ABSTRACT
Various services like Google involve multiple services like YouTube, calender, finance and so on under a single roof. The chapter discusses various multi-server scenarios and phases involved in the multi-server environment. It also discusses models of adversaries to have a clear understanding about various loop-holes possible in the multi-server environment. The major difference between multi-server environment in the internet and in the internet of things will be the number of players involved. Multi-servers involve extra entities like registration center and different servers for different applications. The registration server is the first phase of multi-server authentication algorithms. The server registration phase indicates that every server in the multi-server environment does the registration with registration center. User login phase in the multi-server environment is similar to single server environment. User authentication phase ensures the server that user is valid user and ensures user that it is communicating with correct server.
