Receiver selective opening (RSO) security requires that in a situation where there are one sender and multiple receivers, even if an adversary has access to all ciphertexts and adaptively corrupts ...some fraction of the receivers to obtain their secret keys, the (potentially related) ciphertexts of the uncorrupted receivers remain secure. All of the existing works construct RSO secure identity-based encryption (IBE) in the single-challenge setting, where each identity is used only once for encryption. This restriction makes RSO security for IBE unrealistic in practice. It is preferable to have IBE schemes with RSO security in the multi-challenge setting in practice, where each identity can be used to encrypt multiple messages. In this paper, we initiate the study of RSO security in the multi-challenge setting (which we call
RSO
k
security) for IBE. Concretely, we show that the conclusion of lower bound, proposed by Yang et al. (in: ASIACRYPT 2020, Springer, 2020), on the secret key size of RSO secure public-key encryption also holds in the IBE setting (i.e., an IBE scheme cannot be
RSO
k
secure if the length of its secret key is not
k
times larger than the length of message). For construction, we propose a generic construction of IBE achieving
RSO
k
security. Through our generic construction, we can obtain
RSO
k
secure IBE schemes based on decisional linear (DLIN) assumption and learning with error (LWE) assumption. Furthermore, we show that the well-known Fujisaki–Okamoto transformation can be applied to construct a practical IBE scheme achieving
RSO
k
security.
Blockchain and its most selling point decentralization have attracted lots of attentions. However, the problem of centralized mining pools (also called outsourcing problem) is a serious threat to the ...fundamental security of Bitcoin and other blockchains that also use a scratch-off puzzle (Miller et al. in Proceedings of the 22nd ACM SIGSAC conference on computer and communications security, 2015). Although there are some solutions proposing “nonoutsourceable puzzles” to stop the pool operators in the centralized mining pools from outsourcing their mining work to others, we find that none of them can be adopted in real world to support strong nonoutsourceability. In other words, through some special means, e.g., legal prosecution or a tainted public reputation, the pool operator still can outsource his mining work. In this paper, we study the formal definition of strong nonoutsourceability and present constructions that support strong nonoutsourceability. The experimental results also show that our concrete construction is practical.
Abstract
Electronic voting (e-voting) has been studied for many years. Recently, researchers find that blockchain can provide an alternative secure platform for e-voting systems, because of its ...properties of tamper resistance and transparency. However, existing blockchain-based schemes either require central authorities to tally ballots or can only handle a limited number of voters. This paper tries to propose a self-tallying e-voting system, i.e. the public can verify the validity of all ballots and tally the ballots without a centralized authority. To achieve this goal, we solve two challenges, namely how to cancel out all random numbers used for ballots and to prove the validity of ballots using a non-interactive zero knowledge proof. Our scheme is proved to be secure and shown to be practical by experiments.
Abstract
Paper–based voting systems are not only environmentally unfriendly but also require a lot of manpower for tallying. Gongxian Zeng, Meiqi He, Siu Ming Yiu, Zhengan Huang propose an ...alternative in The Computer Journal (Volume 65, issue 12, December 2022)
With the popularity of cloud computing, an increasing number of institutions outsource their data to a third-party cloud system which could be untrusted. The institutions encrypt their data before ...outsourcing to protect data privacy. On the other hand, data mining techniques are used widely but computationally intensive, especially for large datasets. Combining data from different institutions for a big and varied training set helps enhance data mining performance. Therefore, it is important to make the cloud system which has powerful computing abilities run data mining algorithms on the encrypted data from multiple institutions. Two challenges need attention – how to compute on encrypted data under multiple keys and how to verify the correctness of the result. There are no existing methods that solve the two challenges at the same time. Elastic net is a useful linear regression tool to find genomic biomarkers. In this paper, we propose the first privacy-preserving verifiable elastic net protocol based on reduction to support vector machine using two non-colluding servers. We construct a homomorphic cryptosystem that supports one multiply operation and multiple add operations under both single key and different keys. We allow the involved institutions to verify the correctness of the final result. The collaboration between multiple institutions is made possible without jeopardizing the privacy of data records. We formally prove that our protocol is secure and implement the protocol. The experimental results show that our protocol runs reasonably fast, and thus can be applied in practice.
