Compact implementations of BLAKE-32 and BLAKE-64 on FPGA

We propose compact architectures of the SHA-3 candidates BLAKE-32 and BLAKE-64 for several FPGA families. We harness the intrinsic parallelism of the algorithm to interleave the computation of four instances of the G
_i
function. This approach allows us to design an Arithmetic and Logic Unit with four pipeline stages, and to achieve high clock frequencies. With careful scheduling, we completely avoid pipeline bubbles. For the time being, the designs presented in this work are the most compact ones for any of the SHA-3 candidates. We show for instance that a fully autonomous implementation of BLAKE-32 on a Xilinx Virtex-5 device requires 56 slices and two memory blocks.