Efficient Key Verification for Quantum Communication Using Polynomial Interpolation

Quantum communication uses photons to transmit quantum bits (qubits) over long distances. By using this quantum technology, quantum key distribution (QKD), a secure communication protocol, ensures the security of encryption key exchange. Due to noise and eavesdropping in the quantum channel, errors can occur in the shared qubits after QKD key agreement phase. Therefore, we need a key verification phase to deal with inconsistent qubits (i.e. the wrong qubits at the receiving end). This key verification is also called information reconciliation. Recently, some reconciliation algorithms in QKD (RQKD) using polynomial consistency have been proposed. These RQKDs use the consistency property to find the correct polynomial (converted from the qubits) and then check the correctness of other qubits based on this polynomial to achieve reconciliation. All previous consistency-based RQKDs required such an extra step to check the correctness of other qubits after finding the correct polynomial. In this paper, we propose Enhanced RQKD (ERQKD), which uses consistency in a new way to improve key verification efficiency without requiring additional checking steps. Theoretical analysis and experiments indeed show that our ERQKD outperforms the two previous RQKDs.