JSON Web Algorithms (JWA)Microsoftmbj@microsoft.comhttp://self-issued.info/
Security
JOSE Working GroupRFCRequest for CommentsI-DInternet-DraftJavaScript Object NotationJSONJSON Object Signing and EncryptionJOSEJSON Web SignatureJWSJSON Web EncryptionJWEJSON Web KeyJWKJSON Web AlgorithmsJWA
The JSON Web Algorithms (JWA) specification registers
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS),
JSON Web Encryption (JWE), and
JSON Web Key (JWK) specifications.
It defines several IANA registries for these identifiers.
The JSON Web Algorithms (JWA) specification registers
cryptographic algorithms and identifiers to be used with the
JSON Web Signature (JWS) ,
JSON Web Encryption (JWE) , and
JSON Web Key (JWK) specifications.
It defines several IANA registries for these identifiers.
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.
Registering the algorithms and identifiers here,
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.
This also allows changes to the JWS, JWE, and JWK specifications
without changing this document.
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 .
If these words are used without being spelled in uppercase then
they are to be interpreted with their normal natural language meanings.
BASE64URL(OCTETS) denotes the base64url encoding of OCTETS,
per Section 2 of .
UTF8(STRING) denotes the octets of the
UTF-8 representation of STRING.
ASCII(STRING) denotes the octets of the
ASCII representation of STRING.
The concatenation of two values A and B
is denoted as A || B.
These terms defined by the
JSON Web Signature (JWS)
specification are incorporated into this specification:
"JSON Web Signature (JWS)",
"Base64url Encoding",
"Header Parameter",
"JOSE Header",
"JWS Payload",
"JWS Protected Header",
"JWS Signature",
"JWS Signing Input",
and "Unsecured JWS".
These terms defined by the
JSON Web Encryption (JWE)
specification are incorporated into this specification:
"JSON Web Encryption (JWE)",
"Additional Authenticated Data (AAD)",
"Authentication Tag",
"Content Encryption Key (CEK)",
"Direct Encryption",
"Direct Key Agreement",
"JWE Authentication Tag",
"JWE Ciphertext",
"JWE Encrypted Key",
"JWE Initialization Vector",
"JWE Protected Header",
"Key Agreement with Key Wrapping",
"Key Encryption",
"Key Management Mode",
and "Key Wrapping".
These terms defined by the
JSON Web Key (JWK)
specification are incorporated into this specification:
"JSON Web Key (JWK)" and
"JSON Web Key Set (JWK Set)".
These terms defined by the
Internet Security Glossary, Version 2
are incorporated into this specification:
"Ciphertext",
"Digital Signature",
"Message Authentication Code (MAC)",
and "Plaintext".
This term is defined by this specification:
The representation of a positive or zero integer value
as the base64url encoding of the value's
unsigned big endian representation as an octet sequence.
The octet sequence MUST utilize the minimum
number of octets needed to represent the value.
Zero is represented as BASE64URL(single zero-valued octet), which is "AA".
JWS uses cryptographic algorithms to digitally sign or
create a Message Authentication Code (MAC) of the contents
of the JWS Protected Header and the JWS Payload.
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 Param ValueDigital Signature or MAC AlgorithmImplementation RequirementsHS256HMAC using SHA-256RequiredHS384HMAC using SHA-384OptionalHS512HMAC using SHA-512OptionalRS256RSASSA-PKCS-v1_5 using SHA-256RecommendedRS384RSASSA-PKCS-v1_5 using SHA-384OptionalRS512RSASSA-PKCS-v1_5 using SHA-512OptionalES256ECDSA using P-256 and SHA-256Recommended+ES384ECDSA using P-384 and SHA-384OptionalES512ECDSA using P-521 and SHA-512OptionalPS256RSASSA-PSS using SHA-256 and MGF1 with SHA-256OptionalPS384RSASSA-PSS using SHA-384 and MGF1 with SHA-384OptionalPS512RSASSA-PSS using SHA-512 and MGF1 with SHA-512OptionalnoneNo digital signature or MAC performedOptional
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
JWS digital signature and MAC alg (algorithm)
values defined 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 whoever generated the MAC was in possession of the MAC key.
The algorithm for implementing and validating HMACs is
provided in RFC 2104.
A key of the same size as the hash output (for instance, 256
bits for HS256) or larger MUST
be used with this algorithm.
(This requirement is based on Section 5.3.4 (Security Effect of the HMAC Key)
of NIST SP 800-117, which states that the
effective security strength is the minimum of the security strength of the key
and two times the size of the internal hash value.)
The HMAC SHA-256 MAC is generated per RFC 2104,
using SHA-256 as the hash algorithm "H",
using the JWS Signing Input as the "text" value,
and using the shared key.
The HMAC output value is the JWS Signature.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWS Signature
is an HMAC value computed using the corresponding algorithm:
alg Param ValueMAC AlgorithmHS256HMAC using SHA-256HS384HMAC using SHA-384HS512HMAC using SHA-512
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 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 value.
The comparison of the computed HMAC value to the JWS Signature value
MUST be done in a constant-time manner to thwart timing attacks.
Alternatively, the computed HMAC value can be base64url encoded
and compared to the received encoded JWS Signature value
(also in a constant-time manner),
as this comparison produces the same result as comparing
the unencoded values.
In either case, if the values match, the HMAC has been validated.
Securing content and validation 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 algorithms
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-2 hash functions.
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 JWS Signing Input
using RSASSA-PKCS1-V1_5-SIGN
and the SHA-256 hash function
with the desired private key.
This is the JWS Signature value.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWS Signature
is a digital signature value computed using the corresponding algorithm:
alg Param ValueDigital Signature AlgorithmRS256RSASSA-PKCS-v1_5 using SHA-256RS384RSASSA-PKCS-v1_5 using SHA-384RS512RSASSA-PKCS-v1_5 using SHA-512
The RSASSA-PKCS1-V1_5 SHA-256 digital signature for a JWS is validated as follows:
Submit the JWS Signing Input,
the JWS Signature,
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.
Signing and validation 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 algorithms
instead of SHA-256.
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 for many operations.
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 ECDSA P-256 SHA-256 digital signature is generated as follows:
Generate a digital signature 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 octet sequence 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.)
The resulting 64 octet sequence is the JWS Signature value.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWS Signature
is a digital signature value computed using the corresponding algorithm:
alg Param ValueDigital Signature AlgorithmES256ECDSA using P-256 and SHA-256ES384ECDSA using P-384 and SHA-384ES512ECDSA using P-521 and SHA-512
The ECDSA P-256 SHA-256 digital signature for a JWS is validated as follows:
The JWS Signature value MUST be a 64 octet sequence.
If it is not a 64 octet sequence, the validation has failed.
Split the 64 octet sequence into two 32 octet sequences. The first
octet sequence represents R and the second S.
The values R and S are represented as octet sequences
using the Integer-to-OctetString Conversion defined in
Section 2.3.7 of SEC1
(in big endian octet order).
Submit the JWS Signing Input
R, S and the public key (x, y) to the ECDSA P-256
SHA-256 validator.
Signing and validation 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 algorithms
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.
(Note that the Integer-to-OctetString Conversion defined in
Section 2.3.7 of SEC1
used to represent R and S as octet sequences adds zero-valued high-order
padding bits when needed to round the size up to a multiple of 8 bits;
thus, each 521-bit integer is represented using 528 bits in 66 octets.)
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 and SHA-2 hash functions,
always using the
same hash function for both the RSASSA-PSS hash function
and the MGF1 hash function.
The size of the salt value is the same size as the hash function output.
All other algorithm parameters use the defaults specified
in Section A.2.3 of RFC 3447.
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 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.
This is the JWS signature value.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWS Signature
is a digital signature value computed using the corresponding algorithm:
alg Param ValueDigital Signature AlgorithmPS256RSASSA-PSS using SHA-256 and MGF1 with SHA-256PS384RSASSA-PSS using SHA-384 and MGF1 with SHA-384PS512RSASSA-PSS using SHA-512 and MGF1 with SHA-512
The RSASSA-PSS SHA-256 digital signature for a JWS is validated as follows:
Submit the JWS Signing Input,
the JWS Signature,
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.
