Criptografar variavel

function EnDecryptString(StrValue : String; Chave: Word) : String;
var
I: Integer;
OutValue : String;
begin
OutValue := ´´;
for I := 1 to Length(StrValue) do
OutValue := OutValue + char(Not(ord(StrValue[I])-Chave));
Result := OutValue;
end;