Introduction
Although there is no standardized definition of the term “Principal Propagation”, it is commonly understood as the ability of a system to securely forward or propagate the authenticated user (principal) from a sender to a receiver in a way that the forwarded user information is kept confidential and – even more important – cannot be changed during transit. Based on a pre-established trust relationship to the sender, the receiver uses this information to logon the user without asking her again for the credentials.