Signing and validation with the RSASSA-PSS SHA-384 and RSASSA-PSS SHA-512
algorithms 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 an Unsecured JWS.
An Unsecured JWS MUST use the alg
value none, and is formatted
identically to other JWSs, but
MUST use the empty octet sequence as its JWS Signature value.
Recipients MUST verify that the JWS Signature value is the empty octet sequence.
See for security considerations
associated with using this algorithm.
JWE uses cryptographic algorithms to encrypt or determine the
Content Encryption Key (CEK).
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 Param ValueKey Management AlgorithmMore Header ParamsImplementation RequirementsRSA1_5RSAES-PKCS1-V1_5(none)Recommended-RSA-OAEPRSAES OAEP using default parameters(none)Recommended+RSA-OAEP-256RSAES OAEP using SHA-256 and MGF1 with SHA-256(none)OptionalA128KWAES Key Wrap with default initial value using 128 bit key(none)RecommendedA192KWAES Key Wrap with default initial value using 192 bit key(none)OptionalA256KWAES Key Wrap with default initial value using 256 bit key(none)RecommendeddirDirect use of a shared symmetric key as the CEK(none)RecommendedECDH-ESElliptic Curve Diffie-Hellman Ephemeral Static
key agreement using Concat KDF
epk,
apu,
apvRecommended+ECDH-ES+A128KWECDH-ES using Concat KDF and CEK wrapped with
A128KWepk,
apu,
apvRecommendedECDH-ES+A192KWECDH-ES using Concat KDF and CEK wrapped with
A192KWepk,
apu,
apvOptionalECDH-ES+A256KWECDH-ES using Concat KDF and CEK wrapped with
A256KWepk,
apu,
apvRecommendedA128GCMKWKey wrapping with AES GCM using 128 bit keyiv,
tagOptionalA192GCMKWKey wrapping with AES GCM using 192 bit keyiv,
tagOptionalA256GCMKWKey wrapping with AES GCM using 256 bit keyiv,
tagOptionalPBES2-HS256+A128KW
PBES2 with HMAC SHA-256
and A128KW wrapping
p2s,
p2cOptionalPBES2-HS384+A192KW
PBES2 with HMAC SHA-384
and A192KW wrapping
p2s,
p2cOptionalPBES2-HS512+A256KW
PBES2 with HMAC SHA-512
and A256KW wrapping
p2s,
p2cOptional
The More Header Params column indicates what
additional Header Parameters are used by the algorithm,
beyond alg, which all use.
All but dir and
ECDH-ES also produce a JWE Encrypted Key value.
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
JWE alg (algorithm)
values defined 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 for this algorithm.
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)
.
Two sets of parameters for using OAEP are defined,
which use different hash functions.
In the first case,
the default parameters specified by RFC 3447 in Section A.2.1 are used.
(Those default parameters are the SHA-1 hash function and
the MGF1 with SHA-1 mask generation function.)
In the second case, the SHA-256 hash function and
the MGF1 with SHA-256 mask generation function are used.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWE Encrypted Key
is the result of encrypting the CEK
using the corresponding algorithm:
alg Param ValueKey Management AlgorithmRSA-OAEPRSAES OAEP using default parametersRSA-OAEP-256RSAES OAEP using SHA-256 and MGF1 with SHA-256
A key of size 2048 bits or larger MUST be used with these algorithms.
(This requirement is based on Table 4 (Security-strength time frames)
of NIST SP 800-57,
which requires 112 bits of security for new uses,
and Table 2 (Comparable strengths) of the same,
which states that 2048 bit RSA keys provide 112 bits of security.)
An example using RSAES OAEP with the default parameters 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.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWE Encrypted Key
is the result of encrypting the CEK
using the corresponding algorithm and key size:
alg Param ValueKey Management AlgorithmA128KWAES Key Wrap with default initial value using 128 bit keyA192KWAES Key Wrap with default initial value using 192 bit keyA256KWAES Key Wrap with default initial value using 256 bit key
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.
Refer to the security considerations on key lifetimes
in and AES GCM in
when considering utilizing direct encryption.
This section defines the specifics of key agreement with
Elliptic Curve Diffie-Hellman Ephemeral Static ,
in combination with 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 the
A128KW,
A192KW,
or A256KW
algorithms, in the Key Agreement with Key Wrapping mode.
A new ephemeral public key
value MUST be generated for each key agreement operation.
In Direct Key Agreement mode,
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.
The alg Header Parameter value
ECDH-ES
is used in the Direct Key Agreement mode.
In Key Agreement with Key Wrapping mode,
the output of the Concat KDF MUST be a key of the
length needed for the specified key wrapping algorithm.
In this case, the JWE Encrypted Key is the CEK wrapped with the agreed upon key.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWE Encrypted Key
is the result of encrypting the CEK
using the result of the key agreement algorithm
as the key encryption key for the corresponding key wrapping algorithm:
alg Param ValueKey Management AlgorithmECDH-ES+A128KWECDH-ES using Concat KDF and CEK wrapped with
A128KWECDH-ES+A192KWECDH-ES using Concat KDF and CEK wrapped with
A192KWECDH-ES+A256KWECDH-ES using Concat KDF and CEK wrapped with
A256KW
The following Header Parameter names
are used for key agreement as defined below.
The epk (ephemeral public key)
value created by the originator for the use in key agreement algorithms.
This key is represented as a JSON Web Key
public key value.
It MUST contain only public key parameters and
SHOULD contain only the minimum JWK parameters necessary to represent the key;
other JWK parameters included can be checked for consistency and honored or can be ignored.
This Header Parameter MUST be present and MUST be understood and processed
by implementations when these algorithms are used.
The apu (agreement PartyUInfo)
value for key agreement algorithms using it
(such as ECDH-ES),
represented as a base64url encoded string.
When used, the PartyUInfo value contains information about the producer.
Use of this Header Parameter is OPTIONAL.
This Header Parameter MUST be understood and processed
by implementations when these algorithms are used.
The apv (agreement PartyVInfo)
value for key agreement algorithms using it
(such as ECDH-ES),
represented as a base64url encoded string.
When used, the PartyVInfo value contains information about the recipient.
Use of this Header Parameter is OPTIONAL.
This Header Parameter MUST be understood and processed
by implementations when these algorithms are used.
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,
ECDH-ES+A192KW,
and ECDH-ES+A256KW,
this is 128, 192, and 256, respectively.
The AlgorithmID 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.
In the Direct Key Agreement case,
Data is set to
the octets of the UTF-8 representation of the
enc Header Parameter value.
In the Key Agreement with Key Wrapping case,
Data is set to
the octets of the UTF-8 representation of the
alg Header Parameter value.
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.
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.
The PartyVInfo 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.
If an apv (agreement PartyVInfo)
Header Parameter is present, Data is set to the result of
base64url decoding the apv 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 keydatalen represented as a
32 bit big endian integer.
This is set to the empty octet sequence.
Applications need to specify how the
apu and apv parameters
are used for that application.
The apu and apv
values MUST be distinct, when used.
Applications wishing to conform to
need to provide values that meet the requirements of that document,
e.g., by using values that identify the producer and recipient.
Alternatively, applications MAY conduct key derivation in a manner similar to
The Diffie-Hellman Key Agreement Method :
In that case, the apu field MAY either be omitted
or represent a random 512-bit value
(analogous to PartyAInfo in Ephemeral-Static mode in RFC 2631)
and the apv field SHOULD NOT be present.
See for an example key agreement computation
using this method.
This section defines the specifics of encrypting a
JWE Content Encryption Key (CEK) with
Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM)
[, ].
Use of an Initialization Vector of size 96 bits is
REQUIRED with this algorithm.
The Initialization Vector is represented in base64url encoded form
as the iv (initialization vector)
Header Parameter value.
The Additional Authenticated Data value used is
the empty octet string.
The requested size of the Authentication Tag output MUST be
128 bits, regardless of the key size.
The JWE Encrypted Key value is the Ciphertext output.
