From Practice to Theory: The "Bright Illumination" Attack on Quantum Key Distribution Systems

The "Bright Illumination" attack [Lydersen et al., Nat. Photon. 4, 686-689 (2010)] is a practical attack, fully implementable against quantum key distribution systems. In contrast to almost all developments in quantum information processing (for example, Shor's factorization algorithm, quantum teleportation, Bennett-Brassard (BB84) quantum key distribution, the "Photon-Number Splitting" attack, and many other examples), for which theory has been proposed decades before a proper implementation, the "Bright Illumination" attack preceded any sign or hint of a theoretical prediction. Here we explain how the "Reversed-Space" methodology of attacks, complementary to the notion of "quantum side-channel attacks" (which is analogous to a similar term in "classical" - namely, non-quantum - computer security), has missed the opportunity of predicting the "Bright Illumination" attack.