Public Traceability Research Articles

Self-tallying e-voting with public traceability based on blockchain

In the post-epidemic era, the prevalence of remote collaborations in modern work environments highlight the importance of e-voting as a critical component in facilitating distributed decision-making. Most of the existing e-voting systems heavily rely on a centralized tally authority which requires a high degree of moral trust. However, this kind of architecture is insufficient for expected decentralization and verifiability in remote decision-making. A self-tallying e-voting system is more in line with our developed demands, nonetheless, it suffers adaptive and abortive issues inherently and as a result, fairness cannot be guaranteed. In this paper, we try to provide rational trust by building a blockchain-based self-tallying e-voting system with public traceability. We improve fairness and achieve a balance between privacy and accountability by taking advantage of a time-lock puzzle and traceable ring signature, in which the puzzle-solving time does not impose a real burden. We propose a concrete construction and prove that our protocol satisfies time-limited ballot secrecy, anonymity, exculpability, public traceability, self-tallying and fairness. We implement the prototype both on-chain and off-chain, and the results of time overhead of each phase demonstrate the practicability of our proposal.

Cloud assisted semi-static secure accountable authority identity-based broadcast encryption featuring public traceability without random oracles

Cloud assisted semi-static secure accountable authority identity-based broadcast encryption featuring public traceability without random oracles

Publicly Traceable Attribute-Based Anonymous Authentication and Its Application to Voting

Numerous anonymous authentication schemes are designed to provide efficient authentication services while preserving privacy. Such schemes may easily neglect access control and accountability, which are two requirements that play an important role in some particular environments and applications. Prior designs of attribute-based anonymous authentication schemes did not concentrate on providing full anonymity while at the same time holding public traceability. To address this problem, we formally define and present a new primitive called traceable attribute-based anonymous authentication (TABAA) which achieves (i) full anonymity, i.e., both registration and authentication cannot reveal user’s privacy; (ii) reusable credential, i.e., a registered credential can be repeatedly used without being linked; (iii) access control, i.e., only when the user’s attribute satisfies the access policy can the user be involved in authentication; and (iv) public traceability, i.e., anyone, without help from the trusted third party, can trace a misbehaving user who has authenticated two messages corresponding to a common address. Then, we formally define the security requirements of TABAA, including unforgeability, anonymity, and accountability, and give a generic construction satisfying the security requirements. Furthermore, based on TABAA, we propose the first attribute-based, decentralized, fully anonymous, publicly traceable e-voting, which enables voters to engage in a number of different voting activities without repeated registration.

Event-oriented linkable and traceable anonymous authentication and its application to voting

In the pursuit of anonymous authentication schemes that balance anonymity and accountability, various authentication schemes have been proposed. However, most of existing schemes cannot achieve linkability while holding public traceability. In this paper, we introduce a new variant of anonymous authentication called event-oriented linkable and traceable anonymous authentication (EOLTAA) and provide a generic construction. In an EOLTAA scheme, a message to be authenticated binds an event. If two different messages binding the same event are authenticated by an identical user, anyone can link the two authentications and further reveal the user’s identity. Then we formally define the security requirements of EOLTAA, including unforgeability, anonymity, linkability and public traceability. We give a generic construction satisfying the security requirements. With this new authentication scheme, we construct the first decentralized, anonymous, linkable and publicly traceable e-voting based on blockchain.

Efficient Policy-Hiding and Large Universe Attribute-Based Encryption With Public Traceability for Internet of Medical Things

Modern day medical systems are closely integrated and interconnected with other systems, such as those comprising Internet-of-Medical Things (IoMT) devices that facilitate remote healthcare services, say during pandemics (e.g., COVID-19). Attribute-based encryption (ABE) is a promising cryptographic primitive to support fine-grained access control in the ciphertext environment; in other words, ABE can potentially be used to ensure data confidentiality and user privacy in the IoMT ecosystem. In this article, we propose an efficient partially-policy-hidden and large universe ABE scheme with public traceability to construct a practical IoMT system (hereafter referred to as PTIoMT). The system is designed to achieve the following features: 1) the access policy is partially hidden: only nonsensitive attribute labels/names are displayed, while sensitive attribute values are hidden in the encrypted electronic health records (EHRs); 2) the number of the attributes is independent of the public parameters and, thus, can be arbitrarily large; 3) any user who discloses the decryption key can be efficiently tracked; and 4) fewer bilinear pairing operations are required during the decryption process. The security analysis and performance evaluation demonstrate the security and efficiency of PTIoMT.

