type t = {
  pub: Mirage_crypto_ec.Ed25519.pub;
  sign:
    (* TODO sig type
       should be
       string -> EddsaSignature.t
       + b32 *)
    string ->
    string;
  stamp_start: Ptime.t;
  stamp_expire: Ptime.t;
  stamp_end: Ptime.t;
}

let make ~name =
  let finally _key = () in
  Vif.Device.v ~name ~finally [] @@ fun () ->
  (* TODO
       - look if it exists
       - if not, create it (TOFU initialization scheme)
       - write it *)
  (* TODO time
     correctly set those: *)
  let stamp_start = Ptime_clock.now () in
  let stamp_expire =
    match Ptime.add_span stamp_start Config.Exchange.signkey_legal_duration with
    | None ->
        Fmt.failwith "Ptime.add_span: result is not in the range [min;max]"
    | Some v -> v
  in
  let stamp_end = stamp_expire in
  let priv, pub = Mirage_crypto_ec.Ed25519.generate () in
  {
    pub;
    sign= Mirage_crypto_ec.Ed25519.sign ~key:priv;
    stamp_start;
    stamp_expire;
    stamp_end;
  }

let signkey_device = make ~name:"signkey"

(* the actual exchange's signing key
   signed by the secmod signkey *)
let exchange_device = make ~name:"exchange"
let denom_device = make ~name:"denom"