JSON Web Algorithms (JWA)
Microsoft
mbj@microsoft.com
http://self-issued.info/
Security
JOSE Working Group
RFC
Request for Comments
I-D
Internet-Draft
JavaScript Object Notation
JSON
JSON Web Token
JWT
JSON Web Signature
JWS
JSON Web Encryption
JWE
JSON Web Key
JWK
JSON Web Algorithms
JWA
The JSON Web Algorithms (JWA) specification enumerates
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS),
JSON Web Encryption (JWE), and
JSON Web Key (JWK) specifications.
The JSON Web Algorithms (JWA) specification enumerates
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS) ,
JSON Web Encryption (JWE) , and
JSON Web Key (JWK) specifications.
All these specifications utilize
JavaScript Object Notation (JSON)
based data structures.
This specification also describes the semantics and operations
that are specific to these algorithms and key types.
Enumerating the algorithms and identifiers for them in this
specification, rather than in the JWS, JWE, and JWK
specifications, is intended to allow them to remain unchanged
in the face of changes in the set of required, recommended,
optional, and deprecated algorithms over time.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" in this document are to be interpreted as
described in
Key words for use in RFCs to Indicate Requirement Levels .
These terms defined by the
JSON Web Signature (JWS)
specification are incorporated into this specification:
A data structure representing a digitally signed or MACed message.
The structure represents three values:
the JWS Header,
the JWS Payload, and
the JWS Signature.
A UTF-8
encoded text string representing a JSON object;
the syntax of JSON objects is defined in
Section 2.2 of .
A JSON Text Object
(or JSON Text Objects, when using the JWS JSON Serialization)
that describes the
digital signature or MAC operation applied to
create the JWS Signature value.
The members of the JWS Header object(s) are Header Parameters.
The sequence of octets to be secured -- a.k.a., the message.
The payload can contain an arbitrary sequence of octets.
A sequence of octets containing the cryptographic material that
ensures the integrity of
the JWS Protected Header
and the JWS Payload.
The JWS Signature value is a digital signature or MAC value
calculated over the JWS Signing Input using the parameters
specified in the JWS Header.
A JSON Text Object that contains the portion of the
JWS Header that is integrity protected.
For the JWS Compact Serialization, this comprises the entire JWS Header.
For the JWS JSON Serialization, this is one component of the JWS Header.
The URL- and filename-safe Base64 encoding
described in RFC 4648,
Section 5, with the (non URL-safe) '=' padding characters
omitted, as permitted by Section 3.2. (See Appendix C of
for notes on implementing base64url
encoding without padding.)
Base64url encoding of the JWS Protected Header.
Base64url encoding of the JWS Payload.
Base64url encoding of the JWS Signature.
The concatenation of the Encoded JWS Header, a period ('.')
character, and the Encoded JWS Payload.
A namespace that allows names to be allocated in a manner
such that they are highly unlikely to collide with other names.
For instance, collision resistance can be achieved through
administrative delegation of portions of the namespace or
through use of collision-resistant name allocation functions.
Examples of Collision Resistant Namespaces include:
Domain Names,
Object Identifiers (OIDs) as defined in the ITU-T X.660
and X.670 Recommendation series, and
Universally Unique IDentifiers (UUIDs)
.
When using an administratively delegated namespace,
the definer of a name needs to take
reasonable precautions to ensure they are in control of
the portion of the namespace they use to define the name.

These terms defined by the
JSON Web Encryption (JWE)
specification are incorporated into this specification:
A data structure representing an encrypted message.
The structure represents five values:
the JWE Header, the JWE Encrypted Key,
the JWE Initialization Vector, the JWE Ciphertext, and
the JWE Authentication Tag.
An Authenticated Encryption algorithm is one that
provides an integrated content integrity check.
Authenticated Encryption 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.
The sequence of octets to be encrypted -- a.k.a., the message.
The plaintext can contain an arbitrary sequence of octets.
An encrypted representation of the Plaintext.
An input to an Authenticated Encryption operation that
is integrity protected but not encrypted.
An output of an Authenticated Encryption 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 Authenticated Encryption algorithm
used to encrypt the Plaintext for the
recipient to produce the Ciphertext and the Authentication Tag.
A JSON Text Object
(or JSON Text Objects, when using the JWE JSON Serialization)
that describes the
encryption operations applied to create the JWE Encrypted
Key, the JWE Ciphertext, and the JWE Authentication Tag.
The members of the JWE Header object(s) are Header Parameters.
The result of encrypting the Content Encryption Key (CEK) with the
intended recipient's key using the specified algorithm.
Note that for some algorithms, the JWE Encrypted Key
value is specified as being the empty octet sequence.
A sequence of octets containing the Initialization Vector 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.
A sequence of octets containing the Ciphertext for a JWE.
A sequence of octets containing the Authentication Tag for a JWE.
A JSON Text Object that contains the portion of the
JWE Header that is integrity protected.
For the JWE Compact Serialization, this comprises the entire JWE Header.
For the JWE JSON Serialization, this is one component of the JWE Header.
Base64url encoding of the JWE Protected Header.
Base64url encoding of the JWE Encrypted Key.
Base64url encoding of the JWE Initialization Vector.
Base64url encoding of the JWE Ciphertext.
Base64url encoding of the JWE Authentication Tag.
A method of determining the Content Encryption Key (CEK) 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 Content Encryption Key (CEK) value
is encrypted to the intended recipient using an asymmetric encryption algorithm.
A Key Management Mode in which the Content Encryption Key (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 Content Encryption Key (CEK) value.
A Key Management Mode in which a key agreement algorithm is used to agree upon
a symmetric key used to encrypt the Content Encryption Key (CEK) value
to the intended recipient using a symmetric key wrapping algorithm.
A Key Management Mode in which the Content Encryption Key (CEK) value
used is the secret symmetric key value shared between the parties.

These terms defined by the
JSON Web Key (JWK)
specification are incorporated into this specification:
A JSON object that represents a cryptographic key.
A JSON object that contains an array of JWKs as
the value of its keys member.

These terms are defined for use by this specification:
A name/value pair that is member of a
JWS Header or JWE Header.
The name of a member of a JSON object representing a
JWS Header or JWE Header.
The value of a member of a JSON object representing a
JWS Header or JWE Header.

