Secure and high-capacity secret information transmission is an important task of the image hiding research. The existing image hiding methods face some critical issues: cover-based methods offer high capacity but introduce image distortion and security risks, whereas secure coverless methods have low capacity. To address these issues, this paper proposes a novel generative-based coverless multi-image hiding method called GCL-MIH, which can achieve high capacity and high security. The GCL-MIH first utilizes a feature reverse module to compress multiple secret images into multiple feature vectors and then normalizes them to generate a vector that conforms to a standard normal distribution, and finally inputs this vector into an invertible generative network (Flow-GAN) to generate a face image, enabling coverless multiple-image hiding without a predefined cover image. Experimental results demonstrate that the GCL-MIH successfully hides up to four images within a single generated face image, achieving a maximum embedding rate of 32 bpp. This capacity far exceeds those of the existing coverless methods. On the COCO test set, the generated stego images of the GCL-MIH are highly realistic (FID score: 11.98), and the recovered secret images exhibit satisfactory fidelity (the average PSNR and SSIM of four recovered secret images are 33.18 dB and 0.9412).

In a (k, n)-threshold secret image sharing (SIS) scheme, a secret image is encoded intonshadow images and distributed to the corresponding participants, enabling lossless reconstruction with anykcorrect shadow images. This inherent fault tolerance allows up ton–kshadow images to be lost or corrupted. However, in real-world scenarios, all shadow images are susceptible to malicious tampering, cropping, or noise during transmission and storage, making it difficult to guarantee the availability ofkintact shadows. Robust secret image sharing (RSIS) schemes have been proposed to address this issue, yet existing methods often suffer significant degradation in reconstruction quality as the attack strength increases, revealing limitations in their robustness. To address these issues, we propose an RSIS scheme against malicious shadow images by Reusing Polynomial Coefficients with hash function (RSIS-RPC), which provides both malicious shadow detection and error correction capabilities. The correction capability improves with the degree of coefficient reuse, where greater reuse provides stronger resilience to pixel corruption. However, as more coefficients are reused, the size of the generated shadow images increases correspondingly, resulting in higher storage requirements. This trade-off between robustness and efficiency makes the proposed scheme adaptable to diverse application scenarios requiring secure and resilient image sharing. Experimental results and analyses demonstrate that the proposed scheme achieves superior robustness compared to existing schemes.

Reversible data hiding (RDH) in shared images is an effective technique for securely storing and managing confidential images. However, most existing methods suffer from a noticeable data expansion and cannot achieve a good trade-off between data expansion and embedding rate. To address this issue, we propose a novel RDH in shared images (RDHSI) using overlapped coefficients in polynomials. In the proposed method, an original image is compressed losslessly to reduce its size before sharing, and then the compressed image is divided into a series of groups, where any two adjacent groups have an overlapped part. Next, each group is shared by our proposed (k,n)-threshold based sharing technique, which is performed by the polynomial over Galois field GF(28) with overlapped coefficients. Finally, data embedding is performed on each shared image by bit replacement according to a constructed 0-1 matrix. Experimental results demonstrate that the proposed method can effectively reduce the sizes of the shared images and achieve a high embedding capacity.

Visual cryptography scheme (VCS) and polynomial-based secret image sharing (PSIS) are two primary types of secret sharing for protecting images. VCS and PSIS have their respective pros and cons. For VCS, the benefits of perfect security and easy decoding are provided. But it suffers from the limitations of lossy secret recovery and binary image-oriented. PSIS can deal with grayscale/color images and offers lossless secret reconstruction. Whereas, the secret decoding is computationally intensive (i.e.,O(klog2k) for (k,n) threshold) and the residual-image problem in PSIS compromises the security. In this paper, we are motivated to investigate a sharing technique that can preserve the advantages of both VCS and PSIS. Differing from existing VCS and PSIS, the proposed sharing method is accomplished based on the access structure partition (ASP) result. Essentially, an ASP guided image secret sharing approach is developed and three optimal ASP algorithms are designed. When compared with existing partition method, significant improvement is offered by our partition techniques especially for the (k,n) threshold with a largern. Take the (2; 15), (2; 18), and (4; 12) thresholds for example, the numbers of involved sub-access structures by our method are 4, 5, and 19, while the quantities by existing approach are 8, 10, and 45. The percentages of improvement are 100%, 100%, and 137%. Further, based on the partition result from ASP algorithms, we can employ (k,k) probabilistic VCS (PVCS) to constitute a (k,n) sharing method for encoding gray-level/color images. Experiments are demonstrated to confirm the effectiveness of the sharing method and ASP algorithms. Meanwhile, comparisons are included to show that the merits of perfect security, low decoding complexity (i.e.,O(d)), lossless secret recovery (i.e., PSNR= ∞, SSIM= 1), and grayscale/color image-oriented are provided by our sharing method.

To ensure the authenticity and validity of Secret Image Sharing (SIS) schemes, Verifiable Secret Image Sharing (VSIS) methods have been proposed. However, existing VSIS schemes are vulnerable to attacks from Dishonest Participant (DP). The dishonest participants may still accessk-1 valid shares when they are identified, enabling them to recover the secret image. To address this issue, a VSIS based on polynomial interpolation for resisting Dishonest Participant Attacks (VSIS-RDPA) is proposed. Unlike traditional SIS schemes, where secret pixels are used as polynomial coefficients, our scheme treats secret pixel values as function values of the polynomial. On the contrary, the secret key and secret pixel values serve as inputs to reconstruct ak-2-degree polynomial using Lagrange interpolation, enhancing security against malicious participants. Authentication parameters generated by a hash function are combined with thek-2-degree polynomial to form a completek-1-degree polynomial, which subsequently is utilized to generate shares. On the receiver end, thek-1-degree polynomial is first reconstructed, and the authentication parameters generated by the hash function are compared with those obtained from the reconstructed polynomial. If the two sets of values match, the authentication is successful, allowing for the recovery of the secret image. In addition, a modified authentication phase with ECC is also proposed to enhance the robustness of authentication. Experimental results and analysis demonstrate that the proposed schemes can resist DP attacks and ensure efficiency, verifiability, and security.