Using vehicular ad-hoc network, smart vehicles can detect dangerous events on the road and announce warnings to other vehicles to ensure road safety. The other vehicles nearby may receive the warning ...messages and accordingly choose a different route. But, because of the presence of malicious users on the road and errors in the detection system, some warning messages may prove dubious. Therefore, to distinguish between genuine and dubious messages, an element of trust has to be infused into the warning system. One common approach for this is to enable the receivers count the popularity of the reports of a warning event, i.e., the trust level. Once the trust level meets a predefined threshold, the vehicle's on-board unit will trust the warning event and warn the driver. Yet, owing to security and privacy concerns, anonymous counting problem does exist, because it is hard to fulfill both anonymity and counting requirements. In this paper, the authors define the anonymous counting problem and then propose a conditional distinguishable pseudo identities scheme that achieves conditional anonymity to overcome the counting problem. To achieve this feature of pseudo identities, time slot was added to minimize the influence of the adversary. Randomized batch verification was applied to enhance efficiency. Furthermore, it is shown how to achieve those features and provide proof on pairing equations. Finally, the time complexity of the proposed scheme was analyzed and its performance evaluated by Simulation of Urban Mobility.
Searching encrypted database is an important topic as more users want to leverage a third-party cloud system to store and process their data in encrypted form. Despite a lot of wonderful results, ...there are still a number of unsolved problems. In particular, the problems of pattern matching (not keyword search), e.g. with wildcards, that supports secure boolean queries and how to determine the value of k automatically of a top-k search for different queries on encrypted data are not properly addressed. In this paper, we provide solutions to solve these problems. Also, most existing secure databases employ different encryption functions to support different operators. The only exception is SDB (SIGMOD'2014) that was designed to support data interoperability between integers with a unified encryption scheme so that sophisticated queries can be answered by the database. However, SDB does not support string matching queries. We show that our solutions can be made compatible with SDB to fill this gap. To the best of our knowledge, we are the first to investigate these problems. We prove that our scheme is secure against chosen query attack. We have evaluated the performance of our scheme on large (105 strings) real-world datasets, and showed that our scheme can achieve a high search quality of 99.9% recall and 98.6% accuracy with reasonable response time.
A Nonoutsourceable Puzzle Under GHOST Rule Zeng, Gongxian; Yiu, Siu Ming; Zhang, Jun ...
2017 15th Annual Conference on Privacy, Security and Trust (PST)
Conference Proceeding
Blockchain technology has attracted a lot of attention in recent years. Applications of blockchain are not only restricted to cybercurrencies, but have also been extended to other areas such as ...finance, e-health, music, and other business. One of the key components of blockchain is the design for miners who are responsible for adding new transactions (blocks) by solving a puzzle and receive some rewards in return. As a result, miners tend to join centralized mining pools to outsource their computing resources in order to gain more steady rewards, which may affect the security and fairness of the system. This motivates the researchers to propose nonoutsourceable puzzles. However, existing nonoutsourceable puzzles do not work well under the high-rate transaction processing protocol (GHOST). In this paper, we propose the first nonoutsourceable puzzle that can satisfy all security requirements of GHOST. Our experimental results show that our puzzle is practical.
Searchable compressed data structures (e.g.Burrows-Wheeler Transform) enable one to create a memoryefficient index for large datasets such as human genomes. On the other hand, storing such an index ...in a third-party server, e.g., cloud, may have the privacy and confidentiality issues. An open problem in the community is to construct a secure variant of such a data structure. This problem is challenging as most of the existing works were shown to be insecure and none of them is able to perform pattern matching. In this paper, we provide the first solution based on Burrows-Wheeler Transform (BWT) to solve this problem (our scheme can do both compression and pattern matching). A new security definition, called isomophism-restricted IND-CPA security, is proposed. We show that our scheme is secure under this definition and our scheme is practical by experiments.
