Internet DRAFT - draft-rha-jose-hpke-encrypt
draft-rha-jose-hpke-encrypt
JOSE T. Reddy
Internet-Draft Nokia
Intended status: Standards Track H. Tschofenig
Expires: 3 September 2024
A. Banerjee
Nokia
O. Steele
Transmute
M. Jones
independent
2 March 2024
Use of Hybrid Public-Key Encryption (HPKE) with Javascript Object
Signing and Encryption (JOSE)
draft-rha-jose-hpke-encrypt-05
Abstract
This specification defines Hybrid public-key encryption (HPKE) for
use with Javascript Object Signing and Encryption (JOSE). HPKE
offers a variant of public-key encryption of arbitrary-sized
plaintexts for a recipient public key.
HPKE works for any combination of an asymmetric key encapsulation
mechanism (KEM), key derivation function (KDF), and authenticated
encryption with additional data (AEAD) function. Authentication for
HPKE in JOSE is provided by JOSE-native security mechanisms or by one
of the authenticated variants of HPKE.
This document defines the use of the HPKE with JOSE.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-rha-jose-hpke/.
Discussion of this document takes place on the jose Working Group
mailing list (mailto:jose@ietf.org), which is archived at
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https://www.ietf.org/mailman/listinfo/jose/.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
4. HPKE for JOSE . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. HPKE Encryption . . . . . . . . . . . . . . . . . . . . . 5
4.3. HPKE Decryption . . . . . . . . . . . . . . . . . . . . . 6
4.4. Encapsulated JSON Web Keys . . . . . . . . . . . . . . . 6
4.4.1. HPKE Direct Encryption . . . . . . . . . . . . . . . 6
4.4.2. HPKE Key Encryption . . . . . . . . . . . . . . . . . 8
5. Ciphersuite Registration . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6.1. Plaintext Compression . . . . . . . . . . . . . . . . . . 12
6.2. Header Parameters . . . . . . . . . . . . . . . . . . . . 12
6.3. Ensure Cryptographic Keys Have Sufficient Entropy . . . . 12
6.4. Validate Cryptographic Inputs . . . . . . . . . . . . . . 12
6.5. Use Appropriate Algorithms . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7.1. JSON Web Key Types . . . . . . . . . . . . . . . . . . . 13
7.2. JSON Web Key Parameters . . . . . . . . . . . . . . . . . 13
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7.3. JSON Web Signature and Encryption Algorithms . . . . . . 13
7.4. JSON Web Signature and Encryption Header Parameters . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . 17
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
Hybrid public-key encryption (HPKE) [RFC9180] is a scheme that
provides public key encryption of arbitrary-sized plaintexts given a
recipient's public key.
This specification enables JSON Web Encryption (JWE) to leverage
HPKE, bringing support for KEMs and the possibility of Post Quantum
or Hybrid KEMs to JWE.
2. Conventions and Definitions
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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Conventions and Terminology
This specification uses the following abbreviations and terms:
* Key Type (kty), see [RFC7517].
* Content Encryption Key (CEK), is defined in [RFC7517].
* Hybrid Public Key Encryption (HPKE) is defined in [RFC9180].
* pkR is the public key of the recipient, as defined in [RFC9180].
* skR is the private key of the recipient, as defined in [RFC9180].
* Key Encapsulation Mechanism (KEM), see [RFC9180].
* Key Derivation Function (KDF), see [RFC9180].
* Authenticated Encryption with Associated Data (AEAD), see
[RFC9180].
* Additional Authenticated Data (AAD), see [RFC9180].
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4. HPKE for JOSE
4.1. Overview
JSON Web Encryption (JWE) [RFC7516] defines several serializations
for expressing encrypted content with JSON:
* Compact JWE Serialization
* General JWE JSON Serialization
* Flattened JWE JSON Serialization
JSON Web Algorithms (JWA) Section 4.6 of [RFC7518] defines two ways
to use public key cryptography with JWE:
* Direct Key Agreement
* Key Agreement with Key Wrapping
The specification enables Hybrid Public Key Encryption (HPKE)
[RFC9180] to be used with the serializations defined in JWE.
