Cryptology ePrint Archive: Report 2019/398

Constant-Round Group Key Exchange from the Ring-LWE Assumption

Daniel Apon and Dana Dachman-Soled and Huijing Gong and Jonathan Katz

Abstract: Group key-exchange protocols allow a set of N parties to agree on a shared, secret key by communicating over a public network. A number of solutions to this problem have been proposed over the years, mostly based on variants of Diffie-Hellman (two-party) key exchange. There has been relatively little work, however, looking at candidate post-quantum group key-exchange protocols.

Here, we propose a constant-round protocol for unauthenticated group key exchange (i.e., with security against a passive eavesdropper) based on the hardness of the Ring-LWE problem. By applying the Katz-Yung compiler using any post-quantum signature scheme, we obtain a (scalable) protocol for authenticated group key exchange with post-quantum security. Our protocol is constructed by generalizing the Burmester-Desmedt protocol to the Ring-LWE setting, which requires addressing several technical challenges.

Category / Keywords: public-key cryptography / Group key exchange, Ring learning with errors, Post-quantum cryptography

Original Publication (with minor differences): PQCrypto 2019

Date: received 15 Apr 2019

Contact author: daniel apon at nist gov,danadach@ece umd edu,gong@cs umd edu,jkatz@cs umd edu

Available format(s): PDF | BibTeX Citation

Version: 20190418:192341 (All versions of this report)

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