member is present),
let this value be the empty string.
Let the Additional Authenticated Data encryption parameter be
ASCII(Encoded Protected Header).
However, if a JWE AAD value is present
(which can only be the case when using the JWE JSON Serialization),
instead let the Additional Authenticated Data encryption parameter be
ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
Decrypt the JWE Ciphertext using the CEK, the JWE Initialization Vector,
the Additional Authenticated Data value,
and the JWE Authentication Tag
(which is the Authentication Tag input to the calculation)
using the specified content encryption algorithm,
returning the decrypted plaintext and validating the JWE Authentication Tag
in the manner specified for the algorithm,
rejecting the input without emitting any decrypted output
if the JWE Authentication Tag is incorrect.
If a zip parameter was included,
uncompress the decrypted plaintext using the specified compression algorithm.
If there was no recipient for which all of the decryption steps succeeded,
then the JWE MUST be considered invalid.
Otherwise, output the plaintext.
In the JWE JSON Serialization case, also return a result to the application
indicating for which of the recipients the decryption succeeded and failed.
Finally, note that it is an application decision which algorithms
may be used in a given context.
Even if a JWE can be successfully decrypted,
unless the algorithms used in the JWE are acceptable
to the application, it SHOULD consider the JWE to be invalid.
The string comparison rules for this specification are the same as
those defined in
Section 5.3 of .
The key identification methods for this specification are the same as
those defined in
Section 6 of , except that
the key being identified is
the public key to which the JWE was encrypted.
JWEs use one of two serializations: the
JWE Compact Serialization
or the
JWE JSON Serialization.
Applications using this specification need to specify what serialization
and serialization features are used for that application.
For instance, applications might specify
that only the JWE JSON Serialization is used,
that only JWE JSON Serialization support for a single recipient is used,
or that support for multiple recipients is used.
JWE implementations only need to implement the features needed
for the applications they are designed to support.
The JWE Compact Serialization represents encrypted
content as a compact, URL-safe string.
This string is:
BASE64URL(UTF8(JWE Protected Header)) || '.' ||BASE64URL(JWE Encrypted Key) || '.' ||BASE64URL(JWE Initialization Vector) || '.' ||BASE64URL(JWE Ciphertext) || '.' ||BASE64URL(JWE Authentication Tag)
Only one recipient is supported by the JWE Compact Serialization
and it provides no syntax to represent
JWE Shared Unprotected Header,
JWE Per-Recipient Unprotected Header,
or JWE AAD values.
The JWE JSON Serialization represents encrypted
content as a JSON object.
This representation is neither optimized for compactness nor URL safe.
Two closely related syntaxes are defined for the JWE JSON Serialization:
a fully general syntax,
with which content can be encrypted to more than one recipient,
and a flattened syntax, which is optimized for
the single-recipient case.
The following members are defined for use in
top-level JSON objects used for the
fully general JWE JSON Serialization syntax:
The protected member MUST be present and contain the value
BASE64URL(UTF8(JWE Protected Header)) when the JWE Protected Header
value is non-empty; otherwise, it MUST be absent.
These Header Parameter values are integrity protected.
The unprotected member MUST be present and contain the value
JWE Shared Unprotected Header when the JWE Shared Unprotected Header
value is non-empty; otherwise, it MUST be absent.
This value is represented as an unencoded JSON object,
rather than as a string.
These Header Parameter values are not integrity protected.
The iv member MUST be present and contain the value
BASE64URL(JWE Initialization Vector) when the JWE Initialization Vector
value is non-empty; otherwise, it MUST be absent.
The aad member MUST be present and contain the value
BASE64URL(JWE AAD)) when the JWE AAD
value is non-empty; otherwise, it MUST be absent.
A JWE AAD value
can be included to supply a base64url-encoded value
to be integrity protected but not encrypted.
The ciphertext member MUST be present and contain the value
BASE64URL(JWE Ciphertext).
The tag member MUST be present and contain the value
BASE64URL(JWE Authentication Tag) when the JWE Authentication Tag
value is non-empty; otherwise, it MUST be absent.
The recipients member value MUST be
an array of JSON objects.
Each object contains information specific to a single recipient.
This member MUST be present with exactly one array element per recipient,
even if some or all of the array element values are the empty JSON object
{}
(which can happen when all Header Parameter values are shared
between all recipients and when no encrypted key is used,
such as when doing Direct Encryption).