Large-Universe Attribute-Based Encryption With Public Traceability for Cloud Storage

Attribute-based encryption (ABE) can be utilized to achieve both data security and fine-grained access control in a cloud computing environment. However, we need to consider the risks of key abuse and key escrow in such a setting. Specifically, the former risk category includes the illegal sharing of user’s keys (i.e., user key abuse) and illegal key distribution by an authority (i.e., authority key abuse), and the latter includes the scenario where some ciphertext is decrypted by the authority without the user’s approval. Hence, in this article, we seek to address both key abuse and key escrow concerns when deploying ABE in a cloud computing environment. In our construction, two authorities [i.e., a key generation center (KGC) and an attribute authority (AA)] participate in the generation of the user’s secret key. Both KGC and AA will not know the full decryption key or have the capability to forge one. As a result, neither KGC nor AA can illegally distribute the user’s private key to unauthorized users or decrypt user’s ciphertexts without the user’s approval. In addition, in our scheme, any private keys modified by malicious users cannot be successfully used for decryption. In the event that some user illegally shares his/her original private key, the scheme has in place a mechanism to trace the abused private key (since the user’s identity information is embedded in the private key). Hence, our scheme supports public traceability, key abuse, and key escrow. In addition, our scheme is based on prime order bilinear groups, and is shown to be selectively secure in the standard model.

An Anonymous Authentication System for Pay-As-You-Go Cloud Computing

Cloud computing offers on-demand availability of computing resources over the Internet. To attract users, cloud providers offer their resources as services at reasonable prices and provide various price models to reflect higher level of quality of service (QoS), which are referred as pricing schemes. <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -times anonymous authentication ( <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA) is an attractive approach to construct pricing schemes, providing access controllability, user anonymity and public traceability. In <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA schemes, authenticated users are permitted to anonymously access services from a provider at most <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> times, while the ones whose the number of access times exceeds <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> can be publicly traced. That is, <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA schemes offer a prepaid plan that charges users based on the amount of access times. Alternatively, pay-as-you-go (PAYG) is a pricing strategy that allows users to be charged based on the amount of usage, reducing the costs on unnecessary resources. Adopting <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA schemes to PAYG model, the access bound <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> is decided by the prepayment amount and the service usage is tracked by the number of access times. However, this approach is impractical, since existing <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA schemes only allow an one-time access in an authentication. This article aims to bridge this gap in the literature by designing an efficient and secure authentication system for PAYG cloud computing, supporting flexible access controllability, user anonymity and public traceability. To achieve this, we propose a new <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA primitive, called <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -times anonymous pay-as-you-go authentication ( <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA-PAYG), that allows users to access services for multiple times in an authentication as long as the number of their access times does not exceed <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> . We first formalize the definition and security model for <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA-PAYG scheme. Subsequently, we present a concrete construction of <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA-PAYG scheme, with the computational complexity as <inline-formula><tex-math notation="LaTeX">$O(1)$</tex-math></inline-formula> and the constant communicational cost. Finally, comparing with the most efficient <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA scheme proposed by Emura <i>et al.</i> , the experimental results show that our <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA-PAYG scheme is 2.5 to 3 times faster and saves up to 66 percent storage in grant processes. The time cost of an authentication of our <inline-formula><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -TAA-PAYG scheme is constant (1.4-2.4 ms), while Emura <i>et al.</i> ’s scheme needs more than one second when the number of access time is greater than 1, 000.

Black‐Box and Public Traceability in Multi‐authority Attribute Based Encryption

Ciphertext-policy Attribute-based encryption (CP-ABE) is a promising tool for implementing finegrained cryptographic access control. While the uniqueness of generating private keys brings extra security issues. The key escrow is inherent in CP-ABE systems because the trusted authority has the power to decrypt every ciphertext. The private keys are only associated with the attributes nor the user's identity. Some malicious users might be tempted to leak their decryption privileges for financial gain without the risk of being caught as the decryption privilege could be shared by multiple users who own the same set of attributes. We propose a new multiauthority CP-ABE with blackbox and public traceability, where the private keys are assigned by the cooperation between one central authority and multi-authorities. The performance and security analyses indicate that the proposed scheme is highly efficient and provably secure under the security model.

