The metaverse transforms how individuals interact, work, and engage in virtual environments, creating new opportunities in gaming, education, e-commerce, and social networking. At the core of this experience are avatars (i.e., digital representations of users that serve as their proxies in virtual spaces). Ensuring secure and privacy-preserving communication between avatars presents critical challenges, particularly in protecting metaverse user privacy by preventing the linking of avatars to users' social and professional lives. Adopting anonymous schemes such as ring signature schemes requires access to all public keys within the anonymity set, which is impractical in the metaverse. In this paper, we proposeSPARTA(Secure andPrivacy-preserving protocol withRole separation andTrustworthiness forAvatars in the metaverse), a protocol that enables avatar authentication and maintains avatar unlinkability. By leveraging mercurial signatures, our approach allows metaverse users to generate multiple unlinkable avatars without requiring repeated registration with the metaverse service provider, thereby enabling seamless role separation. Additionally, by using a time-based hash chain, only avatars in possession of a reputation token from the time-based hash chain can submit their feedback on a smart contract based on their interactions. Given the soundness property of zero-knowledge proof and the origin-hiding property of mercurial signatures, we formally prove that${\sf SPARTA}$achieves mutual authentication, avatar unlinkability, and penalization enforcement. Additionally, we analyze the performance overheads introduced by its cryptographic primitives and compare${\sf SPARTA}$with existing metaverse authentication protocols. Furthermore, we implement the protocol using socket programming. This implementation simulates real-time message exchanges between protocol entities, resulting in an end-to-end latency of 105 ms. Compared to existing metaverse authentication frameworks,${\sf SPARTA}$provides unlinkable avatar authentication that achieves mutual authentication, role separation, and data sovereignty without reliance on an online trusted third party. The concurrent implementation between two Raspberry Pi devices demonstrates the scalability of${\sf SPARTA}$, achieving a total completion time of 17.338 seconds for 1000 concurrent authentications, corresponding to a throughput of approximately 57.7 authentications per second, confirming its practicality for large-scale metaverse environments.

Vehicular Ad Hoc Networks (VANETs) empower vehicles equipped with onboard units to exchange traffic-related messages, enhancing vehicle navigation safety and efficiency. Providing secure privacy-preserving authentication schemes for VANETs is indispensable. It ensures that only legitimate vehicles can communicate, preventing external adversaries from injecting falsifiable information that could mislead vehicles, cause accidents, or disrupt traffic flow. Simultaneously, the privacy-preserving features prevent curious adversaries from compromising vehicle privacy and tracking users. Secure centralized vehicular communication protocols, where a single entity issues certificates for all vehicles, face challenges in enabling cross-domain communications. Adoption of such centralized protocols necessitates that vehicles within each domain possess their certificate authority, restricting cross-domain communication due to inherent distrust in the certificate authorities of other domains. In this paper, we propose a Conditional Privacy-preserving Message Authentication protocol for VANET Emergency message exchange (CP-MAVE), designed to ensure message authentication, integrity, and anonymity of vehicles across different domains. In the event of misbehavior, distributed key generation centers collaborate to trace back the identity of the vehicle. To evaluate the security of our protocol, we formally prove the existential unforgeability of CP-MAVE against chosen message attacks based on the intractability of the elliptic curve discrete logarithm problem. Additionally, we demonstrate that CP-MAVE achieves message authentication, conditional privacy preservation, and resilience against replay and modification attacks. Moreover, we model and analayze CP-MAVE using the Tamarin prover and show that CP-MAVE maintains the secrecy and the message authentication of the vehicle traffic messages. Furthermore, we evaluate CP-MAVE’s performance regarding communication overhead and computation complexity. On a Raspberry Pi 4 Model B/8GB, equipped with a 1.5 GHz 64-bit Quad-core ARM Cortex-A72 processor, CP-MAVE requires a 304-byte communication overhead and 9.4897 msec as cryptographic operation overhead. Finally, to simulate the flow of messages between entities in our protocol, we implement CP-MAVE using socket programming, resulting in an end-to-end delay of 111.05 msec.

The IoT-edge-cloud paradigm enables resource-constrained IoT devices to offload their computation, thereby meeting the required quality-of-service for real-time applications. However, the deployment of IoT devices in public places, such as smart cities, exposes them to various security threats, including physical attacks. To address these security concerns, we propose a physical unclonable function (PUF)-based IoT-edge-cloud symmetric key authentication protocol with forward secrecy (SKAFS), which ensures the anonymity of transacting IoT devices, resilience to desynchronization-based denial-of-service attacks, and PUF modeling attacks. To evaluate the security of our protocol, we conduct a formal security analysis using the automated AVISPA tool. In addition, based on the indistinguishability property of the PUF, we formally prove that SKAFS is secure under the Canetti-Krawczyk-adversary model. Moreover, we implement the protocol using socket programming between a Raspberry Pi 1 as an IoT device, a Raspberry Pi 4 as an IoT gateway, and an 11th Gen Intel Core i7–11800H laptop as the cloud admin to simulate the message flow between the protocol entities in a real-time experiment and calculate its end-to-end latency. Finally, we compare SKAFS with other PUF-based protocols in terms of computation time, communication cost, and storage requirements.

The three-tier IoT–Edge–Cloud paradigm enables low-end devices to use the computation capabilities of the more powerful edge nodes to meet efficiency constraints for real-time applications. Many symmetric-key-based schemes rely on an online trusted cloud admin (CA) to establish session keys between IoT devices and edge nodes. In this study, we propose a new provably-secure mutual authentication privacy-preserving protocol with forward secrecy (MAPFS), which eliminates the requirement for an online CA during IoT authentication. To achieve anonymity, our construction utilizes zero-knowledge proofs and randomizes the IoT authentication request. The security of our construction is based on the well-studied discrete logarithm and decisional Diffie–Hellman assumptions in elliptic curve groups. We formally prove that MAPFS ensures mutual authentication and semantic security for session keys. We also evaluate MAPFS performance in terms of the communication overhead, storage requirements, and computation complexity. Finally, we test the performance of MAPFS on a Raspberry Pi 4 and compare it against other certificate-less protocols.

In this paper, we present a$\textsf {S}$ymmetric$\textsf {K}$ey$\textsf {I}$nter-$\textsf {C}$loud$\textsf {A}$uthentication and redeemable micropayment$\textsf {P}$rotocol ($\textsf {SKICAP}$) for IoT-Edge computing applications. The proposed protocol takes into account the mobile and limited resource nature of IoT devices by enabling them to register with their home cloud admin for computation offloading service provided by foreign Edge-Cloud instances. More precisely,$\textsf {SKICAP}$ensures that mobile IoT devices can be authenticated and serviced by edge nodes outside of their home cloud coverage, while guaranteeing the associated charge redemption. Additionally, since our protocol considers the mobile and anywhere deployable requirements of IoT devices, we utilize physical unclonable function and cryptographic hash function to make it privacy-preserving and resilient to hardware compromise. Under the assumption of an indistinguishably secure physical unclonable function, we provide a formal security analysis of our protocol. Finally, we report$\textsf {SKICAP}$performance on an ARM Cortex-A72 processor, and compare it with other closely related protocols.