Investigating the use of pixel scrambling and diffusion in secure radiographic inspections

In warhead verification, physical encryption technology could play a critical role in protecting confidential information on geometric structure and isotopic composition of a true warhead. As an important supplement to physical encryption, algorithmic encryption still has great potential in improving defense-in-depth security for nuclear arms control verification. To further supplement feasible nuclear arms control verification technologies, we propose a verification method based on neutron induced fission reactions employing both physical field flux encryption and algorithm encryption. Physical encryption processes the classified geometry or composition information by encrypting the fission neutron signal of the tested item with a randomly shielded mask. Algorithm encryption adopts pixel scrambling, pixel diffusion for secondary encryption. To verify the robustness and security of this new verification method, numerical simulations are performed using the Monte Carlo toolkit Geant4. Verification results indicate a high level of robustness and security with a low level of noise (∼<0.5%).