The Authentication Tag output is represented in base64url encoded form
as the tag (authentication tag)
Header Parameter value.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWE Encrypted Key
is the result of encrypting the CEK
using the corresponding algorithm and key size:
alg Param ValueKey Management AlgorithmA128GCMKWKey wrapping with AES GCM using 128 bit keyA192GCMKWKey wrapping with AES GCM using 192 bit keyA256GCMKWKey wrapping with AES GCM using 256 bit key
The following Header Parameters are used for AES GCM key encryption.
The iv (initialization vector)
Header Parameter value is the base64url encoded representation of the
96 bit Initialization Vector value used for the key encryption operation.
This Header Parameter MUST be present and MUST be understood and processed
by implementations when these algorithms are used.
The tag (authentication tag)
Header Parameter value is the base64url encoded representation of the
128 bit Authentication Tag value resulting from the key encryption operation.
This Header Parameter MUST be present and MUST be understood and processed
by implementations when these algorithms are used.
This section defines the specifics of
performing password-based encryption of a JWE CEK,
by first deriving a key encryption key from a user-supplied password
using PBES2 schemes as specified in Section 6.2 of ,
then by encrypting the JWE CEK using the derived key.
These algorithms use HMAC SHA-2 algorithms as the Pseudo-Random Function (PRF)
for the PBKDF2 key derivation and
AES Key Wrap for the encryption scheme.
The PBES2 password input is an octet sequence;
if the password to be used is represented as a text string
rather than an octet sequence, the UTF-8 encoding of the text string
MUST be used as the octet sequence.
The salt parameter MUST be computed from
the p2s (PBES2 salt input) Header Parameter value
and the alg (algorithm) Header Parameter value
as specified in the p2s definition below.
The iteration count parameter MUST be provided as the
p2c Header Parameter value.
The algorithms respectively use HMAC SHA-256, HMAC SHA-384, and HMAC SHA-512
as the PRF and use 128, 192, and 256 bit AES Key Wrap keys.
Their derived-key lengths respectively are 16, 24, and 32 octets.
The following alg (algorithm)
Header Parameter values are used to indicate that the JWE Encrypted Key
is the result of encrypting the CEK
using the result of the corresponding password-based encryption algorithm
as the key encryption key for the corresponding key wrapping algorithm:
alg Param ValueKey Management AlgorithmPBES2-HS256+A128KW
PBES2 with HMAC SHA-256
and A128KW wrapping
PBES2-HS384+A192KW
PBES2 with HMAC SHA-384
and A192KW wrapping
PBES2-HS512+A256KW
PBES2 with HMAC SHA-512
and A256KW wrapping
See Appendix C of JSON Web Key (JWK)
for an example key encryption computation using
PBES2-HS256+A128KW.
The following Header Parameters are used for
Key Encryption with PBES2.
The p2s (PBES2 salt input) Header Parameter
encodes a Salt Input value, which is used as part of the PBKDF2 salt value.
The p2s value is BASE64URL(Salt Input).
This Header Parameter MUST be present and MUST be understood and processed
by implementations when these algorithms are used.
The salt expands the possible keys that can be derived
from a given password.
A Salt Input value containing 8 or more octets MUST be used.
A new Salt Input value MUST be generated randomly for every encryption operation;
see RFC 4086 for considerations on generating random values.
The salt value used is (UTF8(Alg) || 0x00 || Salt Input),
where Alg is the alg Header Parameter value.
The p2c (PBES2 count) Header Parameter contains
the PBKDF2 iteration count, represented as a positive JSON integer.
This Header Parameter MUST be present and MUST be understood and processed
by implementations when these algorithms are used.
The iteration count adds computational expense,
ideally compounded by the possible range
of keys introduced by the salt.
A minimum iteration count of 1000 is RECOMMENDED.
JWE uses cryptographic algorithms to encrypt and integrity protect the Plaintext
and to also integrity protect additional authenticated data.
The table below is the set of
enc (encryption algorithm) Header Parameter values that
are defined by this specification for use with JWE.
enc Param ValueContent Encryption AlgorithmImplementation RequirementsA128CBC-HS256
AES_128_CBC_HMAC_SHA_256 authenticated encryption algorithm,
as defined in RequiredA192CBC-HS384
AES_192_CBC_HMAC_SHA_384 authenticated encryption algorithm,
as defined in OptionalA256CBC-HS512
AES_256_CBC_HMAC_SHA_512 authenticated encryption algorithm,
as defined in RequiredA128GCMAES GCM using 128 bit keyRecommendedA192GCMAES GCM using 192 bit keyOptionalA256GCMAES GCM using 256 bit keyRecommended
All also use a JWE Initialization Vector value and
produce JWE Ciphertext and JWE Authentication Tag values.
See for a table cross-referencing the
JWE enc (encryption algorithm)
values defined in this specification with the equivalent identifiers
used by other standards and software packages.
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 #7 padding , Section 6.3 operations and
HMAC [, ] operations.
This algorithm family is called AES_CBC_HMAC_SHA2.
It also defines three instances of this family,
the first using 128 bit CBC keys and HMAC SHA-256,
the second using 192 bit CBC keys and HMAC SHA-384,
and the third 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 option is discussed in Appendix B of that specification.
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 #7 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.
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.
Sections
through
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, additional authenticated 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 additional authenticated 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.
The number of octets in the
input key K MUST be the sum of MAC_KEY_LEN and ENC_KEY_LEN.
The values of these parameters are specified
by the Authenticated Encryption algorithms
in Sections
through .
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 #7 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
the additional authenticated data A
expressed as a 64-bit unsigned big endian integer.
A message authentication tag T is computed by applying
HMAC to the following data, in
order:
the additional authenticated 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, additional authenticated data,
initialization vector, and
ciphertext, respectively.
MAC_KEY = initial MAC_KEY_LEN octets of K,
ENC_KEY = final ENC_KEY_LEN octets of K,
E = CBC-PKCS5-ENC(ENC_KEY, P),
M = MAC(MAC_KEY, A || IV || E || AL),
T = initial T_LEN octets of M.
The authenticated decryption operation has five inputs:
K, A, IV, 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 Authenticated Encryption decryption
operation returns an indication that it failed, and the
operation halts.
(But see Section 11.5 of for
security considerations on thwarting timing attacks.)
The value E is decrypted and the PKCS #7 padding is checked and 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 #7 padding and a 128 bit initialization vector (IV) value.
The AES_CBC_HMAC_SHA2 parameters specific to AES_128_CBC_HMAC_SHA_256 are:
The input key K is 32 octets long.
ENC_KEY_LEN is 16 octets.
MAC_KEY_LEN is 16 octets.
The SHA-256 hash algorithm is used for the HMAC.
The HMAC-SHA-256 output is truncated to T_LEN=16 octets,
by stripping off the final 16 octets.
AES_192_CBC_HMAC_SHA_384 is based on AES_128_CBC_HMAC_SHA_256,
but with the following differences:
The input key K is 48 octets long instead of 32.
ENC_KEY_LEN is 24 octets instead of 16.
MAC_KEY_LEN is 24 octets instead of 16.
SHA-384 is used for the HMAC instead of SHA-256.
The HMAC SHA-384 value is truncated to T_LEN=24 octets instead of 16.
AES_256_CBC_HMAC_SHA_512 is based on AES_128_CBC_HMAC_SHA_256,
but with the following differences:
The input key K is 64 octets long instead of 32.
ENC_KEY_LEN is 32 octets instead of 16.
MAC_KEY_LEN is 32 octets instead of 16.
SHA-512 is used for the HMAC instead of SHA-256.
The HMAC SHA-512 value is truncated to T_LEN=32 octets instead of 16.
This section defines the specifics of performing authenticated encryption with
the AES_CBC_HMAC_SHA2 algorithms.
The CEK is used as the secret key K.
