Jung-San Lee

Distortion-free secret image sharing mechanism using modulus operator

The (t, n)-threshold has been extended to secret image sharing due to its practicability. In this article, we provide a novel version that employs the modulus operator to embed the secret share into a host image. The simulator shows that the modulus operator is useful for decreasing shadow image distortion. Using Rabins signature cryptosystem, participants can detect if a cheater exists in the cooperation. In particular, the new mechanism permits involved members to restore a lossless secret image and to reconstruct a distortion-free host image.

Protecting the content integrity of digital imagery with fidelity preservation

Fragile watermarking is applied to protect the content integrity of digital images. The main concerns related to watermarking include retaining the quality of the watermarked image and retaining the ability to detect whether any manipulation has occurred. Because recent watermarking techniques seriously distort the quality of the protected image after embedding the authentication code into the image content, attention has been drawn to how to satisfy both the need for image fidelity and detection ability. To account for the influence from both essentials, a novel algorithm is proposed in this article. The new scheme utilizes a weighted-sum function to embed (n + 1) authentication bits into a block with 2n pixels by modifying only one original pixel with (±1). With fewer authentication codes, the new process can protect the content of the image. The experimental results demonstrate that the approach can guarantee the fidelity of the watermarked image while retaining tamper-proof functionality.

Dual Digital Watermarking for Internet Media Based on Hybrid Strategies

This paper presents a novel dual watermarking mechanism for digital media that embeds a recognizable pattern into the spatial domain and an invisible logo into the frequency domain. Undoubtedly, visible watermarking is important for protecting online resources from unauthorized reproduction. Due to the visibility of embedded patterns, however, watermarked digital media are vulnerable to the inpainting attack and common signal processing operations. Utilizing hybrid strategies, simulation results show that the novel method can resist these attacks. In particular, the new mechanism allows legal subscribers to restore an unmarked image, whereas other dual watermarking schemes do not. This feature makes it suitable for protecting artistic and valuable media.

A Novel Illumination-Balance Technique for Improving the Quality of Degraded Text-Photo Images

Content digitization transforms a source into its digital form through digital cameras or scanners. This transformation often leads to the irregular distribution of image illumination, which may distort the quality of digital images. Engineers have provided many mechanisms to solve the degradation problem; however, these works mainly focus on dealing with full text images. In this letter, we propose a novel method to balance the illumination distribution of the transformed image. Experimental results show that the new method is capable of improving the quality of degraded text images. Particularly, unlike related works, the new method can effectively adjust the illumination distribution of a text-photo image to enhance the image quality.

Contrast-Adaptive Removable Visible Watermarking (CARVW) mechanism

Abstract Engineers have proposed many watermark mechanisms for protecting the content of digital media from unauthorized use. The visible watermark scheme indicates the copyright of digital media posted over the Internet by embedding an inconspicuous but recognizable pattern into media. However, the embedding process often results in serious distortion of the protected image. Since the strength of the watermark in conventional methods mainly depends on the feature of protected media, this may lead to unsatisfactory transparency of watermarked images. This paper proposes a removable solution for visible watermark mechanism. By adopting the subsampling technique, the method proposes a contrast-adaptive strategy to solve this problem. This method can also guarantee the essentials of general visible watermark schemes. Experimental results show that the proposed method outperforms related works in terms of preserving the quality of the restored image.

Preserving user-friendly shadow and high-contrast quality for multiple visual secret sharing technique

Traditional secret sharing scheme that encrypts secret image based on mathematical calculation to construct shadows often requires the complicated computation to extract the secret. Later on, conventional visual cryptography scheme was developed to deal with the perplexed calculation in encryption and extraction of previous schemes. The stack-to-see technique can be used easily to reveal the secret by human visual system, which can shorten computation time. However, the expansion of image size and the noise-liked shares of previous schemes lead to the difficulty in transmission and storage. This study uses a pre-defined codebook to encode two secret images into two meaningful transparencies without pixel expansion. According to the turning mechanism, two secret images can be embedded into two shares simultaneously. The decryption process allows the user to get two secrets via turning and stacking. A notable feature of our scheme is that the black pixel value of the secret image can be completely extracted and the vision quality of stacking results can be identified clearly.

Lightweight Secure Roaming Mechanism Between GPRS/UMTS and Wireless LANs

The third generation partner project (3GPP) has standardized general packet radio service (GPRS) and the universal mobile telecommunications system (UMTS) to provide cell phone communications and wireless Internet services. Although the data transmission rate is lower than that of wireless local area networks (WLANs), GPRS/UMTS covers larger areas. Hence, to achieve higher speed ubiquitous access, we propose a lightweight secure roaming mechanism (LSRM) that integrates GPRS/UMTS and WLAN. Taking advantage of these two technologies, LSRM offers anonymous roaming and friendly subscriber management. Besides, we give a formal security analysis to LSRM based on BAN authentication logic.

Renovating Contaminative Image Archives Based on Patch Propagation and Adaptive Confidence Collation

The preservation of classical archives is an essential task in the digitization of culture. So far, there remain two crucial challenges in archiving treasurable but aged image records. The first one is to eliminate a large-scale smudge located in a smooth ground, while the second one is to improve the readability of text content. Undoubtedly, the quality of an aged image is always degraded by antiquated smears, and the same situation occurs to obscure the content of a text image. In this paper, the authors apply the concept of patch propagation to help renovating contaminative images and introduce an adaptive confidence collation strategy to avoid the phenomenon of error diffusion, which often results in serious distortion in repairing. Furthermore, the techniques of Canny detection and center-weighted median filter are adopted in the proposed mechanism to refine the blurry target. In particular, the obscured text of aged images can be improved in the new mechanism, while it is seldom concerned in related works.

A Self-Reference Watermarking Scheme Based on Wet Paper Coding

Fragile watermarking is applied to protect the integrity of the digital media. Current fragile watermarking schemes mainly provide the functionality of detecting and locating the tampered regions of an authorized image. The capability to recover the tampered regions has rarely been discussed in the literature. In fact, the recovery ability is an important issue while proving and maintaining the image integrity. For achieving these purposes, we first utilize the concept of self-reference to preserve the significant information of a protected image. Then we embed the information into the protected image using the technique of wet paper coding. According to experimental results, the new scheme is highly sensitive to detect and locate the tampered area. In particular, the results show that the quality of recovery image is satisfactory.

Fast authentication mechanism with provable correctness for cluster-based VANETs

Vehicle ad hoc networks are self-configurable networks with dynamic topologies. All involved nodes in vehicle ad hoc networks, including vehicles and roadside devices, have to share the responsibility for achieving handover operation and providing communication services. Such networks are more vulnerable to the malicious attacks than traditional wireless networks because of the shortage of the fixed infrastructure. Moreover, because the vehicles always move from one area to another very quick, how to handle the handover between roadside devices has become a crucial challenge in designing the system. For providing secure and seamless communications in such networks, we develop a robust and fast handover mechanism. We have conducted essential experiments to demonstrate the superiority of the new mechanism to other works. In particular, we have applied the BAN logic model to prove the correctness of mutual authentication between involved participants. Copyright