Security of quantum key distribution with arbitrary individual imperfections

We consider the security of the Bennett-Brassard 1984 protocol for quantum key distribution, with arbitrary individual imperfections simultaneously in the source and detectors. We provide the secure key generation rate and show that three parameters must be bounded to ensure security; the basis dependence of the source, a detector-blinding parameter, and a detector leakage parameter. The system may otherwise be completely uncharacterized and contain large losses.