The following members are defined for use in
the JSON objects that are elements of
the recipients array:
The header member MUST be present and contain the value
JWE Per-Recipient Unprotected Header when the JWE Per-Recipient Unprotected Header
value is non-empty; otherwise, it MUST be absent.
This value is represented as an unencoded JSON object,
rather than as a string.
These Header Parameter values are not integrity protected.
The encrypted_key member MUST be present and contain the value
BASE64URL(JWE Encrypted Key) when the JWE Encrypted Key
value is non-empty; otherwise, it MUST be absent.
At least one of the
header,
protected,
and unprotected
members MUST be present so that alg
and enc
Header Parameter values are conveyed for each recipient computation.
Additional members can be present in both the JSON objects defined above;
if not understood by implementations encountering them, they MUST be ignored.
Some Header Parameters, including the alg
parameter, can be shared among all recipient computations.
Header Parameters in the JWE Protected Header and
JWE Shared Unprotected Header values are shared among all recipients.
The Header Parameter values used when creating or validating
per-recipient ciphertext and Authentication Tag values are
the union of the three sets of Header Parameter values that may be present:
(1) the JWE Protected Header represented in the
protected member,
(2) the JWE Shared Unprotected Header represented in the
unprotected member, and
(3) the JWE Per-Recipient Unprotected Header represented in the
header
member of the recipient's array element.
The union of these sets of Header Parameters comprises the JOSE Header.
The Header Parameter names in the three locations MUST be disjoint.
Each JWE Encrypted Key value is computed using the
parameters of the corresponding JOSE Header value
in the same manner as for the JWE Compact Serialization.
This has the desirable property that each
JWE Encrypted Key value
in the recipients array
is identical to the value
that would have been computed for the same parameter
in the JWE Compact Serialization.
Likewise, the JWE Ciphertext and JWE Authentication Tag values
match those produced for the JWE Compact Serialization,
provided that the JWE Protected Header value
(which represents the integrity-protected Header Parameter values)
matches that used in
the JWE Compact Serialization.
All recipients use the same
JWE Protected Header,
JWE Initialization Vector,
JWE Ciphertext,
and JWE Authentication Tag values,
when present, resulting in
potentially significant space savings if the message is large.
Therefore, all Header Parameters that specify the treatment of
the plaintext value MUST be the same for all recipients.
This primarily means that the enc (encryption algorithm) Header Parameter
value in the JOSE Header for each recipient
and any parameters of that algorithm MUST be the same.
See for an example
JWE using the general JWE JSON Serialization syntax.
The flattened JWE JSON Serialization syntax is based upon
the general syntax, but flattens it,
optimizing it for the single-recipient case.
It flattens it by removing
the recipients member and
instead placing those members defined for use in
the recipients array
(the header and
encrypted_key members)
in the top-level JSON object
(at the same level as the ciphertext member).
The recipients member MUST NOT
be present when using this syntax.
Other than this syntax difference, JWE JSON Serialization objects
using the flattened syntax are processed identically to those
using the general syntax.
Note that when using the flattened syntax,
just as when using the general syntax,
any unprotected Header Parameter values can reside in either
the unprotected member or
the header member, or in both.
See for an example
JWE using the flattened JWE JSON Serialization syntax.
The Transport Layer Security (TLS) requirements for this specification are the same as
those defined in
Section 8 of .
There are several ways of distinguishing whether an object is a
JWS or JWE.
All these methods will yield the same result for all legal input values;
they may yield different results for malformed inputs.
If the object is using the JWS Compact Serialization or
the JWE Compact Serialization, the number of base64url-encoded segments
separated by period ('.') characters differs for JWSs and JWEs.
JWSs have three segments separated by two period ('.') characters.
JWEs have five segments separated by four period ('.') characters.
If the object is using the JWS JSON Serialization or
the JWE JSON Serialization, the members used will be different.
JWSs have a payload member and JWEs do not.
JWEs have a ciphertext member and JWSs do not.
The JOSE Header for a JWS can be distinguished from
the JOSE Header for a JWE by
examining the alg
(algorithm) Header Parameter value.
If the value represents a digital signature or MAC algorithm,
or is the value none, it is for a JWS;
if it represents a Key Encryption, Key Wrapping, Direct Key Agreement,
Key Agreement with Key Wrapping, or Direct Encryption algorithm, it is for a JWE.