The following enc (encryption algorithm)
Header Parameter values are used to indicate that the JWE Ciphertext
and JWE Authentication Tag values
have been computed using the corresponding algorithm:
enc Param ValueContent Encryption AlgorithmA128CBC-HS256
AES_128_CBC_HMAC_SHA_256 authenticated encryption algorithm,
as defined in A192CBC-HS384
AES_192_CBC_HMAC_SHA_384 authenticated encryption algorithm,
as defined in A256CBC-HS512
AES_256_CBC_HMAC_SHA_512 authenticated encryption algorithm,
as defined in
This section defines the specifics of performing authenticated encryption with
Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM)
[, ].
The CEK is used as the encryption key.
Use of an initialization vector of size 96 bits is
REQUIRED with this algorithm.
The requested size of the Authentication Tag output MUST be
128 bits, regardless of the key size.
The following enc (encryption algorithm)
Header Parameter values are used to indicate that the JWE Ciphertext
and JWE Authentication Tag values
have been computed using the corresponding algorithm and key size:
enc Param ValueContent Encryption AlgorithmA128GCMAES GCM using 128 bit keyA192GCMAES GCM using 192 bit keyA256GCMAES GCM using 256 bit key
An example using this algorithm is shown in
Appendix A.1 of .
A JSON Web Key (JWK) is a
JSON
data structure that represents a cryptographic key.
These keys can be either asymmetric or symmetric.
They can hold both public and private information about the key.
This section defines the parameters for keys
using the algorithms specified by this document.
The table below is the set of
kty (key type) parameter
values that are defined by this specification for use in JWKs.
kty Param ValueKey TypeImplementation RequirementsECElliptic Curve Recommended+RSARSA RequiredoctOctet sequence (used to represent symmetric keys)Required
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 is EC.
An elliptic curve public key is represented by a pair of coordinates
drawn from a finite field, which together define a point on an elliptic curve.
The following members MUST be present for all elliptic curve public keys:
crvx
The following member MUST also be present for elliptic curve
public keys for the three curves defined in the following section:
y
The crv (curve) member identifies
the cryptographic curve used with the key. Curve values
from used by this specification are:
P-256P-384P-521
These values are registered in the IANA
JSON Web Key Elliptic Curve registry
defined in
.
Additional crv values can be registered by other specifications.
Specifications registering additional curves must define what parameters
are used to represent keys for the curves registered.
The crv value is a case-sensitive string.
SEC1 point compression is not supported for any of
these three curves.
The x (x coordinate) member contains the
x coordinate for the elliptic curve point.
It is represented as the base64url encoding of the
octet string representation of the coordinate,
as defined in Section 2.3.5 of SEC1.
The length of this octet string MUST be the full size of a coordinate
for the curve specified in the crv parameter.
For example, if the value of crv is
P-521, the octet string must be 66 octets long.
The y (y coordinate) member contains the
y coordinate for the elliptic curve point.
It is represented as the base64url encoding of the
octet string representation of the coordinate,
as defined in Section 2.3.5 of SEC1.
The length of this octet string MUST be the full size of a coordinate
for the curve specified in the crv parameter.
For example, if the value of crv is
P-521, the octet string must be 66 octets long.
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
octet string representation of the private key value,
as defined in Section 2.3.7 of SEC1.
The length of this octet string MUST be ceiling(log-base-2(n)/8)
octets (where n is the order of the curve).
JWKs can represent RSA keys. In
this case, the kty
member value is RSA.
The following 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 a Base64urlUInt encoded value.
Note that implementers have found that some cryptographic libraries
prefix an extra zero-valued octet to the modulus representations they return,
for instance, returning 257 octets for a 2048 bit key, rather than 256.
Implementations using such libraries will need to take care to omit
the extra octet from the base64url encoded representation.
The e (exponent) member contains
the exponent value for the RSA public key.
It is represented as a Base64urlUInt encoded value.
For instance, when representing the value 65537,
the octet sequence to be base64url encoded MUST consist of the
three octets [1, 0, 1];
the resulting representation for this value is "AQAB".
In addition to the members used to represent RSA public keys,
the following members are used to represent RSA private keys.
The parameter d is REQUIRED for RSA private keys.
The others enable optimizations and SHOULD be included by producers
of JWKs representing RSA private keys.
If the producer includes any of the other private key parameters,
then all of the others MUST be present,
with the exception of oth,
which MUST only be present when more than two prime factors were used.
The d (private exponent) member contains
the private exponent value for the RSA private key.
It is represented as a Base64urlUInt encoded value.
The p (first prime factor) member contains
the first prime factor.
It is represented as a Base64urlUInt encoded value.
The q (second prime factor) member contains
the second prime factor.
It is represented as a Base64urlUInt encoded value.
The dp (first factor CRT exponent)
member contains the Chinese Remainder Theorem (CRT) exponent
of the first factor.
It is represented as a Base64urlUInt encoded value.
The dq (second factor CRT exponent)
member contains the Chinese Remainder Theorem (CRT) exponent
of the second factor.
It is represented as a Base64urlUInt encoded value.
The qi (first CRT coefficient)
member contains the Chinese Remainder Theorem (CRT)
coefficient of the second factor.
It is represented as a Base64urlUInt encoded value.
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.
For more information on this case,
see the description of the OtherPrimeInfo parameters in
Section A.1.2 of RFC 3447,
upon which the following parameters are modelled.
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.
It is represented as a Base64urlUInt encoded value.
The d (Factor CRT Exponent) parameter
within an oth array member
represents the CRT exponent of the corresponding prime factor.
It is represented as a Base64urlUInt encoded value.
The t (factor CRT coefficient) parameter
within an oth array member
represents the CRT coefficient of the corresponding prime factor.
It is represented as a Base64urlUInt encoded value.
When the JWK kty
member value is oct (octet sequence),
the member k is used to represent
a symmetric key (or another key whose value is a single octet sequence).
An alg member SHOULD also be present
to identify the algorithm intended to be used with the key,
unless the application uses another means
or convention to determine the algorithm used.
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.
The following registration procedure is used for all the
registries established by this specification.
Values are registered on a Specification Required
basis after a three-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 the 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.
Registration requests that are undetermined for
a period longer than 21 days can be brought to the IESG's attention
(using the iesg@ietf.org mailing list) for resolution.
Criteria that should be applied by the Designated Expert(s) includes
determining whether the proposed registration duplicates existing functionality,
determining whether it is likely to be of general applicability
or whether it is useful only for a single application,
and whether the registration description is clear.
IANA must only accept registry updates from the Designated Expert(s) and should direct
all requests for registration to the review mailing list.
It is suggested that multiple Designated Experts be appointed who are able to
represent the perspectives of different applications using this specification,
in order to enable broadly-informed review of registration decisions.
In cases where a registration decision could be perceived as
creating a conflict of interest for a particular Expert,
that Expert should defer to the judgment of the other Expert(s).
[[ Note to the RFC Editor and IANA:
Pearl Liang of ICANN had requested that the draft supply the following
proposed registry description information.
It is to be used for all registries established by this specification.
Protocol Category: JSON Object Signing and Encryption (JOSE)
Registry Location: http://www.iana.org/assignments/jose
Webpage Title: (same as the protocol category)
Registry Name: (same as the section title, but excluding the word "Registry",
for example "JSON Web Signature and Encryption Algorithms")
]]
This specification establishes the
IANA JSON Web Signature and Encryption Algorithms registry
for values of the JWS and JWE
alg (algorithm) and
enc (encryption algorithm)
Header Parameters.
The registry records the algorithm name,
the algorithm usage locations,
implementation requirements,
and a reference to the specification that defines it.
The same algorithm name can be registered multiple times,
provided that the sets of usage locations are disjoint.
It is suggested that when multiple variations of algorithms are being registered
that use keys of different lengths and the key lengths for each need to be fixed
(for instance, because they will be created by key derivation functions),
that the length of the key be included in the algorithm name.
This allows readers of the JSON text to more easily make security decisions.
The Designated Expert(s) should perform reasonable due diligence
that algorithms being registered are either currently considered
cryptographically credible or are being registered as Deprecated
or Prohibited.
The implementation requirements of an algorithm may be changed
over time 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.
Changes of implementation requirements are only permitted
on a Specification Required basis after review by the Designated Experts(s),
with the new specification
defining the revised implementation requirements level.
