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Composite Public and Private Keys For Use In Internet PKI

Document Type Expired Internet-Draft (individual)
Expired & archived
Authors Mike Ounsworth , John Gray , Massimiliano Pala , Jan Klaußner
Last updated 2023-11-30 (Latest revision 2023-05-29)
RFC stream (None)
Intended RFC status (None)
Additional resources GitHub Repository
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


The migration to post-quantum cryptography is unique in the history of modern digital cryptography in that neither the old outgoing nor the new incoming algorithms are fully trusted to protect data for the required data lifetimes. The outgoing algorithms, such as RSA and elliptic curve, may fall to quantum cryptalanysis, while the incoming post-quantum algorithms face uncertainty about both the underlying mathematics as well as hardware and software implementations that have not had sufficient maturing time to rule out classical cryptanalytic attacks and implementation bugs. Cautious implementers may wish to layer cryptographic algorithms such that an attacker would need to break all of them in order to compromise the data being protected using either a Post-Quantum / Traditional Hybrid, Post-Quantum / Post-Quantum Hybrid, or combinations thereof. This document, and its companions, defines a specific instantiation of hybrid paradigm called "composite" where multiple cryptographic algorithms are combined to form a single key, signature, or key encapsulation mechanism (KEM) such that they can be treated as a single atomic object at the protocol level. This document defines the structures CompositePublicKey and CompositePrivateKey, which are sequences of the respective structure for each component algorithm. Explicit pairings of algorithms are defined which should meet most Internet needs. This document is intended to be coupled with corresponding documents that define the structure and semantics of composite signatures and encryption, such as [I-D.ounsworth-pq-composite-sigs] and [I-D.ounsworth-pq-composite-kem].


Mike Ounsworth
John Gray
Massimiliano Pala
Jan Klaußner

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)