Paper 2022/375
A Note on the Security Framework of Two-key DbHtS MACs
Tingting Guo and Peng Wang
Abstract
Double-block Hash-then-Sum (DbHtS) MACs are a class of MACs achieve beyond-birthday-bound (BBB) security, including SUM-ECBC, PMAC_Plus, 3kf9 and LightMAC_Plus etc. Recently, Shen et al. (Crypto 2021) proposed a security framework for two-key DbHtS MACs in the multi-user setting, stating that when the underlying blockcipher is ideal and the universal hash function is regular and almost universal, the two-key DbHtS MACs achieve 2n/3-bit security. Unfortunately, the regular and universal properties can not guarantee the BBB security of two-key DbHtS MACs. We propose three counter-examples which are proved to be 2n/3-bit secure in the multi-user setting by the framework, but can be broken with probability 1 using only O(2^{n/2}) queries even in the single-user setting. We also point out the miscalculation in their proof leading to such a flaw. However, we haven’t found attacks against 2k-SUM-ECBC, 2k-PMAC_Plus and 2k-LightMAC_Plus proved 2n/3-bit security in their paper.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Preprint. MINOR revision.
- Keywords
- MACDbHtSBeyond-birthday-bound securityMulti-user security
- Contact author(s)
-
guotingting @ iie ac cn
w rocking @ gmail com - History
- 2022-04-17: last of 8 revisions
- 2022-03-22: received
- See all versions
- Short URL
- https://ia.cr/2022/375
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2022/375,
author = {Tingting Guo and Peng Wang},
title = {A Note on the Security Framework of Two-key {DbHtS} {MACs}},
howpublished = {Cryptology {ePrint} Archive, Paper 2022/375},
year = {2022},
url = {https://eprint.iacr.org/2022/375}
}
