]> Nokia

Bangalore Karnataka India k.tirumaleswar_reddy@nokia.com

Germany hannes.tschofenig@gmx.net

Security COSE PQC COSE JOSE Hybrid HPKE Post-Quantum This document specifies the use of Post-Quantum (PQ) and Post-Quantum/Traditional (PQ/T) Hybrid Key Encapsulation Mechanisms (KEMs) within the Hybrid Public Key Encryption (HPKE) for JOSE and COSE. It defines algorithm identifiers and key formats to support pure post-quantum algorithms (ML-KEM) and their PQ/T hybrid combinations. About This Document Status information for this document may be found at . Discussion of this document takes place on the cose Working Group mailing list (), which is archived at . Subscribe at .

Introduction The migration to Post-Quantum Cryptography (PQC) is unique in the history of modern digital cryptography in that neither the traditional algorithms nor the post-quantum algorithms are fully trusted to protect data for the required data lifetimes. The traditional algorithms, such as RSA and elliptic curve cryptography (ECC), will fall to quantum cryptanalysis, while the post-quantum algorithms face uncertainty about the underlying mathematics, compliance issues, unknown vulnerabilities, hardware and software implementations that have not had sufficient maturing time to rule out classical cryptanalytic attacks and implementation bugs. During this transition, deployments may adopt different strategies depending on their security posture, risk tolerance, and external constraints. Hybrid key exchange is generally preferred over pure PQC key exchange because it provides defense in depth by combining the strengths of both traditional and post-quantum algorithms. This approach ensures continued security even if one of the component algorithms is compromised during the transitional period. However, pure PQC key exchange may be required for specific deployments with regulatory or compliance mandates that necessitate the exclusive use of post-quantum cryptography. Such requirements may arise in environments governed by stringent cryptographic standards that prohibit reliance on traditional public-key algorithms. Hybrid Public Key Encryption (HPKE) specifies a scheme for encrypting arbitrary-length plaintexts to a recipient’s public key. The use of HPKE with JOSE and COSE is specified in and , respectively. HPKE can be extended to support both pure PQC and post-quantum/traditional (PQ/T) hybrid Key Encapsulation Mechanisms (KEMs), as defined in . This document specifies the use of these KEMs in HPKE for JOSE and COSE. Supporting both pure PQC and PQ/T hybrid KEMs enables flexible deployment choices: hybrid mechanisms provide a conservative transition strategy with defense in depth, while pure PQC mechanisms accommodate deployments with regulatory, compliance, or policy-driven requirements for exclusive use of PQC.

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 when, and only when, they appear in all capitals, as shown here. This document makes use of the terms defined in . For the purposes of this document, it is helpful to be able to divide cryptographic algorithms into two classes: "Traditional Algorithm": An asymmetric cryptographic algorithm based on integer factorisation, finite field discrete logarithms, elliptic curve discrete logarithms, or related mathematical problems. In the context of JOSE, examples of traditional key exchange algorithms include Elliptic Curve Diffie-Hellman Ephemeral Static . In the context of COSE, examples of traditional key exchange algorithms include Ephemeral-Static (ES) DH and Static-Static (SS) DH . "Post-Quantum Algorithm": An asymmetric cryptographic algorithm that is believed to be secure against attacks using quantum computers as well as classical computers. Examples of PQC key exchange algorithms include ML-KEM. "Post-Quantum Traditional (PQ/T) Hybrid Scheme": A multi-algorithm scheme where at least one component algorithm is a post-quantum algorithm and at least one is a traditional algorithm. "PQ/T Hybrid Key Encapsulation Mechanism": A multi-algorithm KEM made up of two or more component KEM algorithms where at least one is a post-quantum algorithm and at least one is a traditional algorithm.