Image sharing is a crucial security technique of protecting the original image. Most image sharing methods elaborate on the uncompressed formats and cannot be applied directly to compressed formats such as JPEG format. Recently, some related JPEG sharing methods were proposed. However, these methods are short in size reduction. To address this issue, we introduce a novel JPEG image sharing method that significantly reduces the file sizes of shared images while maintaining compatibility with the JPEG standard. Specifically, an original JPEG bitstream is parsed to obtain three components, namely, DC appended bits (DCAs), AC Huffman codes (ACHs), and AC appended bits (ACAs). Different sharing mechanisms are applied for these three components. The DCAs are shared over GF(2m) in a way that prevents overflow in the shared DC coefficients. The ACH sharing is performed by polynomials over GF(p) with an intermediate process by Huffman table mapping and the ACAs are shared by polynomials over GF(2m) with directed codes. Consequently, the ACH and ACA shares with smaller sizes are generated, respectively. To be compatible with the JPEG standard, the shared ACAs are adaptively modulated according to the shared ACHs. Finally, the shared JPEG images can be reconstructed by the shared DCAs, ACHs, ACAs and the original partial JPEG information. The experimental results demonstrate that the proposed method can efficiently reduce the file sizes of shared JPEG images and preserve the JPEG format for each shared image.

The (k,n)-threshold Secret Image Sharing (SIS) is a naturally fault-tolerant technique for image privacy protection. A secret image is processed through secret sharing to generatenshadow images, which are then distributed tondifferent recipients. During the recovery phase, the complete secret image can be reconstructed by anykout ofnshadow images. Although (k,n)-threshold SIS itself allows for the loss of up to$n-k$shadow images, if there are pixel errors in the remainingkshadow images, the recovery of the secret image will be declared a failure. Therefore, Robust Secret Image Sharing (RSIS) has been proposed to address the issue. However, the current proposed RSIS schemes only demonstrated limited robustness against noise attacks. This paper presents a novelk-consistency-based RSIS scheme to resist malicious attacks, including noise, JPEG compression, tampering, and cropping. In the sharing phase, a dual-SIS mechanism is first designed to perform two rounds of secret sharing on the secret image. In the recovery phase, high-quality secret image can be reconstructed based onk-consistency after attacking. The experimental results demonstrated that our scheme not only provides comprehensive robustness but also allows for flexible adjustment of shadow images’ sizes, ensuring both security and efficiency during image sharing.

Reversible data hiding (RDH) is one special type of data hiding, and is widely used for many intended applications. Moreover, to protect the cover image, RDH in encrypted image (RDHEI) schemes are accordingly proposed. In RDHEI, if the marked image is lost, the cover image and the secret data cannot be restored. To address the issue of losing sub marked images, RDH in shared image (RDHSI) by secret sharing (SS) is proposed to achieve fault-tolerance. Recently, an anonymous application scenario using RDHSI is introduced, on which multiple data hiders in RDHSI serve as reviewers in a committee. When the number of agreement votes is above the threshold of SS, the application is approved. However, there are weaknesses in this application framework: (i) reviewers cannot provide equal right to vote (namely, they cannot cast “Yes” and “No” votes, respectively), and (ii) anonymous submission is not really achieved. In the paper, we propose a new RDHSI to allow data hiders can hide approved sub data or disapproved sub data into sub images. Therefore, how to perform recovery and extraction from n marked images (some embedded with “Yes” votes and some with “No” votes) should be carefully designed. Based on the consistency property of polynomial interpolation, we conduct verification, recovery and extraction algorithms from n marked images. In addition, we use Hamming codewords to represent pixel difference instead of directly hiding pixel difference for reversibility, and this improvement also improves the embedding capacity. Compare with the current anonymous application scheme using RDHSI, the embedding rate in this paper can reach 3.5 bits per pixel (bpp), which is an improvement of 2 bpp. Thus, it is more suitable for the anonymous submission of application framework.

In this article, a secret image sharing (SIS) scheme for general access structures (GAS) is designed for distributed multi-user scenario. In the proposed distributed multi-user SIS (DM-SIS), multiple secret images are encoded into shadows which are then distributed to the corresponding storage nodes of a network. By collecting the shadows from nodes, each user is capable of decrypting the corresponding secret image. Fundamentally, we utilize an invertible target matrix, which is initially obtained from the GAS and a base matrix with Vandermonte coordinates, to construct shadows. To deal with the case of non-invertible target matrix, three matrix-adjusting procedures are further introduced. Theoretical analysis, numerical examples, and experiments are provided to verify the feasibility of the proposed technique. When compared to previous methods, the proposed approach can implement GAS sharing strategy in distributed multi-user environment. Meantime, significant improvements on storage overhead and sharing capacity are also achieved.

Passwords are widely used for authentication in Internet applications. Recently, users tend to adopt graphical passwords instead of traditional alphanumeric passwords, since it is much easier for humans to remember images than verbal representations. However, the existing graphical password authentication systems generally suffer from three main issues. 1) It is required to remember and perform complicated operations during the registration/login phases, which significantly limits the systems’ usability; 2) The users’ passwords are simply stored as plaintexts in servers, and thus the security is compromised; 3) The users need to register/login to each server separately when they are applied in multi-server environment. To address the above issues, we propose a user-friendly and secure Google map-based graphical password (FS-GMGP) system using tolerant distance and homomorphic encryption. By using a homomorphic encryption scheme, each user encrypts his password point and response point selected on Google map, while the servers compute and decrypt the distance between the two encrypted points and then compare the resulting value with a tolerant distance for authentication. Moreover, the FS-GMGP system is extended for multi-server environment. The evaluation results and security analysis show that the FS-GMGP and its extended version achieve desirable usability and security in single-server environment and multi-server environment, respectively.

