Table 1 The table tabulates the equivalent Shannon information entropy per n-qubit permutation space for n from 2 to 5. We also illustrate the number of gates to achieve the equivalent classical 256 bits of entropy and classical key bit length. The last row displays the number of qubits required per circuit to achieve the quantum security, counting qubits corresponding to the message and the pre-shared key

From: Quantum encryption with quantum permutation pad in IBMQ systems