JWS uses cryptographic algorithms to digitally sign or
create a Message Authentication Codes (MAC) of the contents
of the JWS Header and the JWS Payload. The
use of the following algorithms for producing JWSs is defined in
this section.
The table below is the set of
alg (algorithm) header
parameter values defined by this specification for use with JWS, each of which
is explained in more detail in the following sections:
alg Parameter Value
Digital Signature or MAC Algorithm
Implementation Requirements
HS256
HMAC using SHA-256 hash algorithm
REQUIRED
HS384
HMAC using SHA-384 hash algorithm
OPTIONAL
HS512
HMAC using SHA-512 hash algorithm
OPTIONAL
RS256
RSASSA-PKCS-v1_5 using SHA-256 hash algorithm
RECOMMENDED
RS384
RSASSA-PKCS-v1_5 using SHA-384 hash algorithm
OPTIONAL
RS512
RSASSA-PKCS-v1_5 using SHA-512 hash algorithm
OPTIONAL
ES256
ECDSA using P-256 curve and SHA-256 hash algorithm
RECOMMENDED+
ES384
ECDSA using P-384 curve and SHA-384 hash algorithm
OPTIONAL
ES512
ECDSA using P-521 curve and SHA-512 hash algorithm
OPTIONAL
PS256
RSASSA-PSS using SHA-256 hash algorithm and MGF1 mask generation function with SHA-256
OPTIONAL
PS512
RSASSA-PSS using SHA-512 hash algorithm and MGF1 mask generation function with SHA-512
OPTIONAL
none
No digital signature or MAC value included
REQUIRED
All the names are short because a core goal of JWS is
for the representations to be compact. However, there is no
a priori length restriction on alg values.
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
See for a table cross-referencing the
digital signature and MAC alg (algorithm)
values used in this specification
with the equivalent identifiers used by other
standards and software packages.
Hash-based Message Authentication Codes (HMACs) enable one to
use a secret plus a cryptographic hash function to generate a
Message Authentication Code (MAC). This can be used to
demonstrate that the MAC matches the hashed content, in this
case the JWS Signing Input, which therefore demonstrates that
whoever generated the MAC was in possession of the secret.
The means of exchanging the shared key is outside the scope
of this specification.
The algorithm for implementing and validating HMACs is
provided in RFC 2104. This
section defines the use of the HMAC SHA-256, HMAC SHA-384,
and HMAC SHA-512 functions . The
alg (algorithm) header parameter values
HS256, HS384, and HS512 are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded HMAC value using the respective hash function.
A key of the same size as the hash output (for instance, 256
bits for HS256) or larger MUST
be used with this algorithm.
The HMAC SHA-256 MAC is generated per RFC 2104,
using SHA-256 as the hash algorithm "H",
using the octets of the ASCII representation
of the JWS Signing Input as the "text" value,
and using the shared key.
The HMAC output value is the JWS Signature.
The JWS signature is base64url encoded to produce the Encoded JWS Signature.
The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC value per RFC 2104,
using SHA-256 as the hash algorithm "H",
using the octets of the ASCII representation
of the received JWS Signing Input as the "text" value,
and using the shared key.
This computed HMAC value is then compared to the result of
base64url decoding the received Encoded JWS signature.
Alternatively, the computed HMAC value can be base64url encoded
and compared to the received Encoded JWS Signature,
as this comparison produces the same result as comparing
the unencoded values.
In either case, if the values match, the HMAC has been validated.
If the validation fails, the JWS MUST be rejected.
Securing content with the HMAC SHA-384 and HMAC SHA-512
algorithms is performed identically to the procedure for
HMAC SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger minimum key sizes and result values:
384 bits each for HMAC SHA-384 and 512 bits each for HMAC SHA-512.
An example using this algorithm is shown in
Appendix A.1 of .
This section defines the use of the RSASSA-PKCS1-V1_5
digital signature algorithm as defined in
Section 8.2 of RFC 3447
(commonly known as PKCS #1),
using SHA-256, SHA-384, or SHA-512
as the hash functions.
The alg (algorithm) header
parameter values RS256, RS384, and RS512 are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded RSASSA-PKCS1-V1_5 digital signature using the respective hash function.
A key of size 2048 bits or larger MUST be used with these algorithms.
The RSASSA-PKCS1-V1_5 SHA-256 digital signature is generated as follows:
Generate a digital signature of the octets of the ASCII representation
of the JWS Signing Input
using RSASSA-PKCS1-V1_5-SIGN
and the SHA-256 hash function
with the desired private key.
The output will be an octet sequence.
Base64url encode the resulting octet sequence.

The output is the Encoded JWS Signature for that JWS.
The RSASSA-PKCS1-V1_5 SHA-256 digital signature for a JWS is validated as follows:
Take the Encoded JWS Signature and base64url decode it into
an octet sequence. If decoding fails, the JWS MUST
be rejected.
Submit the octets of the ASCII representation of the JWS Signing Input
and the public key corresponding to the private key used
by the signer to the RSASSA-PKCS1-V1_5-VERIFY algorithm
using SHA-256 as the hash function.
If the validation fails, the JWS MUST be rejected.

Signing with the RSASSA-PKCS1-V1_5 SHA-384 and RSASSA-PKCS1-V1_5 SHA-512
algorithms is performed identically to the procedure for
RSASSA-PKCS1-V1_5 SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger result values:
384 bits for RSASSA-PKCS1-V1_5 SHA-384 and 512 bits for RSASSA-PKCS1-V1_5 SHA-512.
An example using this algorithm is shown in
Appendix A.2 of .
The Elliptic Curve Digital Signature Algorithm (ECDSA)
provides for the use of Elliptic Curve cryptography, which is
able to provide equivalent security to RSA cryptography but
using shorter key sizes and with greater processing
speed. This means that ECDSA digital signatures will be substantially
smaller in terms of length than equivalently strong RSA
digital signatures.
This specification defines the use of ECDSA with the P-256
curve and the SHA-256 cryptographic hash function, ECDSA
with the P-384 curve and the SHA-384 hash function, and
ECDSA with the P-521 curve and the SHA-512 hash
function. The P-256, P-384, and P-521 curves are
defined in . The alg (algorithm) header parameter values ES256, ES384, and ES512 are used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded ECDSA P-256 SHA-256, ECDSA P-384 SHA-384, or ECDSA
P-521 SHA-512 digital signature, respectively.
The ECDSA P-256 SHA-256 digital signature is generated as follows:
Generate a digital signature of the octets of the ASCII representation
of the JWS Signing Input
using ECDSA P-256 SHA-256 with
the desired private key. The output will be the pair
(R, S), where R and S are 256 bit unsigned integers.
Turn R and S into octet sequences in big endian order,
with each array being be 32 octets long.
The array representations MUST NOT be shortened
to omit any leading zero octets contained in the values.
Concatenate the two octet sequences in the order R and then S.
(Note that many ECDSA implementations will directly produce
this concatenation as their output.)
Base64url encode the resulting 64 octet sequence.

The output is the Encoded JWS Signature for the JWS.
The ECDSA P-256 SHA-256 digital signature for a JWS is validated as follows:
Take the Encoded JWS Signature and base64url decode it into
an octet sequence. If decoding fails, the JWS MUST
be rejected.
The output of the base64url decoding MUST be a 64 octet sequence.
If decoding does not result in a 64 octet sequence, the JWS MUST be rejected.
Split the 64 octet sequence into two 32 octet sequences. The first
array will be R and the second S
(with both being in big endian octet order).
Submit the octets of the ASCII representation of the JWS Signing Input
R, S and the public key (x, y) to the ECDSA P-256
SHA-256 validator.
If the validation fails, the JWS MUST be rejected.

Note that ECDSA digital
signature contains a value referred to as K, which is a random
number generated for each digital signature instance. This
means that two ECDSA digital signatures using exactly the same
input parameters will output different signature values because
their K values will be different. A consequence of this is
that one cannot validate an ECDSA signature by recomputing
the signature and comparing the results.
Signing with the ECDSA P-384 SHA-384 and ECDSA P-521 SHA-512
algorithms is performed identically to the procedure for
ECDSA P-256 SHA-256 -
just using the corresponding hash algorithm
with correspondingly larger result values.
For ECDSA P-384 SHA-384, R and S will be 384 bits each,
resulting in a 96 octet sequence.
For ECDSA P-521 SHA-512, R and S will be 521 bits each,
resulting in a 132 octet sequence.
Examples using these algorithms are shown in
Appendices A.3 and A.4 of .
This section defines the use of the RSASSA-PSS
digital signature algorithm as defined in
Section 8.1 of RFC 3447
with the MGF1 mask generation function, always using the
same hash function for both the RSASSA-PSS hash function
and the MGF1 hash function.
Use of both SHA-256 and SHA-512 as these hash functions is defined.
All other algorithm parameters use the defaults specified
in Section A.2.3 of RFC 3447.
The alg (algorithm) header
parameter values PS256
and PS512
is used in the JWS Header
to indicate that the Encoded JWS Signature contains a base64url
encoded RSASSA-PSS digital signature using
the respective hash function in both roles.
A key of size 2048 bits or larger MUST be used with this algorithm.
The RSASSA-PSS SHA-256 digital signature is generated as follows:
Generate a digital signature of the octets of the ASCII representation
of the JWS Signing Input
using RSASSA-PSS-SIGN,
the SHA-256 hash function, and
the MGF1 mask generation function with SHA-256
with the desired private key.
The output will be an octet sequence.
Base64url encode the resulting octet sequence.