Construction ML-KEM is a one-pass (store-and-forward) cryptographic mechanism for an originator to securely send keying material to a recipient using the recipient's ML-KEM public key. Three parameter sets for ML-KEMs are specified by . In order of increasing security strength (and decreasing performance), these parameter sets are ML-KEM-512, ML-KEM-768, and ML-KEM-1024. For pure PQC, the ML-KEM algorithms are used as standalone KEMs within the HPKE framework as defined in . While this document defines ciphersuites for all three parameter sets, implementers should follow the guidance in Section 3 of regarding the selection of security levels. Specifically, it is noted that while ML-KEM-512 provides NIST security category 1, the use of ML-KEM-768 or ML-KEM-1024 is generally preferred to provide a higher security margin against potential future cryptanalysis. PQ/T algorithms for HPKE use a multi-algorithm scheme, where one component algorithm is a post-quantum algorithm and another one is a traditional algorithm. The hybrid combiner construction, such as the C2PRICombiner defined in , combines the shared secrets and public values from a post-quantum KEM and a traditional KEM to derive a single shared secret for HPKE.

Alignment with JOSE HPKE Modes The JOSE HPKE specification and the COSE HPKE specification define the use of HPKE with two Key Management Modes:

• Key Encryption, and
• Integrated Encryption.

In both JOSE and COSE, the selected Key Management Mode determines how HPKE is applied at the message layer. In Key Encryption mode, HPKE is used to encrypt a Content Encryption Key (CEK), which is then used to encrypt the payload. In Integrated Encryption mode, HPKE is used directly to encrypt the payload, and no separate CEK is employed. Each Key Management Mode is identified by a distinct algorithm identifier (alg) in both JOSE and COSE. This document registers separate HPKE algorithm identifiers for Key Encryption and Integrated Encryption for both pure PQC and PQ/T hybrid HPKE instantiations. This separation ensures that JOSE and COSE implementations can determine the intended HPKE Key Management Mode solely from the alg value, without ambiguity, and preserves compatibility with existing HPKE processing models.

Ciphersuite Registration This specification registers a set of pure PQC and PQ/T hybrid KEMs for use with HPKE. In this context, an HPKE ciphersuite is defined as a combination of the following algorithm components:

• KEM algorithm, which may be either:
  • a pure PQC KEM (for example, ML-KEM-768), or
  • a PQ/T hybrid KEM that combines a PQC KEM with a traditional key-exchange algorithm (for example, ML-KEM-768 + X25519, defined as "MLKEM768-X25519" in )
• KDF algorithm
• AEAD algorithm

The values for KEM, KDF, and AEAD are drawn from the HPKE IANA registry . Consequently, JOSE and COSE can only use algorithm combinations that are already defined and registered for HPKE. The HPKE ciphersuites defined for use with JOSE and COSE, including both pure PQC and PQ/T hybrid KEMs, are specified in . Note that the pure PQC and PQ/T hybrid KEMs defined for HPKE are not authenticated KEMs. As a result, only the HPKE Base mode is supported when using these KEMs, in accordance with the HPKE and JOSE/COSE HPKE specifications.

AKP Key Type for Use with PQC and PQ/T Hybrid HPKE Algorithms This section describes the required parameters for an "AKP" key type, as defined in , and its use with pure PQC and PQ/T hybrid algorithms for HPKE, as defined in {#XWING} and {#XWING-KE}. An example key representation is also provided for illustration.

Required Parameters A JSON Web Key (JWK) or COSE_Key with a key type (kty) for use with pure PQC or PQ/T hybrid algorithms for HPKE includes the following parameters:

• kty (Key Type)
  The kty parameter MUST be present and MUST be set to "AKP".
• alg (Algorithm)
  The alg parameter MUST be present and MUST identify the pure PQC or PQ/T hybrid algorithm for HPKE, as defined in {#XWING} or {#XWING-KE}.
  HPKE algorithms using pure PQC or PQ/T hybrid KEMs are those registered in the "JSON Web Signature and Encryption Algorithms" registry and the "COSE Algorithms" registry, and are derived from the corresponding KEM identifiers in the HPKE IANA registry.
• pub (Public Key)
  The pub parameter MUST be present and MUST contain the public encapsulation key (pk) as defined in Section 5.1 of . For hybrid KEMs, the PQC KEM public key MUST be placed first, followed immediately by the traditional public key, as specified in . No padding or delimiters are used between the keys. When represented as a JWK, this value MUST be base64url-encoded.
• priv (Private Key)
  When representing a private key, the priv parameter MUST be present and MUST contain the private decapsulation key (sk) as defined in Section 5.1 of . For hybrid KEMs, the PQC KEM private key MUST be placed first, followed immediately by the traditional private key.
  When represented as a JWK, this value MUST be base64url-encoded.