Unless otherwise stated, no changes to the processes described in
[RFC7516] have been made.
This specification describes two modes of use for HPKE in JWE:
* HPKE Direct Encryption mode, where HPKE is used to encrypt the
plaintext. This mode can only be used with a single recipient.
This setup is conceptually similar to Direct Key Agreement.
* HPKE Key Encryption mode, where HPKE is used to encrypt a content
encryption key (CEK) and the CEK is subsequently used to encrypt
the plaintext. This mode supports multiple recipients. This
setup is conceptually similar to Key Agreement with Key Wrapping.
When the alg value or enc value is set to any of algorithms
registered by this specification then the 'epk' header parameter MUST
be present, and it MUST be a JSON Web Key as defined in Section 4.4
of this document.
The "ek" member of an 'epk' will contain the base64url encoded "enc"
value produced by the encapsulate operation of the HPKE KEM.
In all serializations, "ct" will be base64url encoded.
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If the 'alg' header parameter is set to the 'HPKE-DirEnc' value (as
defined in Section 7), HPKE is used in Direct Encryption mode;
otherwise, it is in Key Encryption mode.
Interested readers will observe this is due to all recipients using
the same JWE Protected Header when JSON Serializations are used, as
described in Section 7.2.1 of [RFC7516].
We provide the following table for additional clarity:
+============+============+================+============+=========+
| Name | Recipients | Serializations | Content |Similar |
| | | | Encryption |to |
| | | | Key | |
+============+============+================+============+=========+
| Direct | 1 | Compact, JSON | Derived |Direct |
| Encryption | | | from HPKE |Key |
| | | | |Agreement|
+------------+------------+----------------+------------+---------+
| Key | 1 or More | Compact, JSON | Encrypted |Key |
| Encryption | | | by HPKE |Agreement|
| | | | |with Key |
| | | | |Wrapping |
+------------+------------+----------------+------------+---------+
Table 1: JOSE HPKE Serializations and Modes
4.2. HPKE Encryption
The message encryption process is as follows.
1. The sending HPKE context is created by invoking invoking
SetupBaseS() (Section 5.1.1 of [RFC9180]) with the recipient's
public key "pkR" and "info". The HPKE specification defines the
"info" parameter as a context information structure that is used
to ensure that the derived keying material is bound to the
context of the transaction. The SetupBaseS function will be
called with the default value of an empty string for the 'info'
parameter. This yields the context "sctxt" and an encapsulation
key "enc".
There exist two cases of HPKE plaintext which need to be
distinguished:
* In HPKE Direct Encryption mode, the plaintext "pt" passed into
Seal is the content to be encrypted. Hence, there is no
intermediate layer utilizing a CEK.
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* In HPKE Key Encryption mode, the plaintext "pt" passed into Seal
is the CEK. The CEK is a random byte sequence of length
appropriate for the encryption algorithm. For example, AES-
128-GCM requires a 16 byte key and the CEK would therefore be 16
bytes long.
4.3. HPKE Decryption
The recipient will create the receiving HPKE context by invoking
SetupBaseR() (Section 5.1.1 of [RFC9180]) with "skR", "enc" (output
of base64url decoded 'ek'), and "info" (empty string). This yields
the context "rctxt". The receiver then decrypts "ct" by invoking the
Open() method on "rctxt" (Section 5.2 of [RFC9180]) with "aad",
yielding "pt" or an error on failure.
The Open function will, if successful, decrypts "ct". When
decrypted, the result will be either the CEK (when Key Encryption
mode is used), or the content (if Direct Encryption mode is used).
The CEK is the symmetric key used to decrypt the ciphertext.
4.4. Encapsulated JSON Web Keys
An encapsulated key is represented as JSON Web Key as described in {
Section 4 of RFC7515 }.
The "kty" parameter MUST be "EK".
