Paper 2020/1145

Improved Security Analysis for Nonce-based Enhanced Hash-then-Mask MACs

Wonseok Choi, Byeonghak Lee, Yeongmin Lee, and Jooyoung Lee

Abstract

In this paper, we prove that the nonce-based enhanced hash-then-mask MAC (nEHtM) is secure up to 23n4 MAC queries and 2n verification queries (ignoring logarithmic factors) as long as the number of faulty queries μ is below 23n8, significantly improving the previous bound by Dutta et al. Even when μ goes beyond 23n8, nEHtM enjoys graceful degradation of security. The second result is to prove the security of PRF-based nEHtM; when nEHtM is based on an n-to-s bit random function for a fixed size s such that 1sn, it is proved to be secure up to any number of MAC queries and verification queries, if (1) and or (2) and , or (3) and . This result leads to the security proof of truncated that returns only bits of the original tag since a truncated permutation can be seen as a pseudorandom function. In particular, when , the truncated is secure up to MAC queries and verification queries as long as . For example, when (resp. ), the truncated is secure up to (resp. ) MAC queries. So truncation might provide better provable security than the original with respect to the number of MAC queries.

Note: Correct a typo in the Abstract in this page (the submitted file is not changed)

Metadata
Available format(s)
PDF
Category
Secret-key cryptography
Publication info
A minor revision of an IACR publication in ASIACRYPT 2020
Keywords
message authentication codesbeyond-birthday-bound securitymirror theorygraceful degradationtruncation
Contact author(s)
krwioh @ kaist ac kr
lbh0307 @ kaist ac kr
dudals4780 @ kaist ac kr
hicalf @ kaist ac kr
History
2020-09-21: received
Short URL
https://ia.cr/2020/1145
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2020/1145,
      author = {Wonseok Choi and Byeonghak Lee and Yeongmin Lee and Jooyoung Lee},
      title = {Improved Security Analysis for Nonce-based Enhanced Hash-then-Mask {MACs}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2020/1145},
      year = {2020},
      url = {https://eprint.iacr.org/2020/1145}
}
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