Making Quantum Cryptography Truly Secure
27 July 2011
"Quantum key distribution has matured into a true competitor to classical key distribution. This attack highlights the areas we need to pay attention to ensure the security of this technology."
Prof Christian Kurtsiefer, CQT Principal Investigator and NUS Professor
(From left) Dr Ilja Gerhardt, Prof Antía Lamas-Linares and Prof Kurtsiefer setting up a quantum cryptography system.
Photo: 2009 Vadim Makarov (www.vad1.com)
Mobile toolkit for eavesdropping on a quantum cryptography link
Photo: 2010 NTNU Info / Geir Mogen
Physicists from the Centre for Quantum Technologies (CQT) at NUS and collaborators from Norway took on the role of hackers to point the way to tighter security for a secure communications technology.
In the 14 June issue of Nature Communications, researchers from NUS Professor Christian Kurtsiefer’s group, and scientists from the Norwegian University of Science and Technology in Trondheim and the University Graduate Centre in Kjeller, Norway, described the first full field-implemented hack of a Quantum key distribution (QKD) system, in which an eavesdropper acquired a full secret “key” without being noticed.
QKD enables secure communication by providing each party with a key to scramble and unscramble their messages. A key highlight of QKD is that the security of the key exchange is guaranteed by the laws of physics.
“Quantum key distribution has matured into a true competitor to classical key distribution. This attack highlights the areas we need to pay attention to ensure the security of this technology,” said Prof Kurtsiefer.
The attack did not target the QKD protocol but a practical behaviour of detectors typically used to implement it. Detectors which were meant to receive the key sent one photon at a time were blinded, essentially overriding the system’s ability to detect a breach of security. The open publication of how the “perfect eavesdropper” was built has already enabled this particular loophole in QKD to be closed.
By Centre for Quantum Technologies