Secure Messaging with Strong Compromise Resilience, Temporal Privacy, and Immediate Decryption

Cas Cremers; Mang Zhao

Paper 2022/1481

Secure Messaging with Strong Compromise Resilience, Temporal Privacy, and Immediate Decryption

Cas Cremers

, Helmholtz Center for Information Security

Mang Zhao, Helmholtz Center for Information Security

Abstract

Recent years have seen many advances in designing secure messaging protocols, aiming at provably strong security properties in theory or high efficiency for real-world practical deployment. However, important trade-off areas of the design space inbetween these elements have not yet been explored. In this work we design the first provably secure protocol that at the same time achieves (i) strong resilience against finegrained compromise, (ii) temporal privacy, and (iii) immediate decryption with constant-size overhead, notably, in the postquantum (PQ) setting. Besides these main design goals, we introduce a novel definition of offline deniability suitable for our setting, and prove that our protocol meets it, notably when combined with a PQ offline deniable initial key exchange.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Published elsewhere. Major revision. IEEE S&P 2024
Contact author(s): cremers @ cispa de
mang zhao @ cispa de
History: 2023-08-17: revised; 2022-10-28: received; See all versions
Short URL: https://ia.cr/2022/1481
License: CC BY

BibTeX

@misc{cryptoeprint:2022/1481,
      author = {Cas Cremers and Mang Zhao},
      title = {Secure Messaging with Strong Compromise Resilience, Temporal Privacy, and Immediate Decryption},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1481},
      year = {2022},
      note = {\url{https://eprint.iacr.org/2022/1481}},
      url = {https://eprint.iacr.org/2022/1481}
}