There is no such thing as an absolutely secure microcontroller. I have worked with Smartcards for e-purse applications for years and even these are vulnerable to attack. The point that Erik already made is: Is it worth the effort?

There is an article by Anderson and Kuhn on tamper resistance of secure devices, including microcontrollers. Peter: I'm afraid the DS5000 family is not as secure as they say, no matter how expensive it is ... :o)

Rob.