Low cost implementation of Pomaranch S-Box

This paper presents a compact implementation of the S-Box of Pomaranch stream cipher using composite field arithmetic in GF((2
³
)
³
). It describes a systematic exploration of different choices for the irreducible polynomials that generate the extension fields. It also examines all possible transformation matrices that map one field representation to another. We evaluated the optimal candidates using Xilinx and Altera FPGA implementations.