### {\sf TrCBC} is Insecure

Debrup Chakraborty and Samir Kundu

##### Abstract

{\sf TrCBC} is a variant of CBC-MAC which appeared in {\em Information Processing Letters}, 112(7):302-307, 2012. The authors claimed {\sf TrCBC} to be a secure message authentication code (MAC) with some interesting properties. If ${\sf TrCBC}$ is instantiated with a block cipher with block length $n$, then it requires $\lceil \lambda /n \rceil$ block cipher calls for authenticating a $\lambda$-bit message and requires a single key, which is the block cipher key. We show that with high probability, an adversary can forge {\sf TrCBC} with just three queries. The attack that we show can be applied to forge a large class of messages.

Available format(s)
Category
Secret-key cryptography
Publication info
Preprint. Minor revision.
Keywords
Message authentication codes (MACs)CBC-MACTrCBCTruncated MAC.
Contact author(s)
samirkundu3 @ gmail com
debrup chakraborty @ gmail com
History
Short URL
https://ia.cr/2022/476

CC BY

BibTeX

@misc{cryptoeprint:2022/476,
author = {Debrup Chakraborty and Samir Kundu},
title = {{\sf TrCBC} is Insecure},
howpublished = {Cryptology ePrint Archive, Paper 2022/476},
year = {2022},
note = {\url{https://eprint.iacr.org/2022/476}},
url = {https://eprint.iacr.org/2022/476}
}

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