Experimental optical encryption system based on a single-lens imaging architecture combined with a phase retrieval algorithm

Single-random phase encoding architecture using a focus tunable lens

“…matches experimental results previously reported in [24,25] for the phase. Moreover, we studied the robustness of the system simulating information loss by partially occluding some of the image set composing the delocalized cyphertext.…”

“…Therefore, the resistance to brute-force attacks of this architecture is analogous to the one appearing in [24]. Otherwise, the security will be compromised, like in other conventional systems [11][12][13][14][15][16][17][18], if an intruder has access to a subset of images belonging to the cyphertext and the optical parameters sent by different transmission channels as discussed in [24,25]. Consequently, this system is more secure than conventional holographic systems.…”

“…Then, the original data are successfully decrypted by employing a simulation of the optical encoding system and an iterative phase retrieval algorithm on the set of speckle patterns registered by the camera. Also, we have presented a DRPE architecture based on a single-lens imaging system and a phase retrieval procedure applied to a set of intensity samples produced by a tridimensional speckle distribution (ciphertext) [25]. These contributions highlight the advantages of using a delocalized ciphertext instead of standard encryption techniques based on holographic recording.…”

“…This change presents three important advantages: avoids positioning errors, achieves faster acquisition times, and further reduces the size of the encryption system. In this work, condensed versions of the architectures reported in [24,25] are discussed by the introduction of a focus tunable lens. To our knowledge, this is the first discussion of such setup; furthermore, the introduction of a variable focal length requires a new iterative phase retrieval algorithm.…”

“…[23][24][25], we set at a fixed position a focus tunable lens, f v , and a CMOS camera-atz o and z z o r + from the object, respectively, figure 1(a). By tuning the lens to different focal length values, f f f , ,..., N 0 }, multiple intensity distributions of the speckle field (delocalized ciphertext) are sampled at a single plane (improving recording times).…”