Internet of Things (IoT) end devices are increasingly expected to support privacy-sensitive batch inference, yet their limited computational resources often make full local execution of convolutional neural networks impractical. This paper presents a latency-optimal adaptive split inference framework for privacy-preserving cloud-edge-end collaboration. The end device acts as the trust anchor, executes the plaintext model prefix, encrypts the split activation using fully homomorphic encryption (FHE), and keeps the secret key locally, while the edge and cloud execute assigned model segments only on FHE ciphertexts. We formulate collaborative encrypted inference as a split-pair selection problem over an end-side split point and an edge-side termination point. The proposed planner jointly models plaintext prefix execution, encryption, communication, edge-side FHE execution, and cloud-side FHE completion, and supports both convolution-level and block-level split granularities. Experiments on CIFAR-10 and PathMNIST show that the proposed convolution-level collaborative scheme achieves amortized end-to-end speedups of approximately 12.9 times over full-cloud FHE and 3.9 times over the block-level alternative, while preserving the corresponding plaintext-model accuracy. Including modeled communication, the amortized latencies are 1033.279 s/sample on CIFAR-10 and 1023.429 s/sample on PathMNIST.

With the development of Internet, privacy has become a primary concern of users. Anonymous authentication plays an important role in privacy-preserving systems. A $k$-times anonymous authentication ($k$-TAA) scheme allows a group member to anonymously authenticate to the application provider up to $k$ times. Considering quantum computing attacks, lattice-based $k$-TAA was introduced. However, existing schemes neither support the dynamic granting and revocation of users nor enable users to control the release of their attributes. In this paper, we construct the first lattice-based dynamic $k$-TAA, which offers limited times anonymous authentication, dynamic member management, attribute-based authentication, and post-quantum security. We present a concrete construction, and reduce its security to standard complexity assumptions. Notably, compared with existing related schemes based on lattices, our scheme is efficient in terms of communication cost.

With highly mobile and flexible-configurable, autonomous aerial vehicles (AAVs) are becoming crucial wireless communication infrastructures. To improve the reliability and throughput of data delivery for wireless networks, network coding, as a progressive technology, can be applied in AAV networks. However, network coding incurs a security problem called pollution attacks for AAV networks. Although homomorphic network coding signature can prevent pollution attacks, existing schemes are not suitable for AAV networks due to cumbersome certificate management, the key-escrow issue, or insecurity. In this article, we propose an efficient certificateless homomorphic network coding signature scheme for secure transmission of AAV networks, which can avoid certificate management and the key-escrow issue. Then our scheme is proven to be secure against adaptive chosen identity-and-subspace attacks in the random oracle model, thus our scheme can guarantee data integrity and authenticity to resist pollution attacks. We provide a performance evaluation for the proposed scheme and prior research, and experimental results illustrate the efficiency and feasibility of our scheme for practical application, reducing the verification overhead by 42.918% for a 72-dimensional data vector.

IoT-based sharing economy is a win-win business model, where a transferor owns idle IoT devices and transfers the right to use a device to a user for a fee. Considering usage of multiple devices and privacy preservation, anonymous single-sign-on (ASSO) is a feasible solution for authentication. ASSO allows a user to access multiple devices with one token issued by the transferor and prevents the transferor from identifying the user. We also observe that in the scenario of IoT-based sharing economy, the token should (i) support attributes since a device should be available only to users with specific attributes (e.g., age) and (ii) avoid incurring significant communication/computation overhead as IoT devices are resource-constrained. In this paper, we proposed PILOT, a privacy-preserving single-sign-on with fine-grained access control for IoT devices. When a user attempts to access a device, he/she requests a token from the transferor. The token is actually a blind signature that cannot be tracked, and contains the user's attributes which facilitate fine-grained access control on the device. Besides, the token consists of only four group elements and verification of the token involves only several exponentiation operations. This renders PILOT superior in terms of communication/computation overhead and suitable for IoT devices.

