Continuous key agreement with reduced bandwidth

Nir Drucker, Shay Gueron

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Continuous Key Agreement (CKA) is a two-party procedure used by Double Ratchet protocols (e. g., Signal). This is a continuous and synchronous protocol that generates a fresh key for every sent/received message. It guarantees forward secrecy and post-compromise security. Alwen et al. have recently proposed a new KEM-based CKA construction where every message contains a ciphertext and a fresh public key. This can be made quantum-safe by deploying a quantum-safe KEM. They mention that the bandwidth can be reduced when using an ElGamal KEM (which is not quantum-safe). In this paper, we generalized their approach by defining a new primitive, namely Merged KEM (MKEM). This primitive merges the key generation and the encapsulation steps of a KEM. This is not possible for every KEM and we discuss cases where a KEM can be converted to an MKEM. One example is the quantum-safe proposal BIKE1, where the BIKE-MKEM saves 50% of the communication bandwidth, compared to the original construction. In addition, we offer the notion and two constructions for hybrid CKA.

Original languageEnglish
Title of host publicationCyber Security Cryptography and Machine Learning - 3rd International Symposium, CSCML 2019, Proceedings
EditorsShlomi Dolev, Danny Hendler, Sachin Lodha, Moti Yung
PublisherSpringer Verlag
Pages33-46
Number of pages14
ISBN (Print)9783030209506
DOIs
StatePublished - 2019
Event3rd International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2019 - Beer Sheva, Israel
Duration: 27 Jun 201928 Jun 2019

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11527 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference3rd International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2019
Country/TerritoryIsrael
CityBeer Sheva
Period27/06/1928/06/19

Bibliographical note

Funding Information:
Acknowledgments. This research was supported by: The Israel Science Foundation (grant No. 1018/16); The BIU Center for Research in Applied Cryptography and Cyber Security, in conjunction with the Israel National Cyber Bureau in the Prime Minister’s Office; the Center for Cyber Law & Policy at the University of Haifa in conjunction with the Israel National Cyber Directorate in the Prime Minister’s Office.

Publisher Copyright:
© Springer Nature Switzerland AG 2019.

Keywords

  • BIKE
  • Code-based cryptography
  • Continuous Key Agreement
  • Double Ratchet protocol
  • Post Quantum Cryptography

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science (all)

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