Copy detection is crucial for protecting image copyright. This paper proposes a robust image hashing approach via Weighted Saliency Map (WSM) and Laplacian Eigenmaps (LE) (hereafter WSM-LE approach). An important contribution is the WSM construction via the edge map and the saliency map. As the WSM can indicate the interest regions of image, hash calculation based on WSM can provide robustness of our WSM-LE approach. Another contribution is the low-dimensional feature learning by the LE technique. As the LE technique can effectively learn the internal geometric relationships of image, the extracted low-dimensional features can improve discrimination of our WSM-LE approach. In addition, the low-dimensional features are treated as vectors and the vector distances are used to create a compact and encrypted hash. Numerous experiments and comparisons are conducted to confirm the effectiveness and superiority of our WSM-LE approach. The results indicate that our WSM-LE approach has excellent classification and copy detection performances than some baseline approaches.

A systematic investigation of evolving visual cryptography scheme (EVCS) is carried out in this article. The evolving scheme, denoted as \((k,\infty)\) , differs from the \((k,n)\) threshold in that it permits an arbitrary and perhaps unlimited number of participants. More importantly, the access structure can be updated dynamically by adding new users. First of all, a preliminary implementation strategy for the \((2,\infty)\) EVCS is introduced. Then, by employing the \((2,2)\) VCS recursively with the \((2,\infty)\) EVCS, a \((k,\infty)\) EVCS is created. In order to enhance the performance, an improved scheme is constructed based on the multi-secret VCS (MVCS) and a series of EVCS schemes with thresholds of \((1,\infty)\) , \(\cdots\) , \((k-1,\infty)\) . Moreover, Boolean XOR operation is adopted for secret recovery to further improve the visual quality. To facilitate the XOR decryption, a novel access structure partition algorithm is presented. Additionally, the proposed partition method can successfully solve the security issue in existing multi-secret XOR-based VCS (MXVCS). By integrating the more secure MXVCS into the improved scheme, XOR decryption is provided. The two proposed methods are shown to be effective and advantageous through extensive experiments and comparisons.

In existing secret medical-image sharing (SMIS) schemes, to protect and manage secret medical-images (SMIs), the sharing and recovery of each SMI are implemented by local servers of medical institutions. However, since a lot of SMIs are produced by personal smart terminal devices in Internet of Things (IoT) environment, directly implementing the sharing and recovery processes will cause excessive communication and computing burden for those local servers, which makes the existing SMIS schemes not suitable for IoT environment. To address the above issue, we propose an encrypted domain SMIS (Enc-SMIS) scheme with secure outsourcing computation for protecting and managing medical images in IoT environment. In the proposed scheme, the medical images are first encrypted using fully homomorphic encryption (FHE) and then outsourced to a cloud server for generating a set of image shares. Subsequently, these shares are stored separately in different local servers of medical institutions. Furthermore, the recovery process is also outsourced to the cloud server when doctors need to observe the patients’ medical images. Compared with the existing SMIS schemes, the proposed Enc-SMIS scheme alleviates the computing and communication burden on local servers significantly with secure outsourcing computation in the semi-honest model, and thus supports the storage and management of medical images well in IoT environment.

Secret sharing (SS) is a threshold technology that shares a secret value by generating and distributing${n}$shares in the way that a set of any${k}$shares can recover the secret. On the other hand, blockchain is a decentralized system establishing a secure data structure for storing data in the form of a hash chain. Combining SS and blockchain is definitely a promising paradigm in the data security field. Recently, the fast healthcare interoperability resources (FHIRs) standard is defined for medical data exchange across various medical institutions. In this article, we combine SS, ElGamal’s encryption/decryption, and blockchain to propose a multihospital FHIR database authorization (MFDA). To achieve a secure MFDA, the group-based SS (GSS) and the notion using GSS on exponent (referred to as EGSS) are proposed. The secrets of GSS and EGSS have the discrete logarithm problem (DLP) relation, on which the secrets can be used as ElGamal’s private key and public key, respectively. Also, their shares will have DLP relation. By uploading public shares of EGSS on blockchain and using private shares of GSS in a private network, we can recover ElGamal’s public key from a deployed smart contract on blockchain and recover ElGamal’s private key from a qualified set. Meantime, when recovering private key, the private shares of GSS can be authenticated by public shares on blockchain to check tampering and corrupted of private shares during the communication in a private network. Theorems, examples, and experiments demonstrate that the proposed MFDA has efficient and secure database authorization.

Reversible data hiding is widely utilized for secure communication and copyright protection. Recently, to improve embedding capacity and visual quality of stego-images, some Partial Reversible Data Hiding (PRDH) schemes are proposed. But these schemes are over the plaintext domain. To protect the privacy of the cover image, Reversible Data Hiding in Encrypted Images (RDHEI) techniques are preferred. In addition, the full separability of cover image reconstruction and data restoration is also an important characteristic that cannot be achieved by most RDHEI schemes. To solve the issues, a partial and a complete Reversible Data Hiding in Shared Images with Separate Cover Image Reconstruction and Secret Extraction (RDHSI-SRE) are proposed in this paper. In the proposed schemes, the secret data is divided by Secret Sharing (SS). Then, the marked shared images are generated based on the proposed modify-and-recalculate strategy. The receiver can extract embedded data and reconstruct the image separably usingk-out-of-nmarked shared images. In the embedding phase of partial RDHSI-SRE (PRDHSI-SRE), the pixel values are modified according to the proposed Minimizing-Square-Errors Strategy to achieve high visual quality, and the complete RDHSI-SRE (CRDHSI-SRE) embeds data by modifying random coefficients to achieve reversibility. The experimental results and theoretical analyses demonstrate that the proposed schemes have a high embedding performance. Most importantly, the proposed schemes are fault-tolerant and completely separable.

Invertible secret image sharing with authentication (ISISA) distributes comprehensible stego images generated from secret images and cover images to involved participants. The secret image and cover image can be correctly recovered after authentication. However, existing ISISA schemes suffer from issues such as a single kind of image, limited embedding capacity, poor visual quality and a lack of authentication capability. To address these issues, this paper provides a novel invertible secret image sharing scheme with authentication for embedding color palette images into true color images. In this scheme, the pixels of the palette secret image and the bits of the cover pixel are used as coefficients of the polynomial. Share is embedded into a true color cover image to generate an intermediate stego image. Authentication information is then derived from the intermediate stego image and hidden in the cover image. The final stego images that resemble the cover image are obtained and sent to authorized participants. At the receiver end, once k stego images are verified, the secret image and cover image can be losslessly recovered for a (k, n)-threshold scheme. The experimental results and theoretical analysis demonstrated the superiority and practicality of the scheme.

