Cloud storage systems provide several benefits, such as scalable storage capacity, cost efficiency with pay-as-you-go pricing models, easy access from any location with an internet connection, and robust data backup options. These advantages drive the growing popularity of cloud storage, resulting in a rapid increase in the volume of data stored on the cloud. Deduplication is an effective data management technique used in these systems to reduce storage costs and enhance efficiency through the elimination of redundant data. However, in a deduplication system, a hash digest, i.e., a small piece of information, is used as ownership proof of the entire file. Therefore, a malicious user can gain access to a sensitive file already stored on the cloud by obtaining and presenting the hash digest of that file. On the other hand, data stored in the cloud may be susceptible to loss or damage due to various accidental or intentional reasons. Hence, there is a need for an ownership verification protocol where both the user and server can verify each other’s file ownership without revealing details about the file. Some existing state-of-the-art schemes consider the server as a trusted entity and focus solely on verifying the ownership of the user, while others emphasize bidirectional ownership verification but do not incorporate obliviousness in their solutions. In this paper, we propose a novel bidirectional and oblivious ownership verification scheme for deduplication systems. We cryptographically prove that adversaries lacking complete ownership of the file, cannot successfully pass ownership verification with non-negligible probability. Additionally, we show that adversaries cannot gain any knowledge about the file through the ownership verification process. We implement our scheme in two real cloud scenarios and analyze performance compared to the recent state-of-the-art schemes. The experimental results demonstrate that our approach incurs moderate computational, communication, storage, and energy overheads while achieving ownership authentication and maintaining obliviousness in deduplicated cloud storage systems.

As the Metaverse evolves, robust authentication is essential to protect digital avatar privacy from identity threats such as theft, unauthorized access, and avatar spoofing. A user’s gait, serving as an intrinsic biometric signature of their avatar, offers a seamless and continuous authentication mechanism, enhancing security. Traditional authentication methods, including passwords, biometrics, and facial or fingerprint recognition, face challenges in virtual environments due to occlusions, spoofing risks, and hardware dependencies. To address these limitations, we introduce AutoGaitAnalyzer, a novel gait authentication framework that uses 16 gait features from a large-scale simulation of 5,000 users. Benchmarked against over 10 state-of-the-art models, AutoGaitAnalyzer outperforms all, establishing a new standard for avatar security in the Metaverse.

As cloud computing continues to support diverse and critical applications, ensuring secure, efficient, and privacy-preserving data sharing across dynamic, multi-cloud environments remains a significant challenge. Traditional solutions often suffer from inflexible access policies, high computational overhead, and complex key management, making them unsuitable for scalable and real-time scenarios. In this paper, we propose a lightweight and practical Data Protection as Service (DPaaS) framework that enables fine-grained access control, efficient key management, and secure deduplication. Our scheme integrates ciphertext-policy attribute-based encryption (CP-ABE) with policy attribute masking to protect user privacy and utilizes distributed key management to support dynamic role updates without re-encrypting the entire dataset. Additionally, the system incorporates client-side deduplication techniques to reduce storage overhead while maintaining data confidentiality. We implement a prototype and evaluate its performance and security in a real cloud environment. Experimental results demonstrate that our scheme achieves low computation time, supports secure access control, and minimizes resource consumption, making it suitable for deployment in resource-constrained and large-scale cloud-based systems.

The prominence of the Internet of Things (IoT) has surged in recent years due to tech-nological advancements, increased connectivity, and the widespread adoption of smart devices. Currently, IoT solutions are pervasive across various sectors, including smart homes, wearable devices, health-care, transportation, and industrial automation. The Long Range Wide Area Network (LoRaWAN) is a wireless communication protocol designed to provide reliable connection over long distances, spanning many kilometers, using low-power and wide-area networks (LPWANs) often used in IoT applications. However, LoRaWAN is vulnerable to bit-flipping attacks, where transmitted data is intercepted and maliciously altered by flipping specific bits in the message payload. Such attacks have the potential to undermine the trustworthiness and dependability of the system. In this paper, we propose a novel security enhancement for LoRaWAN. Our scheme incorporates a hash digest along with the end device's payload, enabling the application server to detect any malicious alterations in the received content using the hash value. We analyze the security of the proposed scheme against bit-flipping attacks and measure its performance through experiments in a real testbed. Our observations indicate that the proposed mecha-nism not only secures communication against these attacks but also incurs minimal overhead in terms of power consumption, transmission overhead, and latency.

Long Range Wide Area Network (LoRaWAN) is a wireless communication protocol that facilitates efficient and wide-range communication under low-power conditions. Over-the-air activation (OTAA) is a process recommended by Lo-Ra Wan v1.0.4 (latest version) that enables end devices to join the network with the help of the joining server and generate the session keys for further communications. However, OTAA is vulnerable to potential security threats due to unencrypted join request messages and the reuse of the same encryption keys. In this paper, we present a new security enhancement that addresses the aforesaid security issues. In the proposed scheme, we encrypt the join request message using a secret key to ensure data confidentiality. In addition, we incorporate the use of a random nonce in the proposed joining procedure to protect LoRaWAN against attacks related to the reuse of the same key. We show that the adversary cannot learn sensitive information from the join request message and reuse the AppKey to execute the eavesdropping and unauthorized activation attacks with non-negligible probability.

