  We control using bright light an actively-quenched avalanche single-photon
detector. Actively-quenched detectors are commonly used for quantum key
distribution (QKD) in the visible and near-infrared range. This study shows
that these detectors are controllable by the same attack used to hack
passively-quenched and gated detectors. This demonstrates the generality of our
attack and its possible applicability to eavsdropping the full secret key of
all QKD systems using avalanche photodiodes (APDs). Moreover, the commercial
detector model we tested (PerkinElmer SPCM-AQR) exhibits two new blinding
mechanisms in addition to the previously observed thermal blinding of the APD,
namely: malfunctioning of the bias voltage control circuit, and overload of the
DC/DC converter biasing the APD. These two new technical loopholes found just
in one detector model suggest that this problem must be solved in general, by
incorporating generally imperfect detectors into the security proof for QKD.
