Digital images have unique features that include being both easily transmittable over the Internet and being easy to tamper. With the advancement of digital processing techniques and an increasing number of valuable digital images being transmitted via the Internet, image authentication has been made more crucial than ever. In this paper, we present an image authentication scheme with tamper localization and self-recovery using fragile watermarking. We embed the fragile watermarks consisting of the authentication code and the recovery information onto the image to verify its integrity. The proposed fragile watermarking scheme can authenticate the image without accessing the original image, localizing the modifications as well as verifying the integrity, and even reconstructing the tampered regions. We use an AMBTC compressed code as the authentication code to minimize the distortion introduced by embedding. To reduce the blocking effect that occurs in the reconstructed image, a VQ compressed code is applied instead of the average intensity as the recovery information. Several representative test images and 200 different test images were randomly selected from BOWS to examine the performance of the proposed scheme. Experimental results confirm that the proposed scheme can effectively resist a cutting attack and a copy-paste attack while retaining the high accuracy of tamper localization. The average TPR and average FTP rate were around 97% and 0.12%, respectively, while maintaining the image quality of the watermarked image and restoring the image at up to 48 dB and 39.28 dB, respectively.

Internet of Things (IoT) is composed of various kinds of devices such as cars, electrical appliances, machines and sensors. With IoT technologies, devices can exchange information through the network, people are allowed to get information collected by devices without interacting with them, and automatic operations for devices are realized. Because of the variety of IoT devices, some of them possess limited computational capability. On the other hand, data transmission in IoT networks is usually through a public channel. To ensure efficiency and security for IoT environments, Lee et al. proposed a three-factor authentication scheme with hash function and XOR operation. They claimed their scheme possessed superior properties and could resist common attacks. After analyzing their scheme, we find that their scheme is vulnerable to five flaws. In this paper, how these found flaws threaten Lee et al.’s scheme is shown in detail. Then, we propose an improvement to overcome the found flaws and preserve the advantages by employing ECC.

The boom in cloud computing and social networking has led to a large number of online users in the networks. It is necessary to use appropriate privacy protection mechanisms to prevent personal privacy leakage. In general, image privacy protection techniques proceed with the whole image. However, the image may contain multiple users’ information, and different people’s data may require different privacy protection. In addition, cloud servers are semi-trusted instead of trusted service providers due to unknown security vulnerabilities and the possibility of grabbing sensitive data from the cloud server. In order to provide image protection with different privacy-preserved access rights and to prevent the cloud server from retrieving sensitive information from the image, we propose a privacy-preserved scheme that supports different privacy-preserved access rights in a single image based on the difficulty of solving the factorization problem and the discrete logarithm problem. The cloud server performed the image management method without knowing the privacy information contained in the protected images. By working out the proposed scheme in detail, we experimentally validate the scheme and discuss various options of access rights in practice.

User authentication is the key to ensuring that only authorized users can deal with specific affairs and access services. Applications or systems possessing different properties or requirements need different authentication schemes. For example, some institutions or companies need executives to manage or inspect their corresponding departments while the inspected department should not know who the executives are but only can verify their legitimacy. This paper designs a non-repudiation and anonymity-ensured user authentication system to meet the mentioned special requirements. We also propose a user authentication scheme to ensure that the designed system can work as claimed. In the system, a department is equipped with an authentication device, namely the department authentication device, to authenticate an executive while the executive’s identity is not revealed to the department and only the department’s authentication device can identify the executive for non-repudiation. An executive is equipped with an authentication device to have himself/herself authenticated by the department’s authentication device. Moreover, authentication data stored in an executive’s authentication device does not need to be updated even when management personnel changes are made.