The "ek" parameter MUST be present, and MUST be the base64url encoded
output of the encap operation defined for the HPKE KEM.
As described in { Section 4 of RFC7515 }, additional members can be
present in the JWK; if not understood by implementations encountering
them, they MUST be ignored.
This example demonstrates the representaton of an encapsulated key as
a JWK.
{
"kty": "EK",
"ek": "BHpP-u5JKziyUpqxNQqb0apHx1ecH2UzcRlhHR4ngJVS__gNu21DqqgPweuPpjglnXDnOuQ4kt9tHCs3PUzPxQs"
}
4.4.1. HPKE Direct Encryption
This mode only supports a single recipient.
HPKE is employed to directly encrypt the plaintext, and the resulting
ciphertext is included in the JWE ciphertext.
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In HPKE Direct Encryption mode:
* The "epk" Header Parameter MUST be present, it MUST contain an
Encapsulated JSON Web Key and it MUST occur only within the JWE
Protected Header.
* The "alg" Header Parameter MUST be "HPKE-DirEnc", "enc" MUST be an
HPKE algorithm from JSON Web Signature and Encryption Algorithms
in [JOSE-IANA] and they MUST occur only within the JWE Protected
Header.
* The JWE Ciphertext MUST be the resulting HPKE ciphertext ('ct'
value) encoded using base64url.
* The JWE Initialization Vector value MUST be absent.
* The JWE Authentication Tag MUST be absent.
* The JWE Encrypted Key MUST be absent.
* The HPKE "aad" parameter MUST be set to the JWE Additional
Authenticated Data encryption parameter defined in Step 14 of
Section 5.1 of [RFC7516] as input.
The following example demonstrates the use of Direct Encryption with
Compact Serialization:
eyJhbGciOiJkaXIiLCJlbmMiOiJIUEtFLUJhc2UtUDI1Ni1TSEEyNTYtQUVTMTI4R0NNIiwiZXBrIjp7Imt0eSI6IkVLIiwiZWsiOiJCR05ranp0MDc2YnNSR2o3OGFYNUF6VF9IRU9KQmJZOXEyWm9fNWU3dGJLMGFQcXU0ZVQxV0kxNmp2UmxacXBNeXFaZlAtUndSNEp3dGF6XzhVOXRoWEEifX0...DG3qygxcMHw3iACy5mX_T4N4EqWc03W0nkTHjMJsC4nb6JS6vVj6wTGdlr5TOSr0ykaoyzpePXEvEyHhvpUwCyQQr6kbGlGuZsrJdUbZ728vmA.
Figure 1: Direct Encryption with Compact Serialization
In the above example, the JWE Protected Header value is:
{
"alg": "HPKE-DirEnc",
"enc": "HPKE-Base-P256-SHA256-AES128GCM",
"epk": {
"kty": "EK",
"ek": "BGNkjzt076bsRGj78aX5AzT_HEOJBbY9q2Zo_5e7tbK0aPqu4eT1WI16jvRlZqpMyqZfP-RwR4Jwtaz_8U9thXA"
}
}
{
"protected": "eyJhbGciOiJkaXIiLCJlbmMiOiJIUEtFLUJhc2UtUDI1Ni1TSEEyNTYtQUVTMTI4R0NNIiwiZXBrIjp7Imt0eSI6IkVLIiwiZWsiOiJCTzRFbGZXd0xKRDZWcERza3c5LWxWMm9OMDJ2U1FKTW55ZHk3enhvSVlKZ1kydk9taE44Q1BqSHdRM1NONkhTcnNHNElacVpHVUR3dExKZjBoeHFTWGsifX0",
"ciphertext": "1ATsw0jshqPrv8CFcm9Rem9Wfi1Ygv30sozlRTtNNzcaaZ828GqP0AXtqQ1Msv8YXI9XZqh81MK3QnlZ7pOBC1BP7j00J1rrHujdb3zvnOpmJg"
}
Figure 2: Direct Encryption with JSON Serialization
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In the above example, the JWE Protected Header value is:
{
"alg": "HPKE-DirEnc",
"enc": "HPKE-Base-P256-SHA256-AES128GCM",
"epk": {
"kty": "EK",
"ek": "BGNkjzt076bsRGj78aX5AzT_HEOJBbY9q2Zo_5e7tbK0aPqu4eT1WI16jvRlZqpMyqZfP-RwR4Jwtaz_8U9thXA"
}
}
4.4.2. HPKE Key Encryption
This mode supports more than one recipient.
