Efficient QSDC with Identity Authentication

Although it is typically assumed that both communicating parties in quantum secure direct communication(QSDC) are trustworthy, it is essential to consider the authentication issue. An effective QSDC strategy based on identification authentication is proposed to address the issues of identity legitimacy and communication efficiency in QSDC. The proposed method authenticates and transmits messages using only four single-photon polarization states, detects eavesdropping, and authenticates the receiver's identification with a shared identity key, enabling secure message delivery while validating the receiver's identity. The approach is simple and efficient as it requires no sophisticated entanglement resources. A single-photon sequence transmitted at a time can encode the same number of message blocks of length N, i.e., every single photon contains N times its information and distinguishes them using markings. Moreover, it can be shown that the proposed QSDC with identity authentication is more resistant to typical attacks, thus more appropriate for practical implementations.