Lossy CSI-FiSh: Efficient signature scheme with tight reduction to decisional CSIDH-512 by El Kaafarani, A, Katsumata, S, Pintore, F

“…In this paper, we propose an FS-style signature scheme, called Lossy CSI-FiSh, constructed using the CSIDH-512 parameters and with a security proof based on the "Lossy Keys" technique introduced by Kiltz, Lyubashevsky and Schaffner (Eurocrypt'18). Lossy CSI-FiSh is provably secure under the same assumption which underlies the security of the key exchange protocol CSIDH (Castryck et al. …”