HPKE is used to encrypt the Content Encryption Key (CEK), and the
resulting ciphertext is included in the JWE Encrypted Key. The
plaintext will be encrypted using the CEK as explained in Step 15 of
Section 5.1 of [RFC7516].
When there are multiple recipients, the sender MUST place the 'epk'
parameter in the per-recipient unprotected header to indicate the use
of HPKE. In this case, the 'enc' (Encryption Algorithm) Header
Parameter MUST be a content encryption algorithm from JSON Web
Signature and Encryption Algorithms in [JOSE-IANA], and it MUST be
present in the JWE Protected Header. The integrity-protected 'enc'
parameter provides protection against an attacker who manipulates the
encryption algorithm in the 'enc' parameter. This attack is
discussed in [I-D.draft-ietf-lamps-cms-cek-hkdf-sha256].
In HPKE Key Encryption mode:
* The JWE Encrypted Key MUST be the resulting HPKE ciphertext ('ct'
value) encoded using base64url.
The following example demonstrates the use of Key Encryption with
General JSON Serialization:
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{
"protected": "eyJlbmMiOiJBMTI4R0NNIn0",
"ciphertext": "S0qqrM3xXPUavbmL9LQkgUKRBu8BZ7DQWoT-mdNIZVU-ip_V-fbMokiGwp2aPM57DX3cXCK3TKHqdhZ8rSNduUja",
"iv": "AzaXpooLg3ZxEASQ",
"aad": "8J-SgCBhYWQ",
"tag": "S0omWw35S0H7tyEHsmGLDw",
"recipients": [
{
"encrypted_key": "yDVZLsO7-ecy_GCgEluwn9U723TCHNAzeYRRQPOfpHM",
"header": {
"kid": "urn:ietf:params:oauth:jwk-thumbprint:sha-256:adjwW6fyyZ94ZBjGjx_OpDEKHLGfd1ELkug_YmRAjCk",
"alg": "HPKE-Base-P256-SHA256-AES128GCM",
"epk": {
"kty": "EK",
"ek": "BHpP-u5JKziyUpqxNQqb0apHx1ecH2UzcRlhHR4ngJVS__gNu21DqqgPweuPpjglnXDnOuQ4kt9tHCs3PUzPxQs"
}
}
},
{
"encrypted_key": "iS73TFqJ61gkmh4DHAXADx4wyftA7pnY",
"header": {
"kid": "urn:ietf:params:oauth:jwk-thumbprint:sha-256:D2FKlj9MTIQma5bwdOVXk5Zh3_d60knzlbmD-SyMNAI",
"alg": "ECDH-ES+A128KW",
"epk": {
"kty": "EC",
"crv": "P-256",
"x": "nX6Y3DWC0olVe5H7-NkCzVDghsYSa_L9da3jzkHYkV8",
"y": "wDshQdcaY0J08wx25V3ystQSNe_qjsCaaFeeRWJqcE0"
}
}
}
]
}
Figure 3: Key Encryption (multiple recipient) General JSON
Serialization
In the above example, the JWE Protected Header value is:
{
"enc": "A128GCM"
}
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{
"protected": "eyJhbGciOiAiSFBLRS1CYXNlLVAyNTYtU0hBMjU2LUFFUzEyOEdDTSIsImVuYyI6IkExMjhHQ00iLCJlcGsiOnsia3R5IjoiRUsiLCJlayI6IkJQUlRLbjhtUUw0aE4xYXlva1I4Z2twVHk1SFFsZDROMEhYWEI5Y1h0alVJUTM3enNKREw3VHVnVmttRDFhRllUeC0wYk0wdGZ4emVqTGN0U0RLak1RcyJ9fQ",
"encrypted_key": "zR0ArfrVVRQ9-X_heDU2riwx36QxLBffRrKAWU-tLC4",
"iv": "o3v11Hw6gUxUN-pY",