The output is the Encoded JWS Signature for that JWS.
The RSASSA-PSS SHA-256 digital signature for a JWS is validated as follows:
Take the Encoded JWS Signature and base64url decode it into
an octet sequence. If decoding fails, the JWS MUST
be rejected.
Submit the octets of the ASCII representation of the JWS Signing Input
and the public key corresponding to the private key used
by the signer to the RSASSA-PSS-VERIFY algorithm
using SHA-256 as the hash function and using
MGF1 as the mask generation function with SHA-256.
If the validation fails, the JWS MUST be rejected.

Signing with the RSASSA-PSS SHA-512
algorithm is performed identically to the procedure for
RSASSA-PSS SHA-256 -
just using the alternative hash algorithm in both roles.
JWSs MAY also be created that do not provide integrity protection.
Such a JWS is called a "Plaintext JWS".
Plaintext JWSs MUST use the alg
value none, and are formatted
identically to other JWSs, but
with the empty string for its JWS Signature value.
Additional algorithms MAY be used to protect JWSs with
corresponding alg (algorithm)
header parameter values being defined to refer to them.
New alg header parameter values SHOULD
either be registered in the IANA JSON Web Signature and Encryption Algorithms
registry or be
a value that contains a Collision Resistant Namespace.
In particular, it is permissible to use the algorithm identifiers defined in
XML DSIG,
XML DSIG 2.0,
and related specifications as
alg values.
As indicated by the common registry, JWSs and JWEs share a
common alg value space.
The values used by the two specifications MUST be distinct,
as the alg value can be used
to determine whether the object is a JWS or JWE.
Likewise, additional reserved Header Parameter Names can be defined
via the IANA
JSON Web Signature and Encryption Header Parameters registry
.
As indicated by the common registry, JWSs and JWEs share a
common header parameter space; when a parameter is used by
both specifications, its usage must be compatible
between the specifications.
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.
The table below is the set of alg (algorithm) header parameter values
that are defined by this specification for use with JWE.
These algorithms are used to encrypt the CEK, producing the
JWE Encrypted Key, or to use key agreement to agree upon the CEK.
alg Parameter Value
Key Management Algorithm
Implementation Requirements
RSA1_5
RSAES-PKCS1-V1_5
REQUIRED
RSA-OAEP
RSAES using Optimal Asymmetric Encryption Padding (OAEP)
, with the
default parameters specified by RFC 3447 in Section A.2.1
OPTIONAL
A128KW
Advanced Encryption Standard (AES) Key Wrap Algorithm
using the default initial value specified in Section 2.2.3.1 and
using 128 bit keys
RECOMMENDED
A256KW
AES Key Wrap Algorithm
using the default initial value specified in Section 2.2.3.1 and
using 256 bit keys
RECOMMENDED
dir
Direct use of a shared symmetric key as the Content Encryption Key (CEK)
for the block encryption step
(rather than using the symmetric key to wrap the CEK)
RECOMMENDED
ECDH-ES
Elliptic Curve Diffie-Hellman Ephemeral Static
key agreement using the
Concat KDF, as defined in Section 5.8.1 of ,
with the agreed-upon key being used directly as the Content Encryption Key (CEK)
(rather than being used to wrap the CEK),
as specified in
RECOMMENDED+
ECDH-ES+A128KW
Elliptic Curve Diffie-Hellman Ephemeral Static key agreement
per ECDH-ES and ,
but where the agreed-upon key is used to wrap the Content Encryption Key (CEK)
with the A128KW function
(rather than being used directly as the CEK)
RECOMMENDED
ECDH-ES+A256KW
Elliptic Curve Diffie-Hellman Ephemeral Static key agreement
per ECDH-ES and ,
but where the agreed-upon key is used to wrap the Content Encryption Key (CEK)
with the A256KW function
(rather than being used directly as the CEK)
RECOMMENDED
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
The table below is the set of
enc (encryption method) header parameter values that
are defined by this specification for use with JWE. These algorithms are used
to encrypt the Plaintext, which produces the Ciphertext.
enc Parameter Value
Block Encryption Algorithm
Implementation Requirements
A128CBC-HS256
The AES_128_CBC_HMAC_SHA_256 authenticated encryption algorithm,
as defined in .
This algorithm uses a 256 bit key.
REQUIRED
A256CBC-HS512
The AES_256_CBC_HMAC_SHA_512 authenticated encryption algorithm,
as defined in .
This algorithm uses a 512 bit key.
REQUIRED
A128GCM
AES in Galois/Counter Mode (GCM)
using 128 bit keys
RECOMMENDED
A256GCM
AES GCM
using 256 bit keys
RECOMMENDED
All the names are short because a core goal of JWE is
for the representations to be compact. However, there is no
a priori length restriction on alg values.
See for a table cross-referencing the
encryption alg (algorithm) and
enc (encryption method)
values used in this specification
with the equivalent identifiers used by other
standards and software packages.
This section defines the specifics of encrypting a JWE CEK with
RSAES-PKCS1-V1_5 .
The alg header parameter value
RSA1_5 is used in this case.
A key of size 2048 bits or larger MUST be used with this algorithm.
An example using this algorithm is shown in
Appendix A.2 of .
This section defines the specifics of encrypting a JWE CEK with
RSAES using Optimal Asymmetric Encryption Padding (OAEP)
, with the
default parameters specified by RFC 3447 in Section A.2.1.
The alg header parameter value
RSA-OAEP is used in this case.
A key of size 2048 bits or larger MUST be used with this algorithm.
An example using this algorithm is shown in
Appendix A.1 of .
This section defines the specifics of encrypting a JWE CEK with
the Advanced Encryption Standard (AES) Key Wrap Algorithm
using the default initial value specified in Section 2.2.3.1
using 128 or 256 bit keys.
The alg header parameter values
A128KW or A256KW
are used in this case.
An example using this algorithm is shown in
Appendix A.3 of .
This section defines the specifics of directly performing symmetric key
encryption without performing a key wrapping step. In this case,
the shared symmetric key is used directly as the Content Encryption Key (CEK)
value for the enc algorithm.
An empty octet sequence is used as the JWE Encrypted Key value.
The alg header parameter value
dir
is used in this case.
This section defines the specifics of key agreement with
Elliptic Curve Diffie-Hellman Ephemeral Static ,
and using the
Concat KDF, as defined in Section 5.8.1 of .
The key agreement result can be used in one of two ways:
directly as the Content Encryption Key (CEK) for the
enc algorithm, in the Direct Key Agreement mode, or
as a symmetric key used to wrap the CEK with either the
A128KW or A256KW
algorithms, in the Key Agreement with Key Wrapping mode.