Example The following is an example JWK representation of an "AKP" key for the "MLKEM768-X25519-SHAKE256-AES-256-GCM" algorithm:

Security Considerations The security considerations in , and are to be taken into account. The shared secrets computed in the hybrid key exchange must be computed in a way that achieves the "hybrid" property: the resulting secret is secure as long as at least one of the component key exchange algorithms is unbroken. PQC KEMs used in the manner described in this document MUST explicitly be designed to be secure in the event that the public key is reused, such as achieving IND-CCA2 security.ML-KEM has such security properties.

Post-Quantum Security for Multiple Recipients In HPKE JWE Key Encryption, when encrypting the Content Encryption Key (CEK) for multiple recipients, it is crucial to consider the security requirements of the message to safeguard against "Harvest Now, Decrypt Later" attacks. For messages requiring post-quantum security, all recipients MUST use algorithms supporting post-quantum cryptographic methods, such as PQC KEMs or Hybrid PQ/T KEMs. Using traditional algorithms (e.g., ECDH-ES) for any recipient in these scenarios compromises the overall security of the message.

IANA Considerations

JOSE This document requests IANA to add new values to the "JSON Web Signature and Encryption Algorithms" registry.

JOSE Algorithms for Integrated Encryption

• Algorithm Name: HPKE-8
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-9
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-10
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-11
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-12
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-13
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Documents(s): TODO
• Algorithm Name: HPKE-14
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-512 KEM, the SHAKE256 KDF, and the AES-128-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-15
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-768 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-16
• Algorithm Description: Integrated Encryption with HPKE using ML-KEM-1024 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO

JOSE Algorithms for Key Encryption

• Algorithm Name: HPKE-8-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-9-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-10-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-11-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-12-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-13-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-14-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-512 KEM, the SHAKE256 KDF, and the AES-128-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-15-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-768 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO
• Algorithm Name: HPKE-16-KE
• Algorithm Description: Key Encryption with HPKE using ML-KEM-1024 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Algorithm Usage Location(s): "alg"
• JOSE Implementation Requirements: Optional
• Change Controller: IANA
• Specification Document(s): [[TBD: This RFC]]
• Algorithm Analysis Document(s): TODO

COSE This document requests IANA to add new values to the 'COSE Algorithms' registry.

COSE Algorithms Registry

• Name: HPKE-8
• Value: TBD1
• Description: COSE HPKE Integrated Encryption using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-9
• Value: TBD2
• Description: COSE HPKE Integrated Encryption using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-10
• Value: TBD3
• Description: COSE HPKE Integrated Encryption using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-11
• Value: TBD4
• Description: COSE HPKE Integrated Encryption using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-12
• Value: TBD5
• Description: COSE HPKE Integrated Encryption using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-13
• Value: TBD6
• Description: COSE HPKE Integrated Encryption using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-14
• Value: TBD7
• Description: COSE HPKE Integrated Encryption using ML-KEM-512 KEM, the SHAKE256 KDF, and the AES-128-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-15
• Value: TBD8
• Description: COSE HPKE Integrated Encryption using ML-KEM-768 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-16
• Value: TBD9
• Description: COSE HPKE Integrated Encryption using ML-KEM-1024 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-8-KE
• Value: TBD10
• Description: COSE HPKE Key Encryption using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-9-KE
• Value: TBD11
• Description: COSE HPKE Key Encryption using ML-KEM-768 + P-256 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-10-KE
• Value: TBD12
• Description: COSE HPKE Key Encryption using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-11-KE
• Value: TBD13
• Description: COSE HPKE Key Encryption using ML-KEM-768 + X25519 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-12-KE
• Value: TBD14
• Description: COSE HPKE Key Encryption using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-13-KE
• Value: TBD15
• Description: COSE HPKE Key Encryption using ML-KEM-1024 + P-384 Hybrid KEM, the SHAKE256 KDF, and the ChaCha20Poly1305 AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-14-KE
• Value: TBD16
• Description: COSE HPKE Key Encryption using ML-KEM-512 KEM, the SHAKE256 KDF, and the AES-128-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-15-KE
• Value: TBD17
• Description: COSE HPKE Key Encryption using ML-KEM-768 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No
• Name: HPKE-16-KE
• Value: TBD18
• Description: COSE HPKE Key Encryption using ML-KEM-1024 KEM, the SHAKE256 KDF, and the AES-256-GCM AEAD.
• Capabilities: [kty]
• Change Controller: IESG
• Reference: [[TBD: This RFC]]
• Recommended: No

Acknowledgments Thanks to Ilari Liusvaara and Orie Steele for the discussion and comments.

