Structured light carrying optical vortices have gained significant attention in information security as they offer high-dimensional orthogonal states for encoding. These states are usually associated with the orbital angular momentum of light. In this letter, we demonstrate a novel method for binary image encryption using structured phase encoding. The structured phase is obtained by multiple lattices of spatially distributed phase singularity points with varying azimuthal indices. It has been shown that data encoding using orthogonal sets of optical vortex modes enable noise-free decryption and provide robustness against atmospheric turbulence in short propagation distance.