In the 21st century, social infrastructures, such as economic systems, transportation systems and governmental service systems, are redesigned and reconstructed based on information technologies. In this paper, basic information technologies of the new social infrastructures are proposed. The personal identifier (PID) system for bidirectional authentication and an RFID tag system will play important roles in the new social infrastructures. Using PID and RFID tag, we can bridge a gap between the real world and the virtual world on computers automatically. We call the society, in which all persons and goods have their own digital names and recognizable both in the real and virtual world, "Digitally Named World". The systems require technologies of SoC, networking, security and software. Technical challenges and social requirements for the new technologies are presented.