TWO-WAY QUANTUM-BIT-STRING COMMITMENT

Abstract

Due to the high cost of the qubit generating device (QGD) (the single photon source), QGD may not be available at the same time in both communicating parties (Alice and Bob) who have to execute the quantum bit string commitment (QBSC) protocol for some application environments. All the existing QBSC protocols allow one-way commitment i.e., only the party (Bob) who possesses the QGD is allowed to commit a bit string to Alice who does not have the QGD, but not the other way around. However, what happens if Alice, who does not have the QGD, is required to commit a bit string to Bob? The current QBSC protocols fail to provide a solution in this case. Therefore, the purpose of this paper is to allow Alice, who is not equipped with the QGD, to commit a bit string to Bob who has the QGD. With our proposed protocol, together with previously proposed QBSC protocols, Alice and Bob can perform two-way commitment, even though Bob is the only party who is equipped with the QGD.