On the security of the quantum oblivious transfer and key distribution protocols

Abstract

No quantum key distribution (QKD) protocol has been proved fully secure. A remaining problem is the eavesdropper’s ability to make coherent measurements on the joint properties of large composite systems. This problem has been recently solved by Yao in the case of the security of a quantum oblivious transfer (QOT) protocol. We consider an extended OT task which, in addition to Alice and Bob, includes an eavesdropper Eve among the participants. An honest Eve is inactive and receives no information at all about Alice’s input when Bob and Alice are honest. We prove that the security of a QOT protocol against Bob implies its security against Eve as well as the security of a QKD protocol.