Paper 2022/049

Small MACs from Small Permutations

Maria Eichlseder, Ahmet Can Mert, Christian Rechberger, and Markus Schofnegger

Abstract

The concept of lightweight cryptography has gained in popularity recently, also due to various competitions and standardization efforts specifically targeting more efficient algorithms, which are also easier to implement. One of the important properties of lightweight constructions is the area of a hardware implementation, or in other words, the size of the implementation in a particular environment. Reducing the area usually has multiple advantages like decreased production cost or lower power consumption. In this paper, we focus on MAC functions and on ASIC implementations in hardware, and our goal is to minimize the area requirements in this setting. For this purpose, we design a new MAC scheme based on the well-known Pelican MAC function. However, in an effort to reduce the size of the implementation, we make use of smaller internal permutations. While this certainly leads to a higher internal collision probability, effectively reducing the allowed data, we show that the full security is still maintained with respect to other attacks, in particular forgery and key recovery attacks. This is useful in scenarios which do not require large amounts of data. Our detailed estimates, comparisons, and concrete benchmark results show that our new MAC scheme has the lowest area requirements and offers competitive performance. Indeed, we observe an area advantage of up to 30% in our estimated comparisons, and an advantage of around 13% compared to the closest competitor in a concrete implementation.