Computational ghost imaging is widely used in classical cryptographic key distribution (CKD) because its measurement and reconstruction are equivalent to the encoding and decoding of signals. Although the measurement efficiency and key-generation rate can be improved by using snapshot compressive ghost-imaging technique, it is still hard to deal with the risk of private key leakage. In this paper, we propose a cascade snapshot CKD protocol over a public network. In each round of communication, multiframe binary block diagrams embedded with cryptographic keys, Arnold transform parameters (derived from the checksum data of recovered images in the previous communication), and users' authentication information are superimposed into one image frame that is measured within a single exposure of an array detector, here the Arnold transformation is applied to randomly disrupt the previously used modulation patterns according to the above parameters, which greatly enhances the nonstealability of private keys and makes the temporary intrusion of a fake identity nowhere to hide. Both simulation and experimental results have demonstrated the feasibility of this protocol and its ability to detect illegal attacks. We believe that the introduction of the cascade idea will accelerate the practicalization process of snapshot CKD.
Computational ghost imaging is widely used in classical cryptographic key distribution (CKD) because its measurement and reconstruction are equivalent to the encoding and decoding of signals. Although the measurement efficiency and key-generation rate can be improved by using snapshot compressive ghost-imaging technique, it is still hard to deal with the risk of private key leakage. In this paper, we propose a cascade snapshot CKD protocol over a public network. In each round of communication, multiframe binary block diagrams embedded with cryptographic keys, Arnold transform parameters (derived from the checksum data of recovered images in the previous communication), and users' authentication information are superimposed into one image frame that is measured within a single exposure of an array detector, here the Arnold transformation is applied to randomly disrupt the previously used modulation patterns according to the above parameters, which greatly enhances the nonstealability of private keys and makes the temporary intrusion of a fake identity nowhere to hide. Both simulation and experimental results have demonstrated the feasibility of this protocol and its ability to detect illegal attacks. We believe that the introduction of the cascade idea will accelerate the practicalization process of snapshot CKD.
In existing cryptographic key distribution (CKD) protocols based on computational ghost imaging (CGI), the interaction among multiple legitimate users is generally neglected, and the channel noise has a serious impact on the performance. To overcome these shortcomings, we propose a multi-party interactive CKD protocol over a public network, which takes advantage of the cascade ablation of fragment patterns (FPs). The server splits a quick-response (QR) code image into multiple FPs and embeds different "watermark" labels into these FPs. By using a CGI setup, the server will acquire a series of bucket value sequences with respect to different FPs and send them to multiple legitimate users through a public network. The users reconstruct the FPs and determine whether there is an attack in the public channel according to the content of the recovered "watermark" labels, so as to complete the self-authentication. Finally, these users can extract their cryptographic keys by scanning the QR code (the cascade ablation result of FPs) returned by an intermediary. Both simulation and experimental results have verified the feasibility of this protocol. The impacts of different attacks and the noise robustness have also been investigated.
In the existing ghost-imaging-based cryptographic key distribution (GCKD) protocols, the cryptographic keys need to be encoded by using many modulated patterns, which undoubtedly incurs long measurement time and huge memory consumption. Given this, based on snapshot compressive ghost imaging, a public network cryptographic key distribution protocol is proposed, where the cryptographic keys and joint authentication information are encrypted into several color block diagrams to guarantee security. It transforms the previous single-pixel sequential multiple measurements into multi-pixel single exposure measurements, significantly reducing sampling time and memory storage. Both simulation and experimental results demonstrate the feasibility of this protocol and its ability to detect illegal attacks. Therefore, it takes GCKD a big step closer to practical applications.
Optical communication has an increasing need for security in public transmission scenarios. Here, we present a protocol for cryptographic key distribution over a public network via a photon-counting compressive imaging system with watermarking, which utilizes a watermarking technique to distribute secure keys, and uses reconstructed images for simultaneous identity authentication and tampering identification. The watermark is embedded in the rearranged compressed measurements of the object, and then the signal is transmitted through a public network. At the receiving terminal, legitimate users can easily extract the watermark as the cryptographic key by using initial keys and the variance characteristic of random measurements. Artificial tampering and attacks can be detected by accurately retrieved images. The realization of this protocol is a step forward toward practical applications, and will be beneficial for the broader fields of optical security in many ways.
We present a protocol for the amplification and distribution of a one-time-pad cryptographic key over a point-to-multipoint optical network based on computational ghost imaging (GI) and compressed sensing (CS). It is shown experimentally that CS imaging can perform faster authentication and increase the key generation rate by an order of magnitude compared with the scheme using computational GI alone. The protocol is applicable for any number of legitimate user, thus, the scheme could be used in real intercity networks where high speed and high security are crucial.
Computational ghost imaging (CGI) is a method of acquiring object information by measuring light field intensity, which would be used to achieve imaging in a complicated environment. The main issue to be addressed in CGI technology is how to achieve rapid and high-quality imaging while assuring the secure transmission of detection data in practical distant imaging applications. In order to address the mentioned issues, this paper proposes a remote secure CGI method based on quantum communication technology. Using the quantum key distribution (QKD) network, the CGI system can be reconstructed while solving the problem of information security transmission between the detector and the reconstructed computing device. By exploring the influence of different random measurement matrices on the quality of image reconstruction, it is found that the randomness of the numerical sequence constituting the matrix is positively correlated with the imaging quality. Based on this discovery, a new type of quantum cryptography measurement matrix is constructed using quantum cryptography with good randomness. In addition, through further orthogonalization and normalization of the matrix, the matrix has both good randomness and orthogonality, and high-quality imaging results can be obtained at a low sampling rate. The feasibility and effectiveness of the method are verified by simulation imaging experiments. Compared with the traditional GI system, the method proposed in this paper has higher transmission security and high-quality imaging under this premise, which provides a new idea for the practical development of CGI technology.
An optical encryption (OE) scheme based on the spread spectrum ghost imaging (SSGI), named as SSGI-OE, is proposed to obtain a high security with a smaller key. In the scheme, the randomly selected row number of a Hadamard matrix of order N is used as the secure key, and shared with the authorized user, Bob, through a private channel. Each corresponding row vector of the order-N Hadamard matrix is then used as the direct sequence code to modulate a speckle pattern for the ghost imaging system, and an image is encrypted with the help of the SSGI. The measurement results from the bucket detector, named as ciphertext, are then transmitted to Bob through a public channel. The illuminating speckle patterns are also shared with Bob by the public channel. With the correct secure key, Bob could reconstruct the image with the aid of the SSGI system, whereas the unauthorized user, Eve, could not obtain any useful information of the encrypted image. The numerical simulations and experimental results show that the proposed scheme is feasible with a higher security and a smaller key. For the 32 × 32 pixels image, the number of bits sent from Alice to Bob by using SSGI-OE (M = 1024, N = 2048) scheme is only 0.0107 times over a computational ghost imaging optical encryption scheme. When the eavesdropping ratio (ER) is less than 40%, the eavesdropper cannot acquire any information of the encrypted image. The extreme circumstance for the proposed SSGI-OE scheme is also discussed, where the eavesdropper begins to extract the information when ER is up to 15%.