The name requested (e.g., "HS256").
This name is case-sensitive.
Names may not match other registered names in a case-insensitive manner
unless the Designated Expert(s) state that there is a compelling reason
to allow an exception in this particular case.
Brief description of the Algorithm (e.g., "HMAC using SHA-256").
The algorithm usage location. This must be one or more of the values
alg or
enc
if the algorithm is to be used with JWS or JWE.
The value JWK is used if the algorithm
identifier will be used as a JWK alg
member value, but will not be used with JWS or JWE;
this could be the case, for instance, for non-authenticated encryption algorithms.
Other values may be used with the approval of a Designated Expert.
The algorithm implementation requirements for JWS and JWE, which must be one the words
Required, Recommended, Optional, Deprecated, or Prohibited.
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.
Any identifiers registered for non-authenticated encryption algorithms
or other algorithms that are otherwise unsuitable for direct use
as JWS or JWE algorithms must be registered as "Prohibited".
For Standards Track RFCs, state "IESG". 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 Description: HMAC using SHA-256
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Required
Change Controller: IESG
Specification Document(s):
of [[ this document ]]
Algorithm Name: HS384
Algorithm Description: HMAC using SHA-384
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s):
of [[ this document ]]
Algorithm Name: HS512
Algorithm Description: HMAC using SHA-512
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s):
of [[ this document ]]
Algorithm Name: RS256
Algorithm Description: RSASSA-PKCS-v1_5 using SHA-256
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: RS384
Algorithm Description: RSASSA-PKCS-v1_5 using SHA-384
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: RS512
Algorithm Description: RSASSA-PKCS-v1_5 using SHA-512
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ES256
Algorithm Description: ECDSA using P-256 and SHA-256
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended+
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ES384
Algorithm Description: ECDSA using P-384 and SHA-384
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ES512
Algorithm Description: ECDSA using P-521 and SHA-512
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PS256
Algorithm Description: RSASSA-PSS using SHA-256 and MGF1 with SHA-256
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PS384
Algorithm Description: RSASSA-PSS using SHA-384 and MGF1 with SHA-384
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PS512
Algorithm Description: RSASSA-PSS using SHA-512 and MGF1 with SHA-512
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: none
Algorithm Description: No digital signature or MAC performed
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: RSA1_5
Algorithm Description: RSAES-PKCS1-V1_5
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended-
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: RSA-OAEP
Algorithm Description: RSAES OAEP using default parameters
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended+
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: RSA-OAEP-256
Algorithm Description: RSAES OAEP using SHA-256 and MGF1 with SHA-256
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A128KW
Algorithm Description: AES Key Wrap using 128 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A192KW
Algorithm Description: AES Key Wrap using 192 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A256KW
Algorithm Description: AES Key Wrap using 256 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: dir
Algorithm Description: Direct use of a shared symmetric key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ECDH-ES
Algorithm Description: ECDH-ES using Concat KDF
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended+
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ECDH-ES+A128KW
Algorithm Description: ECDH-ES using Concat KDF
and A128KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ECDH-ES+A192KW
Algorithm Description: ECDH-ES using Concat KDF
and A192KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: ECDH-ES+A256KW
Algorithm Description: ECDH-ES using Concat KDF
and A256KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A128GCMKW
Algorithm Description: Key wrapping with AES GCM using 128 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A192GCMKW
Algorithm Description: Key wrapping with AES GCM using 192 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A256GCMKW
Algorithm Description: Key wrapping with AES GCM using 256 bit key
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PBES2-HS256+A128KW
Algorithm Description: PBES2 with HMAC SHA-256
and A128KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PBES2-HS384+A192KW
Algorithm Description: PBES2 with HMAC SHA-384
and A192KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: PBES2-HS512+A256KW
Algorithm Description: PBES2 with HMAC SHA-512
and A256KW wrapping
Algorithm Usage Location(s): alg
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A128CBC-HS256
Algorithm Description:
AES_128_CBC_HMAC_SHA_256 authenticated encryption algorithm
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Required
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A192CBC-HS384
Algorithm Description:
AES_192_CBC_HMAC_SHA_384 authenticated encryption algorithm
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A256CBC-HS512
Algorithm Description:
AES_256_CBC_HMAC_SHA_512 authenticated encryption algorithm
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Required
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A128GCM
Algorithm Description: AES GCM using 128 bit key
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A192GCM
Algorithm Description: AES GCM using 192 bit key
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Algorithm Name: A256GCM
Algorithm Description: AES GCM using 256 bit key
Algorithm Usage Location(s): enc
JOSE Implementation Requirements: Recommended
Change Controller: IESG
Specification Document(s): of [[ this document ]]
This specification registers the Header Parameter names defined in
, ,
and in the IANA
JSON Web Signature and Encryption Header Parameters registry
defined in
.
Header Parameter Name: epk
Header Parameter Description: Ephemeral Public Key
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: apu
Header Parameter Description: Agreement PartyUInfo
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: apv
Header Parameter Description: Agreement PartyVInfo
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: iv
Header Parameter Description: Initialization Vector
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: tag
Header Parameter Description: Authentication Tag
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: p2s
Header Parameter Description: PBES2 salt
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Header Parameter Name: p2c
Header Parameter Description: PBES2 count
Header Parameter Usage Location(s): JWE
Change Controller: IESG
Specification Document(s): of [[ this document ]]
This specification establishes the
IANA JSON Web Encryption Compression Algorithms registry
for JWE zip member values.
The registry records the compression algorithm value
and a reference to the specification that defines it.
The name requested (e.g., "DEF").
Because a core goal of this specification is for the resulting
representations to be compact, it is RECOMMENDED that the name be short
-- not to exceed 8 characters without a compelling reason to do so.
This name is case-sensitive.
Names may not match other registered names in a case-insensitive manner
unless the Designated Expert(s) state that there is a compelling reason
to allow an exception in this particular case.
Brief description of the compression algorithm (e.g., "DEFLATE").
For Standards Track RFCs, state "IESG". 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.
Compression Algorithm Value: DEF
Compression Algorithm Description: DEFLATE
Change Controller: IESG
Specification Document(s): JSON Web Encryption (JWE)
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,
implementation requirements,
and a reference to the specification that defines it.
The implementation requirements of a key type may be changed
over time as the
cryptographic landscape evolves, for instance,
to change the status of a key type to Deprecated, or
to change the status of a key type from Optional
to Recommended+ or Required.
Changes of implementation requirements are only permitted
on a Specification Required basis after review by the Designated Experts(s),
with the new specification
defining the revised implementation requirements level.
The name requested (e.g., "EC").
Because a core goal of this specification is for the resulting
representations to be compact, it is RECOMMENDED that the name be short
-- not to exceed 8 characters without a compelling reason to do so.
This name is case-sensitive.
Names may not match other registered names in a case-insensitive manner
unless the Designated Expert(s) state that there is a compelling reason
to allow an exception in this particular case.
Brief description of the Key Type (e.g., "Elliptic Curve").
For Standards Track RFCs, state "IESG". 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 key type implementation requirements for JWS and JWE, which must be one the words
Required, Recommended, Optional, Deprecated, or Prohibited.
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.
This specification registers the values defined in
.
"kty" Parameter Value: EC
Key Type Description: Elliptic Curve
JOSE Implementation Requirements: Recommended+
Change Controller: IESG
Specification Document(s): of [[ this document ]]
"kty" Parameter Value: RSA
Key Type Description: RSA
JOSE Implementation Requirements: Required
Change Controller: IESG
Specification Document(s): of [[ this document ]]
"kty" Parameter Value: oct
Key Type Description: Octet sequence
JOSE Implementation Requirements: Required
Change Controller: IESG
Specification Document(s): of [[ this document ]]
This specification registers the parameter names defined in
Sections ,
, and
in the
IANA JSON Web Key Parameters registry
defined in
.
