Digestif (and Rakia) provid some hashes functions in OCaml. Rakia provides theses functions by a C stub and Digestif is a pure implementation in OCaml of theses hashes. So these hashes functions can be used in an OCaml/Mirage/JavasScript world. Obviously, Rakia is more faster than Digestif (the hot loop was implemented in C) but it's possible than Rakia can't compile in your architecture. In this case, it's better to use Digestif or send a PR to fix Rakia.