post-quantum

This document defines Post-Quantum Traditional (PQ/T) Hybrid key exchange methods based on the quantum-resistant Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) standard and traditional Elliptic-Curve Diffie-Hellman (ECDH) key exchange schemes. These methods are defined for use in the Secure Shell (SSH) transport layer protocol.

This document describes classification of design goals and security considerations for hybrid digital signature schemes, including proof composability, non-separability of the component signatures given a hybrid signature, backwards and forwards compatibility, hybrid generality, and Simultaneous Verification (SV).

Hybrid key exchange refers to using multiple key exchange algorithms simultaneously and combining the result with the goal of providing security even if a way is found to defeat the encryption for all but one of the component algorithms. It is motivated by the transition to post-quantum cryptography. This document provides a construction for hybrid key exchange in the Transport Layer Security (TLS) protocol version 1.3.

This document defines a post-quantum public key algorithm extension for the OpenPGP protocol, extending RFC 9580. Given the generally assumed threat of a cryptographically relevant quantum computer, this extension provides a basis for long-term secure OpenPGP signatures and ciphertexts. Specifically, it defines composite public key encryption based on ML-KEM (formerly CRYSTALS-Kyber), composite public key signatures based on ML-DSA (formerly CRYSTALS-Dilithium), both in combination with Elliptic Curve Cryptography (ECC), and SLH-DSA (formerly SPHINCS+) as a standalone public key signature scheme.

The advent of a cryptographically relevant quantum computer (CRQC) would render state-of-the-art, traditional public key algorithms deployed today obsolete, as the mathematical assumptions underpinning their security would no longer hold. To address this, protocols and infrastructure must transition to post-quantum algorithms, which are designed to resist both traditional and quantum attacks. This document explains why engineers need to be aware of and understand post-quantum cryptography (PQC), and it details the impact of CRQCs on existing systems and the challenges involved in transitioning to post-quantum algorithms. Unlike previous cryptographic updates, this shift may require significant protocol redesign due to the unique properties of post-quantum algorithms.

This document describes a widely deployed hybrid key exchange method in the Secure Shell (SSH) protocol that is based on Streamlined NTRU Prime sntrup761 and X25519 with SHA-512.

An Internet Key Exchange Protocol Version 2 (IKEv2) extension defined in RFC 8784 allows IPsec traffic to be protected against someone storing VPN communications and decrypting them later, when (and if) a Cryptographically Relevant Quantum Computer (CRQC) is available. The protection is achieved by means of a Post-quantum Preshared Key (PPK) that is mixed into the session keys calculation. However, this protection does not cover an initial IKEv2 Security Association (SA), which might be unacceptable in some scenarios. This specification defines an alternative way to provide protection against quantum computers, which is similar to the solution defined in RFC 8784, but it also protects the initial IKEv2 SA.

RFC 8784 assumes that PPKs are static and thus they are only used when an initial IKEv2 SA is created. If a fresh PPK is available before the IKE SA expires, then the only way to use it is to delete the current IKE SA and create a new one from scratch, which is inefficient. This specification defines a way to use PPKs in active IKEv2 SAs for creating additional IPsec SAs and rekey operations.

This document defines a new Certificate Signing Request (CSR) attribute, relatedCertRequest, and a new X.509 certificate extension, RelatedCertificate. The use of the relatedCertRequest attribute in a CSR and the inclusion of the RelatedCertificate extension in the resulting certificate together provide additional assurance that two certificates each belong to the same end entity. This mechanism is particularly useful in the context of non-composite hybrid authentication, which enables users to employ the same certificates in hybrid authentication as in authentication done with only traditional or post-quantum algorithms.

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.

The Quantum Internet has the potential to improve application functionality by incorporating quantum information technology into the infrastructure of the overall Internet. This document provides an overview of some applications expected to be used on the Quantum Internet and categorizes them. Some general requirements for the Quantum Internet are also discussed. The intent of this document is to describe a framework for applications and to describe a few selected application scenarios for the Quantum Internet. This document is a product of the Quantum Internet Research Group (QIRG).

This document describes how to extend the Internet Key Exchange Protocol Version 2 (IKEv2) to allow multiple key exchanges to take place while computing a shared secret during a Security Association (SA) setup.

This document utilizes the IKE_INTERMEDIATE exchange, where multiple key exchanges are performed when an IKE SA is being established. It also introduces a new IKEv2 exchange, IKE_FOLLOWUP_KE, which is used for the same purpose when the IKE SA is being rekeyed or is creating additional Child SAs.

This document updates RFC 7296 by renaming a Transform Type 4 from "Diffie-Hellman Group (D-H)" to "Key Exchange Method (KE)" and renaming a field in the Key Exchange Payload from "Diffie-Hellman Group Num" to "Key Exchange Method". It also renames an IANA registry for this Transform Type from "Transform Type 4 - Diffie- Hellman Group Transform IDs" to "Transform Type 4 - Key Exchange Method Transform IDs". These changes generalize key exchange algorithms that can be used in IKEv2.

The vision of a quantum internet is to enhance existing Internet technology by enabling quantum communication between any two points on Earth. To achieve this goal, a quantum network stack should be built from the ground up to account for the fundamentally new properties of quantum entanglement. The first quantum entanglement networks have been realised, but there is no practical proposal for how to organise, utilise, and manage such networks. In this document, we attempt to lay down the framework and introduce some basic architectural principles for a quantum internet. This is intended for general guidance and general interest. It is also intended to provide a foundation for discussion between physicists and network specialists. This document is a product of the Quantum Internet Research Group (QIRG).

This document defines a new exchange, called "Intermediate Exchange", for the Internet Key Exchange Protocol Version 2 (IKEv2). This exchange can be used for transferring large amounts of data in the process of IKEv2 Security Association (SA) establishment. An example of the need to do this is using key exchange methods resistant to Quantum Computers (QCs) for IKE SA establishment. The Intermediate Exchange makes it possible to use the existing IKE fragmentation mechanism (which cannot be used in the initial IKEv2 exchange), helping to avoid IP fragmentation of large IKE messages if they need to be sent before IKEv2 SA is established.

This document describes a scheme for hybrid public key encryption (HPKE). This scheme provides a variant of public key encryption of arbitrary-sized plaintexts for a recipient public key. It also includes three authenticated variants, including one that authenticates possession of a pre-shared key and two optional ones that authenticate possession of a key encapsulation mechanism (KEM) private key. HPKE works for any combination of an asymmetric KEM, key derivation function (KDF), and authenticated encryption with additional data (AEAD) encryption function. Some authenticated variants may not be supported by all KEMs. We provide instantiations of the scheme using widely used and efficient primitives, such as Elliptic Curve Diffie-Hellman (ECDH) key agreement, HMAC-based key derivation function (HKDF), and SHA2.

This document is a product of the Crypto Forum Research Group (CFRG) in the IRTF.

The possibility of quantum computers poses a serious challenge to cryptographic algorithms deployed widely today. The Internet Key Exchange Protocol Version 2 (IKEv2) is one example of a cryptosystem that could be broken; someone storing VPN communications today could decrypt them at a later time when a quantum computer is available. It is anticipated that IKEv2 will be extended to support quantum-secure key exchange algorithms; however, that is not likely to happen in the near term. To address this problem before then, this document describes an extension of IKEv2 to allow it to be resistant to a quantum computer by using preshared keys.