Orthros: A Low-Latency PRF

We present Orthros, a 128-bit block pseudorandom function. It is designed with primary focus on latency of fully unrolled circuits. For this purpose, we adopt parallel structure comprising two keyed permutations. The round function each permutation similar to Midori, low-energy cipher, however thoroughly revise it reduce latency, and introduce different rounds significantly improve cryptographic strength in small number rounds. provide comprehensive, dedicated security analysis. hardware implementation, Orthros achieves the lowest among state-of-the-art low-latency primitives. example, using STM 90nm library, minimum around 2.4 ns, while other constructions like PRINCE, Midori-128 QARMA9-128- σ0 achieve 2.56 4.10 4.38 ns respectively.