"ciphertext": "Ny-2IDGHMI3MzVsUAVMGNoKAZfoewTZ1dkAIBikPy4eZUfHW_LPhhKpD6Mf4zYGkhAeLwGgJKjyDoFIj0EuDsEtJ",
"tag": "0sfzHJvxVoWt02EPxMTh8w"
}
Figure 4: Key Encryption (single recipient) Flattened JSON
Serialization
In the above example, the JWE Protected Header value is:
{
"alg": "HPKE-Base-P256-SHA256-AES128GCM",
"enc": "A128GCM",
"epk": {
"kty": "EK",
"ek": "BPRTKn8mQL4hN1ayokR8gkpTy5HQld4N0HXXB9cXtjUIQ37zsJDL7TugVkmD1aFYTx-0bM0tfxzejLctSDKjMQs"
}
}
eyJhbGciOiAiSFBLRS1CYXNlLVAyNTYtU0hBMjU2LUFFUzEyOEdDTSIsImVuYyI6IkExMjhHQ00iLCJlcGsiOnsia3R5IjoiRUsiLCJlayI6IkJKN3JkTmJrdnd1bnNzZGp1NVdEa0FhekxhQlgzSWRjTFJqeTFSRFNBOXNpajAwamR5YmFIdVFQVHQ2UDMxQmkwbkUya1lXXzdMX3RhQXFBRks3NURlayJ9fQ.xaAa0nFxNJxsQQ5J6EFdzUYROd2aV517o2kZnfwhO7s.AgBYEWTj-EMji17I.Ejwu2iEP4xs3FfGO_zTZYu35glQmUvd_qpHpvB1hNqg6Yz5ek3NsZRGMzd--HYWvABNslxBkRwrkZDXnv_BTgOTj.u0ac86ipoAwUZuYwkaKwNw
Figure 5: Key Encryption (single recipient) Compact
In the above example, the JWE Protected Header value is:
{
"alg": "HPKE-Base-P256-SHA256-AES128GCM",
"enc": "A128GCM",
"epk": {
"kty": "EK",
"ek": "BJ7rdNbkvwunssdju5WDkAazLaBX3IdcLRjy1RDSA9sij00jdybaHuQPTt6P31Bi0nE2kYW_7L_taAqAFK75Dek"
}
}
5. Ciphersuite Registration
This specification registers a number of ciphersuites for use with
HPKE. A ciphersuite is a group of algorithms, often sharing
component algorithms such as hash functions, targeting a security
level. An HPKE ciphersuite, is composed of the following choices:
* HPKE Mode
* KEM Algorithm
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* KDF Algorithm
* AEAD Algorithm
The "KEM", "KDF", and "AEAD" values are chosen from the HPKE IANA
registry [HPKE-IANA].
For readability the algorithm ciphersuites labels are built according
to the following scheme:
HPKE-<Mode>-<KEM>-<KDF>-<AEAD>
The "Mode" indicator may be populated with the following values from
Table 1 of [RFC9180]:
* "Base" refers to "mode_base" described in Section 5.1.1 of
[RFC9180], which only enables encryption to the holder of a given
KEM private key.
* "PSK" refers to "mode_psk", described in Section 5.1.2 of
[RFC9180], which authenticates using a pre-shared key.
* "Auth" refers to "mode_auth", described in Section 5.1.3 of
[RFC9180], which authenticates using an asymmetric key.
* "Auth_Psk" refers to "mode_auth_psk", described in Section 5.1.4
of [RFC9180], which authenticates using both a PSK and an
asymmetric key.
For a list of ciphersuite registrations, please see Section 7.
6. Security Considerations
This specification is based on HPKE and the security considerations
of [RFC9180] are therefore applicable also to this specification.
