Quantum Byzantine Agreement via Hardy correlations and entanglement swapping
This addresses secure communication in distributed systems, offering a novel quantum solution to prevent cheating in Byzantine agreement.
The paper tackles the Byzantine Generals problem by proposing a device-independent quantum protocol for three parties, where if messages are readable, cheating by the commanding general is impossible without requiring message exchange between receivers.
We present a device-independent quantum scheme for the {\em Byzantine Generals} problem. The protocol is for three parties. Party $C$ is to send two identical one bit messages to parties $A$ and $B$. The receivers $A$ and $B$ may exchange two one bit messages informing the other party on the message received from $C$. A bit flipping error in one of the transmissions, does not allow the receiving parties to establish what was the message of $C$. Our quantum scheme has the feature that if the messages of the Byzantine protocol are readable (that is give an unambiguous bit value for any of the receivers), then any error by $C$ (cheating by one of the commanding general) is impossible. $A$ and $B$ do not have to exchange protocol messages to be sure of this.