## CryptoDB

### Paper: Blockcipher-Based Authenticated Encryption: How Small Can We Go?

Authors: Avik Chakraborti Tetsu Iwata Kazuhiko Minematsu Mridul Nandi DOI: 10.1007/978-3-319-66787-4_14 Search ePrint Search Google CHES 2017 This paper presents a design of authenticated encryption (AE) focusing on minimizing the implementation size, i.e., hardware gates or working memory on software. The scheme is called $\textsf {COFB}$, for COmbined FeedBack. $\textsf {COFB}$ uses an n-bit blockcipher as the underlying primitive, and relies on the use of a nonce for security. In addition to the state required for executing the underlying blockcipher, $\textsf {COFB}$ needs only n / 2 bits state as a mask. Till date, for all existing constructions in which masks have been applied, at least n bit masks have been used. Thus, we have shown the possibility of reducing the size of a mask without degrading the security level much. Moreover, it requires one blockcipher call to process one input block. We show $\textsf {COFB}$ is provably secure up to $O(2^{n/2}/n)$ queries which is almost up to the standard birthday bound. We also present our hardware implementation results. Experimental implementation results suggest that our proposal has a good performance and the smallest footprint among all known blockcipher-based AE.
##### BibTeX
@inproceedings{ches-2017-28921,
title={Blockcipher-Based Authenticated Encryption: How Small Can We Go?},
booktitle={Cryptographic Hardware and Embedded Systems – CHES 2017},
series={Lecture Notes in Computer Science},
publisher={Springer},
volume={10529},
pages={277-298},
doi={10.1007/978-3-319-66787-4_14},
author={Avik Chakraborti and Tetsu Iwata and Kazuhiko Minematsu and Mridul Nandi},
year=2017
}