(Extracting the alg value to examine is
straightforward when using the JWS Compact Serialization or
the JWE Compact Serialization and may be more difficult when
using the JWS JSON Serialization or the JWE JSON Serialization.)
The JOSE Header for a JWS can also be distinguished from
the JOSE Header for a JWE by
determining whether an
enc (encryption algorithm) member exists.
If the enc member exists, it is a JWE;
otherwise, it is a JWS.
This section registers the Header Parameter names defined in
in the IANA
"JSON Web Signature and Encryption Header Parameters" registry
established by
.
Header Parameter Name: alg
Header Parameter Description: Algorithm
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: enc
Header Parameter Description: Encryption Algorithm
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: zip
Header Parameter Description: Compression Algorithm
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: jku
Header Parameter Description: JWK Set URL
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: jwk
Header Parameter Description: JSON Web Key
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: kid
Header Parameter Description: Key ID
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: x5u
Header Parameter Description: X.509 URL
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: x5c
Header Parameter Description: X.509 Certificate Chain
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: x5t
Header Parameter Description: X.509 Certificate SHA-1 Thumbprint
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: x5t#S256
Header Parameter Description: X.509 Certificate SHA-256 Thumbprint
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: typ
Header Parameter Description: Type
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: cty
Header Parameter Description: Content Type
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
Header Parameter Name: crit
Header Parameter Description: Critical
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of RFC 7516
All of the security issues that are pertinent to any cryptographic application
must be addressed by JWS/JWE/JWK agents. Among these issues are protecting
the user's asymmetric private and symmetric secret keys and
employing countermeasures to various attacks.
All the security considerations in the JWS specification
also apply to this specification.
Likewise, all the security considerations in
XML Encryption 1.1
also apply, other than those that are XML specific.
See Section 10.1 of for security considerations on
key entropy and random values.
In addition to the uses of random values listed there, note that
random values are also used for
Content Encryption Keys (CEKs) and Initialization Vectors (IVs)
when performing encryption.
See Section 10.2 of for security considerations on
key protection.
In addition to the keys listed there that must be protected,
implementations performing encryption must protect
the key encryption key and the Content Encryption Key.
Compromise of the key encryption key may result
in the disclosure of all contents protected with that key.
Similarly, compromise of the Content Encryption Key may result in
disclosure of the associated encrypted content.
Algorithms of matching strengths should be used together whenever possible.
For instance, when AES Key Wrap is used with a given key size,
using the same key size is recommended when AES GCM is also used.
If the key encryption and content encryption algorithms are different,
the effective security is determined by the weaker of the two algorithms.
Also, see RFC 3766 for information on
determining strengths for public keys used for exchanging symmetric keys.
When decrypting, particular care must be taken not to allow
the JWE recipient to be used as an oracle for decrypting messages.
RFC 3218 should be consulted for specific
countermeasures to attacks on RSAES-PKCS1-v1_5.
An attacker might modify the contents of the alg
Header Parameter from RSA-OAEP to
RSA1_5 in order to generate a
formatting error that can be detected and used to recover the CEK
even if RSAES-OAEP was used to encrypt the CEK.
It is therefore particularly important to report all
formatting errors to the CEK, Additional Authenticated Data,
or ciphertext as a single error when the encrypted content is rejected.
Additionally, this type of attack can be prevented by
restricting the use of a key to a limited set of algorithms
-- usually one.
This means, for instance, that if the key is marked as being for
RSA&nbhy;OAEP only, any attempt to decrypt a message
using the RSA1_5 algorithm with that key should
fail immediately due to invalid use of the key.
To mitigate the attacks described in RFC 3218,
the recipient MUST NOT distinguish between format, padding, and
length errors of encrypted keys. It is strongly recommended,
in the event of receiving an improperly formatted key,
that the recipient substitute a randomly generated
CEK and proceed to the next step, to mitigate timing attacks.
ASCII format for Network InterchangeUniversity California Los Angeles (UCLA)The Unicode StandardThe Unicode ConsortiumJSON Web Signature (JWS)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jpJSON Web Key (JWK)Microsoftmbj@microsoft.comhttp://self-issued.info/JSON Web Algorithms (JWA)Microsoftmbj@microsoft.comhttp://self-issued.info/JavaScript Message Security FormatXML Encryption Syntax and Processing Version 1.1Advanced Encryption Standard (AES)National Institute of Standards and Technology (NIST)
Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMACNational Institute of Standards and Technology (NIST)
JSON Simple EncryptionindependentNomura Research Institute
This section provides examples of JWE computations.
