@misc{cryptoeprint:2021:1621,
author = {Dmytro Tymokhanov and
Omer Shlomovits},
title = {Alpha-Rays: Key Extraction Attacks on Threshold ECDSA Implementations},
howpublished = {Cryptology ePrint Archive, Report 2021/1621},
year = {2021},
note = {\url{https://ia.cr/2021/1621}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.