Image copy-move forgery detection (CMFD) has become a challenging problem due to increasingly powerful editing software that makes forged images increasingly realistic. Existing algorithms that directly connect multiple scales of features in the encoder part may not effectively aggregate contextual information, resulting in poor performance. In this paper, an end-to-end context multiscale cross-fusion network (CMCF-Net) is proposed to detect image copy-move forgery. The proposed network consists of a multiscale feature extraction fusion (MSF) module and a multi-information fusion decoding (MFD) module. Multiscale information is efficiently extracted and fused in the MSF module utilizing stacked-scale feature fusion, which improves the network's forgery localization ability on objects of different scales. The MFD module employs contextual information combination and weighted fusion of multiscale information to guide the network in obtaining relevant clues from correlated information at multiple different scales. Experimental results and analysis have demonstrated that the proposed CMCF-Net achieves the best localization results with higher robustness.

Reversible data hiding in encrypted images (RDHEI) is an effective technology of protecting private data. In this paper, a high-capacity RDHEI method with asymmetric coding and bit-plane block compression is proposed. Our major contributions are twofold. (1) We propose an asymmetric coding technique for processing prediction error (PE) blocks before encryption. The proposed asymmetric coding technique does not generate the sign bit-plane and facilitates massive 0s converging on the high bit-planes. This is beneficial to reserve the embedding room. (2) We present a bit-plane block compression technique for improving the embedding capacity. This technique divides the PE codes in a block into two parts which are both compressed and thus contribute a large embedding room. Experimental results demonstrate that the average embedding rates of the proposed method are 4.156, 4.063 and 3.450 bpp on the BOSSBase, BOWS-2 and UCID datasets, respectively. Comparisons show that our average embedding rates on the three datasets are all bigger than those of some state-of-the-art methods.

Recently, three visual cryptography schemes with t -error-correcting capability (VCSs- t EC) were introduced for preventing the shadows carrying additional information from being corrupted by noise interference. However, the concerns on VCS- t EC, such as the average amount of carrying information, decoding of information from shadows, and the demonstration way of a secret, should be considered and improved. In this article, two schemes, namely the ( k, n ) probabilistic VCS- t EC (PVCS- t EC) and the (2, n ) deterministic VCS- t EC (DVCS- t EC), are proposed. The concept of probabilistic VCS is combined with the Bose-Chaudhuri-Hocquenghem code (BCH code) for designing the ( k, n ) PVCS- t EC. Furthermore, some constant-weight BCH codewords are adopted to build the (2, n )-DVCS- t EC. Comprehensive results and experiments are demonstrated to clarify the enhancement of information-carrying and decoding by the two proposed methods.

Secret Image Sharing (SIS) is the technology that shares any given secret image by generating and distributing$n$shadow images in the way that any subset of$k$shadow images can restore the secret image. However, in the existing SIS schemes, the shadow images will be easily tampered and corrupted during the communication, which will pose serious security issues. Recently, blockchain has emerged as a promising paradigm in the field of data communication and information security. To securely communicate and effectively protect the secret image data in wireless networks, we propose a Blockchain-based Secure and Efficient Secret Image Sharing (BC-SESIS) scheme with outsourcing computation in wireless networks. In the proposed BC-SESIS scheme, the shadow images are encrypted and stored in the blockchain to prevent them from being tampered and corrupted. The identity authentication-enabled smart contract is deployed to achieve the$(k,n)$threshold for secret image restoring. Furthermore, to reduce the computational burden of smart contract and users, an efficient outsourcing computation method is designed to outsource the restoring task, which is securely implemented by agent miners in the encryption domain. Theoretical analysis and extensive experiments demonstrate that the BC-SESIS scheme can achieve desirable communication security and high computational efficiency in the wireless networks.

In the industrial Internet of Things (IoT), large amounts of image data are collected, stored, and transmitted by low-power cooperative sensors and heterogeneous devices, such as monitoring pictures taken by surveillance cameras in intelligent transportation. Thus, the increasing image data would be outsourced and shared between different distributed servers. Recently, some secret image sharing with authentication (SISA) schemes were proposed, which can provide image sharing in the distributed IoT system. However, if the IoT data are tampered with by malicious attackers, the error cannot be corrected, which causes unreliability and data loss. Therefore, in order to solve the above issues, we propose a secure and reliable secret image-sharing system based on extended Hamming codes (RSIS) in IoT. In RSIS, a novel distributed IoT architecture-based secret sharing is proposed. A secret image is shared into a series of stego-images. These stego-images can be distributed among multiple edge servers in IoT, which is not easy to attract attentions of attackers. In RSIS, check bits generated by authentication bits and hamming code are embedded into the stego-images to identify the tampered places with a high probability. Theoretical analysis and experiments prove that the proposed scheme achieves a high authentication capability, and the bit errors of data can be accurately detected and corrected. Generally, the scheme is effective and practical.

Reversible Data Hiding in Encrypted Images (RDHEI) has drawn increasing concern in multimedia cloud computing scenarios. It embeds secret message into the encrypted carrier while preserving the confidentiality of the image. However, most RDHEI schemes have only one hider and one image carrier which are not efficient for the distributed system with multiple participants. Moreover, if the stego-image is lost, the cover image and the embedded data cannot be restored. To solve above issues, this paper proposes Reversible Data Hiding in Shared Images based on syndrome decoding and homomorphism (RDHSI). In RDHSI, the cover image and secret data are distributed using secret sharing. Multiple data hiders embed shared data into the shared images based on the Syndrome Decoding of Hamming codes and the additive homomorphism of the polynomial. On the receiver side, the lossless cover image and secret data are obtained. The reversibility and privacy preserving of the cover image, the complete extraction of secret data, and the fault-tolerance of the proposed schemes are achieved. The experimental results show that PSNR of the marked image is above 54 dB at the embedding rate of 0.43bpp. In order to improve the payload of secret data, the Modified RDHSI is further proposed. Generally, the proposed schemes are secure, effective and fault-tolerant.