This example encrypts the plaintext
"The true sign of intelligence is not knowledge but imagination."
to the recipient using RSAES-OAEP for key encryption
and AES GCM for content encryption.
The representation of this plaintext (using JSON array notation) is:
[84, 104, 101, 32, 116, 114, 117, 101, 32, 115, 105, 103, 110, 32, 111, 102,
32, 105, 110, 116, 101, 108, 108, 105, 103, 101, 110, 99, 101, 32, 105, 115,
32, 110, 111, 116, 32, 107, 110, 111, 119, 108, 101, 100, 103, 101, 32, 98,
117, 116, 32, 105, 109, 97, 103, 105, 110, 97, 116, 105, 111, 110, 46]
The following example JWE Protected Header declares that:
The Content Encryption Key is encrypted to the recipient
using the RSAES-OAEP algorithm to produce
the JWE Encrypted Key.
Authenticated encryption is performed on the plaintext
using the AES GCM algorithm with a 256-bit key
to produce the ciphertext and the Authentication Tag.
Encoding this JWE Protected Header as
BASE64URL(UTF8(JWE Protected Header)) gives this value:
Generate a 256-bit random CEK.
In this example, the value (using JSON array notation) is:
[177, 161, 244, 128, 84, 143, 225, 115, 63, 180, 3, 255, 107, 154, 212, 246,
138, 7, 110, 91, 112, 46, 34, 105, 47, 130, 203, 46, 122, 234, 64, 252]
Encrypt the CEK with the recipient's public key using the RSAES&nbhy;OAEP
algorithm to produce the JWE Encrypted Key.
This example uses the RSA key
represented in JSON Web Key format below
(with line breaks within values for display purposes only):
The resulting JWE Encrypted Key value is:
[56, 163, 154, 192, 58, 53, 222, 4, 105, 218, 136, 218, 29, 94, 203, 22,
150, 92, 129, 94, 211, 232, 53, 89, 41, 60, 138, 56, 196, 216, 82, 98,
168, 76, 37, 73, 70, 7, 36, 8, 191, 100, 136, 196, 244, 220, 145, 158,
138, 155, 4, 117, 141, 230, 199, 247, 173, 45, 182, 214, 74, 177, 107, 211,
153, 11, 205, 196, 171, 226, 162, 128, 171, 182, 13, 237, 239, 99, 193, 4,
91, 219, 121, 223, 107, 167, 61, 119, 228, 173, 156, 137, 134, 200, 80, 219,
74, 253, 56, 185, 91, 177, 34, 158, 89, 154, 205, 96, 55, 18, 138, 43,
96, 218, 215, 128, 124, 75, 138, 243, 85, 25, 109, 117, 140, 26, 155, 249,
67, 167, 149, 231, 100, 6, 41, 65, 214, 251, 232, 87, 72, 40, 182, 149,
154, 168, 31, 193, 126, 215, 89, 28, 111, 219, 125, 182, 139, 235, 195, 197,
23, 234, 55, 58, 63, 180, 68, 202, 206, 149, 75, 205, 248, 176, 67, 39,
178, 60, 98, 193, 32, 238, 122, 96, 158, 222, 57, 183, 111, 210, 55, 188,
215, 206, 180, 166, 150, 166, 106, 250, 55, 229, 72, 40, 69, 214, 216, 104,
23, 40, 135, 212, 28, 127, 41, 80, 175, 174, 168, 115, 171, 197, 89, 116,
92, 103, 246, 83, 216, 182, 176, 84, 37, 147, 35, 45, 219, 172, 99, 226,
233, 73, 37, 124, 42, 72, 49, 242, 35, 127, 184, 134, 117, 114, 135, 206]
Encoding this JWE Encrypted Key as
BASE64URL(JWE Encrypted Key) gives this value
(with line breaks for display purposes only):
Generate a random 96-bit JWE Initialization Vector.
In this example, the value is:
[227, 197, 117, 252, 2, 219, 233, 68, 180, 225, 77, 219]
Encoding this JWE Initialization Vector as
BASE64URL(JWE Initialization Vector) gives this value:
Let the Additional Authenticated Data encryption parameter be
ASCII(BASE64URL(UTF8(JWE Protected Header))).
