One of the country's most closely guarded business secrets was moved under heavy guard Tuesday to a temporary undisclosed location in Louisville.The recipe for Kentucky Fried Chicken created 68 years ago by Colonel Harland Sanders will stay at the secret site during security upgrades at KFC's Louisville corporate headquarters.KFC hired New York security expert Bo Dietl (pictured) to modernize the vault that houses the recipe."We noticed that they could have some complementary security work that could be done in here," Dietl said. "Sixty-eight years is a long time, there's been a lot of security technology that we have and can implement, and are going to implement. But i'm not going to tell you what we're going to do inside this safe."KFC officials wouldn't say how long the security upgrade will take.