A novel optical image encryption is proposed based on two-step-only quadrature phase-shifting interferometry. Only two interferograms are needed to reconstruct a zero-order-and twin-image-free hologram in this phase-shifting digital holography interference. Such technique precludes the need from recording either the reference wave or the object wave intensity. The object wavefront propagates with two Fresnel transforms in the light path, combined with the double random phase encoding. The following is that introducing zero and л/2 phase into reference waves respectively and recording two digital holograms as encrypted image. As long as the correct key is given in the decryption, a clear original image can be reconstructed by a simple calculation. The feasibility and its robustness against occlusion and noise attacks are verified by a series of numerical simulations.