This value is:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69, 116,
84, 48, 70, 70, 85, 67, 73, 115, 73, 109, 86, 117, 89, 121, 73, 54,
73, 107, 69, 121, 78, 84, 90, 72, 81, 48, 48, 105, 102, 81]
Perform authenticated encryption on the plaintext
with the AES GCM algorithm
using the CEK as the encryption key,
the JWE Initialization Vector,
and the Additional Authenticated Data value above,
requesting a 128-bit Authentication Tag output.
The resulting ciphertext is:
[229, 236, 166, 241, 53, 191, 115, 196, 174, 43, 73, 109, 39, 122, 233, 96,
140, 206, 120, 52, 51, 237, 48, 11, 190, 219, 186, 80, 111, 104, 50, 142,
47, 167, 59, 61, 181, 127, 196, 21, 40, 82, 242, 32, 123, 143, 168, 226,
73, 216, 176, 144, 138, 247, 106, 60, 16, 205, 160, 109, 64, 63, 192]
The resulting Authentication Tag value is:
[92, 80, 104, 49, 133, 25, 161, 215, 173, 101, 219, 211, 136, 91, 210, 145]
Encoding this JWE Ciphertext as
BASE64URL(JWE Ciphertext) gives this value
(with line breaks for display purposes only):
Encoding this JWE Authentication Tag as
BASE64URL(JWE Authentication Tag) gives this value:
Assemble the final representation:
The Compact Serialization of this result is the string
BASE64URL(UTF8(JWE Protected Header))
|| '.' || BASE64URL(JWE Encrypted Key)
|| '.' || BASE64URL(JWE Initialization Vector)
|| '.' || BASE64URL(JWE Ciphertext)
|| '.' || BASE64URL(JWE Authentication Tag).
The final result in this example
(with line breaks for display purposes only) is:
This example illustrates the process of creating a JWE with
RSAES&nbhy;OAEP for key encryption
and AES GCM for content encryption.
These results can be used to validate JWE decryption implementations for these algorithms.
Note that since the RSAES-OAEP computation includes random values,
the encryption results above will not be completely reproducible.
However, since the AES GCM computation is deterministic, the JWE Encrypted Ciphertext
values will be the same for all encryptions performed using these inputs.
This example encrypts the plaintext
"Live long and prosper."
to the recipient using RSAES-PKCS1-v1_5 for key encryption
and AES_128_CBC_HMAC_SHA_256 for content encryption.
The representation of this plaintext (using JSON array notation) is:
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
111, 115, 112, 101, 114, 46]
The following example JWE Protected Header declares that:
The Content Encryption Key is encrypted to the recipient
using the RSAES-PKCS1-v1_5 algorithm to produce
the JWE Encrypted Key.
Authenticated encryption is performed on the plaintext
using the AES_128_CBC_HMAC_SHA_256 algorithm
to produce the ciphertext and the Authentication Tag.
Encoding this JWE Protected Header as
BASE64URL(UTF8(JWE Protected Header)) gives this value:
Generate a 256-bit random CEK.
In this example, the key value is:
[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206,
107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]
Encrypt the CEK with the recipient's public key using the RSAES&nbhy;PKCS1&nbhy;v1_5
algorithm to produce the JWE Encrypted Key.