Accountable authority identity-based broadcast encryption with constant-size private keys and ciphertexts

Identity-based broadcast encryption (IBBE) enables a sender to broadcast a message to multiple identities efficiently. Nevertheless, since IBBE is based on identity-based cryptography (IBC), it suffers from the inherent key escrow problem. As a consequence, not only the user knows its private key, but also the private key generator (PKG). This property leads to that the creator of a given pirated private key, named a private key from an unknown source, is untraceable since both the PKG and suspected user can generate such a pirated private key for this identity. To mitigate this problem, accountable authority IBBE (A-IBBE) was proposed to provide accountability for IBBE, where white-box A-IBBE can distinguish the creator of a given pirated private key between the PKG and suspected user and black-box A-IBBE can further trace the creator of a decoder box. However, all prior constructions of black-box A-IBBE do not capture constant-size private keys and ciphertexts simultaneously. In this paper, to fill this gap, we propose a weak black-box A-IBBE scheme with constant-size private keys and ciphertexts. Our construction supports public traceability such that tracing can be performed with the public tracing key of suspected user instead of its secret key. We first define the weak black-box A-IBBE with public traceability. Then, we give our construction where the private key and ciphertext consist of two and five group elements respectively. Furthermore, the proposed scheme is proven to be secure with random oracles.

Traceability Management for the Food Safety along the Supply Chain Collaboration of Agricultural Products

The heightened awareness of food-related safety issues among food consumers drives the demand for more information about the vertical and horizontal food supply chain of food products. Transparency in the way agriculture was grown and handled throughout the supply chain process resulted in an important issue of 'traceability' in global food trade and safety. Traceability is an essential subsystem of quality management and must be managed by setting up a traceability system, which keeps the data tracking of product routes and of selected attributes. A collaborative research project for the supply and logistics of agricultural products in Tianjin was proposed recently. System analysis for the traceability information of the food supply chain is studied. Specific requirements and the system architecture for the logistic management solutions are proposed. Development of this research is crucial for both the public traceability system as well as the private traceability system. The consumers’ confidence for food safety choices can hence be improved.

Hardness of k-LWE and Applications in Traitor Tracing

We introduce the k- $$\mathrm {LWE}$$ problem, a Learning With Errors variant of the k-SIS problem. The Boneh-Freeman reduction from SIS to k-SIS suffers from an exponential loss in k. We improve and extend it to an LWE to k-LWE reduction with a polynomial loss in k, by relying on a new technique involving trapdoors for random integer kernel lattices. Based on this hardness result, we present the first algebraic construction of a traitor tracing scheme whose security relies on the worst-case hardness of standard lattice problems. The proposed $$\mathrm {LWE}$$ traitor tracing is almost as efficient as the $$\mathrm {LWE}$$ encryption. Further, it achieves public traceability, i.e., allows the authority to delegate the tracing capability to “untrusted” parties. To this aim, we introduce the notion of projective sampling family in which each sampling function is keyed and, with a projection of the key on a well chosen space, one can simulate the sampling function in a computationally indistinguishable way. The construction of a projective sampling family from k- $$\mathrm {LWE}$$ allows us to achieve public traceability, by publishing the projected keys of the users. We believe that the new lattice tools and the projective sampling family are quite general that they may have applications in other areas.

An Empirical Study for the Mobile Food Trace ability: Private Trace ability System for the White Gourd in Tianjin, China

As the food supply chain globalization became inevitable, transparency in the way agriculture was grown and handled throughout the supply chain process resulted in an important issue of ‘traceability’ in global food trade and safety for health management. Traceability in agriculture is faced with the technological challenges including food product label and identification, activity/process characterization, information systems for data capture, analysis, storage, and the integration of the overall traceable data for the supply chain, i.e., from farm to table. While some field data can be automatically acquired and transmitted by sensor networking, most agricultural activity information was recorded by manual handwriting for the traceability information systems. System architecture, operation scenarios, and the implementation examples for the mobile farming data collection system to automatically record the agricultural activities information for famers were proposed in this research. The farming information for farming activities is coded in two-dimensional labels of quick response (QR) codes. By scanning the proper operation labels, the corresponding farming data can be captured and uploaded simultaneously to the back-end web server. A collaborative research project for the traceability of white gourd planting in Tianjin was performed. The system can be implemented for public traceability system data collection and importing, as well as playing the roles of a private traceability system. The consumers’ confidence for healthy food choices with clear food traceability can be improved.