This paper proposes “Compound-CTR” mode—a simple variation of Counter mode (CTR) with an n bits block cipher. Its goal is to increase the allowed length of a single message and the total number of messages that can be encrypted under a single key. Compound-CTR encrypts a message and a (randomly chosen) nonce with length greater or equal n bits. It uses a master key to derive a nonce-based encryption key and subsequently uses it for encrypting the message in CTR mode. We show how Compound-CTR mode achieves its goal and explain why it can be used as a valid variation of CTR mode that could be of interest in some practical scenarios. Compared to CTR mode, the overhead of Compound-CTR is only the per-message key derivation and one extra key expansion (for the block cipher). We show here key derivation options that require only a few extra block cipher calls.
|Title of host publication||Cyber Security, Cryptology, and Machine Learning - 6th International Symposium, CSCML 2022, Proceedings|
|Editors||Shlomi Dolev, Amnon Meisels, Jonathan Katz|
|Publisher||Springer Science and Business Media Deutschland GmbH|
|Number of pages||8|
|State||Published - 2022|
|Event||6th International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2022 - Beer Sheva, Israel|
Duration: 30 Jun 2022 → 1 Jul 2022
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||6th International Symposium on Cyber Security Cryptography and Machine Learning, CSCML 2022|
|Period||30/06/22 → 1/07/22|
Bibliographical noteFunding Information:
This research was supported by: NSF-BSF Grant 2018640; The Israel Science Foundation (grant No. 3380/19); The Center for Cyber Law and Policy at the University of Haifa, in conjunction with the Israel National Cyber Bureau in the Prime Minister’s Office.
© 2022, Springer Nature Switzerland AG.
- Block ciphers
- Counter mode
- Modes of operation
ASJC Scopus subject areas
- Theoretical Computer Science
- Computer Science (all)