This example uses the RSA key
represented in JSON Web Key format below
(with line breaks within values for display purposes only):
The resulting JWE Encrypted Key value is:
[80, 104, 72, 58, 11, 130, 236, 139, 132, 189, 255, 205, 61, 86, 151, 176,
99, 40, 44, 233, 176, 189, 205, 70, 202, 169, 72, 40, 226, 181, 156, 223,
120, 156, 115, 232, 150, 209, 145, 133, 104, 112, 237, 156, 116, 250, 65, 102,
212, 210, 103, 240, 177, 61, 93, 40, 71, 231, 223, 226, 240, 157, 15, 31,
150, 89, 200, 215, 198, 203, 108, 70, 117, 66, 212, 238, 193, 205, 23, 161,
169, 218, 243, 203, 128, 214, 127, 253, 215, 139, 43, 17, 135, 103, 179, 220,
28, 2, 212, 206, 131, 158, 128, 66, 62, 240, 78, 186, 141, 125, 132, 227,
60, 137, 43, 31, 152, 199, 54, 72, 34, 212, 115, 11, 152, 101, 70, 42,
219, 233, 142, 66, 151, 250, 126, 146, 141, 216, 190, 73, 50, 177, 146, 5,
52, 247, 28, 197, 21, 59, 170, 247, 181, 89, 131, 241, 169, 182, 246, 99,
15, 36, 102, 166, 182, 172, 197, 136, 230, 120, 60, 58, 219, 243, 149, 94,
222, 150, 154, 194, 110, 227, 225, 112, 39, 89, 233, 112, 207, 211, 241, 124,
174, 69, 221, 179, 107, 196, 225, 127, 167, 112, 226, 12, 242, 16, 24, 28,
120, 182, 244, 213, 244, 153, 194, 162, 69, 160, 244, 248, 63, 165, 141, 4,
207, 249, 193, 79, 131, 0, 169, 233, 127, 167, 101, 151, 125, 56, 112, 111,
248, 29, 232, 90, 29, 147, 110, 169, 146, 114, 165, 204, 71, 136, 41, 252]
Encoding this JWE Encrypted Key as
BASE64URL(JWE Encrypted Key) gives this value
(with line breaks for display purposes only):
Generate a random 128-bit JWE Initialization Vector.
In this example, the value is:
[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
Encoding this JWE Initialization Vector as
BASE64URL(JWE Initialization Vector) gives this value:
Let the Additional Authenticated Data encryption parameter be
ASCII(BASE64URL(UTF8(JWE Protected Header))).
This value is:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69, 120,
88, 122, 85, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66,
77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
73, 110, 48]
Perform authenticated encryption on the plaintext
with the AES_128_CBC_HMAC_SHA_256 algorithm
using the CEK as the encryption key,
the JWE Initialization Vector,
and the Additional Authenticated Data value above.
The steps for doing this using the values from
are detailed in .
The resulting ciphertext is:
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
The resulting Authentication Tag value is:
[246, 17, 244, 190, 4, 95, 98, 3, 231, 0, 115, 157, 242, 203, 100, 191]
Encoding this JWE Ciphertext as
BASE64URL(JWE Ciphertext) gives this value:
Encoding this JWE Authentication Tag as
BASE64URL(JWE Authentication Tag) gives this value:
Assemble the final representation:
The Compact Serialization of this result is the string
BASE64URL(UTF8(JWE Protected Header))
|| '.' || BASE64URL(JWE Encrypted Key)
|| '.' || BASE64URL(JWE Initialization Vector)
|| '.' || BASE64URL(JWE Ciphertext)
|| '.' || BASE64URL(JWE Authentication Tag).
The final result in this example
(with line breaks for display purposes only) is:
This example illustrates the process of creating a JWE with
RSAES&nbhy;PKCS1&nbhy;v1_5 for key encryption
and AES_CBC_HMAC_SHA2 for content encryption.
These results can be used to validate JWE decryption implementations for these algorithms.
Note that since the RSAES&nbhy;PKCS1&nbhy;v1_5 computation includes random values,
the encryption results above will not be completely reproducible.
However, since the AES-CBC computation is deterministic, the JWE Encrypted Ciphertext
values will be the same for all encryptions performed using these inputs.
This example encrypts the plaintext
"Live long and prosper."
to the recipient using AES Key Wrap for key encryption
and AES_128_CBC_HMAC_SHA_256 for content encryption.
The representation of this plaintext (using JSON array notation) is:
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
111, 115, 112, 101, 114, 46]
The following example JWE Protected Header declares that:
The Content Encryption Key is encrypted to the recipient
using the AES Key Wrap algorithm with a 128-bit key to produce
the JWE Encrypted Key.
Authenticated encryption is performed on the plaintext
using the AES_128_CBC_HMAC_SHA_256 algorithm
to produce the ciphertext and the Authentication Tag.
Encoding this JWE Protected Header as
BASE64URL(UTF8(JWE Protected Header)) gives this value:
Generate a 256-bit random CEK.
In this example, the value is:
[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206,
107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]
Encrypt the CEK with the shared symmetric key using the AES Key Wrap
algorithm to produce the JWE Encrypted Key.