Reversible Data Hiding in Encrypted Image (RDHEI) schemes may redistribute the data hiding procedure to other parties and can preserve privacy of the cover image. Recently, cloud computing technology has led to the rapid growth of networked media, and many multimedia rights are owned by multiple parties, such as a film's producer and multiple distributors. Thus, the data hiding task could be distributed to multiple distributed servers. Multi-party data hiding has become an important demand for networked media. In addition, it is essential to preserve multi-server and multi-message privacy and data integrity. However, most of the RDHEI schemes involve only one data hider. That inspired us to design the secure multi-party embedding over distributed encrypted-image servers as a solution for multi-party RDHEI applications. In this article, we propose a novel Reversible Data Hiding over Distributed Encrypted-Image Servers (RDH-DES) based on secret sharing. The Chinese remainder theorem, secret sharing, and block-level scrambling are developed as a lightweight cryptography to generate the encrypted image shares. These shares are distributed to different image servers and are used to embed secret data in the proposed framework. The marked encrypted image can be constructed through the marked encrypted shares from different parties, and the decryption and extraction can be completed by the receiver. The experimental results and theoretical analysis have demonstrated that the proposed scheme is secure and effective.

With the rapid development of network media, increasing research on reversible watermarking has focused on improving its robustness to resisting attacks during digital media transmission. There are some other reversible watermarking schemes that work in the encrypted domain for preserving the privacy of the cover image. The robustness of the watermarking and the privacy preserving of the cover image have become the key factors of reversible watermarking. However, there are few robust reversible watermarking schemes in the encrypted domain that could resist common attacks (such as JPEG compression, noise addition) and preserve privacy at the same time. In addition, the embedding capacity of a robust watermark and the efficiency of the encryption method must be considered. Recently, cloud computing technology has led to the rapid growth of network media, and many multimedia properties are owned by multiple parties, such as a film’s producer and multiple distributors. Multi-party watermarking has become an important demand for network media to protect all parties’ rights. In this paper, a Robust Reversible Watermarking scheme in Encrypted Image with Secure Multi-party (RRWEI-SM) based on lightweight cryptography is first proposed. Additive secret sharing and block-level scrambling are developed to generate the encrypted image. Then, the robust reversible watermarking based on significant bit Prediction Error Expansion (PEE) is performed by Secure Multi-party Computation (SMC). For applications with high robustness, a Modified RRWEI-SM is proposed by exploiting two-stage architecture. Furthermore, both the RRWEI-SM scheme and Modified RRWEI-SM scheme are separable and can be applied to multiparty copyright protection. The experimental results and theoretical analysis demonstrate here that the RRWEI-SM and the Modified RRWEI-SM are secure, robust and effective.

Determination of image authenticity usually requires the identification and localization of the manipulated regions of images. Hence, image manipulation detection has become one of the most important tasks in the field of multimedia forensics. Recently, Convolutional Neural Networks (CNNs) have achieved promising performance in image manipulation detection. However, it is hard for the existing CNN-based manipulation detection approaches to accurately identify and localize the manipulated regions that have undergone geometric transformations, since CNNs are limited by their inability to be geometrically invariant. To address this issue, we propose a geometric rectification-based neural network architecture for image manipulation detection. In this type of network architecture, following the detection of a set of potential manipulated regions (PMRs) using Region Proposal Network, the Spatial Transformer Network is employed to geometrically rectify the convolutional feature maps (CFMs) of these regions to obtain the geometrically rectified CFMs (GR-CFMs). Subsequently, the residual feature maps (RFMs) are computed to capture the characteristic inconsistency between the CFMs and GR-CFMs of each PMR. Finally, the computed RFMs are automatically integrated with the GR-CFMs by a designed attention module to determine whether each PMR is a manipulated region and to localize the manipulated part at the pixel-level. Extensive experiments on the public data set as well as on our challenging data set demonstrate that the proposed network architecture achieves desirable performance in identifying and localizing regions with common tampering artifacts, which involve geometric transformations.

Because of the importance of digital images and their extensive application to digital watermarking, block chain, access control, identity authentication, distributive storage in the cloud and so on, image secret sharing (ISS) is attracting ever-increasing attention. Share authentication is an important issue in its practical application. However, most ISS schemes with share authentication ability require a dealer to participate in the authentication (namely, dealer participatory authentication). In this paper, we design an ISS for a$(k,n)$-threshold with separate share authentication abilities of both dealer participatory authentication and dealer nonparticipatory authentication. The advantages of polynomial-based ISS and visual secret sharing (VSS) are skillfully fused to achieve these two authentication abilities without sending a share by using a screening operation. In addition, the designed scheme has the characteristics of low decryption (authentication) complexity, lossless decryption and no pixel expansion. Experiments and theoretical analyses are performed to show the effectiveness of the designed scheme.

A ( k, n) visual cryptographic scheme (VCS) shares a secret image into n shadow images that are distributed over n involved participants. When k participants stack their shadow images, the secret is revealed. The secret image of VCS is a visual secret. Even though black/white dots in shadows suffer from interference by noise, the color may still retain the corresponding darkness with high probability. Therefore, VCS has noise immunity for secret recovery. Hence, it seems that there is no need to design a VCS that is robust to noise interference when transmitting or storing the files of shadow images. However, some VCSs use the permutations of subpixels in shadow images as information to realize multiple decoding options. For such schemes, we absolutely should ensure the correctness of the shadows. In this article, we investigate a VCS with t-error correcting capability (VCS- tEC). To the best of our knowledge, VCS- tEC is introduced for the first time. Three ( k, n)-VCS- tEC schemes are proposed: the separated scheme, the integrated scheme, and the nonsystematic scheme.

