Known-plaintext attack and ciphertext-only attack for encrypted single-pixel imaging

📝 Abstract

In many previous works, a single-pixel imaging (SPI) system is constructed as an optical image encryption system. Unauthorized users are not able to reconstruct the plaintext image from the ciphertext intensity sequence without knowing the illumination pattern key. However, little cryptanalysis about encrypted SPI has been investigated in the past. In this work, we propose a known-plaintext attack scheme and a ciphertext-only attack scheme to an encrypted SPI system for the first time. The known-plaintext attack is implemented by interchanging the roles of illumination patterns and object images in the SPI model. The ciphertext-only attack is implemented based on the statistical features of single-pixel intensity values. The two schemes can crack encrypted SPI systems and successfully recover the key containing correct illumination patterns.

💡 Analysis

In many previous works, a single-pixel imaging (SPI) system is constructed as an optical image encryption system. Unauthorized users are not able to reconstruct the plaintext image from the ciphertext intensity sequence without knowing the illumination pattern key. However, little cryptanalysis about encrypted SPI has been investigated in the past. In this work, we propose a known-plaintext attack scheme and a ciphertext-only attack scheme to an encrypted SPI system for the first time. The known-plaintext attack is implemented by interchanging the roles of illumination patterns and object images in the SPI model. The ciphertext-only attack is implemented based on the statistical features of single-pixel intensity values. The two schemes can crack encrypted SPI systems and successfully recover the key containing correct illumination patterns.

📄 Content

Known-plaintext attack and ciphertext-only attack for encrypted single-pixel imaging

Shuming Jiao,1 Yang Gao,1 Ting Lei,1 Zhenwei Xie,1 and, Xiaocong Yuan,1,* 1 Nanophotonics Research Center, Shenzhen University, Shenzhen, Guangdong, 518060, China

• xcyuan@szu.edu.cn

Abstract:
In many previous works, a single-pixel imaging (SPI) system is constructed as an optical image encryption system. Unauthorized users are not able to reconstruct the plaintext image from the ciphertext intensity sequence without knowing the illumination pattern key. However, little cryptanalysis about encrypted SPI has been investigated in the past. In this work, we propose a known-plaintext attack scheme and a ciphertext-only attack scheme to an encrypted SPI system for the first time. The known-plaintext attack is implemented by interchanging the roles of illumination patterns and object images in the SPI model. The ciphertext-only attack is implemented based on the statistical features of single-pixel intensity values. The two schemes can crack encrypted SPI systems and successfully recover the key containing correct illumination patterns.
Keywords: single-pixel imaging, ghost imaging, encryption, attack, plaintext, ciphertext

1. Introduction Optical encryption, authentication and watermarking systems [1-3] can be constructed for information security applications, with advantages such as multi-dimensional parallel processing capabilities, fast processing speed and direct processing of physical objects without digitalization. In previous works, an image encryption system can be physically implemented with various types of optical imaging systems, including but not limited to double random phase encoding (DRPE) [4], holography [5,6], integral imaging [7-9], ptychography [10,11], and single-pixel imaging [12-21]. In these systems, the plaintext image is converted to a light field, which is optically transformed into a ciphertext light field with certain physical encryption keys (e.g. random phase masks or random illumination patterns).

Fig. 1. Optical setup for a single-pixel imaging system.

Single-pixel imaging (SPI) [22,23] is an optical imaging technique that captures an object image with a single-pixel detector instead of a pixelated sensor array. After the target object is sequentially illuminated with many varying patterns and a single-pixel intensity sequence is recorded, the object image can be computationally reconstructed. Compared with other optical encryption architectures [4-11], the sensor is a simple bucket light detector and a real intensity value instead of a complex light field is recorded each time in an encrypted SPI system, which is easier to implement experimentally. A typical optical setup for a SPI system is shown in Fig. 1. For any type of encryption system, the security strength is always a crucial concern. Attacking methods can be developed to uncover the security flaws of an existing encryption system. In the meanwhile, the security strength of an encryption system can be further enhanced against these attacking methods. Like a shield and spear relationship, encryption methods and attacking methods (or cryptanalysis) are upgraded against each other iteratively to finally produce a more secure system. The common attacking methods for an image encryption system include chosen- plaintext attack (CPA), known-plaintext attack (KPA) and ciphertext-only attack (COA). In CPA, it is assumed that the attacker can access the encryption system and control the input plaintext content. The security keys are recovered based on selected pairs of plaintexts and ciphertexts. The CPA is relatively easy to implement but the assumption that the attacker can freely choose the plaintext may be invalid in many practical situations. In KPA, a number of plaintext-ciphertext pairs are available, which are given randomly instead of being selected by attackers. KPA can threaten an encryption system under more general conditions compared with CPA. In COA, the attacker can only access a certain number of ciphertexts and does not know any plaintext information. COA requires the least amount of information to crack an encryption system and reveals the most severe security flaw of an encryption system. At the same time, COA is usually most difficult to realize for an attacker. For other types of optical encryption systems such as DRPE [4], various implementations of encryption systems [24-28] and various types of cryptanalysis [29- 35] including CPA, KPA and COA have been extensively investigated. However, for encrypted SPI, many works have been conducted on the design of encryption systems [12-21] since the earliest attempt [12] but little cryptanalysis has been investigated previously. As far as the author knows, only one such work [36] can be found, in which some CPA methods are proposed. No KPA or COA schemes have even been proposed for encrypted SPI systems in

This content is AI-processed based on ArXiv data.