The implications of quantum information technology for cybersecurity and strategic stability seem worrisome. In theory, an adversary with a quantum computer could defeat the asymmetric encryption protocols that underwrite internet security, while an adversary using quantum communications guaranteed secure by the laws of physics could deny intelligence warning of surprise attack. To assess these claims, Jon Lindsay discusses the general political logic of cryptology grounded in the bargaining model of war, which understands uncertainty as an important cause of war and institutions as an important source of information. Cryptology of any technological vintage is shaped by both aspects of this logic, with ambiguous implications for strategic stability. In practice, strategic interaction between intelligence competitors using real quantum systems implemented in fallible human organizations will mitigate the impact of quantum computing. The upshot is that the revolutionary scientific innovation of quantum computing will probably have only marginal political impact, in part because the fields of cryptology and computing have already undergone important transformations in recent decades.

Jon R. Lindsay is Assistant Professor at the Munk School of Global Affairs & Public Policy and the Department of Political Science at the University of Toronto. His research examines the relationship between technology and global security. His publications include China and Cybersecurity: Espionage, Strategy, and Politics in the Digital Domain (Oxford University Press, 2015) with Tai Ming Cheung and Derek Reveron and Cross-Domain Deterrence: Strategy in an Era of Complexity (Oxford University Press, 2019) with Erik Gartzke. Another book manuscript, Shifting the Fog of War: Information Technology and Practice in Military Organizations, is currently under review. He holds a Ph.D. in Political Science from the Massachusetts Institute of Technology, and an M.S. in Computer Science and B.S. in Symbolic Systems from Stanford University. He has also served in the U.S. Navy with operational assignments in Europe, Latin America, and the Middle East.