Secret Image Sharing (SIS) as a secure data sharing scheme in multiple cover images, has become an increasing researchers' concern. In traditional SIS, the cover image can't be recovered losslessly. The distorted cover images would reduce the practicability of the scheme, especially in medical and military images. The lossless recovery of cover images is required since all details of these images are very critical. In current Invertible SIS (ISIS), the secret image and the cover image may not be reconstructed losslessly. In addition, the authentication capability, visual quality of the stego cover image and embedding rate are limited in spatial domain-based ISIS. As an important carrier, the binary cover image is desired in real applications. Therefore, this paper proposes Transform domain-based Invertible and Lossless Secret Image Sharing schemes with Authentication (T-ILSISA), namely Integer Wavelet Transform-based ILSISA (IWT-ILSISA) and Binarization Transform-based ILSISA (BT-ILSISA) respectively. In (k,n) threshold IWT-ILSISA, the pixels of secret image and the data of cover image are regarded as the coefficients of the (k-1) degree polynomial. The values of generated share are embedded into IWT domain of the cover image. In BT-ILSISA, many different cover images are applied. The generated shares are transformed to the meaningful images since noise-like shares are easy to attract the attacker's attention, are suspected to censors and are difficult for identification and management. In the two schemes, the original secret image and the cover image can be recovered losslessly. The experimental results and theoretical analysis demonstrate that the performances of IWT-ILSISA are better than other similar schemes in the terms of embedding capacity, authentication capability and visual quality of the stego cover image. The BT-ILSISA has a lower computational complexity of the recovery.

Video traffic monitoring is an inexpensive and convenient source of traffic data. Traffic images processing are widely used to check traffic conditions and they can determine traffic control strategies in intelligent transportation systems (ITS). However, these traffic images always contain privacy-related data, such as vehicles registration numbers, human faces. Misuse of such data is a threat to the privacy of vehicles divers, passengers, pedestrians, etc. This paper proposes a thresholds-based images extraction solution for ITS. At first, a Faster Region Convolutional Neural Networks (RCNN) model is used to segment a traffic image into multi-regions with different importance levels; then, multi-threshold image extraction schemes are designed based on progressive secret image sharing schemes to extract images contain key traffic information, such as reg number, human faces, in which the region with higher importance level requires higher threshold for extraction. For different roles in ITS, they can extract images with different details, which can protect privacy and anonymity. The proposed methods provide a safe and intelligent way to extract images that can be used for further analysis in ITS.

Recently, multiple (k, n) region-incrementing VCSs (RIVCSs) have been proposed that can gradually reconstruct secrets in a single image. In (k, n)-RIVCS, the secret image is subdivided into multiple regions in such a way that any t shadow images, where k ≤ t ≤ n, can be used to reveal the secret in the (t - k + 1)th region. This region-incrementing property provides progressive decoding. However, the regions in previous RIVCSs are disjointed: no two regions have overlapping areas. In this paper, we discuss a (k, n) region-in-region progressive VCS (RPVCS). Our (k, n)-RPVCS has (n - k + 1) secrecy-level regions, and each region can be located within any previous region. This new type of region allocation not only provides more areas in which to hide the secret compared with the non-overlapping regions in RIVCS but also provides different presentation methods in progressive decoding.

Currently, searchable encryption is a hot topic in the field of cloud computing. The existing achievements are mainly focused on keyword-based search schemes, and almost all of them depend on predefined keywords extracted in the phases of index construction and query. However, keyword-based search schemes ignore the semantic representation information of users' retrieval and cannot completely match users' search intention. Therefore, how to design a content-based search scheme and make semantic search more effective and context-aware is a difficult challenge. In this paper, for the first time, we define and solve the problems of semantic search based on conceptual graphs (CGs) over encrypted outsourced data in clouding computing (SSCG). We first employ the efficient measure of “sentence scoring” in text summarization and Tregex to extract the most important and simplified topic sentences from documents. We then convert these simplified sentences into CGs. To perform quantitative calculation of CGs, we design a new method that can map CGs to vectors. Next, we rank the returned results based on “text summarization score”. Furthermore, we propose a basic idea for SSCG and give a significantly improved scheme to satisfy the security guarantee of searchable symmetric encryption (SSE). Finally, we choose a real-world dataset, i.e., the CNN dataset to test our scheme. The results obtained from the experiment show the effectiveness of our proposed scheme.

To detect illegal copies of copyrighted images, recent copy detection methods mostly rely on the bag-of-visual-words (BOW) model, in which local features are quantized into visual words for image matching. However, both the limited discriminability of local features and the BOW quantization errors will lead to many false local matches, which make it hard to distinguish similar images from copies. Geometric consistency verification is a popular technology for reducing the false matches, but it neglects global context information of local features and thus cannot solve this problem well. To address this problem, this paper proposes a global context verification scheme to filter false matches for copy detection. More specifically, after obtaining initial scale invariant feature transform (SIFT) matches between images based on the BOW quantization, the overlapping region-based global context descriptor (OR-GCD) is proposed for the verification of these matches to filter false matches. The OR-GCD not only encodes relatively rich global context information of SIFT features but also has good robustness and efficiency. Thus, it allows an effective and efficient verification. Furthermore, a fast image similarity measurement based on random verification is proposed to efficiently implement copy detection. In addition, we also extend the proposed method for partial-duplicate image detection. Extensive experiments demonstrate that our method achieves higher accuracy than the state-of-the-art methods, and has comparable efficiency to the baseline method based on the BOW quantization.

Abstract Human genome project is a grand scale scientific work, which aims at measuring three billion base pairs in human chromosomes (haploid). It brings a great challenging task to store and utilize these gene sequences (GS) securely and effectively. With the development of the cloud computing, the storage of gene information can be out of consideration. However, their secure utilization still puzzles data owners and data users. One popular way is to encrypt these GS and construct searchable indexes for secure retrieval. In this paper, we first define and solve the problem of privacy‐preserving outsourced gene data search in encryption domain. We transfer GS into numerical vectors by reasonable mapping for ease of similarity calculation. We employ secure KNN algorithm to encrypt the query, index, and gene data and compute relevance scores securely. We test our scheme through a real‐world dataset: plant GS from National Center of Biotechnology Information. Extensive experiments are conducted to demonstrate the efficiency of the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.

