Wen Wang, Bernhard Jungk, Julian Wälde, Shuwen Deng, Naina Gupta, Jakub Szefer, and Ruben Niederhagen, "XMSS and Embedded Systems - XMSS Hardware Accelerators for RISC-V", in Cryptology ePrint Archive, Report 2018/1225, 2018.
ePrint version of the paper is available from: https://eprint.iacr.org/2018/1225