The alg header parameter value
ECDH-ES
is used in the Direct Key Agreement mode
and the values
ECDH-ES+A128KW and
ECDH-ES+A256KW
are used in the Key Agreement with Key Wrapping mode.
In the Direct Key Agreement case,
the output of the Concat KDF MUST be a key of the
same length as that used by the
enc algorithm;
in this case, the empty octet sequence is used as the JWE Encrypted Key value.
In the Key Agreement with Key Wrapping case,
the output of the Concat KDF MUST be a key of the
length needed for the specified key wrapping algorithm,
either 128 or 256 bits respectively.
A new epk (ephemeral public key)
value MUST be generated for each key agreement transaction.
The key derivation process derives the agreed upon key from the
shared secret Z established through the ECDH algorithm,
per Section 6.2.2.2 of .
Key derivation is performed using the Concat KDF, as
defined in Section 5.8.1 of , where the Digest
Method is SHA-256.
The Concat KDF parameters are set as follows:
This is set to the representation of the shared secret Z as an octet sequence.
This is set to the number of bits in the desired output key.
For ECDH-ES, this is length of the key
used by the enc algorithm.
For ECDH-ES+A128KW, and
ECDH-ES+A256KW, this is
128 and 256, respectively.
This is set to
the octets of the UTF-8 representation of the
alg header parameter value.
PartyUInfo contains a random data value provided by the sender.
If provided, this value MUST contain at least 512 bits
and a unique value SHOULD be used for each recipient.
Use of PartyUInfo is OPTIONAL when a different ephemeral key
is used for each key agreement transaction.
The PartyUInfo value is of the form Datalen || Data, where
Data is a variable-length string of zero or more octets,
and Datalen is a fixed-length, big endian 32 bit counter that
indicates the length (in octets) of Data, with || being concatenation.
If an apu (agreement PartyUInfo)
header parameter is present, Data is set to the result of
base64url decoding the apu value
and Datalen is set to the number of octets in Data.
Otherwise, Datalen is set to 0 and Data is set to the empty octet sequence.
This is set to the empty octet sequence.
This is set to the keydatalen represented as a
32 bit big endian integer.
This is set to the empty octet sequence.

This section defines a family of authenticated encryption algorithms
built using a composition of
Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with PKCS #5 padding
operations and
HMAC operations.
This algorithm family is called AES_CBC_HMAC_SHA2.
It also defines two instances of this family,
one using 128 bit CBC keys and HMAC SHA-256
and the other using 256 bit CBC keys and HMAC SHA-512.
Test cases for these algorithms can be found in
.
These algorithms are based upon
Authenticated Encryption with AES-CBC and HMAC-SHA,
performing the same cryptographic computations,
but with the Initialization Vector and Authentication Tag values remaining
separate, rather than being concatenated with
the Ciphertext value in the output representation.
This algorithm family is a generalization of the algorithm family in
, and can be used to
implement those algorithms.
We use the following notational conventions.
CBC-PKCS5-ENC(X, P) denotes the AES CBC encryption of P
using PKCS #5 padding using the cipher with the key X.
MAC(Y, M) denotes the application of the Message
Authentication Code (MAC) to the message M, using the key Y.
The concatenation of two octet strings A and B
is denoted as A || B.

This section defines AES_CBC_HMAC_SHA2 in a manner that is
independent of the AES CBC key size or hash function to be used.
and define the
generic encryption and decryption algorithms.
and
define instances of AES_CBC_HMAC_SHA2 that
specify those details.
The authenticated
encryption algorithm takes as input four octet strings: a
secret key K, a plaintext P, associated data A, and
an initialization vector IV.
The authenticated ciphertext value E
and the authentication tag value T
are provided as outputs.
The data in the plaintext are encrypted and
authenticated, and the associated data are authenticated,
but not encrypted.
The encryption process is as follows, or
uses an equivalent set of steps:
The secondary keys MAC_KEY and ENC_KEY are generated
from the input key K as follows. Each of these two
keys is an octet string.
MAC_KEY consists of the initial MAC_KEY_LEN octets of
K, in order.
ENC_KEY consists of the final ENC_KEY_LEN octets of
K, in order.

Here we denote the number of octets in the MAC_KEY as
MAC_KEY_LEN, and the number of octets in ENC_KEY as
ENC_KEY_LEN; the values of these parameters are specified
by the AEAD algorithms (in and
). The number of octets in the
input key K is the sum of MAC_KEY_LEN and ENC_KEY_LEN.
When generating the secondary keys from K, MAC_KEY and ENC_KEY
MUST NOT overlap.
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 identifier "AES_CBC_HMAC_SHA2".
The Initialization Vector (IV) used is a 128 bit value
generated randomly or pseudorandomly
for use in the cipher.
The plaintext is CBC encrypted using PKCS #5 padding
using ENC_KEY as the key, and the IV.
We denote the ciphertext output from this step as E.
The octet string AL is equal to the number
of bits in A expressed as a 64-bit unsigned integer in network byte
order.
A message authentication tag T is computed by applying
HMAC to the following data, in
order:
the associated data A,
the initialization vector IV,
the ciphertext E computed in the previous step, and
the octet string AL defined above.

The string MAC_KEY is used as the MAC key. We denote
the output of the MAC computed in this step as M.
The first T_LEN bits of M are used as T.
The Ciphertext E and the Authentication Tag T
are returned as the outputs of the authenticated encryption.

The encryption process can be illustrated as follows. Here
K, P, A, IV, and E denote the key, plaintext, associated data,
initialization vector, and
ciphertext, respectively.
MAC_KEY = initial MAC_KEY_LEN bytes of K,
ENC_KEY = final ENC_KEY_LEN bytes of K,
E = CBC-PKCS5-ENC(ENC_KEY, P),
M = MAC(MAC_KEY, A || IV || E || AL),
T = initial T_LEN bytes of M.

The authenticated decryption operation has four inputs: K,
A, E, and T as defined above. It has only
a single output, either a plaintext value P or a special
symbol FAIL that indicates that the inputs are not
authentic. The authenticated decryption algorithm is
as follows, or uses an equivalent set of steps:
The secondary keys MAC_KEY and ENC_KEY are generated
from the input key K as in Step 1 of .
The integrity and authenticity of A and E are checked
by computing an HMAC with the inputs as in Step 5 of
.
The value T, from the previous step, is compared to the
first MAC_KEY length bits of the
HMAC output. If those values are identical, then A and
E are considered valid, and processing is
continued. Otherwise, all of the data used in the MAC
validation are discarded, and the AEAD decryption
operation returns an indication that it failed, and the
operation halts.
(But see Section 10 of for
security considerations on thwarting timing attacks.)
The value E is decrypted and the PKCS #5 padding is removed.
The value IV is used as the initialization vector.
The value ENC_KEY is used as the decryption key.
The plaintext value is returned.

This algorithm is a concrete instantiation of the
generic AES_CBC_HMAC_SHA2 algorithm above.
It uses the HMAC message
authentication code with the
SHA-256 hash function to provide
message authentication, with the HMAC output
truncated to 128 bits, corresponding to the
HMAC-SHA-256-128 algorithm defined in .
For encryption, it uses AES
in the cipher block chaining (CBC) mode of operation as
defined in Section 6.2 of , with
PKCS #5 padding.
The input key K is 32 octets long.
The AES CBC IV is 16 octets long. ENC_KEY_LEN is 16
octets.
The SHA-256 hash algorithm is used in HMAC. MAC_KEY_LEN is 16
octets. The HMAC-SHA-256 output is truncated to T_LEN=16 octets,
by stripping off the final 16 octets.
AES_256_CBC_HMAC_SHA_512 is based on AES_128_CBC_HMAC_SHA_256,
but with the following differences:
A 256 bit AES CBC key is used instead of 128.
SHA-512 is used in HMAC instead of SHA-256.
ENC_KEY_LEN is 32 octets.
MAC_KEY_LEN is 32 octets.
The length of the input key K is 64 octets.
The HMAC SHA-512 value is truncated to T_LEN=32 octets instead of 16 octets.