As the Internet of Things (IoT) is poised to become a global phenomenon, it is imperative to schedule the transmissions of IoT devices effectively and in a fair way. Leveraging Long Range (LoRa) technology, we can achieve transmissions that consume minimal power while covering vast distances, aligning with the requirements of IoT devices. However, the proximity of multiple devices within the same area often leads to packet interference and collisions. To address this, our study introduces a pioneering scheduling method utilizing a constellation of Low Earth Orbit (LEO) satellites to manage and streamline the transmission of data from End Devices (EDs). This method employs two LEO satellites: the first satellite assigns the sequence for EDs to dispatch their packets, and the second collects these packets in the predetermined sequence before forwarding them to the LoRa Network Server (LNS). For urgent (URG) communications, EDs can alert the first satellite, which then coordinates with the LNS to schedule these priority transmissions. The LNS generates a schedule that is relayed to the second satellite, informing EDs with URG packets of their specific transmission times and channels. This scheduling approach is designed to optimize channel usage effectively while accommodating the transmission of urgent data.

Fog computing is an extension of cloud computing and presents additional devices called fog devices near IoT devices providing services on behalf of cloud servers. Although fog computing brings several advantages, rapid growth in the data generated by IoT devices increases communication and computational costs. As data sensed by IoT devices may correlate, there is a high possibility of duplicate copies in the sensed data. Data deduplication is a compression technique that reduces communication and storage overhead by skipping the upload and storage of duplicate copies of data. However, deduplication for a fog-enabled IoT system introduces new security issues. In this paper, we propose a novel secure deduplication approach with dynamic key management in a fog-enabled IoT system. We introduce a multilayer encryption scheme with dynamic key management to prevent the access of revoked users to the data. We implement the proposed scheme in a realistic scenario using Raspberry Pi and Firebase cloud services. The performance analysis shows that our approach achieves confidentiality and forward secrecy along with lower storage, computational, and communication costs.

Deduplication is a ubiquitous compression technique for cloud storage servers. It reduces storage and bandwidth requirements by avoiding duplicate copies of data. However, developing an encryption scheme for deduplication is a critical challenge because traditional encryption techniques are not compatible with deduplication. The existing state-of-the-art encryption schemes are at risk of brute-force attacks as they use deterministic techniques for key generation. Moreover, the user in the recent schemes suffers from storage overhead of deduplication metadata and encryption keys. In this paper, we introduce a secure and efficient key management scheme for deduplication. In our scheme, the user divides the file into blocks and encrypts each block using a random key. As a result, our scheme protects against brute-force attacks. In addition, the user securely shares the encryption keys on public storage servers with the aid of a private server. As a result, the proposed approach causes lower storage overhead. We implement our scheme in a real cloud scenario and evaluate the performance of our approach in terms of storage and computation overhead.

Deduplication is a popular data reduction technique that minimises storage and communication costs. However, in a deduplicated system, an adversary can obtain access to the entire file on the server by showing just hash of file. A standard solution is that the server sends a file-based challenge to verify the client's file-ownership. Unfortunately, in the state-of-the-art schemes, adversary can correctly respond to the challenge with knowledge of the hash of file-blocks, where |Hash(blocks)| < < |File|. In this paper, we propose a secure proof of ownership scheme. In our proposal, the server randomly selects a set of file-blocks as a challenge. Therefore, if the client knows the complete file, he can correctly respond and get file access. We derive lower bound for no. of blocks in challenge. We prove that adversary cannot get success by learning former challenges-responses. We implement our approach in a realistic environment and compare performance with the state-of-the-art schemes.

The rapid increment in volume of outsourced data has raised an issue of data management for Cloud Storage Server. To solve this issue, Deduplication, a data compression technique was introduced which avoids duplicate data storage. However, Deduplication is vulnerable to malicious access to genuine Cloud Clients' files. An adversary can get access to file by learning small piece of knowledge about the file. In this paper, we propose secure and efficient Proof of Ownership for Deduplicated Cloud Storage. Our approach employs a technique of random matrix based challenges retrieved from the file. We evaluate security and efficiency of our approach by theoretical proofs and experimental results.

Administrators often prefer to keep related sets of files in different locations or media, as it is easier to maintain them separately. Users, however, prefer to see all files in one location for convenience. One solution that accommodates both needs is virtual namespace unification---providing a merged view of several directories without physically merging them. For example, namespace unification can merge the contents of several CD-ROM images without unpacking them, merge binary directories from different packages, merge views from several file servers, and more. Namespace unification can also enable snapshotting by marking some data sources read-only and then utilizing copy-on-write for the read-only sources. For example, an OS image may be contained on a read-only CD-ROM image---and the user's configuration, data, and programs could be stored in a separate read-write directory. With copy-on-write unification, the user need not be concerned about the two disparate file systems.It is difficult to maintain Unix semantics while offering a versatile namespace unification system. Past efforts to provide such unification often compromised on the set of features provided or Unix compatibility---resulting in an incomplete solution that users could not use.We designed and implemented a versatile namespace unification system called Unionfs . Unionfs maintains Unix semantics while offering advanced namespace unification features: dynamic insertion and removal of namespaces at any point in the merged view, mixing read-only and read-write components, efficient in-kernel duplicate elimination, NFS interoperability, and more. Since releasing our Linux implementation, it has been used by thousands of users and over a dozen Linux distributions, which helped us discover and solve many practical problems.