Logistics Management Systems (LMS) are crucial to global supply chains, ensuring efficient planning, data analysis and control of various logistics management processes. However, traditional LMS face complex challenges in mitigating cyber threats and data breaches. Blockchain technology emerges as a revolutionary solution, equipping LMS with traceability, immutability, and anonymity. While previous solutions focus on blockchain's theoretical potential or its application to singular aspects of logistics such as goods tracking or auction facilitation, our proposed Decentralized Logistics Management System (DLMS) distinguishes itself in two ways: first, driven by practical insights, we investigate the concurrent challenges and the advantages of blockchain that can be integrated into industrial LMS; second, we design a blockchain-based Decentralized Logistic Management System (DLMS) that includes comprehensive functional modules, including identity authentication, fair bidding mechanisms, and goods tracking. Finally, we implement a prototype of our proposed system and deploy the prototype on the Ethereum testnet to evaluate the performance of the proposed architecture. The experimental findings demonstrate the efficiency of our system and its potential as an effective solution to the identified challenges.

Single-sign-on authentication (SSO) enables a user to obtain a token from an identity server, and access multiple service providers with the token. In conventional SSO, the identity server can identify the user through the token, which compromises the user’s privacy. Anonymous SSO is proposed to solve this problem. However, the unconditional anonymity precludes identification of fraudulent users and leads to increase in illegitimate activities. In this paper, we propose SONAR, an anonymous single-sign-on authentication protocol that supports fraud detection. The identity server first accesses a user’s trustworthiness using fraud detection. We observe that directly refusing to issue tokens to an untrustworthy user allows the user to immediately realize that he have been detected, which poses security problems. Instead, we postpone the moment the user realizes he has been detected until he attempts to access a service provider. We also illustrate the benefits of this postponement using denial of service attacks as an example. In the proposed SONAR, the identity server issues the user (regardless of his trustworthiness) with a token that contains a covert channel, which is restricted to conveying only a 0/1 bit that is hidden from the user. The restriction of the channel prevents the identity server from tracking the user by embedding specific information in the channel, and meanwhile the 0/1 bit indicates whether the user is trustworthy or not. The token is actually a randomizable signature and can be randomized by the user, while the embedded bit remains unchanged. The user accesses a service provider with a randomized token, which protects the user from being identified as well as informs the service provider whether the user’s access should be permitted. We provide a formal security proof to demonstrate that SONAR is secure, and conduct a performance evaluation to show efficiency of SONAR.

Blockchain systems enable new applications, such as cryptocurrencies and smart contracts, using decentralized consensus without trusted authorities. A number of blockchain systems based on proof-of-stake techniques have been proposed, many of which use verifiable random functions (VRFs) as fundamental building blocks, such as Ouroboros, Algorand, and Dfinity, etc. The secret key of a VRF scheme is critical to the security of a VRF and the entire blockchain system built on it. To protect the secret keys of VRFs and maintain the efficiency of the proof-of-stake protocol, we extend the objective of cryptographic program obfuscation to VRFs and propose an obfuscatable VRF scheme. In particular, we propose an obfuscator that can transform the implementation of the scheme's random string generation algorithm and the given secret key into an unintelligible form. Obfuscated implementations of the random string generation algorithm are deployed on peers of a blockchain for supporting normal routines of the proof-of-stake protocol. Even if a hacker has controlled a peer's host, the owner's secret key will not be compromised because the key has been hardwired into the obfuscated implementation in an "encrypted manner". We formally prove the correctness and the security of the proposed VRF and obfuscator. Since the proposed scheme supports the general semantics of verifiable random functions, it can be used as a building block for all blockchain systems that adopt proof-of-stake protocols based on VRFs. The experimental result indicated that the scheme performs well on various platforms, such as cloud servers, workstations, smartphones, and embedded devices.