This paper presents a predictor-based watermark scheme that embeds secret bit streams and a DSA signature into an image. For the copyrighting of digital media, a DSA signature is appropriate as a watermarking technique. To improve security, we apply an Arnold transform (AT) to secret messages. We propose new predictors, Left-Top , which the predict current pixel values using neighboring pixel values. Our proposed scheme conceals secret messages by using the difference between current pixel values and predictive pixel values. Experimental results show that our method has low complexity and achieves a higher embedding performance with good perceptual quality compared to the earlier arts. Experimental results verified our proposed watermark method in multimedia communications.

Tallini and Bose defined a random walk function on which an efficient encoding/decoding algorithm for second-order spectral-null (2-OSN) codes was based. Later, Yang enhanced Tallini-Bose code by using quasi 2-OSN codes. Both 2-OSN codes encode the information word into a balanced word and then append extra bits to make the length of this balanced word equal to 0 (or 2) modulo 4. The main innovation is to eliminate the need for appended bits, thereby increasing the code rate.

ABSTRACT A ( k , n )‐scalable secret image sharing (SSIS) scheme shares a secret image into n independent shadow images. This ( k , n )‐SSIS scheme can simultaneously provide the properties of threshold ( k or more shadow images are required in reconstruction; but k − 1 or less shadow images reveal no information on the secret image) and the scalability (when k or more than k shadow images participate in reconstruction, more shadow images can reveal more information amount of secret image). In this paper, we deal with ( k , n )‐SSIS scheme with the smooth scalability such that the information amount of revealed image is “smoothly” proportional to the number of involved shadows, the whole secret image can be reconstructed only when all the n shadow images participate in reconstruction. Comparing with the existing smooth ( k , n )‐SSIS schemes, the proposed scheme has the less size of shadow image. Copyright © 2014 John Wiley & Sons, Ltd.

A (k,n) visual cryptographic scheme (VCS) encodes a secret image into n shadow images (printed on transparencies) distributed among n participants. When any k participants superimpose their transparencies on an overhead projector (OR operation), the secret image can be visually revealed by a human visual system without computation. However, the monotone property of OR operation degrades the visual quality of reconstructed image for OR-based VCS (OVCS). Accordingly, XOR-based VCS (XVCS), which uses XOR operation for decoding, was proposed to enhance the contrast. In this paper, we investigate the relation between OVCS and XVCS. Our main contribution is to theoretically prove that the basis matrices of (k,n)-OVCS can be used in (k,n)-XVCS. Meantime, the contrast is enhanced 2(k-1)times.

The visual cryptography scheme (VCS) is an encryption technique that utilizes the human visual system in recovering a secret image and it does not require any complex calculation. However, the contrast of the reconstructed image could be quite low. A number of reversing-based VCSs (or VCSs with reversing) (RVCS) have been proposed for binary secret images, allowing participants to perform a reversing operation on shares (or shadows). This reversing operation can be easily implemented by current copy machines. Some existing traditional VCS schemes without reversing (nRVCS) can be extended to RVCS with the same pixel expansion for binary image, and the RVCS can achieve ideal contrast, significantly higher than that of the corresponding nRVCS. In the application of grayscale VCS, the contrast is much lower than that of the binary cases. Therefore, it is more desirable to improve the contrast in the grayscale image reconstruction. However, when grayscale images are involved, one cannot take advantage of this reversing operation so easily. Many existing grayscale nRVCS cannot be directly extended to RVCS. In this paper, we first give a new grayscale nRVCS with minimum pixel expansion and propose an optimal-contrast grayscale RVCS (GRVCS) by using basis matrices of perfect black nRVCS. Also, we propose an optimal GRVCS even though the basis matrices are not perfectly black. Finally, we design an optimal-contrast GRVCS with a minimum number of shares held by each participant. The proposed schemes can satisfy different user requirements; previous RVCSs for binary images can be viewed as special cases in the schemes proposed here.

Recently, Rey proposed an efficient (2,n) matrix- based secret image sharing (MSIS) scheme based on simple binary matrix operations. However, the threshold property of Rey's (2,n)-MSIS scheme is compromised. Elsheh and Hamza showed a weakness that if the ranks of the singular matrices used in Rey's scheme are not low enough then one can retrieve the secret information from only one shadow image. In this paper, we overcome this weakness. Our new (2,n)-MSIS scheme satisfies the threshold condition, and has low computational complexity for recovery.

Recently, Wang introduced a novel (2,n) region incrementing visual cryptographic scheme (RIVCS), which can gradually reconstruct secrets in a single image with multiple security levels. In RIVCS, the secret image is subdivided into multiple regions in such a way that anytshadow images, where 2 ≤t≤n, can be used to reveal the (t-1) th region. However, Wang's scheme suffers from the incorrect-color problem, which the colors of reconstructed images may be reversed (i.e., the black and white are reversed). If the color of text is also the secret information, the incorrect-color problem will compromise the secret. Additionally, Wang's scheme is only suitable for the 2-out-of-ncase, i.e., (k,n)-RIVCS wherek=2. In this paper, we propose a general (k,n)-RIVCS, wherekandnare any integers, that is able to reveal correct colors of all regions. This paper has made three main contributions: 1) our scheme is a general (k,n)-RIVCS, wherekandncan be any integers; 2) the incorrect-color problem is solved; and 3) our (k,n)-RIVCS is theoretically proven to satisfy the security and contrast conditions.

Second-order spectral-null (2-OSN) codes are, in general, constructed from concatenating any codewords in 2-OSN code. Most 2-OSN codes adopt the Tallini-Bose random walk method in encoding and decoding, which exchanges two adjacent bits each time in a binary vector. In this brief contribution, we give a new implementation of the Tallini-Bose random walk method for 2-OSN codes which is shown by experiment to be faster.

Many secure micropayment schemes have been proposed as the desire to support the low-value and the high-volume purchases of some e-commerce applications such as mobile commerce services or web-based interactive video services. However it seems that no one studies how to add the ability of returning changes in micropayment schemes. In this paper, we take the lead in studying the micropayment schemes with ability to return changes (MSRC), which reduce the hash operations in transaction phase. When compared with the previous micropayment schemes, the proposed MSRC have the low computation costs and thus is more suitable and practical for mobile commerce environments, where have the limited computation capability and the limited bandwidth.

