Edge Cryptography and the Codevelopment of Computer Networks and Cybersecurity
Quinn DuPont, Bradley Fidler · IEEE Annals of the History of Computing · 2016
Developed around 1973 by BBN under contract from DARPA, the private line interface (PLI), a cryptographic cybersecurity device used on the Arpanet, operated with minimal modification of the existing network infrastructure, sitting at the "edge" of the network between the network switches and the connected host computers. As a result of the developmental and infrastructural trajectory set in motion by the PLI, significant cryptographic resources remain at the edges (or ends) of the networks that constitute the Internet today. This study of the PLI is an entry into the historical relationship between cryptography and packet-switched computer networks.