Paper 2022/476
On the Security of TrCBC
, Indian Statistical Institute, Indian Statistical InstituteAbstract
TrCBC is a variant of CBC-MAC which appeared in Information Processing Letters, 112(7):302-307, 2012. The authors claimed TrCBC to be a secure message authentication code (MAC) with some interesting properties. If TrCBC is instantiated with a block cipher with block length n, then it requires ⌈λ/n⌉ block cipher calls for authenticating a λ-bit message and requires a single key, which is the block cipher key. The authors state that TrCBC can have tag lengths of size less than n/2. We show that with high probability, an adversary can forge TrCBC with tag length n/2 − 1 with just three queries. The attack that we show can be applied to forge a large class of messages. The authors proved TrCBC to be a pseudorandom function (PRF). A scrutiny of the claimed PRF bound shows that for some recommended values of tag lengths, the bound turns out to be quite large. Thus, the security theorem does not imply security of TrCBC for all recommended tag lengths.
Metadata
- Available format(s)
-
PDF
- Category
- Attacks and cryptanalysis
- Publication info
- Preprint.
- Keywords
- Message authentication codes (MACs) CBC-MAC TrCBC Truncated MAC.
- Contact author(s)
-
debrup chakraborty @ gmail com
samirkundu3 @ gmail com - History
- 2022-08-31: last of 2 revisions
- 2022-04-23: received
- See all versions
- Short URL
- https://ia.cr/2022/476
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2022/476,
author = {Debrup Chakraborty and Samir Kundu},
title = {On the Security of TrCBC},
howpublished = {Cryptology ePrint Archive, Paper 2022/476},
year = {2022},
note = {\url{https://eprint.iacr.org/2022/476}},
url = {https://eprint.iacr.org/2022/476}
}
