This paper introduces a new optical double-image encryption and decryption scheme that provides higher security by integrating an interference-based encryption scheme with a spatial encoding method. In this research, two binary fingerprint images were encoded with a random amplitude mask (RAM) to produce a complex random phase distribution. This distribution is embedded in an interference-based encryption layer, producing encrypted outputs that overcome the silhouette issue regularly found in interference-based traditional cryptosystems. This paper presents a method of treating the random amplitude mask as a random phase distribution, which creates a supplementary encryption key and strengthens security. This technique fortifies system robustness by populating the phase mask keys generated during the encryption procedure, hence augmenting its resistance to various attacks. Numerical simulations confirm the efficacy and safety of the proposed systems, illustrating their feasibility for secure biometric verification in optical security applications.