Replacing non-polynomial functions (e.g., non-linear activation functions such as ReLU) in a neural network with their polynomial approximations is a standard practice in privacy-preserving machine learning. The resulting neural network, called polynomial approximation of neural network (PANN) in this paper, is compatible with advanced cryptosystems to enable privacy-preserving model inference. Using ``highly precise'' approximation, state-of-the-art PANN offers similar inference accuracy as the underlying backbone model. However, little is known about the effect of approximation, and existing literature often determined the required approximation precision empirically. In this paper, we initiate the investigation of PANN as a standalone object. Specifically, our contribution is two-fold. Firstly, we provide an explanation on the effect of approximate error in PANN. In particular, we discovered that (1) PANN is susceptible to some type of perturbations; and (2) weight regularisation significantly reduces PANN's accuracy. We support our explanation with experiments. Secondly, based on the insights from our investigations, we propose solutions to increase inference accuracy for PANN. Experiments showed that combination of our solutions is very effective: at the same precision, our PANN is 10% to 50% more accurate than state-of-the-arts; and at the same accuracy, our PANN only requires a precision of $2^{-9}$ while state-of-the-art solution requires a precision of $2^{-12}$ using the ResNet-20 model on CIFAR-10 dataset.

We present an efficient zero-knowledge argument of knowledge system customized for the Paillier cryptosystem. Our system enjoys sublinear proof size, low verification cost, and acceptable proof generation effort, while also supporting batch proof generation/verification. Existing works specialized for Paillier cryptosystem feature linear proof size and verification time. Using existing sublinear argument systems for generic statements (e.g., zk-SNARK) results in unaffordable proof generation cost since it involves translating the relations to be proven into an inhibitive large Boolean or arithmetic circuit over a prime order field. Our system does not suffer from these limitations. The core of our argument systems is a constraint system defined over the ring of residue classes modulo a composite number, together with novel techniques tailored for arguing binary values in this setting. We then adapt the approach from Bootle et al. (EUROCRYPT 2016) to compile the constraint system into a sublinear argument system. Our constraint system is generic and can be used to express typical relations in Paillier cryptosystems including range proof, correctness proof, relationships between bits of plaintext, relationships of plaintexts among multiple ciphertexts, and more. Our argument supports batch proof generation and verification, with the amortized cost outperforming state-of-the-art protocol specialized for Paillier when the number of Paillier ciphertext is in the order of hundreds. We report an end-to-end prototype and conduct comprehensive experiments across multiple scenarios. Scenario 1 is Paillier with packing. When we pack 25.6K bits into 400 ciphertexts, a proof that all these ciphertexts are correctly computed is 17 times smaller and is 3 times faster to verify compared with the naive implementation: using 25.6K OR-proofs without packing. Furthermore, we can prove additional statements almost for free, e.g., one can prove that the sum of a subset of the witness bits is less than a threshold t. Another scenario is range proof. To prove that each plaintext in 200 Paillier ciphertexts is of size 256 bits, our proof size is 10 times smaller than the state-of-the-art. Our analysis suggests that our system is asymptotically more efficient than existing protocols, and is highly suitable for scenarios involving a large number (more than 100) of Paillier ciphertexts, which is often the case for data analytics applications.

The vehicular ad hoc network (VANET) is a basic component of intelligent transportation systems. Due to the growing security and privacy-preserving requirements of the VANET, a lot of conditional privacy-preserving authentication (CPPA) protocols have been proposed in recent years. Unfortunately, the traditional CPPA protocols, which are based on a trusted authority (TA) and rely solely on classical mathematical problems, cannot resist quantum attacks. Moreover, these protocols do not take into account the increasingly complex traffic flow in the VANET and cannot utilize fog nodes (FNs) to assist in the TA’s authentication work. In this paper, we design a lattice-based and fog-assisted conditional privacy-preserving authentication (LFCPPA) protocol to solve the above challenges. Compared to existing solutions, we have made the following improvements. First, our protocol is resistant to quantum attacks. Second, the solution supports batch processing of signature verification and mutual authentication of identity between the TA / FNs and vehicles. Third, in our design, FNs reduce the computing pressure of the TA to improve the efficiency of the system. In addition, we demonstrate the security of the protocol under the random oracle model with provable security. Finally, the efficiency and security of this scheme are better than similar solutions. Specifically, compared with the latest scheme, in terms of computational cost, our scheme is reduced by 74.47%, 85.58%, 19.69%, and 85.90% in the four stages of the protocol. Meanwhile, in terms of communication cost, our protocol reduces it by 89.98%.