The algorithm value A128CBC-HS256
is used as the alg value when using
AES_128_CBC_HMAC_SHA_256 with JWE.
The algorithm value A256CBC-HS512
is used as the alg value when using
AES_256_CBC_HMAC_SHA_512 with JWE.
The Additional Authenticated Data value used is
the octets of the ASCII representation of
the Encoded JWE Header value.
The JWE Initialization Vector value used is the IV value.
This section defines the specifics of encrypting the JWE Plaintext with
Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM)
using 128 or 256 bit keys.
The enc header parameter values
A128GCM or A256GCM
are used in this case.
The CEK is used as the encryption key.
Use of an initialization vector of size 96 bits is
REQUIRED with this algorithm.
The Additional Authenticated Data value used is
the octets of the ASCII representation of
the Encoded JWE Header value.
The requested size of the Authentication Tag output MUST be
128 bits, regardless of the key size.
The JWE Authentication Tag is set
to be the Authentication Tag value produced by the encryption.
During decryption, the received JWE Authentication Tag is used as the
Authentication Tag value.
An example using this algorithm is shown in
Appendix A.1 of .
Additional algorithms MAY be used to protect JWEs with
corresponding alg (algorithm) and
enc (encryption method)
header parameter values being
defined to refer to them. New
alg and
enc
header parameter values SHOULD
either be registered in the IANA JSON Web Signature and Encryption Algorithms
registry or be
a value that contains a Collision Resistant Namespace.
In particular, it is permissible to use the algorithm identifiers defined in
XML Encryption,
XML Encryption 1.1,
and related specifications as
alg and
enc values.
As indicated by the common registry, JWSs and JWEs share a
common alg value space.
The values used by the two specifications MUST be distinct,
as the alg value can be used
to determine whether the object is a JWS or JWE.
Likewise, additional reserved Header Parameter Names can be defined
via the IANA JSON Web Signature and Encryption Header Parameters registry
.
As indicated by the common registry, JWSs and JWEs share a
common header parameter space; when a parameter is used by
both specifications, its usage must be compatible
between the specifications.
A JSON Web Key (JWK) is a
JavaScript Object Notation (JSON)
data structure that represents a cryptographic key. A JSON Web Key Set
(JWK Set) is a JSON data structure for representing a set of JWKs.
This section specifies a set of key types to be used
for those keys and the key type specific
parameters for representing those keys.
Parameters are defined for public, private, and symmetric keys.
The table below is the set of
kty (key type) parameter
values that are defined by this specification for use in JWKs.
kty Parameter Value
Key Type
Implementation Requirements
EC
Elliptic Curve key type
RECOMMENDED+
RSA
RSA key type
REQUIRED
oct
Octet sequence key type (used to represent symmetric keys)
RECOMMENDED+
All the names are short because a core goal of JWK is
for the representations to be compact. However, there is no
a priori length restriction on kty values.
The use of "+" in the Implementation Requirements
indicates that the requirement strength is likely
to be increased in a future version of the specification.
JWKs can represent Elliptic Curve keys. In
this case, the kty
member value MUST be EC.
These members MUST be present for Elliptic Curve public keys:
The crv (curve) member identifies
the cryptographic curve used with the key. Curve values
from used by this specification are:
P-256
P-384
P-521

Additional crv values MAY be used, provided
they are understood by implementations using that Elliptic Curve key.
The crv value is a case sensitive string.
The x (x coordinate) member contains the
x coordinate for the elliptic curve point. It is
represented as the base64url encoding of the
coordinate's big endian representation as an octet sequence.
The array representation MUST NOT be shortened
to omit any leading zero octets contained in the value.
For instance, when representing 521 bit integers,
the octet sequence to be base64url encoded MUST contain 66 octets,
including any leading zero octets.
The y (y coordinate) member contains the
y coordinate for the elliptic curve point. It is
represented as the base64url encoding of the
coordinate's big endian representation as an octet sequence.
The array representation MUST NOT be shortened
to omit any leading zero octets contained in the value.
For instance, when representing 521 bit integers,
the octet sequence to be base64url encoded MUST contain 66 octets,
including any leading zero octets.
In addition to the members used to represent Elliptic Curve public keys,
the following member MUST be present to represent Elliptic Curve private keys:
The d (ECC private key) member contains
the Elliptic Curve private key value.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The array representation MUST NOT be shortened
to omit any leading zero octets.
For instance, when representing 521 bit integers,
the octet sequence to be base64url encoded MUST contain 66 octets,
including any leading zero octets.
JWKs can represent RSA keys. In
this case, the kty
member value MUST be RSA.
These members MUST be present for RSA public keys:
The n (modulus) member contains
the modulus value for the RSA public key. It is
represented as the base64url encoding of the value's
unsigned big endian representation as an octet sequence.
The array representation MUST NOT be shortened
to omit any leading zero octets.
For instance, when representing 2048 bit integers,
the octet sequence to be base64url encoded MUST contain 256 octets,
including any leading zero octets.
The e (exponent) member contains
the exponent value for the RSA public key. It is
represented as the base64url encoding of the value's
unsigned big endian representation as an octet sequence.
The array representation MUST utilize the minimum
number of octets to represent the value.
For instance, when representing the value 65537,
the octet sequence to be base64url encoded MUST consist of the
three octets [1, 0, 1].
In addition to the members used to represent RSA public keys,
the following members are used to represent RSA private keys.
All are REQUIRED for RSA private keys except for
oth, which is sometimes REQUIRED
and sometimes MUST NOT be present, as described below.
The d (private exponent) member contains
the private exponent value for the RSA private key.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The array representation MUST NOT be shortened
to omit any leading zero octets.
For instance, when representing 2048 bit integers,
the octet sequence to be base64url encoded MUST contain 256 octets,
including any leading zero octets.
The p (first prime factor) member contains
the first prime factor, a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The q (second prime factor) member contains
the second prime factor, a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The dp (first factor CRT exponent)
member contains the Chinese Remainder Theorem (CRT) exponent
of the first factor, a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The dq (second factor CRT exponent)
member contains the Chinese Remainder Theorem (CRT) exponent
of the second factor, a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The dp (first CRT coefficient)
member contains the Chinese Remainder Theorem (CRT)
coefficient of the second factor, a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The oth (other primes info)
member contains an array of information about any third and subsequent
primes, should they exist.
When only two primes have been used (the normal case),
this parameter MUST be omitted.
When three or more primes have been used, the number of array
elements MUST be the number of primes used minus two.
Each array element MUST be an object with the following members:
The r (prime factor) parameter
within an oth array member
represents the value of a subsequent prime factor,
a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The d (Factor CRT Exponent) parameter
within an oth array member
represents the CRT exponent of the corresponding prime factor,
a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
The t (factor CRT coefficient) parameter
within an oth array member
represents the CRT coefficient of the corresponding prime factor,
a positive integer.
It is represented as the base64url encoding of the
value's unsigned big endian representation as an octet sequence.
When the JWK kty
member value is oct (octet sequence),
the following member is used to represent
a symmetric key (or another key whose value is a single octet sequence):
The k (key value) member contains
the value of the symmetric (or other single-valued) key.
It is represented as the base64url encoding of the
octet sequence containing the key value.
Keys using additional key types can be represented
using JWK data structures with corresponding
kty (key type) parameter
values being defined to refer to them.
New kty parameter values SHOULD
either be registered in the
IANA JSON Web Key Types registry or be
a value that contains a Collision Resistant Namespace.
Likewise, parameters for representing keys for additional
key types or additional key properties
SHOULD either be registered in the
IANA JSON Web Key Parameters registry or be
a value that contains a Collision Resistant Namespace.
The following registration procedure is used for all the
registries established by this specification.
Values are registered with a Specification Required
after a two-week review period on the [TBD]@ietf.org mailing
list, on the advice of one or more Designated Experts. However, to allow for the
allocation of values prior to publication, the Designated Expert(s) may approve
registration once they are satisfied that such a specification will be published.
Registration requests must be sent to the [TBD]@ietf.org mailing list for review and
comment, with an appropriate subject (e.g., "Request for access token type: example").
[[ Note to RFC-EDITOR: The name of the mailing list should be determined in consultation
with the IESG and IANA. Suggested name: jose-reg-review. ]]
Within the review period, the Designated Expert(s) will either approve or
deny the registration request, communicating this decision to the review list and IANA.
Denials should include an explanation and, if applicable, suggestions as to how to make
the request successful.
IANA must only accept registry updates from the Designated Expert(s) and should direct
all requests for registration to the review mailing list.
This specification establishes the
IANA JSON Web Signature and Encryption Algorithms registry
for values of the JWS and JWE
alg (algorithm) and
enc (encryption method)
header parameters.
The registry records the algorithm name,
the algorithm usage locations from the set
alg and
enc,
implementation requirements,
and a reference to the specification that defines it.
The same algorithm name MAY be registered multiple times,
provided that the sets of usage locations are disjoint.
The implementation requirements of an algorithm MAY be changed
over time by the Designated Experts(s) as the
cryptographic landscape evolves, for instance,
to change the status of an algorithm to DEPRECATED, or
to change the status of an algorithm from OPTIONAL
to RECOMMENDED or REQUIRED.
The name requested (e.g., "example").
This name is case sensitive. Names that match other registered names
in a case insensitive manner SHOULD NOT be accepted.
The algorithm usage, which must be one or more of the values
alg or
enc.
The algorithm implementation requirements, which must be one the words
REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.
Optionally, the word can be followed by a "+" or "-".
The use of "+" indicates that the requirement strength is likely
to be increased in a future version of the specification.
The use of "-" indicates that the requirement strength is likely
to be decreased in a future version of the specification.
For Standards Track RFCs, state "IETF". For others, give the name of the
responsible party. Other details (e.g., postal address, email address, home page
URI) may also be included.
Reference to the document(s) that specify the parameter, preferably including URI(s) that
can be used to retrieve copies of the document(s). An indication of the relevant
sections may also be included but is not required.

