We review the status of Bell's inequalities in quantum information, stressing
mainly the links with quantum key distribution and distillation of
entanglement. We also prove that for all the eavesdropping attacks using one
qubit, and for a family of attacks of two qubits, acting on half of a maximally
entangled state of two qubits, the violation of a Bell inequality implies the
possibility of an efficient secret-key extraction.Comment: 9 pages, for the Proceedings of EQIS'03 (Kyoto, Sept. 2003