A novel and interesting application of RFID was a banknote attached a tag to determine the authenticity of money and to stop counterfeits. At Financial Cryptography 2003, Juels and Pappu firstly proposed a practical RFID banknote protection scheme (RBPS) by using the optical and the electrical (RFID) contacts. RFID-enabled notes can be tracked by the legal law agency and verified by the merchant. However, some effective attacks on the Juels-Pappu RBPS were subsequently proposed. In this paper, we enhance the Juels-Pappu RBPS to conquer such attacks.

The Visual cryptography scheme (VCS) is a perfect secure method that encrypts a secret image by breaking it into shadow images. A distinctive property of VCS is that one can visually, without computation, decode the secret by superimposing shadow images. However, much of the contrast of the reconstructed image is lost. A different kind of VCS has been recently proposed by Viet and Kurosawa, called VCS with reversing, allowing participants to perform a reversing operation (reverse black and white) on shadow images. Two drawbacks of the Viet–Kurosawa VCS are: (1) one can only reconstruct an almost ideal contrast image but not an ideal contrast image and (2) the Viet–Kurosawa VCS is constructed just from a perfect black VCS. This paper shows a real perfect contrast VCS such that the black and white pixels are perfectly reconstructed within finite runs, no matter what VCS (perfect black or non-perfect black) is used.

Some efficient second-order spectral-null codes encoded an index of random walk function recursively and ended with the short base second-order spectral-null codes. All these codes used the Tallini-Bose random walk function that exchanges two consecutive bits. In this paper, we propose a new random walk function based on cyclic bit-shift, on which the redundancy can be improved. Moreover, the bit-shift can be implemented efficiently by either software or hardware.

Some (k, n)-threshold image secret sharing schemes encrypt the secret image into n noise-like shadow images with size 1/k times that of the original secret image. The small size of shadow image makes this framework suitable for fast transmission in the distributed multimedia system where each shadow image is stored in the distributed storage node. However, noise-like shadow images are difficult to identify and manage. Accordingly, a so-called user-friendly scheme which shadow images show a shrunken version of the secret image was proposed to address the identification and management problems, but the portrait on shadow images had already leaked the secret information. Therefore, this user-friendly scheme is, strictly speaking, not a secret sharing scheme. In this paper, we introduce a new framework that the cost of verifying the validity of shadow images is mitigated by being able to simply superimpose shadow images to preview the image. Meantime the proposed scheme also provides noise-like shadow images to retain the secret sharing feature.

Visual secret sharing (VSS) scheme is a perfectly secure method to divide a secret image into several noise-like shadow images by splitting a secret pixel into black and white subpixels. Unlike other secret sharing schemes, the VSS scheme can be easily decoded by the human visual sight when staking shadow images. However, noise-like shadows are unusual and suspected by censors when delivered by e-mail or fax. Also, noise-like shadows are difficult to identify and manage when distributed. The problem was solved by adding the extended capability, a meaningful shadow image, in the so-called extended visual secret sharing (EVSS) scheme. In this paper, we present a new EVSS scheme by using gray and white subpixels to represent the secret pixel. Our proposed scheme still has the capability of visually revealing the secret image by stacking shadow images without the help of hardware and complex computation. When compared to the previous EVSS scheme, our new scheme has less number of subpixels to represent a secret pixel and the clearer shadow images.

Tallini and Bose introduced a recursive method to construct second-order spectral-null codes which result in short (information length 16) base optimal second-order spectral-null codes that can be easily implemented either with table lookup or enumerative coding. In this paper, the extended base suboptimal second-order spectral-null codes (17 information length 32) obtained from two short base codes by lookup table are used to reduce the overall code length.

An efficient recursive method has been proposed for the encoding/decoding of second-order spectral-null codes, via concatenation by Tallini and Bose. However, this method requires the appending of one, two, or three extra bits to the information word, in order to make a balanced code, with the length being a multiple of 4; this introduces redundancy. Here, we introduce a new quasi-second-order spectral-null code with the length /spl equiv/ 2 (mod 4) and extend the recursive method of Tallini and Bose, to achieve a higher code rate.

Bose and Al-Bassam designed quasi-systematic single asymmetric error-correcting codes that are able to encode k information bits in a systematic way, but cannot encode all 2/sup k/ information words. However, "Construction I" of their paper does not provide an efficient way for computing the number of codewords. In this correspondence, we derive a recursive relation based on generating functions in order to compute the maximum number of codewords in such codes. This recursion allows us to determine those numbers for large code lengths which may not be feasible otherwise.

We introduce a new algorithm that can enumerate the codewords of third-order spectral-null codes. There are some efficient coding methods V. Skachek et al. (1998), R. M. Roth et al. (1994) for third-order spectral-null codes already; however no enumerative coding for third-order codes was proposed up to date.

A common method for constructing t-error correcting/all unidirectional error detecting (t-EC/AUED) codes is to append a tail to t-EC code, where the tail is a function of the weight of the codeword. Here, we present a method to reduce the weight distribution of t-EC codes by using a DC/sub m/(k+d, k) code as the input of t-EC code where a DC/sub m/(k+d, k) code is of length k+dnd 2/sup k/ codewords with the weight distribution between [(k+d-m)/2] and [(k+d+m)/2]. It is shown that our t-EC/AUED codes have the better information rates than the previously developed codes due to the smaller tails.

An efficient algorithm to count the cardinalities of certain subsets of constant weight binary vectors is presented in this paper. The algorithm enables us to design I-symmetric error correcting/all unidirectional error detecting (1-syEC/AUED) codes with the highest cardinality based on the group Z/sub n/. Since a field Z/sub p/ is a group, this algorithm can also be used to design a field 1-syEC/AUED code. We can construct t-syEC/AUED codes for f=2 or 3 by appending a tail to the field 1-syEC/AUED codes. The information rates of the proposed t-syEC/AUED codes are shown to be better than the previously developed codes.