Parameter Name: crv
Parameter Description: Curve
Used with "kty" Value(s): EC
Parameter Information Class: Public
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: x
Parameter Description: X Coordinate
Used with "kty" Value(s): EC
Parameter Information Class: Public
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: y
Parameter Description: Y Coordinate
Used with "kty" Value(s): EC
Parameter Information Class: Public
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: d
Parameter Description: ECC Private Key
Used with "kty" Value(s): EC
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: n
Parameter Description: Modulus
Used with "kty" Value(s): RSA
Parameter Information Class: Public
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: e
Parameter Description: Exponent
Used with "kty" Value(s): RSA
Parameter Information Class: Public
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: d
Parameter Description: Private Exponent
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: p
Parameter Description: First Prime Factor
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: q
Parameter Description: Second Prime Factor
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: dp
Parameter Description: First Factor CRT Exponent
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: dq
Parameter Description: Second Factor CRT Exponent
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: qi
Parameter Description: First CRT Coefficient
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: oth
Parameter Description: Other Primes Info
Used with "kty" Value(s): RSA
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Parameter Name: k
Parameter Description: Key Value
Used with "kty" Value(s): oct
Parameter Information Class: Private
Change Controller: IESG
Specification Document(s): of [[ this document ]]
This specification establishes the
IANA JSON Web Key Elliptic Curve registry
for JWK crv member values.
The registry records the curve name,
implementation requirements,
and a reference to the specification that defines it.
This specification registers the parameter names defined in
.
The implementation requirements of a curve may be changed
over time as the
cryptographic landscape evolves, for instance,
to change the status of a curve to Deprecated, or
to change the status of a curve from Optional
to Recommended+ or Required.
Changes of implementation requirements are only permitted
on a Specification Required basis after review by the Designated Experts(s),
with the new specification
defining the revised implementation requirements level.
The name requested (e.g., "P-256").
Because a core goal of this specification is for the resulting
representations to be compact, it is RECOMMENDED that the name be short
-- not to exceed 8 characters without a compelling reason to do so.
This name is case-sensitive.
Names may not match other registered names in a case-insensitive manner
unless the Designated Expert(s) state that there is a compelling reason
to allow an exception in this particular case.
Brief description of the curve (e.g., "P-256 curve").
The curve implementation requirements for JWS and JWE, which must be one the words
Required, Recommended, Optional, Deprecated, or Prohibited.
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 "IESG". 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.
Curve Name: P-256
Curve Description: P-256 curve
JOSE Implementation Requirements: Recommended+
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Curve Name: P-384
Curve Description: P-384 curve
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
Curve Name: P-521
Curve Description: P-521 curve
JOSE Implementation Requirements: Optional
Change Controller: IESG
Specification Document(s): of [[ this document ]]
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.
The security considerations in
,
,
,
,
,
,
,
,
,
,
,
,
, and
apply to this specification.
Implementers should be aware that cryptographic algorithms become
weaker with time. As new cryptanalysis techniques are developed and
computing performance improves, the work factor to break a particular
cryptographic algorithm will be reduced.
Therefore, implementers and deployments must be prepared for
the set of algorithms that are supported and used to change over time.
Thus, cryptographic algorithm implementations should be modular,
allowing new algorithms to be readily inserted.
Many algorithms have associated security considerations related to
key lifetimes and/or the number of times that a key may be used.
Those security considerations continue to apply when using
those algorithms with JOSE data structures.
See NIST SP 800-57 for specific
guidance on key lifetimes.
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 is commonly implemented.
Keys used with RSAES-PKCS1-v1_5 must follow the constraints in
Section 7.2 of RFC 3447.
Also, keys with a low public key exponent value,
as described in Section 3 of
Twenty years of attacks on the RSA cryptosystem,
must not be used.
Keys used with AES GCM must follow the constraints in
Section 8.3 of , which states:
"The total number of invocations of the authenticated
encryption function shall not exceed 2^32, including all IV
lengths and all instances of the authenticated encryption
function with the given key".
In accordance with this rule, AES GCM MUST NOT be used
with the same key value
more than 2^32 times.
An Initialization Vector value MUST NOT ever be used multiple times
with the same AES GCM key.
One way to prevent this is to store a counter with the key
and increment it with every use.
The counter can also be used to prevent exceeding the 2^32 limit above.
This security consideration does not apply to the
composite AES-CBC HMAC SHA-2 or AES Key Wrap algorithms.
Unsecured JWSs (JWSs that use the alg
value none) provide no integrity protection.
Thus, they must only be used in contexts in which the payload is secured by
means other than a digital signature or MAC value, or need not be secured.
Implementations that support Unsecured JWS objects
MUST NOT accept such objects as valid unless the application
specifies that it is acceptable for a specific object to not be
integrity-protected.
Implementations MUST NOT accept Unsecured JWS objects by default.
For example, the "verify" method of a hypothetical JWS software library
might have a Boolean "acceptUnsigned" parameter
that indicates none is
an acceptable alg value.
As another example, the "verify" method might take a list of algorithms
that are acceptable to the application as a parameter and would reject
Unsecured JWS values if none is not in that list.
In order to mitigate downgrade attacks, applications MUST NOT signal
acceptance of Unsecured JWS objects at a global level,
and SHOULD signal acceptance on a per-object basis.
For example, suppose an application accepts JWS objects over two channels,
(1) HTTP and (2) HTTPS with client authentication.
It requires a JWS signature on objects received over HTTP,
but accepts Unsecured JWS objects over HTTPS.
If the application were to globally indicate that
none is acceptable, then an attacker could
provide it with an unsigned object over HTTP and still have
that object successfully validate.
Instead, the application needs to indicate acceptance of
none for each object received over HTTPS
(e.g., by setting "acceptUnsigned" to "true" for the first hypothetical
JWS software library above), but not for each object received over HTTP.
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
supply content using keys that would result in excessive
cryptographic processing, for example, keys larger than those
mandated in this specification.
Implementations should set and enforce upper limits
on the key sizes they accept.
Section 5.6.1 (Comparable Algorithm Strengths)
of NIST SP 800-57
contains statements on largest approved key sizes that may be applicable.
It is NOT RECOMMENDED to reuse the same entire set of key material
(Key Encryption Key, Content Encryption Key, Initialization Vector, etc.)
to encrypt multiple JWK or JWK Set objects, or to encrypt
the same JWK or JWK Set object multiple times.
One suggestion for preventing re-use is to always generate
at least one new piece of key material for each encryption operation
(e.g., a new Content Encryption Key, a new Initialization Vector, and/or a new PBES2 Salt),
based on the considerations noted in this document
as well as from RFC 4086.
Passwords are vulnerable to
a number of attacks. To help mitigate some of these
limitations, this document applies principles from
RFC 2898 to derive cryptographic keys from
user-supplied passwords.
However, the strength of the password still has a
significant impact. A high-entropy password has greater
resistance to dictionary attacks.
contains guidelines for
estimating password entropy, which can help applications and
users generate stronger passwords.
An ideal password is one that is as large as (or larger than)
the derived key length. However, passwords larger than
a certain algorithm-specific size are first
hashed, which reduces an attacker's effective search space
to the length of the hash algorithm.
It is RECOMMENDED that a password used for
PBES2-HS256+A128KW be
no shorter than 16 octets and no longer than 128 octets and
a password used for PBES2-HS512+A256KW be
no shorter than 32 octets and no longer than 128 octets long.
Still, care needs to be taken in where and how
password-based encryption is used. These algorithms can still be
susceptible to dictionary-based attacks if the iteration count is too small;
this is of particular concern if these algorithms are used to protect data
that an attacker can have indefinite number of attempts to circumvent
the protection, such as protected data stored on a file system.
See Section 10.1 of for security considerations on
key entropy and random values.
See Section 10.5 of for security considerations on
differences between digital signatures and MACs.
See Section 11.3 of for security considerations on
using matching algorithm strengths.
See Section 11.4 of for security considerations on
adaptive chosen-ciphertext attacks.
See Section 10.9 of
and Section 11.5 of for security considerations on
timing attacks.
See Section 9.3 of for security considerations on
RSA private key representations and blinding.
Passwords obtained from users are likely to require
preparation and normalization to account for differences of
octet sequences generated by different input devices, locales, etc.
