Convert C# function to Elixir

BTW, just FYI and FWIW, a bit more idiomatic Elixir would be:

def test(conn, _params) do
  raw_skey = File.read!("/home/danish/www/apis/signtest/keys/private_key.pem")

  [enc_skey] = :public_key.pem_decode(raw_skey)
  skey = :public_key.pem_entry_decode(enc_skey)

  string = ~s("MachineName":"DESKTOP-04VG548","Userame":"inder","Timestamp":"2018-10-26T20:58:48.7840832Z"})

  signature =
    string
    |> :public_key.sign(:sha256, skey,  rsa_padding: :rsa_pkcs1_padding)
    |> Base.encode64

  IO.puts("signature")
  IO.inspect(signature)
  json conn, "ok"
end