Quantum Bit Commitment Based on Qubit Oblivious Transfer

Guang Ping He

Anthony J. Short, Nicolas Gisin, Sandu Popescu

Yaqi Song, Li Yang

Oblivious transfer (OT) and bit commitment (BC) are two-party cryptographic protocols which play crucial roles in the construction of various cryptographic protocols. We propose three practical quantum cryptographic protocols in this paper. We first construct a practical quantum random oblivious transfer (R-OT) protocol based on the fact that non-orthogonal states cannot be reliably distinguished. Then, we construct a fault-tolerant one-out-of-two oblivious transfer ( O T 1 2 ) protocol based on the quantum R-OT protocol. Afterwards, we propose a quantum bit commitment (QBC) protocol which executes the fault-tolerant O T 1 2 several times. Mayers, Lo and Chau (MLC) no-go theorem proves that QBC protocol cannot be unconditionally secure. However, we find that computing the unitary transformation of no-go theorem attack needs so many resources that it is not realistically implementable. We give a definition of physical security for QBC protocols and prove that the practical QBC we proposed is physically secure and can be implemented in the real world.

Ariel Danan, Lev Vaidman A

Li Yang

Constructing oblivious transfer and bit commitment protocols based on chan-nel’s quantum nature to achieve statistical security has always been a basic aspect of quantum cryptography. Here we put forward a scheme to reach this goal. The idea is constructing first a random oblivious transfer (R-OT, an ex-tension of Rabin’s OT) protocol based on non-orthogonal states transmission over a quantum channel, then, as that usually do in modern cryptography, we construct a one-out-of-two oblivious transfer protocol on top of the R-OT protocol. Finally, we present a bit commitment protocol based on the one-out-of-two OT protocol, and show that it is statistically secure both in concealing and binding.

Louis Salvail