anchor.diff:  -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
            terminate/2, code_change/3]).
   
  --export([new/1, open/1, set/3, sign/1, pubkey/0, delete/0,
  +-export([new/1, set/3, sign/1, pubkey/0, delete/0,
            wait_for_pubkey/0]).
   -export([verify/2]).
   -export([check_key_pair/0]).
  
positive.code: -spec check_key_pair() -> boolean().
  check_key_pair() ->
      gen_server:call(?MODULE, check_key_pair).
  
  -spec open(password()) -> {ok, password()} | {error, keys_not_loaded}.
  open(Password) ->
      gen_server:call(?MODULE, {open, Password}).
  
  -spec new(password()) -> {Priv :: binary(), Pub :: binary()} | error.
  new(Password) ->
  
negative.code:             {reply, error, State}
      end;
  
  handle_call({set, Password, Priv, Pub}, _From, #state{pub_file=PubFile, priv_file=PrivFile} = State) when is_binary(Password) ->
      try
          EncPub = encrypt_pubkey(Password, Pub),
  