In this paper, we present a quantum strong coin flipping protocol. In this protocol, an EPR pair and a quantum memory storage are made use of, and losses in the quantum communication channel and quantum memory storage are all analyzed. We obtain the bias in the fair scenario as a function of
p, where
p is the probability that the particle in Bob's quantum memory storage is lost, which means our bias varies as the degree of losses in the quantum memory storage changes. Therefore we call our protocol semi-loss-tolerant. We also show that the bias decreases with decreasing
p. When
p approaches
0, the bias approaches 0.3536, which is less than that of all the previous loss-tolerant protocols. Details of both parties' optimal cheating strategies are also given and analyzed. What's more, experimental feasibility is discussed and demonstrated. Compared with previous qubit-based loss-tolerant SCF protocols, we introduce the EPR pair to keep our protocol loss-tolerant while trying to push down the bias. In addition, a quantum memory storage is used and the losses in it has been taken into account. We obtain the bias in the fair scenario as a function of
p, where
p is the probability that the particle in Bob's quantum memory storage is lost, which means our bias varies as the degree of losses in the quantum memory storage changes. We also show that the bias decreases with decreasing
p. When
p approaches
0, the bias approaches 0.3536, which is less than that of all the previous loss-tolerant protocols. Details of both parties' optimal cheating strategies are also given and analyzed. Besides, experimental feasibility is discussed and demonstrated.
In this paper, we present a novel loss-tolerant quantum strong coin flipping (SCF) protocol. Compared with previous qubit-based loss-tolerant SCF protocols, we introduce the EPR pair to keep our protocol loss-tolerant while trying to push down the bias. In addition, losses in the quantum memory storage besides those in the quantum channel are also taken into account. We obtain the bias in the fair scenario as a function of p, where p is the probability that the particle in Bob’s quantum memory storage is lost, which means our bias varies as the degree of losses in the quantum memory storage changes. We also show that the bias decreases with decreasing p. When p approaches 0, the bias approaches 0.3536, which is less than that of all the previous loss-tolerant protocols. Details of both parties’ optimal cheating strategies are also given and analyzed.
Coin flipping is a cryptographic primitive in which two spatially separated players, who in principle do not trust each other, wish to establish a common random bit. If we limit ourselves to classical communication, this task requires either assumptions on the computational power of the participants or it requires them to send messages to each other with sufficient simultaneity to force their complete independence. Without such assumptions, all classical protocols are so that one dishonest player can completely bias the outcome to his choosing. If we allow for quantum communication, on the other hand, protocols have been introduced that limit the maximal bias that dishonest players can produce. However, those protocols would be very difficult to implement in practice because they cannot tolerate realistic losses on the quantum channel between the participants or in their quantum storage and measurement apparatus. In this paper, we introduce a novel quantum protocol and we prove its unconditional security even when such losses are taken into account.
Coin flipping is a cryptographic primitive in which two spatially separated players, who do not trust each other, wish to establish a common random bit. If we limit ourselves to classical communication, this task requires either assumptions on the computational power of the players or it requires them to send messages to each other with sufficient simultaneity to force their complete independence. Without such assumptions, all classical protocols are so that one dishonest player has complete control over the outcome. If we use quantum communication, on the other hand, protocols have been introduced that limit the maximal bias that dishonest players can produce. However, those protocols would be very difficult to implement in practice because they are susceptible to realistic losses on the quantum channel between the players or in their quantum memory and measurement apparatus. In this paper, we introduce a quantum protocol and we prove that it is completely impervious to loss. The protocol is fair in the sense that either player has the same probability of success in cheating attempts at biasing the outcome of the coin flip. We also give explicit and optimal cheating strategies for both players.