This example uses the symmetric key
represented in JSON Web Key format below:
The resulting JWE Encrypted Key value is:
[232, 160, 123, 211, 183, 76, 245, 132, 200, 128, 123, 75, 190, 216, 22, 67,
201, 138, 193, 186, 9, 91, 122, 31, 246, 90, 28, 139, 57, 3, 76, 124,
193, 11, 98, 37, 173, 61, 104, 57]
Encoding this JWE Encrypted Key as
BASE64URL(JWE Encrypted Key) gives this value:
Generate a random 128-bit JWE Initialization Vector.
In this example, the value is:
[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
Encoding this JWE Initialization Vector as
BASE64URL(JWE Initialization Vector) gives this value:
Let the Additional Authenticated Data encryption parameter be
ASCII(BASE64URL(UTF8(JWE Protected Header))).
This value is:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52,
83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66,
77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
73, 110, 48]
Perform authenticated encryption on the plaintext
with the AES_128_CBC_HMAC_SHA_256 algorithm
using the CEK as the encryption key,
the JWE Initialization Vector,
and the Additional Authenticated Data value above.
The steps for doing this using the values from this example
are detailed in .
The resulting ciphertext is:
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
The resulting Authentication Tag value is:
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]
Encoding this JWE Ciphertext as
BASE64URL(JWE Ciphertext) gives this value:
Encoding this JWE Authentication Tag as
BASE64URL(JWE Authentication Tag) gives this value:
Assemble the final representation:
The Compact Serialization of this result is the string
BASE64URL(UTF8(JWE Protected Header))
|| '.' || BASE64URL(JWE Encrypted Key)
|| '.' || BASE64URL(JWE Initialization Vector)
|| '.' || BASE64URL(JWE Ciphertext)
|| '.' || BASE64URL(JWE Authentication Tag).
The final result in this example
(with line breaks for display purposes only) is:
This example illustrates the process of creating a JWE with
AES Key Wrap for key encryption
and AES GCM for content encryption.
These results can be used to validate JWE decryption implementations for these algorithms.
Also, since both the AES Key Wrap and AES GCM computations are deterministic,
the resulting JWE value will be the same for all encryptions performed using these inputs.
Since the computation is reproducible, these results can also be used to validate
JWE encryption implementations for these algorithms.
This section contains an example using the general JWE JSON Serialization syntax.
This example demonstrates the capability for
encrypting the same plaintext to multiple recipients.
Two recipients are present in this example.
The algorithm and key used for the first recipient
are the same as that used in .
The algorithm and key used for the second recipient
are the same as that used in .
The resulting JWE Encrypted Key values are therefore the same;
those computations are not repeated here.
The plaintext, the CEK, JWE Initialization Vector,
and JWE Protected Header are shared by all recipients
(which must be the case, since the ciphertext and
Authentication Tag are also shared).
The first recipient uses the RSAES-PKCS1-v1_5 algorithm
to encrypt the CEK.
The second uses AES Key Wrap to encrypt the CEK.
Key ID values are supplied for both keys.
The two JWE Per-Recipient Unprotected Header values used to represent
these algorithms and key IDs are:
and
Authenticated encryption is performed on the plaintext
using the AES_128_CBC_HMAC_SHA_256 algorithm
to produce the common JWE Ciphertext and JWE Authentication Tag values.
The JWE Protected Header value representing this is:
Encoding this JWE Protected Header as
BASE64URL(UTF8(JWE Protected Header)) gives this value:
This JWE uses the jku Header Parameter
to reference a JWK Set.
This is represented in the following JWE Shared Unprotected Header value as:
Combining the JWE Per-Recipient Unprotected Header,
JWE Protected Header, and JWE Shared Unprotected Header values
supplied, the JOSE Header values used for the first and second recipient,
respectively, are:
and
Let the Additional Authenticated Data encryption parameter be
ASCII(BASE64URL(UTF8(JWE Protected Header))).
This value is:
[101, 121, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52,
81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]
Perform authenticated encryption on the plaintext
with the AES_128_CBC_HMAC_SHA_256 algorithm
using the CEK as the encryption key,
the JWE Initialization Vector,
and the Additional Authenticated Data value above.
The steps for doing this using the values from
are detailed in .
The resulting ciphertext is:
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
The resulting Authentication Tag value is:
[51, 63, 149, 60, 252, 148, 225, 25, 92, 185, 139, 245, 35, 2, 47, 207]
Encoding this JWE Ciphertext as
BASE64URL(JWE Ciphertext) gives this value:
Encoding this JWE Authentication Tag as
BASE64URL(JWE Authentication Tag) gives this value:
The complete JWE JSON Serialization
for these values is as follows
(with line breaks within values for display purposes only):
This section contains an example using the flattened JWE JSON Serialization syntax.