HPKE assumes the sender is in possession of the public key of the
recipient and HPKE JOSE makes the same assumptions. Hence, some form
of public key distribution mechanism is assumed to exist but outside
the scope of this document.
HPKE in Base mode does not offer authentication as part of the HPKE
KEM. In this case JOSE constructs like JWS and JSON Web Tokens
(JWTs) can be used to add authentication. HPKE also offers modes
that offer authentication.
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HPKE relies on a source of randomness to be available on the device.
In Key Agreement with Key Wrapping mode, CEK has to be randomly
generated and it MUST be ensured that the guidelines in [RFC8937] for
random number generations are followed.
6.1. Plaintext Compression
Implementers are advised to review Section 3.6 of [RFC8725], which
states: Compression of data SHOULD NOT be done before encryption,
because such compressed data often reveals information about the
plaintext.
6.2. Header Parameters
Implementers are advised to review Section 3.10 of [RFC8725], which
comments on application processing of JWE Protected Headers.
Additionally, Unprotected Headers can contain similar information
which an attacker could leverage to mount denial of service, forgery
or injection attacks.
6.3. Ensure Cryptographic Keys Have Sufficient Entropy
Implementers are advised to review Section 3.5 of [RFC8725], which
provides comments on entropy requirements for keys. This guidance is
relevant to both public and private keys used in both Key Encryption
and Direct Encryption. Additionally, this guidance is applicable to
content encryption keys used in Key Encryption mode.
6.4. Validate Cryptographic Inputs
Implementers are advised to review Section 3.4 of [RFC8725], which
provides comments on the validation of cryptographic inputs. This
guidance is relevant to both public and private keys used in both Key
Encryption and Direct Encryption, specifically focusing on the
structure of the public and private keys, as well as the 'ek' value.
These inputs are crucial for the HPKE KEM operations.
6.5. Use Appropriate Algorithms
Implementers are advised to review Section 3.2 of [RFC8725], which
comments on the selection of appropriate algorithms. This is
guidance is relevant to both Key Encryption and Direct Encryption.
When using Key Encryption, the strength of the content encryption
algorithm should not be significantly different from the strengh of
the Key Encryption algorithms used.
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7. IANA Considerations
This document adds entries to [JOSE-IANA].
7.1. JSON Web Key Types
The following entry is added to the "JSON Web Key Types" registry:
* "kty" Parameter Value: "EK"
* Key Type Description: HPKE Encapsulated Key Type (See issue #18)
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
7.2. JSON Web Key Parameters
The following entry is added to the "JSON Web Key Parameters"
registry:
* Parameter Name: "ek"
* Parameter Description: Encapsulated Key
* Parameter Information Class: Public
* Used with "kty" Value(s): "EK"
* Specification Document(s): [[TBD: This RFC]]
7.3. JSON Web Signature and Encryption Algorithms
The following entries are added to the "JSON Web Signature and
Encryption Algorithms" registry:
* Algorithm Name: HPKE-DirEnc
* Algorithm Description: HPKE Direct Encryption mode
* Algorithm Usage Location(s): "alg"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
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* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-P256-SHA256-AES128GCM
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(P-256, HKDF-SHA256) KEM, the HKDF-SHA256 KDF
and the AES-128-GCM AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-P384-SHA384-AES256GCM
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(P-384, HKDF-SHA384) KEM, the HKDF-SHA384 KDF,
and the AES-256-GCM AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-P521-SHA512-AES256GCM
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(P-521, HKDF-SHA512) KEM, the HKDF-SHA512 KDF,
and the AES-256-GCM AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
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* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-X25519-SHA256-AES128GCM
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(X25519, HKDF-SHA256) KEM, the HKDF-SHA256 KDF,
and the AES-128-GCM AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-X25519-SHA256-ChaCha20Poly1305
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(X25519, HKDF-SHA256) KEM, the HKDF-SHA256 KDF,
and the ChaCha20Poly1305 AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-X448-SHA512-AES256GCM
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(X448, HKDF-SHA512) KEM, the HKDF-SHA512 KDF,
and the AES-256-GCM AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
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* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
* Algorithm Name: HPKE-Base-X448-SHA512-ChaCha20Poly1305
* Algorithm Description: Cipher suite for JOSE-HPKE in Base Mode
that uses the DHKEM(X448, HKDF-SHA512) KEM, the HKDF-SHA512 KDF,
and the ChaCha20Poly1305 AEAD.
