I guess they could just kill you again. But would the threat of that happening in the future deter you from lying at time of death, when you have nothing else to lose?
It seems like there would need to be system of proving possession of a password that would have to last 100 years. I have not thought through this kind of scenario (sorry!). Perhaps this has been considered before by those studying the problem in detail (e.g. science fiction authors)? What are the solutions?