Source file `auth.ml`

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open Common

let default_filename = "bitflyer-auth.conf"

type t = { api_key : string; secret : string }

let from_file ?(filename = default_filename) () =
  let ch = open_in filename in
  let api_key = input_line ch in
  let secret = input_line ch in
  close_in ch;
  { api_key; secret }

let auth () = from_file ()
let api_key auth = auth.api_key

let sign auth timestamp method_ path body =
  let text = !%"%d%s%s%s" (Datetime.to_millisec timestamp) method_ path body in
  let secret = auth.secret in
  Hacl_star.EverCrypt.HMAC.mac ~alg:SHA2_256 ~key:(Bytes.of_string secret)
    ~msg:(Bytes.of_string text)
  |> Hex.of_bytes |> Hex.show

let sign_realtime auth ~timestamp ~nonce =
  let text = !%"%d%s" timestamp nonce in
  Hacl_star.EverCrypt.HMAC.mac ~alg:SHA2_256
    ~key:(Bytes.of_string auth.secret)
    ~msg:(Bytes.of_string text)
  |> Hex.of_bytes |> Hex.show

let make_header auth meth path body =
  let timestamp = Datetime.now () in
  let s = sign auth timestamp meth path body in
  [
    ("ACCESS-KEY", auth.api_key);
    ("ACCESS-TIMESTAMP", !%"%d" (Datetime.to_millisec timestamp));
    ("ACCESS-SIGN", s);
    ("Content-Type", "application/json");
  ]