Algorithm Name: HS256
Algorithm Usage Location(s): alg
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s):
of [[ this document ]]

Algorithm Name: HS384
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s):
of [[ this document ]]

Algorithm Name: HS512
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s):
of [[ this document ]]

Algorithm Name: RS256
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: RS384
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: RS512
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ES256
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED+
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ES384
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ES512
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: PS256
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: PS512
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: none
Algorithm Usage Location(s): alg
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: RSA1_5
Algorithm Usage Location(s): alg
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: RSA-OAEP
Algorithm Usage Location(s): alg
Implementation Requirements: OPTIONAL
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A128KW
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A256KW
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: dir
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ECDH-ES
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED+
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ECDH-ES+A128KW
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: ECDH-ES+A256KW
Algorithm Usage Location(s): alg
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A128CBC-HS256
Algorithm Usage Location(s): enc
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A256CBC-HS512
Algorithm Usage Location(s): enc
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A128GCM
Algorithm Usage Location(s): enc
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Algorithm Name: A256GCM
Algorithm Usage Location(s): enc
Implementation Requirements: RECOMMENDED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

This specification establishes the
IANA JSON Web Key Types registry
for values of the JWK
kty (key type) parameter.
The registry records the kty value
and a reference to the specification that defines it.
This specification registers the values defined in
.
The name requested (e.g., "example").
This name is case sensitive. Names that match other registered names
in a case insensitive manner SHOULD NOT be accepted.
For Standards Track RFCs, state "IETF". For others, give the name of the
responsible party. Other details (e.g., postal address, email address, home page
URI) may also be included.
The algorithm implementation requirements, which must be one the words
REQUIRED, RECOMMENDED, OPTIONAL, or DEPRECATED.
Optionally, the word can be followed by a "+" or "-".
The use of "+" indicates that the requirement strength is likely
to be increased in a future version of the specification.
The use of "-" indicates that the requirement strength is likely
to be decreased in a future version of the specification.
Reference to the document(s) that specify the parameter, preferably including URI(s) that
can be used to retrieve copies of the document(s). An indication of the relevant
sections may also be included but is not required.

"kty" Parameter Value: EC
Implementation Requirements: RECOMMENDED+
Change Controller: IETF
Specification Document(s): of [[ this document ]]

"kty" Parameter Value: RSA
Implementation Requirements: REQUIRED
Change Controller: IETF
Specification Document(s): of [[ this document ]]

"kty" Parameter Value: oct
Implementation Requirements: RECOMMENDED+
Change Controller: IETF
Specification Document(s): of [[ this document ]]

This specification registers the parameter names defined in
Sections ,
, and
in the
IANA JSON Web Key Parameters registry .
Parameter Name: crv
Parameter Information Class: Public
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: x
Parameter Information Class: Public
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: y
Parameter Information Class: Public
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: d
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: n
Parameter Information Class: Public
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: e
Parameter Information Class: Public
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: d
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: p
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: q
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: dp
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: dq
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: qi
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: oth
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

Parameter Name: k
Parameter Information Class: Private
Change Controller: IETF
Specification Document(s): of [[ this document ]]