It is RECOMMENDED that applications to perform the steps
outlined in
to prepare a password supplied directly by a user
before performing key derivation and encryption.
ASCII format for Network InterchangeUniversity California Los Angeles (UCLA)For concreteness, we suggest the use of standard 7-bit ASCII embedded in an 8 bit byte whose high order bit is always 0.Secure Hash Standard (SHS)National Institute of Standards and
TechnologyDigital Signature Standard (DSS)National Institute of Standards and
TechnologyAdvanced Encryption Standard (AES)National Institute of Standards and Technology (NIST)
Recommendation for Block Cipher Modes of OperationNational 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)
Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm CryptographyNational Institute of Standards and Technology (NIST)
Recommendation for Key Management - Part 1: General (Revision 3)National Institute of Standards and Technology (NIST)
JSON Web Signature (JWS)Microsoftmbj@microsoft.comhttp://self-issued.info/Ping Identityve7jtb@ve7jtb.comNomura Research Instituten-sakimura@nri.co.jpJSON Web Encryption (JWE)Microsoftmbj@microsoft.comhttp://self-issued.info/Cisco Systems, Inc.jhildebr@cisco.comJSON Web Key (JWK)Microsoftmbj@microsoft.comhttp://self-issued.info/Coded Character Set -- 7-bit American Standard Code for Information InterchangeAmerican National Standards InstituteSEC 1: Elliptic Curve CryptographyStandards for Efficient Cryptography GroupTwenty years of attacks on the RSA cryptosystemXML Signature Syntax and Processing Version 2.0XML Encryption Syntax and Processing Version 1.1Magic SignaturesJSON Simple SignindependentNomura Research InstituteJSON Simple EncryptionindependentNomura Research InstituteCanvas ApplicationsJava Cryptography Architecture (JCA) Reference GuideElectronic Authentication GuidelineNational Institute of Standards and Technology (NIST)Recommendation for Applications Using Approved Hash AlgorithmsNational Institute of Standards and Technology (NIST)
This appendix contains tables cross-referencing the
cryptographic algorithm identifier
values defined in this specification with the equivalent identifiers
used by other standards and software packages.
See XML DSIG,
XML DSIG 2.0,
XML Encryption,
XML Encryption 1.1,
and Java Cryptography Architecture
for more information about the names defined by those
documents.
This section contains a table cross-referencing the
JWS digital signature and MAC alg (algorithm)
values defined in this specification with the equivalent identifiers
used by other standards and software packages.
JWSXML DSIGJCAOIDHS256http://www.w3.org/2001/04/xmldsig-more#hmac-sha256HmacSHA2561.2.840.113549.2.9HS384http://www.w3.org/2001/04/xmldsig-more#hmac-sha384HmacSHA3841.2.840.113549.2.10HS512http://www.w3.org/2001/04/xmldsig-more#hmac-sha512HmacSHA5121.2.840.113549.2.11RS256http://www.w3.org/2001/04/xmldsig-more#rsa-sha256SHA256withRSA1.2.840.113549.1.1.11RS384http://www.w3.org/2001/04/xmldsig-more#rsa-sha384SHA384withRSA1.2.840.113549.1.1.12RS512http://www.w3.org/2001/04/xmldsig-more#rsa-sha512SHA512withRSA1.2.840.113549.1.1.13ES256http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256SHA256withECDSA1.2.840.10045.4.3.2ES384http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384SHA384withECDSA1.2.840.10045.4.3.3ES512http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512SHA512withECDSA1.2.840.10045.4.3.4PS256http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1SHA256withRSAandMGF11.2.840.113549.1.1.10PS384http://www.w3.org/2007/05/xmldsig-more#sha384-rsa-MGF1SHA384withRSAandMGF11.2.840.113549.1.1.10PS512http://www.w3.org/2007/05/xmldsig-more#sha512-rsa-MGF1SHA512withRSAandMGF11.2.840.113549.1.1.10
This section contains a table cross-referencing the
JWE alg (algorithm)
values defined in this specification with the equivalent identifiers
used by other standards and software packages.
JWEXML ENCJCAOIDRSA1_5http://www.w3.org/2001/04/xmlenc#rsa-1_5RSA/ECB/PKCS1Padding1.2.840.113549.1.1.1RSA-OAEPhttp://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1pRSA/ECB/OAEPWithSHA-1AndMGF1Padding1.2.840.113549.1.1.7RSA-OAEP-256http://www.w3.org/2009/xmlenc11#rsa-oaep & http://www.w3.org/2009/xmlenc11#mgf1sha256RSA/ECB/OAEPWithSHA-256AndMGF1Padding & MGF1ParameterSpec.SHA2561.2.840.113549.1.1.7ECDH-EShttp://www.w3.org/2009/xmlenc11#ECDH-ESECDH1.3.132.1.12A128KWhttp://www.w3.org/2001/04/xmlenc#kw-aes128AESWrap2.16.840.1.101.3.4.1.5A192KWhttp://www.w3.org/2001/04/xmlenc#kw-aes192AESWrap2.16.840.1.101.3.4.1.25A256KWhttp://www.w3.org/2001/04/xmlenc#kw-aes256AESWrap2.16.840.1.101.3.4.1.45
This section contains a table cross-referencing the
JWE enc (encryption algorithm)
values defined in this specification with the equivalent identifiers
used by other standards and software packages.
For the composite algorithms A128CBC-HS256,
A192CBC-HS384,
and A256CBC-HS512, the corresponding AES CBC
algorithm identifiers are listed.
JWEXML ENCJCAOIDA128CBC-HS256http://www.w3.org/2001/04/xmlenc#aes128-cbcAES/CBC/PKCS5Padding2.16.840.1.101.3.4.1.2A192CBC-HS384http://www.w3.org/2001/04/xmlenc#aes192-cbcAES/CBC/PKCS5Padding2.16.840.1.101.3.4.1.22A256CBC-HS512http://www.w3.org/2001/04/xmlenc#aes256-cbcAES/CBC/PKCS5Padding2.16.840.1.101.3.4.1.42A128GCMhttp://www.w3.org/2009/xmlenc11#aes128-gcmAES/GCM/NoPadding2.16.840.1.101.3.4.1.6A192GCMhttp://www.w3.org/2009/xmlenc11#aes192-gcmAES/GCM/NoPadding2.16.840.1.101.3.4.1.26A256GCMhttp://www.w3.org/2009/xmlenc11#aes256-gcmAES/GCM/NoPadding2.16.840.1.101.3.4.1.46
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.
This example uses ECDH-ES Key Agreement and the Concat KDF to derive the
Content Encryption Key (CEK) in the manner described in
.
In this example, the ECDH-ES Direct Key Agreement mode
(alg value ECDH-ES)
is used to produce an agreed upon key for AES GCM with a 128 bit key
(enc value A128GCM).
In this example, a sender Alice is encrypting content to a recipient Bob.
The sender (Alice) generates an ephemeral key for the key agreement computation.
Alice's ephemeral key (in JWK format) used for the key agreement computation
in this example (including the private part) is:
The recipient's (Bob's) key (in JWK format) used for the key agreement computation
in this example (including the private part) is:
Header Parameter values used in this example are as follows.
In this example,
the apu (agreement PartyUInfo) parameter value
is the base64url encoding of the UTF-8 string "Alice" and
the apv (agreement PartyVInfo) parameter value
is the base64url encoding of the UTF-8 string "Bob".
The epk parameter is used to communicate
the sender's (Alice's) ephemeral public key value to the recipient (Bob).
The resulting Concat KDF parameter values are:
This is set to the ECDH-ES key agreement output.
(This value is often not directly exposed by libraries,
due to NIST security requirements, and only serves as an input to a KDF.)
In this example, Z is following the octet sequence (using JSON array notation):
[158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132, 38, 156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121, 140, 254, 144, 196].
This value is 128 - the number of bits in the desired output key
(because A128GCM uses a 128 bit key).
