Communication protocol is a fundamental component of modern networking. With proliferation of networking and communication, users have become more concerned about privacy. This leads to development of end-to-end encrypted messaging systems which provides confidential communication. Besides confidentiality, there is an increasing demand for additional security properties such as unforgeability, anonymity, off-the-record (OTR), and consistency. However, efficiently achieving these properties simultaneously, especially on resource-constrained mobile devices, remains a significant challenge. In this paper, we propose MERIT, a novel multi-designated receiver authenticated broadcast encryption scheme that satisfies all the above security guarantees in a highly efficient manner. MERIT ensures the following key properties: (i) unforgeability prevents unauthorized parties from generating valid messages; (ii) privacy safeguards the messages and identities of the sender and receivers from non-designated parties; (iii) OTR ensures that receivers cannot later prove the origin of the messages even with their secret keys; and (iv) consistency ensures that all designated receivers obtain identical decrypted messages and identities. The core building block of MERIT is a practical multi-designated verifier signature (PMDVS), which might be of independent interest. We employed a novel batched cut-and-choose technology to prove that the ciphertext is well-formed. This results in an order-of-magnitude efficiency improvement in our scheme compared to its counterparts that rely on general-purpose zero-knowledge proofs. We then show how MERIT leverages PMDVS to provide unforgeability, privacy, OTR, and consistency in the scenario of group messaging. We provide security analysis to demonstrate that MERIT satisfies these security guarantees. We also conduct a thorough performance implementation, and the experimental results demonstrate that MERIT is highly efficient for deployment on mobile devices.

As agriculture and food industries evolve toward smarter and more efficient practices, uncrewed aerial vehicles (UAVs) are playing an increasingly vital role in tasks, such as data collection and precision spraying, and the reliable identity authentication has emerged as a critical issue for ensuring operational security and data privacy. Traditional authentication mechanisms, including public-key infrastructure-based and ID-based, have provided mutual trust and security of UAVs. However, when deployed on a large scale of UAVs, they suffer from a single point of failure, a heavy computational overhead, and challenges in managing UAVs at a large scale. In this article, we propose a lightweight decentralized authentication scheme with dynamic management for UAVs. Specifically, by leveraging the self-sovereign property of decentralized identifiers (DIDs), we enable each UAV to autonomously generate its own identifier, thereby realizing the decentralized authentication. And for the key pairs required in authentication, we design a secure and lightweight secret key generator based on the physical unclonable function (PUF), which prevents key leakage. In terms of identity management, we propose a cryptographic accumulator-based dynamic lightweight management module (DLMM), which is endowed with dynamic scalability and provides efficient dynamic management with low communication and computation overhead. We evaluate the performance of the proposed scheme, and the results show that the proposed scheme has significant advantages in security and computation overhead compared with the existing schemes.