All of the security issues faced by any cryptographic application
must be faced by a JWS/JWE/JWK agent. Among these issues are protecting
the user's private and symmetric keys, preventing various attacks, and helping the
user avoid mistakes such as inadvertently encrypting a message for
the wrong recipient. The entire list of security considerations is
beyond the scope of this document, but some significant considerations are
listed here.
The security considerations in
,
,
,
,
,
,
,
,
,
,
,
,
, and
apply to this specification.
Eventually the algorithms and/or key sizes currently described
in this specification will no longer be considered
sufficiently secure and will be removed. Therefore,
implementers and deployments must be prepared for this
eventuality.
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.
While Section 8 of RFC 3447
explicitly calls for people not to adopt RSASSA-PKCS-v1_5 for new
applications and instead requests that people transition to
RSASSA-PSS, this specification does include RSASSA-PKCS-v1_5, for
interoperability reasons, because it commonly implemented.
Keys used with RSAES-PKCS1-v1_5 must follow the constraints in
Section 7.2 of RFC 3447 . In particular, keys with
a low public key exponent value must not be used.
Plaintext JWSs (JWSs that use the alg
value none) provide no integrity protection.
Thus, they must only be used in contexts where the payload is secured by
means other than a digital signature or MAC value, or need not be secured.
Receiving agents that validate signatures and sending agents that
encrypt messages need to be cautious of cryptographic processing
usage when validating signatures and encrypting messages using keys
larger than those mandated in this specification. An attacker could
send certificates with keys that would result in excessive
cryptographic processing, for example, keys larger than those
mandated in this specification, which could swamp the processing
element. Agents that use such keys without first validating the
certificate to a trust anchor are advised to have some sort of
cryptographic resource management system to prevent such attacks.
Secure Hash Standard (SHS)
National Institute of Standards and
Technology
Digital Signature Standard (DSS)
National Institute of Standards and
Technology
Advanced Encryption Standard (AES)
National Institute of Standards and Technology (NIST)
Recommendation for Block Cipher Modes of Operation
National Institute of Standards and Technology (NIST)
Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC
National Institute of Standards and Technology (NIST)
Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Revised)
National Institute of Standards and Technology (NIST)
JSON Web Signature (JWS)
Microsoft
mbj@microsoft.com
http://self-issued.info/
Ping Identity
ve7jtb@ve7jtb.com
Nomura Research Institute
n-sakimura@nri.co.jp
JSON Web Encryption (JWE)
Microsoft
mbj@microsoft.com
http://self-issued.info/
RTFM, Inc.
ekr@rtfm.com
Cisco Systems, Inc.
jhildebr@cisco.com
JSON Web Key (JWK)
Microsoft
mbj@microsoft.com
http://self-issued.info/
Coded Character Set -- 7-bit American Standard Code for Information Interchange
American National Standards Institute
Magic Signatures
JSON Simple Sign
independent
Nomura Research Institute
JSON Simple Encryption
independent
Nomura Research Institute
Canvas Applications
Java Cryptography Architecture
This appendix contains a table cross-referencing the
digital signature and MAC alg (algorithm)
values used in this specification
with the equivalent identifiers used by other standards and
software packages. See XML DSIG,
XML DSIG 2.0,
and Java Cryptography Architecture
for more information about the names defined by those
documents.
Algorithm
JWS
XML DSIG
JCA
OID
HMAC using SHA-256 hash algorithm
HS256
http://www.w3.org/2001/04/xmldsig-more#hmac-sha256
HmacSHA256
1.2.840.113549.2.9
HMAC using SHA-384 hash algorithm
HS384
http://www.w3.org/2001/04/xmldsig-more#hmac-sha384
HmacSHA384
1.2.840.113549.2.10
HMAC using SHA-512 hash algorithm
HS512
http://www.w3.org/2001/04/xmldsig-more#hmac-sha512
HmacSHA512
1.2.840.113549.2.11
RSASSA-PKCS-v1_5 using SHA-256 hash algorithm
RS256
http://www.w3.org/2001/04/xmldsig-more#rsa-sha256
SHA256withRSA
1.2.840.113549.1.1.11
RSASSA-PKCS-v1_5 using SHA-384 hash algorithm
RS384
http://www.w3.org/2001/04/xmldsig-more#rsa-sha384
SHA384withRSA
1.2.840.113549.1.1.12
RSASSA-PKCS-v1_5 using SHA-512 hash algorithm
RS512
http://www.w3.org/2001/04/xmldsig-more#rsa-sha512
SHA512withRSA
1.2.840.113549.1.1.13
ECDSA using P-256 curve and SHA-256 hash algorithm
ES256
http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256
SHA256withECDSA
1.2.840.10045.4.3.2
ECDSA using P-384 curve and SHA-384 hash algorithm
ES384
http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384
SHA384withECDSA
1.2.840.10045.4.3.3
ECDSA using P-521 curve and SHA-512 hash algorithm
ES512
http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512
SHA512withECDSA
1.2.840.10045.4.3.4
RSASSA-PSS using SHA-256 hash algorithm and MGF1 mask generation function with SHA-256
PS256
RSASSA-PSS using SHA-512 hash algorithm and MGF1 mask generation function with SHA-512
PS512
This appendix contains a table cross-referencing the alg (algorithm) and enc (encryption method)
values used in this specification with the equivalent
identifiers used by other standards and software packages.
See
XML Encryption,
XML Encryption 1.1,
and Java Cryptography Architecture for more
information about the names defined by those documents.
For the composite algorithms A128CBC-HS256 and
A256CBC-HS512, the corresponding AES CBC
algorithm identifiers are listed.
Algorithm
JWE
XML ENC
JCA
RSAES-PKCS1-V1_5
RSA1_5
http://www.w3.org/2001/04/xmlenc#rsa-1_5
RSA/ECB/PKCS1Padding
RSAES using Optimal Asymmetric Encryption Padding (OAEP)
RSA-OAEP
http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p
RSA/ECB/OAEPWithSHA-1AndMGF1Padding
Elliptic Curve Diffie-Hellman Ephemeral Static
ECDH-ES
http://www.w3.org/2009/xmlenc11#ECDH-ES
Advanced Encryption Standard (AES) Key Wrap Algorithm
using 128 bit keys
A128KW
http://www.w3.org/2001/04/xmlenc#kw-aes128
AES Key Wrap Algorithm
using 256 bit keys
A256KW
http://www.w3.org/2001/04/xmlenc#kw-aes256
AES in Cipher Block Chaining (CBC) mode with PKCS #5 padding
using 128 bit keys
A128CBC-HS256
http://www.w3.org/2001/04/xmlenc#aes128-cbc
AES/CBC/PKCS5Padding
AES in CBC mode with PKCS #5 padding
using 256 bit keys
A256CBC-HS512
http://www.w3.org/2001/04/xmlenc#aes256-cbc
AES/CBC/PKCS5Padding
AES in Galois/Counter Mode (GCM)
using 128 bit keys
A128GCM
http://www.w3.org/2009/xmlenc11#aes128-gcm
AES/GCM/NoPadding
AES GCM
using 256 bit keys
A256GCM
http://www.w3.org/2009/xmlenc11#aes256-gcm
AES/GCM/NoPadding
The following test cases can be used to validate implementations of
the AES_CBC_HMAC_SHA2 algorithms defined in .
They are also intended to correspond to test cases that may appear in a
future version of ,
demonstrating that the cryptographic computations performed are the same.
The variable names are those defined in .
All values are hexadecimal.
Solutions for signing and encrypting JSON content were
previously explored by Magic
Signatures, JSON Simple Sign,
Canvas Applications, JSON Simple Encryption, and JavaScript Message Security
Format, all of which influenced this draft.
The Authenticated Encryption with AES-CBC and HMAC-SHA
specification, upon which the AES_CBC_HMAC_SHA2 algorithms are based,
was written by David A. McGrew and Kenny Paterson.
The test cases for AES_CBC_HMAC_SHA2 are based upon those
for by John Foley.
This specification is the work of the JOSE Working Group,
which includes dozens of active and dedicated participants.
In particular, the following individuals contributed ideas,
feedback, and wording that influenced this specification:
Dirk Balfanz,
Richard Barnes,
John Bradley,
Brian Campbell,
Breno de Medeiros,
Yaron Y. Goland,
Dick Hardt,
Jeff Hodges,
Edmund Jay,
James Manger,
Tony Nadalin,
Axel Nennker,
John Panzer,
Emmanuel Raviart,
Nat Sakimura,
Jim Schaad,
Hannes Tschofenig,
and Sean Turner.
Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
Sean Turner and Stephen Farrell served as Security area directors
during the creation of this specification.
[[ to be removed by the RFC editor before publication as an RFC ]]
-11
Removed the Encrypted Key value from the AAD computation since it is
already effectively integrity protected by the encryption process.
The AAD value now only contains the representation of the JWE Encrypted Header.
Removed apv (agreement PartyVInfo)
since it is no longer used.
Added more information about the use of PartyUInfo during key agreement.
Use the keydatalen as the SuppPubInfo value for the Concat KDF
when doing key agreement, as RFC 2631 does.
Added algorithm identifiers for RSASSA-PSS with SHA-256 and SHA-512.
Added a Parameter Information Class value to the
JSON Web Key Parameters registry, which registers whether
the parameter conveys public or private information.

