function H(Text,Key: String; Encode: boolean): String;
var
  i, KeyLength: integer;
  Sign: ShortInt;
begin
 KeyLength:=Length(Key);
 if Encode then Sign :=-1 else Sign:=1;
 for i:=1 to Length(Text) do
  Text[i]:=chr(ord(Text[i])+Sign*ord(Key[i mod KeyLength+1]));
  Result:=Text;
end;