* Algorithm Usage Location(s): "alg, enc"
* JOSE Implementation Requirements: Optional
* Change Controller: IESG
* Specification Document(s): [[TBD: This RFC]]
* Algorithm Analysis Documents(s): TODO
7.4. JSON Web Signature and Encryption Header Parameters
The following entries are added to the "JSON Web Signature and
Encryption Header Parameters" registry:
* Parameter Name: "psk_id"
* Parameter Description: A key identifier (kid) for the pre-shared
key as defined in { Section 5.1.1 of RFC9180 }
* Parameter Information Class: Public
* Change Controller: IESG
* Specification Document(s): [[This specification]]
* Parameter Name: "auth_kid"
* Parameter Description: A key identifier (kid) for the asymmetric
key as defined in { Section 5.1.4 of RFC9180 }
* Parameter Information Class: Public
* Change Controller: IESG
* Specification Document(s): [[This specification]]
8. References
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8.1. Normative References
[JOSE-IANA]
IANA, "JSON Web Signature and Encryption Algorithms",
n.d., <https://www.iana.org/assignments/jose/jose.xhtml>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<https://www.rfc-editor.org/rfc/rfc7516>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/rfc/rfc7517>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/rfc/rfc7518>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/rfc/rfc8725>.
[RFC9180] Barnes, R., Bhargavan, K., Lipp, B., and C. Wood, "Hybrid
Public Key Encryption", RFC 9180, DOI 10.17487/RFC9180,
February 2022, <https://www.rfc-editor.org/rfc/rfc9180>.
8.2. Informative References
[HPKE-IANA]
IANA, "Hybrid Public Key Encryption (HPKE) IANA Registry",
October 2023,
<https://www.iana.org/assignments/hpke/hpke.xhtml>.
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[I-D.draft-ietf-lamps-cms-cek-hkdf-sha256]
Housley, R., "Encryption Key Derivation in the
Cryptographic Message Syntax (CMS) using HKDF with SHA-
256", Work in Progress, Internet-Draft, draft-ietf-lamps-
cms-cek-hkdf-sha256-00, 29 January 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
cms-cek-hkdf-sha256-00>.
[I-D.ietf-cose-hpke]
Tschofenig, H., Steele, O., Daisuke, A., and L. Lundblade,
"Use of Hybrid Public-Key Encryption (HPKE) with CBOR
Object Signing and Encryption (COSE)", Work in Progress,
Internet-Draft, draft-ietf-cose-hpke-07, 22 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-cose-
hpke-07>.
[RFC8937] Cremers, C., Garratt, L., Smyshlyaev, S., Sullivan, N.,
and C. Wood, "Randomness Improvements for Security
Protocols", RFC 8937, DOI 10.17487/RFC8937, October 2020,
<https://www.rfc-editor.org/rfc/rfc8937>.
Acknowledgments
This specification leverages text from [I-D.ietf-cose-hpke]. We
would like to thank Matt Chanda, Ilari Liusvaara, Aaron Parecki and
Filip Skokan for their feedback.
Authors' Addresses
Tirumaleswar Reddy
Nokia
Bangalore
Karnataka
India
Email: kondtir@gmail.com
Hannes Tschofenig
Austria
Email: hannes.tschofenig@gmx.net
Aritra Banerjee
Nokia
Munich
Germany
Email: aritra.banerjee@nokia.com
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Orie Steele
Transmute
United States
Email: orie@transmute.industries
Michael B. Jones
independent
United States
Email: michael_b_jones@hotmail.com
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