We propose a new physical-layer encryption scheme through pilot designs and MIMO techniques. Under formal reduction proofs and informal reliability analysis, we demonstrate that the decoding complexity for the legitimate user grows linearly with the number of antennas, whereas for the eavesdropper, decoding is computationally infeasible. In comparison to traditional wireless physical-layer security schemes, the proposed scheme remains secure even if the eavesdropper has unlimited computing power, infinite antennas, or knows the legitimate channel. Our scheme leverages the physical-layer wireless channel’s properties to achieve sophisticated network-layer encryption without a pre-shared key. Additionally, our algorithm involving lattices provides a new approach for secure group communication and can be used to enhance the security of the post-quantum cryptosystem in 6G. Experimental results show that the proposed scheme achieves a bit error rate of approximately 0.5 for the eavesdropper and nearly 0 for the legitimate receiver.