Continuous Key Agreement (CKA) is a two-party procedure used by Double Ratchet protocols (e.Â 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 etÂ 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.
|Title of host publication||Cyber Security Cryptography and Machine Learning - 3rd International Symposium, CSCML 2019, Proceedings|
|Editors||Shlomi Dolev, Danny Hendler, Sachin Lodha, Moti Yung|
|Number of pages||14|
|State||Published - 2019|
|Event||3rd International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2019 - Beer Sheva, Israel|
Duration: 27 Jun 2019 → 28 Jun 2019
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||3rd International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2019|
|Period||27/06/19 → 28/06/19|
Bibliographical noteFunding 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.
© Springer Nature Switzerland AG 2019.
- Code-based cryptography
- Continuous Key Agreement
- Double Ratchet protocol
- Post Quantum Cryptography
ASJC Scopus subject areas
- Theoretical Computer Science
- Computer Science (all)