title: ocaml equivalent of php's openssl_verify function
body: <p>I'm trying to make an ocaml version of <a href="https://github.com/Yubico/php-u2flib-server/blob/master/src/u2flib_server/U2F.php" rel="nofollow noreferrer">https://github.com/Yubico/php-u2flib-server/blob/master/src/u2flib_server/U2F.php</a> but it seems like I don't understand all of it, I'm trying to finish the doRegister function.</p>
  
  <p>I can successfully decode all the infos, and I end up with a valid pem certificate, what looks like a proper signature and the data to check. I'm looking for the ocaml equivalent of php's openssl_verify (line 231 of the php file), but looking at the doc I'm not sure of what it does exactly.</p>
  
  <p>I'm targeting MirageOS so I can't just use the C library.</p>