References Normative References Nokia University of Applied Sciences Bonn-Rhein-Sieg Nokia Tradeverifyd Self-Issued Consulting This specification defines how to use Hybrid Public Key Encryption (HPKE) with JSON Web Encryption (JWE). HPKE enables public key encryption of arbitrary-sized plaintexts to a recipient's public key, and provides security against adaptive chosen ciphertext attacks. This specification chooses a specific subset of the HPKE features to use with JWE. This specification updates RFC 7516 (JWE) to enable use of the Integrated Encryption Key Establishment Mode. University of Applied Sciences Bonn-Rhein-Sieg Tradeverifyd bibital Security Theory LLC Self-Issued Consulting This specification defines hybrid public-key encryption (HPKE) for use with CBOR Object Signing and Encryption (COSE). HPKE offers a variant of public-key encryption of arbitrary-sized plaintexts for a recipient public key. HPKE is a general encryption framework utilizing an asymmetric key encapsulation mechanism (KEM), a key derivation function (KDF), and an Authenticated Encryption with Associated Data (AEAD) algorithm. This document defines the use of HPKE with COSE. Authentication for HPKE in COSE is provided by COSE-native security mechanisms or by the pre-shared key authenticated variant of HPKE. Cisco Selkie Cryptography Updating key exchange and public-key encryption protocols to resist attack by quantum computers is a high priority given the possibility of "harvest now, decrypt later" attacks. Hybrid Public Key Encryption (HPKE) is a widely-used public key encryption scheme based on combining a Key Encapsulation Mechanism (KEM), a Key Derivation Function (KDF), and an Authenticated Encryption with Associated Data (AEAD) scheme. In this document, we define KEM algorithms for HPKE based on both post-quantum KEMs and hybrid constructions of post- quantum KEMs with traditional KEMs, as well as a KDF based on SHA-3 that is suitable for use with these KEMs. When used with these algorithms, HPKE is resilient with respect to attacks by a quantum computer. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. SandboxAQ Cisco University of Michigan This document defines generic constructions for hybrid Key Encapsulation Mechanisms (KEMs) based on combining a post-quantum (PQ) KEM with a traditional cryptographic component. Hybrid KEMs built using these constructions provide strong security properties as long as either of the underlying algorithms are secure. Tradeverifyd Tradeverifyd This document specifies JSON Object Signing and Encryption (JOSE) and CBOR Object Signing and Encryption (COSE) serializations for Module- Lattice-Based Digital Signature Standard (ML-DSA), a Post-Quantum Cryptography (PQC) digital signature scheme defined in US NIST FIPS 204. Informative References IANA UK National Cyber Security Centre UK National Cyber Security Centre Naval Postgraduate School One aspect of the transition to post-quantum algorithms in cryptographic protocols is the development of hybrid schemes that incorporate both post-quantum and traditional asymmetric algorithms. This document defines terminology for such schemes. It is intended to be used as a reference and, hopefully, to ensure consistency and clarity across different protocols, standards, and organisations. This note describes the fundamental algorithms of Elliptic Curve Cryptography (ECC) as they were defined in some seminal references from 1994 and earlier. These descriptions may be useful for implementing the fundamental algorithms without using any of the specialized methods that were developed in following years. Only elliptic curves defined over fields of characteristic greater than three are in scope; these curves are those used in Suite B. This document is not an Internet Standards Track specification; it is published for informational purposes. This document defines how to use the Diffie-Hellman algorithms "X25519" and "X448" as well as the signature algorithms "Ed25519" and "Ed448" from the IRTF CFRG elliptic curves work in JSON Object Signing and Encryption (JOSE). Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR. This document, along with RFC 9053, obsoletes RFC 8152.