In recent years, the industry and research have cast great attention to the Internet of Drones (IoD), which is becoming progressively popular since it can bring a great convenience to various application scenarios, such as national map exploration, public safety monitoring and automated military applications. In these scenarios, Unmanned Aerial Vehicles (UAVs) (called drones) will be used to collect private information. Due to the fact that the private information are very sensitive, and drones working in public places easily suffer from physical capture or tampering attacks, the primary concern is that this information could be collected by adversaries or unauthorized users. In addition, as resource-constrained devices, drones are mostly equipped with small memory and have limited computing power. Therefore, how to ensure robust security as much as possible while achieving lightweight computing and communication costs has become an urgent problem to be solved in this field. In this paper, we propose A PUF-based Robust and Lightweight Authentication Protocol for Drone-Gateway and Drone-Drone Communication (PRLAP-IoD) to address these issues. Both formal security validation using conventional tools (ROR Model and AVISPA) and other informal security analysis clearly demonstrate that PRLAP-IoD can not only provide physical security, but also defend against a variety of known attacks. Finally, compared with the recent Authentication and Key Agreement (AKA) schemes, PRLAP-IoD can attain a delicate balance between computation cost and communication cost in IoD environment.

With the rapid developments in sequencing technologies, individuals now have unprecedented access to their genomic data. However, existing data management systems or protocols are inadequate for protecting privacy, limiting individuals’ control over their genomic information, hindering data sharing, and posing a challenge for biomedical research. To fill the gap, an owner-governed system that fulfills owner authority, lifecycle data encryption, and verifiability at the same time is prompted. In this paper, we realized Governome, an owner-governed data management system designed to empower individuals with absolute control over their genomic data during data sharing. Governome uses a blockchain to manage all transactions and permissions, enabling data owners with dynamic permission management and to be fully informed about every data usage. It uses homomorphic encryption and zero-knowledge proofs to enable genomic data storage and computation in an encrypted and verifiable form for its whole lifecycle. Governome supports genomic analysis tasks, including individual variant query, cohort study, GWAS analysis, and forensics. Query of a variant’s genotype distribution among 2,504 1kGP individuals in Governome can be efficiently completed in under 18 hours on an ordinary server. Governome is an open-source project available at . ### Competing Interest Statement The authors have declared no competing interest.

It is tricky to determine whether two ciphertexts contain the same message when the messages are encrypted with different public keys. public key encryption with equality test (PKEET) addresses this problem without decryption. By integrating PKEET with identity-based encryption, identity-based encryption with equality test (IBEET) simplifies the certificate management in PKEET. In this paper, we first propose an IBEET scheme that can resist offline message recovery attacks (OMRA) and requires neither the dual-tester setting nor the group mechanism. With the help of some mathematical assumptions, we demonstrate the security of our scheme. Experiment results reveal that our scheme is efficient. From the perspective of usability, we explain why our scheme is more appropriate to be applied in healthcare social Apps than other OMRA-resistant schemes.

Random numbers play a crucial role in decentralized applications (dApps) like decentralized finance (DeFi) and non-fungible tokens (NFTs). However, their generation faces challenges due to blolckchain's deterministic and decentralized nature, risking smart contract security and ecosystem stability. Prior solutions, including Oracles, employing commit-execute schemes, suffer from higher transaction fees, extended processing times, and increased on-chain storage, compromising efficiency. This paper proposes a novel random number provider (RNP) protocol for smart contracts, eliminating dependencies on traditional commit-execute approaches. Furthermore, we systematically identify potential random number-related attacks on smart contracts, particularly Post-reveal Undo Attacks (PUAs), where attackers may reverse contract operations when randomness is unfavorable, and discuss the security requirements. Our protocol addresses these attacks by (1) incorporating distributed random beacons (DRBs) with consensus processes, bridging the semantic gap between DRB and consensus, and (2) thoroughly analyzing and classifying four types of PUA and offering robust mitigations, alongside presenting a security proof. Our experiments show the protocol significantly enhances response times and security for random number queries in smart contracts, slashing request fees by at least 89% and reducing on-chain data by 76.4% versus current methods. This work advances the integration of DRB protocols and consensus mechanisms, securing and optimizing random number applications in dApps, thus fostering the creation of more dependable, robust systems.