This is set to the octets representing the 32 bit big endian value 7
- [0, 0, 0, 7] - the number of octets in the AlgorithmID content "A128GCM",
followed, by the octets representing the UTF-8 string "A128GCM"
- [65, 49, 50, 56, 71, 67, 77].
This is set to the octets representing the 32 bit big endian value 5
- [0, 0, 0, 5] - the number of octets in the PartyUInfo content "Alice",
followed, by the octets representing the UTF-8 string "Alice"
- [65, 108, 105, 99, 101].
This is set to the octets representing the 32 bit big endian value 3
- [0, 0, 0, 3] - the number of octets in the PartyUInfo content "Bob",
followed, by the octets representing the UTF-8 string "Bob"
- [66, 111, 98].
This is set to the octets representing the 32 bit big endian value 128
- [0, 0, 0, 128] - the keydatalen value.
This is set to the empty octet sequence.
Concatenating the parameters AlgorithmID through SuppPubInfo results in
an OtherInfo value of:
[0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105, 99, 101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]
Concatenating the round number 1 ([0, 0, 0, 1]), Z,
and the OtherInfo value results in the Concat KDF round 1 hash input of:
[0, 0, 0, 1,
158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132, 38, 156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121, 140, 254, 144, 196,
0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105, 99, 101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]
The resulting derived key, which is the first 128 bits of the round 1 hash output is:
[86, 170, 141, 234, 248, 35, 109, 32, 92, 34, 40, 205, 113, 167, 16, 26]
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.
Matt Miller wrote
Using JavaScript Object Notation (JSON)
Web Encryption (JWE) for Protecting JSON Web Key (JWK) Objects,
which the password-based encryption content of this draft is based upon.
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,
Carsten Bormann,
John Bradley,
Brian Campbell,
Alissa Cooper,
Breno de Medeiros,
Vladimir Dzhuvinov,
Roni Even,
Stephen Farrell,
Yaron Y. Goland,
Dick Hardt,
Joe Hildebrand,
Jeff Hodges,
Edmund Jay,
Charlie Kaufman,
Barry Leiba,
James Manger,
Matt Miller,
Kathleen Moriarty,
Tony Nadalin,
Axel Nennker,
John Panzer,
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.
[[ to be removed by the RFC Editor before publication as an RFC ]]
-35
Addressed AppsDir reviews by Carsten Bormann.
Adjusted some table column widths.
-34
Addressed IESG review comments by Barry Leiba, Alissa Cooper, Pete Resnick,
Stephen Farrell, and Richard Barnes.
-33
Changed the registration review period to three weeks.
Acknowledged additional contributors.
-32
Added a note to implementers about libraries that prefix an extra
zero-valued octet to RSA modulus representations returned.
Addressed secdir review comments by Charlie Kaufman, Scott Kelly, and Stephen Kent.
Addressed Gen-ART review comments by Roni Even.
Replaced the term Plaintext JWS with Unsecured JWS.
-31
Referenced NIST SP 800-57 for guidance on key lifetimes.
Updated the reference to draft-mcgrew-aead-aes-cbc-hmac-sha2.
-30
Cleaned up the reference syntax in a few places.
Applied minor wording changes to the Security Considerations section.
-29
Replaced the terms JWS Header, JWE Header, and JWT Header
with a single JOSE Header term defined in the JWS specification.
This also enabled a single Header Parameter definition to be used
and reduced other areas of duplication between specifications.
-28
Specified the use of PKCS #7 padding with AES CBC, rather than PKCS #5.
(PKCS #7 is a superset of PKCS #5, and is appropriate for the 16 octet blocks used by AES CBC.)
Revised the introduction to the Security Considerations section.
Also introduced additional subsection headings for security considerations items
and moved a few security consideration items from here to the JWS and JWE drafts.
-27
Described additional security considerations.
Updated the JCA and XMLENC parameters for
RSA-OAEP-256
and the JCA parameters for
A128KW,
A192KW,
A256KW,
and ECDH-ES.
-26
Added algorithm identifier RSA-OAEP-256 for
RSAES OAEP using SHA-256 and MGF1 with SHA-256.
Clarified that the ECDSA signature values R and S are represented as
octet sequences as defined in Section 2.3.7 of SEC1.
Noted that octet sequences are depicted using JSON array notation.
Updated references, including to W3C specifications.
-25
Corrected an external section number reference that had changed.
-24
Replaced uses of the term "associated data" wherever it was used
to refer to a data value with "additional authenticated data",
since both terms were being used as synonyms, causing confusion.
Updated the JSON reference to RFC 7159.
-23
No changes were made, other than to the version number and date.
-22
Corrected RFC 2119 terminology usage.
Replaced references to draft-ietf-json-rfc4627bis with RFC 7158.
-21
Compute the PBES2 salt parameter as (UTF8(Alg) || 0x00 || Salt Input),
where the p2s Header Parameter
encodes the Salt Input value and
Alg is the alg Header Parameter value.
Changed some references from being normative to informative,
addressing issue #90.
-20
Replaced references to RFC 4627 with draft-ietf-json-rfc4627bis,
addressing issue #90.
-19
Used tables to show the correspondence between algorithm identifiers and
algorithm descriptions and parameters in the algorithm definition sections,
addressing issue #183.
Changed the "Implementation Requirements" registry field names to
"JOSE Implementation Requirements" to make it clear that these
implementation requirements apply only to JWS and JWE implementations.
-18
Changes to address editorial and minor issues
#129, #134, #135, #158, #161, #185, #186, and #187.
Added and used Description registry fields.
-17
Explicitly named all the logical components of a JWS and JWE
and defined the processing rules and serializations
in terms of those components,
addressing issues #60, #61, and #62.
Removed processing steps in algorithm definitions that duplicated
processing steps in JWS or JWE,
addressing issue #56.
Replaced verbose repetitive phases such as
"base64url encode the octets of the UTF-8 representation of X"
with mathematical notation such as "BASE64URL(UTF8(X))".
Terms used in multiple documents are now defined in
one place and incorporated by reference.
Some lightly used or obvious terms were also removed.
This addresses issue #58.
Changes to address minor issue
#53.
-16
Added a DataLen prefix to the AlgorithmID value in the Concat KDF computation.
Added OIDs for encryption algorithms, additional signature algorithm OIDs,
and additional XML DSIG/ENC URIs in the algorithm cross-reference tables.
Changes to address editorial and minor issues
#28, #36, #39, #52, #53, #55, #127, #128, #136, #137, #141,
#150, #151, #152, and #155.
-15
Changed statements about rejecting JWSs to statements about
validation failing,
addressing issue #35.
Stated that changes of implementation requirements are only permitted
on a Specification Required basis,
addressing issue #38.
Made oct a required key type,
addressing issue #40.
Updated the example ECDH-ES key agreement values.
Changes to address editorial and minor issues
#34, #37, #49, #63, #123, #124, #125, #130, #132, #133, #138, #139,
#140, #142, #143, #144, #145, #148, #149, #150, and #162.
-14
Removed PBKDF2 key type and
added p2s and p2c
header parameters for use with the PBES2 algorithms.
Made the RSA private key parameters that are there to enable optimizations
be RECOMMENDED rather than REQUIRED.
Added algorithm identifiers for AES algorithms using 192 bit keys
and for RSASSA-PSS using HMAC SHA-384.
Added security considerations about key lifetimes,
addressing issue #18.
Added an example ECDH-ES key agreement computation.
-13
Added key encryption with AES GCM
as specified in draft-jones-jose-aes-gcm-key-wrap-01,
addressing issue #13.
Added security considerations text limiting the number of times that
an AES GCM key can be used for key encryption or direct encryption,
per Section 8.3 of NIST SP 800-38D,
addressing issue #28.
Added password-based key encryption
as specified in draft-miller-jose-jwe-protected-jwk-02.
-12
In the Direct Key Agreement case,
the Concat KDF AlgorithmID is set to
the octets of the UTF-8 representation of the
enc header parameter value.
Restored the apv (agreement PartyVInfo) parameter.
Moved the
epk,
apu, and
apv
Header Parameter definitions to be with
the algorithm descriptions that use them.
Changed terminology from "block encryption" to "content encryption".
-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".