Henry Semenko

We have come a long way since the first implementation of a quantum key distribution (QKD) system and various attacks have been demonstrated, such as the Trojan Horse Attack (THA). In this attack, the eavesdropper Eve gains information by analysing the back-reflections of light she shines into the QKD system. Almost all attacks have been demonstrated on devices based on fibre components. However, the first chip-scale QKD devices are being developed now, utilising the small size of integrated optics, the stability of the optical system and the ease at which it can be mass-produced, showing great commercial potential. Here we discuss a THA on chip-scale QKD. First, points of reflection in a QKD transmitter chip were found via a reflectometry. Based on this we give an experimental set-up to implement a THA which would give Eve access to 50% of the key. Full experimental results of this attack are expected in the next two to three months.