For the emerging ambient environments, in which interconnected intelligent devices will surround us to increase the comfort of our lives, fault tolerance and security are of paramount importance. In contrast to the computers in a normal distributed system, ambient devices are generally small (meaning they have little computing power or memory space), often battery operated and interconnected much more dynamically. In this paper we discuss the fundamental research issues that emerge while designing the distributed algorithms for such ambient systems that must be both fault tolerant and secure.