windows support for entropy devices

[samoht]

Is there any plan to support entropy devices for windows? The current code for initialising entropy does this:

let devices  = [ "/dev/urandom"; "/dev/random" ]

let fs_exists name =
  Unix.(try ignore (stat name); true with Unix_error (ENOENT, _, _) -> false)

let sys_rng =
  try List.find fs_exists devices with Not_found ->
    failwith "Nocrypto_entropy_unix: no random device"

which obviously fails at runtime on windows. That would be great to fail at compile time instead (or to add the relevant constraints in the opam file).

I guess my best option for now on is are to somehow use mirage-entropy.

[pqwy]

My (rather vague) idea was that this is the _unix module, so I didn't make any effort to make it Win compatible.

Can you even compile the library on Windows without significant problems? How about the current master, which uses the system-wide endian-related headers? How important is this use-case?

In general, Windows are nowhere on my radar. But if this really matters, I can whip up an entropy module that seeds with Crypto API or its NG.

[dbuenzli]

@pqwy in OCaml, the Unix library is actually pretty good Unix/Windows compatibility layer...

[ulrikstrid]

The endian issue is fixed in #161. My fork with that endian fix builds fine on Windows but I hit this issue. If there are any pointers on how i would add a Windows entorpy implementation I would be super happy. This seems to be the last blocker for getting tls to build and work on Windows.