This example demonstrates the capability for
encrypting the plaintext to a single recipient
in a flattened JSON structure.
The values in this example are the same as those for the second recipient
of the previous example in .
The complete JWE JSON Serialization
for these values is as follows
(with line breaks within values for display purposes only):
This example shows the steps in the AES_128_CBC_HMAC_SHA_256
authenticated encryption computation using the values from
the example in .
As described where this algorithm is defined in
Sections 5.2 and 5.2.3 of JWA, the AES_CBC_HMAC_SHA2 family
of algorithms are implemented using
Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with Public-Key
Cryptography Standards (PKCS) #7 padding
to perform the encryption and
an HMAC SHA-2 function to perform the integrity calculation
-- in this case, HMAC SHA-256.
The 256 bit AES_128_CBC_HMAC_SHA_256 key K used in this example (using JSON array notation) is:
[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206,
107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]
Use the first 128 bits of this key as the HMAC SHA-256 key MAC_KEY, which is:
[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206]
Use the last 128 bits of this key as the AES-CBC key ENC_KEY, which is:
[107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]
Note that the MAC key comes before the encryption key in the input key K;
this is in the opposite order of the algorithm names in
the identifiers "AES_128_CBC_HMAC_SHA_256" and
A128CBC-HS256.
Encrypt the plaintext with
AES in CBC mode using PKCS #7 padding
using the ENC_KEY above.
The plaintext in this example is:
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
111, 115, 112, 101, 114, 46]
The encryption result is as follows, which is the ciphertext output:
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
The Additional Authenticated Data (AAD) in this example is:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52,
83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66,
77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
73, 110, 48]
This AAD is 51-bytes long, which is 408-bits long.
The octet string AL, which is the number of bits in AAD
expressed as a big-endian 64-bit unsigned integer is:
[0, 0, 0, 0, 0, 0, 1, 152]
The Initialization Vector value used in this example is:
[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
Concatenate
the AAD,
the Initialization Vector,
the ciphertext,
and the AL value.
The result of this concatenation is:
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52,
83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66,
77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
73, 110, 48, 3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111,
116, 104, 101, 40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152,
230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143,
112, 56, 102, 0, 0, 0, 0, 0, 0, 1, 152]
Compute the HMAC SHA-256 of the concatenated value above. This result M is:
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85,
9, 84, 229, 201, 219, 135, 44, 252, 145, 102, 179, 140, 105, 86, 229, 116]
Use the first half (128 bits) of the HMAC output M as
the Authentication Tag output T. This truncated value is:
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]
Solutions for encrypting JSON content were also explored by
"JSON Simple Encryption" and
"JavaScript Message Security
Format", both of which significantly influenced this document.
This document attempts to explicitly reuse as many of the relevant concepts from
XML Encryption 1.1
and RFC 5652 as possible,
while utilizing simple, compact JSON-based data structures.
Special thanks are due to John Bradley, Eric Rescorla, and Nat Sakimura for
the discussions that helped inform the content of this
specification; to Eric Rescorla and Joe Hildebrand for
allowing the reuse of text from in this document;
and to Eric Rescorla for co-authoring many drafts of this specification.
Thanks to Axel Nennker, Emmanuel Raviart, Brian Campbell, and Edmund Jay
for validating the examples in this specification.
This specification is the work of the JOSE working group,
which includes dozens of active and dedicated participants.
In particular, the following individuals contributed ideas,
feedback, and wording that influenced this specification:
Richard Barnes,
John Bradley,
Brian Campbell,
Alissa Cooper,
Breno de Medeiros,
Stephen Farrell,
Dick Hardt,
Jeff Hodges,
Russ Housley,
Edmund Jay,
Scott Kelly,
Stephen Kent,
Barry Leiba,
James Manger,
Matt Miller,
Kathleen Moriarty,
Tony Nadalin,
Hideki Nara,
Axel Nennker,
Ray Polk,
Emmanuel Raviart,
Eric Rescorla,
Pete Resnick,
Nat Sakimura,
Jim Schaad,
Hannes Tschofenig,
and Sean Turner.
Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
Sean Turner, Stephen Farrell, and Kathleen Moriarty served as Security Area Directors
during the creation of this specification.