Optical encryption with protection against Dirac delta and plain signal attacks

Abstract

This Letter proposes an optical encryption technique that disguises the information with modular arithmetic concepts and time-varying noise components that are unknown to the receiver. Optical encryption systems that use these techniques produce a nondeterministic system response, as well as noise like image data that can easily be generated with ordinary spatial light modulators. The principle of this technique is demonstrated for the double random phase encoding (DRPE) method. The conventional DRPE method has major vulnerabilities for Dirac signal and plain signal attacks, making them impractical for secure encryption. It is shown that the proposed encryption technique provides a robustness against these types of attacks, allowing optical DRPE to be employed in secure encryptions. Moreover, applications of this Letter are not limited to DRPE alone but can also be adopted by other optical encryption techniques such as fractional Fourier transform and Fresnel-transform-based techniques.

High performance compact optical cryptosystem without reference arm

“…For example, the nonlinear modifications previously mentioned [16,17], not only reduces the noise over the recovered data, but also increases the security against to chosen plaintext attacks and cyphertextonly attacks. Other modifications, like the use of cryptographic salting [34] and phase only encryption [35,36] avoid known ciphertext attacks.…”

Optical encryption using phase modulation generated by thermal lens effect

“…Another important attack that must be analyzed is the chosen plaintext attack (CPA) [12,13]. In this case, an intruder with access to the cryptosystem encrypts a Dirac delta function.…”

“…The ongoing research in the optical encryption field led to the discovery of vulnerabilities in the DRPE based schemes [12][13][14][15][16][17][18]. In particular, it was found that certain techniques could be implemented to overcome the security of DRPE cryptosystems.…”

Cryptographic salting for security enhancement of double random phase encryption schemes

“…The first of these categories of attacks is the chosen plaintext attack (CPA), where the attacker has full access to the cryptosystem, and can introduce specially tailored plaintexts to be encrypted in order to deduce the encryption key. This was the first kind of attack demonstrated against the DRPE scheme [6]; however, several methods have been proposed to thwart them [7,8]. In practice, most actual encryption systems, digital or optical, are known to be vulnerable if the attacker has full access to the encryption machine.…”