Enhanced Quantum Permutation Pad for Quantum Based Text Encryption

This paper proposes an advanced quantum text encryption scheme based on an Enhanced Quantum Permutation Pad (QPP). The method begins by generating <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$6 \times 6$</tex> padded matrices derived from all possible permutations of four basis vectors in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbb{R}^{4}$</tex>. These matrices are converted into binary strings and encrypted using two-qubit quantum circuits, where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$X$</tex> and CNOT gates enable quantum entanglement and conditional operations. A binary key is applied to influence the behavior of the quantum circuits during both encryption and decryption. The encryption logic is simulated using Qiskit's AerSimulator, and the resulting binary data is reconstructed into its original structure through matrix extraction. Experimental evaluation using the ENT test demonstrates a high entropy value of 7.66, indicating strong randomness and robustness of the encryption. This methodology presents a secure and structured approach to quantum encryption, combining permutation logic with quantum operations to ensure confidentiality and resistance to classical attacks.