Quantum Cryptography in Practice Chip Elliott Dr. David Pearson Dr. Gregory Troxel BBN Technologies BBN Technologies BBN Technologies 10 Moulton Street 10 Moulton Street 10 Moulton Street Cambridge, MA 02138 Cambridge, MA 02138 Cambridge, MA 02138
[email protected] [email protected] [email protected] ABSTRACT BBN, Harvard, and Boston University are building the DARPA Alice Bob Quantum Network, the world’s first network that delivers end- (the sender) Eve (the receiver) to-end network security via high-speed Quantum Key plaintext (the eavesdropper) plaintext Distribution, and testing that Network against sophisticated eavesdropping attacks. The first network link has been up and encryption public channel decryption steadily operational in our laboratory since December 2002. It algorithm (i.e. telephone or internet) algorithm provides a Virtual Private Network between private enclaves, with user traffic protected by a weak-coherent implementation key key of quantum cryptography. This prototype is suitable for deployment in metro-size areas via standard telecom (dark) quantum state quantum channel quantum state fiber. In this paper, we introduce quantum cryptography, generator (i.e. optical fiber or free space) detector discuss its relation to modern secure networks, and describe its unusual physical layer, its specialized quantum cryptographic protocol suite (quite interesting in its own right), and our Figure 1. Quantum Key Distribution. extensions to IPsec to integrate it with quantum cryptography. authentication and establishment of secret “session” keys, and then protecting all or part of a traffic flow with these session Categories and Subject Descriptors keys. Certain other systems transport secret keys “out of C.2.1 [Network Architecture and Design]: quantum channel,” e.g.