Comment on “quantum oblivious transfer: a secure practical implementation”

Coherent attacks on a practical quantum oblivious transfer protocol

“…It is lower than the values 62.5% (von Neumann measurement) or 64.6% (POVM) achieved by the cheating strategy proposed in Ref. [31] based on 5-body entangled states, and is merely a little higher than the value 1/2 in the honest case. However, it remain nontrivial, and like the strategy in Ref.…”

“…However, it remain nontrivial, and like the strategy in Ref. [31], raising the number of qubits used in the protocol of Ref. [30] (i.e., the values of N and M) cannot lower this probability nor make it harder to cheat.…”

“…Later, however, we found that it is insecure against 5-body entanglement-based attacks. [31] More rigorously, the goal of OT is to provide a method for the sender Alice to transfer a secret bit b to the receiver Bob, and it is called secure if Bob can obtain b unambiguously with probability 1/2 only, while Alice does not know whether Bob has learned b or not. We showed in Ref.…”

“…We showed in Ref. [31] that if Bob has the technology to handle 5-body entangled states, then in the protocol of Ref. [30], he can learn b unambiguously with probability 62.5% using von Neumann measurements, or 64.6% using positive operator-valued measure (POVM).…”