Identification is central to information or content centric networking, in order to enable referencing and access to the information objects. In this work we focus on identifiers and the identification system as a target of a design process, because without careful attention to the identifiers themselves and the approaches to selecting, assigning and using them, they may not meet their design goals. The paper begins with an examination of key issues central to the design of an identification system. With those in mind, we discuss the objectives of pervasiveness and persistence as requirements for identification in an information centric networking (ICN) approach. These lead to a set of design four goals: longevity, scalability, evolvability and security. We apply two key design principles, layering and modularity, to derive our design for the Pervasive Persistent Identification System or PPInS for information centric networking. The contributions of this work include (1) the design issues for identification systems, (2) analysis of goals and key design criteria for identification in an ICN approach, and (3) a principled design of PPInS.