Optical cryptography with biometrics for multi-depth objects

Abstract

We propose an optical cryptosystem for encrypting images of multi-depth objects based on the combination of optical heterodyne technique and fingerprint keys. Optical heterodyning requires two optical beams to be mixed. For encryption, each optical beam is modulated by an optical mask containing either the fingerprint of the person who is sending, or receiving the image. The pair of optical masks are taken as the encryption keys. Subsequently, the two beams are used to scan over a multi-depth 3-D object to obtain an encrypted hologram. During the decryption process, each sectional image of the 3-D object is recovered by convolving its encrypted hologram (through numerical computation) with the encrypted hologram of a pinhole image that is positioned at the same depth as the sectional image. Our proposed method has three major advantages. First, the lost-key situation can be avoided with the use of fingerprints as the encryption keys. Second, the method can be applied to encrypt 3-D images for subsequent decrypted sectional images. Third, since optical heterodyning scanning is employed to encrypt a 3-D object, the optical system is incoherent, resulting in negligible amount of speckle noise upon decryption. To the best of our knowledge, this is the first time optical cryptography of 3-D object images has been demonstrated in an incoherent optical system with biometric keys.

Off-axis optical scanning holography [Invited]

“…Figure 6(b) is the intensity plot of the coherent point spread function (CPSF) given by Eq. (8) [i.e., |b(x , y ; z + z 0 ) 2 |]. Note that the intensity of the CPSF is of the same form of the intensity point spread function (IPSF) of the incoherent case [see Eq.…”

“…Optical scanning holography (OSH) is a single-pixel digital holographic recording technology that is highly sophisticated with many facets and applications [1,2]. Some unique applications have been demonstrated already by OSH, such as fluorescence 3D microscopy [3][4][5], PSF-engineered holography [6], cryptography [7,8], compressive holography [9], 3D pattern recognition [10], preprocessing and sectioning in holography [11,12], and most recently, the direct digital recording of a cylindrical hologram [13]. OSH is based on two principles: optical scanning and heterodyning.…”

Asymmetric cryptosystem based on optical scanning cryptography and elliptic curve algorithm

“…Since Refrégiér and Javidi first proposed the double random phase encoding (DRPE) technique 1 , researchers have introduced many extended optical encryption methods such as a series of optical transforms 2 – 5 , digital holography 6 – 8 , joint transform correlator 9 – 11 and ghost imaging 12 – 14 , etc. Furthermore, optical scanning cryptography (OSC) 15 – 19 envisioned by Poon has become a prospective technology. Different from that of other CCD-based hologram acquisition systems, it can capture the hologram of a physical object with a fast scanning mechanism along with single-pixel recording.…”

Hybrid State Engineering of Phase‐Change Metasurface for All‐Optical Cryptography

“…[ 1–5 ] Apart from computer‐based approaches, optical signal processing (OSP)‐based cryptosystems have recently received a great deal of attention because of their inherent advantages, such as natural 2D imaging capabilities, multiple degrees of freedom, and high‐speed parallelism. [ 6–11 ] Optical cryptographic techniques exploit the interaction between laser beam and complex combinations of various optical devices such as spatial light modulators and interferometers. They have proven to yield well‐protected ciphered information in addition to extremely fast decryption thanks to the nature of photon‐based optical communication.…”