Is Coca Cola legal? (read the detail to see why I ask)?

You probably know that there is an ingredient in coca cola which has been a company secret since the first drink was bottled. ( this is not a speculation google it and you will see they actually admit it ). But as far as it is a secret that means that it is not included in the list of ingredients every product should have on its stamp. Isnt that illegal ? Virtually they might be putting whatever they want there. And why should they hide it ? Why not just registering the formula as a property of the coca cola company the same way they did with the shape of their bottles . Just dont say : Because anyone would be able to make it at home because this isnt the case . Have you seen the places they are producing it ? Even if the ingredients for the formula are so widespread you would probably need some kind of a machine to process them and i doubt that somebody would go to such great lenghts just to spare a dollar.Take coffee for example , nobody grows coffee in the backyard.And even if they found a backdoor in the law dont forget that this drink is distributed all over the world not just in America.