-10
Changed the JWE processing rules for multiple recipients so that
a single AAD value contains the header parameters and encrypted key
values for all the recipients,
enabling AES GCM to be safely used for multiple recipients.

-09
Expanded the scope of the JWK parameters to include
private and symmetric key representations, as specified by
draft-jones-jose-json-private-and-symmetric-key-00.
Changed term "JWS Secured Input" to "JWS Signing Input".
Changed from using the term "byte" to "octet" when referring to 8 bit values.
Specified that AES Key Wrap uses the default initial value
specified in Section 2.2.3.1 of RFC 3394.
This addressed issue #19.
Added Key Management Mode definitions to terminology section
and used the defined terms to provide clearer key management instructions.
This addressed issue #5.
Replaced A128CBC+HS256
and A256CBC+HS512
with A128CBC-HS256
and A256CBC-HS512.
The new algorithms perform the same cryptographic computations as
,
but with the Initialization Vector and Authentication Tag values remaining
separate from the Ciphertext value in the output representation.
Also deleted the header parameters
epu (encryption PartyUInfo) and
epv (encryption PartyVInfo),
since they are no longer used.
Changed from using the term "Integrity Value" to "Authentication Tag".

-08
Changed the name of the JWK key type parameter from
alg to kty.
Replaced uses of the term "AEAD" with "Authenticated Encryption", since
the term AEAD in the RFC 5116 sense implied the use of a particular
data representation, rather than just referring to the class of
algorithms that perform authenticated encryption with associated data.
Applied editorial improvements suggested by
Jeff Hodges.
Many of these simplified the terminology used.
Added seriesInfo information to Internet Draft references.

-07
Added a data length prefix to PartyUInfo and PartyVInfo values.
Changed the name of the JWK RSA modulus parameter from
mod to n
and the name of the JWK RSA exponent parameter from
xpo to e,
so that the identifiers are the same as those used in RFC 3447.
Made several local editorial changes to clean up loose ends
left over from to the decision to only support
block encryption methods providing integrity.

-06
Removed the int and
kdf parameters and defined the new composite
Authenticated Encryption algorithms A128CBC+HS256 and
A256CBC+HS512 to replace the former
uses of AES CBC, which required the use of separate integrity
and key derivation functions.
Included additional values in the Concat KDF calculation -- the
desired output size and the algorithm value,
and optionally PartyUInfo and PartyVInfo values.
Added the optional header parameters
apu (agreement PartyUInfo),
apv (agreement PartyVInfo),
epu (encryption PartyUInfo), and
epv (encryption PartyVInfo).
Changed the name of the JWK RSA exponent parameter from
exp to xpo
so as to allow the potential use of the name exp
for a future extension that might define an expiration parameter for keys.
(The exp name is already used for this
purpose in the JWT specification.)
Applied changes made by the RFC Editor to RFC 6749's registry language
to this specification.

-05
Support both direct encryption using a
shared or agreed upon symmetric key, and the use of a
shared or agreed upon symmetric key to key wrap the CMK.
Specifically, added the alg values
dir,
ECDH-ES+A128KW, and
ECDH-ES+A256KW
to finish filling in this set of capabilities.
Updated open issues.

-04
Added text requiring that any leading zero bytes be retained in
base64url encoded key value representations for fixed-length values.
Added this language to Registration Templates:
"This name is case sensitive. Names that match other registered names
in a case insensitive manner SHOULD NOT be accepted."
Described additional open issues.
Applied editorial suggestions.

-03
Always use a 128 bit "authentication tag" size for
AES GCM, regardless of the key size.
Specified that use of a 128 bit IV is REQUIRED with AES CBC.
It was previously RECOMMENDED.
Removed key size language for ECDSA algorithms, since the
key size is implied by the algorithm being used.
Stated that the int key size
must be the same as the hash output size (and not larger,
as was previously allowed) so that its size is defined for
key generation purposes.
Added the kdf (key derivation function) header parameter
to provide crypto agility for key derivation.
The default KDF remains the Concat KDF with the SHA-256 digest function.
Clarified that the mod and
exp values are unsigned.
Added Implementation Requirements columns to algorithm tables
and Implementation Requirements entries to algorithm registries.
Changed AES Key Wrap to RECOMMENDED.
Moved registries
JSON Web Signature and Encryption Header Parameters and
JSON Web Signature and Encryption Type Values
to the JWS specification.
Moved JSON Web Key Parameters registry to the JWK specification.
Changed registration requirements from RFC Required to
Specification Required with Expert Review.
Added Registration Template sections for defined registries.
Added Registry Contents sections to populate registry values.
No longer say "the UTF-8 representation of the JWS Secured Input
(which is the same as the ASCII representation)". Just call it
"the ASCII representation of the JWS Secured Input".
Added "Collision Resistant Namespace" to the terminology section.
Numerous editorial improvements.

-02
For AES GCM,
use the "additional authenticated data" parameter
to provide integrity for the header, encrypted key, and
ciphertext and use the resulting "authentication tag"
value as the JWE Authentication Tag.
Defined minimum required key sizes for algorithms
without specified key sizes.
Defined KDF output key sizes.
Specified the use of PKCS #5 padding with AES CBC.
Generalized text to allow key agreement to be employed
as an alternative to key wrapping or key encryption.
Clarified that ECDH-ES is a key agreement algorithm.
Required implementation of AES-128-KW and AES-256-KW.
Removed the use of A128GCM and
A256GCM for key wrapping.
Removed A512KW since it turns
out that it's not a standard algorithm.
Clarified the relationship between
typ header parameter values
and MIME types.
Generalized language to refer to Message Authentication Codes (MACs)
rather than Hash-based Message Authentication Codes (HMACs)
unless in a context specific to HMAC algorithms.
Established registries:
JSON Web Signature and Encryption Header Parameters,
JSON Web Signature and Encryption Algorithms,
JSON Web Signature and Encryption "typ" Values,
JSON Web Key Parameters, and
JSON Web Key Algorithm Families.
Moved algorithm-specific definitions from JWK to JWA.
Reformatted to give each member definition its own section heading.

-01
Moved definition of "alg":"none" for JWSs here from the JWT
specification since this functionality is likely to be
useful in more contexts that just for JWTs.
Added Advanced Encryption Standard (AES) Key Wrap Algorithm
using 512 bit keys (A512KW).
Added text "Alternatively, the Encoded JWS Signature MAY be base64url
decoded to produce the JWS Signature and this value can
be compared with the computed HMAC value, as this
comparison produces the same result as comparing the
encoded values".
Corrected the Magic Signatures reference.
Made other editorial improvements suggested by JOSE
working group participants.

-00
Created the initial IETF draft based upon
draft-jones-json-web-signature-04 and
draft-jones-json-web-encryption-02 with no normative changes.
Changed terminology to no longer call both digital
signatures and HMACs "signatures".