The Internet of Medical Things (IoMT) refers to the utilization of the Internet of Things (IoT) technology in the healthcare industry. Access control is particularly important for IoMT due to the sensitive nature of patient data, such as electronic health records (EHR). Although fine-grained access control can be achieved by attribute-based signature (ABS), existing ABS schemes lacks the ability to provide range comparison access policy in which patients can check whether the attribute value is within a certain range. In addition, the dynamic change of doctors’ permissions and the development of quantum technology also require that ABS can provide user revocation and resist quantum attacks. In order to solve these problems and make ABS schemes for IoMT more useful and more secure, we come up with a novel revocable and comparable ABS (RC-ABS) from lattices for IoMT, enabling fine-grained access control, attribute range comparison, and user revocation. First of all, we provide a proof of the unforgeability of our scheme in the standard model (SM) under the selective user revocation list semi-adaptive attribute adaptive message attack, which can resist attacks by semi-honest adversaries and prevent adversaries from attacking the weaknesses of hash functions in IoMT. Furthermore, our ABS scheme leverages the small integer solution problem (SIS) to effectively defends against quantum algorithm attacks. Finally, detailed performance analysis demonstrates that our solution not only possesses enhanced security features and functionalities, such as revocability, comparability, and resistance against quantum attacks, but also maintains a constant computation cost of user revocation, making it more efficient compared to other revocation schemes.

With the rapid growth and popularization of the Internet of Things (IoT), it has been applied to numerous fields such as smart industry, smart agriculture and smart home. Designing practical and robust authentication key agreement (AKA) schemes for smart environments has become a pressing problem to be solved. Due to differences in security requirements and resource allocation in smart environments, which we call security-asymmetry and resource-asymmetry, it is necessary to design specific AKA schemes for this environment. Since the design of remote AKA protocols does not fully consider security-asymmetry and resource-asymmetry, many existing schemes are not practical in smart environments. With regard to security-asymmetry, compared with traditional public-key techniques applied in AKA schemes, chaotic map is more effective than modular exponentiation and scalar multiplication, and it supplies many feasible attributes such as unpredictability, unrepeatability, uncertainty, which can be used to achieve communication security between users and gateways, while security operations based on hash function are sufficient to secure communications between gateways and smart devices. In view of resource-asymmetry, the complex operations in the authentication process can be completed by the gateway, so as to make full use of the rich resources on gateway side and reduce the use of resources on user side and device side. Based on such considerations, an efficient and secure authentication key agreement scheme based on chaotic map and physical unclonable function (PUF) for smart environments is proposed. We present a rigorous informal analysis of the proposed scheme. Moreover, the formal security verification is accomplished using the Automated Validation of Internet Security Protocols and Applications (AVISPA) tool. Finally, performance evaluations indicate the proposed protocol consumes less communication cost and computation cost while achieving more security functions compared to other four state-of-the-art related schemes.

Blockchain is a newly emerging technology in the past decade that has significantly impacted various aspects. “Scientific popularization” among IT practitioners on this technology and its use cases become a pressing need. However, constructing an effective blockchain teaching approach for this purpose is a challenging task. A training framework consisting of constructivist and pragmatic approaches is proposed, aiming to provide IT practitioners with an effective Teaching and Learning (T &L) process about blockchain on both theory and application aspects. The outcomes of this study are to 1) propose an effective teaching methodology, 2) assess the effectiveness of constructivist and pragmatic approaches and 3) extract the elements facilitating blockchain T &L. Mixed quantitative and qualitative research methods were adopted, including questionnaires and knowledge quizzes. 1267 participants were involved in the training that implemented the proposed framework. Their performance and responses indicated that the framework is effective and flexible. The findings from this empirical research can serve as a reference for educators in blockchain to implement a systemic approach that facilitates the T &L process and improves the field of blockchain and education in the future.

