Defense Industry Daily has a bulletin describing some recent government projects in quantum computing largely as applied to cryptography. “A DARPA Quantum Network became fully operational on Oct 23/03 in BBN’s laboratories, running the world’s first Quantum Key Distribution (QKD) network using 24×7 quantum cryptography to provide unprecedented levels of security for standard Internet traffic flows. DARPA’s “Quantum Information Science & Technology” (QuIST) program lists as a completed effort; it won a DARPA award in 2008 for scientific breakthroughs. DARPA’s “High Productivity Computing Systems” effort includes some quantum related efforts, and appears to be ongoing.”
Quantum computing can provide two potential advantages to an information warrior. First, it may make it possible to crack cyphers which are currently unbreakable. “If large-scale quantum computers can be built, they will be able to solve certain problems much faster than any of our current classical computers (for example Shor’s algorithm). … Although quantum computers may be faster than classical computers, those described above can’t solve any problems that classical computers can’t solve.” The other advantage is that it a quantum-encrypted message cannot be read without altering it. Therefore any eavesdropper would give himself away.
But signals can still be compromised in other ways, as this article describes.