A　new　encryption/decryption　system　is　designed　for　information　security.　The　system　used　an　iterative　Fourier　transform　algorithm　to　optimize　the　encrypted　hologram　and　the　decryption　key　as　phase-only　elements.　The　optical　decryption　was　implemented　by　superimposing　the　encrypted　hologram　and　the　decryption　key　in　a　simple　optical　setup.　Numerical　simulation　and　optical　experiment　have　confirmed　the　proposed　technique　as　a　simple　and　easy　implementation　for　optical　decryption,　demonstrating　potential　applications　in　information　security　verification.　This　system　provides　an　advantage　to　encode　information　in　an　invisible　element.　Computer　simulations　have　demonstrated　the　effectiveness　of　this　technique.