In this paper, we introduce a new framework for constructing linkable ring signatures (LRS). Our framework is based purely on signatures of knowledge (SoK) which allows one to issue signatures on behalf of any NP-statement using the corresponding witness. Our framework enjoys the following advantages: (1) the security of the resulting LRS depends only on the security of the underlying SoK; (2) the resulting LRS naturally supports online/offline signing (resp. verification), where the output of the offline signing (resp. verification) can be re-used across signatures of the same ring. For a ring size n, our framework requires an SoK of the NP statement with size log n. To instantiate our framework, we adapt the well-known post-quantum secure non-interactive argument of knowledge (NIAoK), ethSTARK, into an SoK. This SoK is inherently post-quantum secure and has a signature size poly-logarithmic in the size of the NP statement. Thus, our resulting LRS has a signature size of O(polylog(log n)). By comparison, existing post-quantum ring signatures, regardless of linkability considerations, have signature sizes of O(log n) at best. Furthermore, leveraging online/offline verification, part of the verification of signatures on the same ring can be shared, resulting in a state-of-the-art amortized verification cost of O(polylog(log n)). Our LRS also performs favourably against existing schemes in practical scenarios. Concretely, our scheme has the smallest signature size among all post-quantum linkable ring signatures with non-slanderability for ring size larger than 32. In our experiment, at 128-bit security and ring size of 1024, our LRS has a size of 29 KB, and an amortized verification cost of 0.3 ms, surpassing the state-of-the-art by a significant margin. Even without considering amortization, the verification time for a single signature is 128 ms, comparable to those featuring linear signature size. A similar performance advantage can also be seen at signing. Furthermore, our LRS has extremely short public keys (32 bytes), while public keys of existing constructions are in the order of kilobytes.

Smart contracts have been widely used to develop decentralized applications on account-based blockchain. The privacy issues of smart contracts have also received attention from researchers, and many privacy-preserving schemes and applications have been proposed. However, most existing schemes cannot achieve flexible conversion between private and public data. And the overly secure privacy-preserving scheme directly makes the regulation impossible. To mitigate these limitations, we propose a flexible privacy-preserving smart contracts with regulation (RPSC) system over the account-based blockchain. We first design a two-layer commitment structure that enables the fine-grained privacy protection (identity anonymity and data confidentiality) and flexible data state transitions. Then we combine a public-key encryption scheme with a zk-SNARKs scheme to achieve regulation property while keeping user's identity from others. Moreover, we prove that our scheme is secure, including privacy, soundness and traceability. Finally, we integrate RPSC into an account-based blockchain and implement two applications to evaluate the system performance. The evaluation results show our system performs effectively in practical settings.

A Verifiably Encrypted Signature (VES) scheme encrypts a digital signature in a way that allows the public to verify the validity of the encrypted signature. Recently, several practical VES schemes for ECDSA have been proposed to enable escrowed transactions with cryptocurrencies. However, these schemes are inefficient in terms of both communication and computation, or require a large lookup table. In this paper, we present two efficient VES schemes for ECDSA that improve upon previous work. The first scheme is based on Castagnos-Laguillaumie (CL) encryption, while the second is based on modified Joye-Libert (JL) encryption. Our benchmark shows that our schemes outperform existing constructions by a factor of at least 2 in both computation and communication. Additionally, our solution does not rely on any lookup table. We demonstrate that these schemes can also be generalized to design VES for Schnorr signature scheme and EdDSA. The main technical contribution of this paper, which is of independent interest, is a zero-knowledge proof for the equality of the discrete log of an elliptic-curve point and that of a JL ciphertext. Importantly, the security of our proof does not rely on any non-standard assumptions.