Follow blockchain research across journals, conferences, and preprint repositories.
9,005 results · page 296 of 376
Pengfei Li, Jingtian Peng, Long Yang, Qian Zheng · 5 authors
No abstract is available for this record.
Ran Canetti, Yilei Chen, Leonid Reyzin, Ron D. Rothblum
No abstract is available for this record.
Jingyi Li, Jigang Wu, Long Chen, Jiaxing Li
No abstract is available for this record.
Bernhard Beckert, Mihai Herda, Michael Kirsten, Jonas Schiffl
Smart contracts are programs building on blockchain technology. They implement functionality that has been agreed on between the concerned parties on a network. However, their immutability and exposed position make them vulnerable to programming errors, leading to faulty behavior and possible exploits. Therefore, smart contracts demand a particularly thorough analysis, ideally using formal program verification. In this paper, we present an approach for the deductive verification of Hyperledger Fabric smart contracts using the KeY prover. We have extended KeY to handle Fabric ledger implementations; in particular, we have developed mechanisms for reasoning about serialization and object persistence. The feasibility of our approach is demonstrated with a small case study.
Dakshita Khurana
The notion of simulation is central to cryptography: often, to demonstrate that an adversary did not recover any information about private inputs of other participants, we exhibit the existence of a simulator that generates the adversary's view without access to inputs of honest participants. The primary method used to build simulators is rewinding, where a simulator resets the adversary to a previous point in the protocol and tries to complete the protocol tree multiple times until it achieves a favorable outcome.First introduced in the context of zero-knowledge proof systems and secure computation, today the rewinding technique is synonymous with protocol security and polynomial simulation. Prior to this work, all known rewinding techniques in the plain model required multiple rounds of back-and-forth interaction between participants.In this thesis, we demonstrate the first rewinding techniques that require only a single message from each participant. Using these techniques, we overcome several barriers from literature to construct for the first time, based on standard sub-exponential cryptographic assumptions, the following core protocols, and several subsequent applications:- Two message commitments satisfying non-malleability (with respect to commitment).- Two-message delayed-input weak zero-knowledge arguments for NP. These imply arguments for NP satisfying witness hiding and strong witness indistinguishability.
Rick Klomp, Andrea Bracciali
No abstract is available for this record.
Matthias Fitzi, Peter Gaži, Aggelos Kiayias, Alexander Russell
No abstract is available for this record.
Yongjun Ren, Linhui Kong, Yepeng Liu, Jin Wang
No abstract is available for this record.
Abelardo Arredondo
The true innovation behind the Bitcoin protocol is blockchain technology. Blockchain is the underlying distributed database and encryption technology that enables trustless transactions that can be verified, monitored, and enforced without a central institution. This master’s report presents the core concepts behind blockchain that are concerned with carrying instructions for storage, sharing of non-financial data, including an examination of the byzantine fault tolerant cryptography model.\nA literature review describes the types of blockchains, nodes, proof of work, disadvantages, and risks and provides a survey of future applications related to state government records, such as birth certificates, automobile registrations, land deeds, and voting. This review will answer the question: Is it possible for a state government to use blockchain employing trusted nodes given that the nature of blockchain is that of a distributed network of peers accompanied by a public ledger without a central authority?\nFinally, the requirements for a specific application case study will be defined and developed. The desired application will be a smart contract to invoke a statutory durable power of attorney using blockchain technology for oneself in case of incapacitation while still living.
T-H. Hubert Chan, Rafael Pass, Elaine Shi
No abstract is available for this record.
Casimer DeCusatis, Marcus Zimmermann, Anthony Sager
While blockchain services hold great promise to improve many different industries, there are significant cybersecurity concerns which must be addressed. In this paper, we present experimental test bed results for a novel method of user identity management for cloud-based blockchain applications. Using a BlackRidge Technology endpoint on a Windows host, we insert cryptographic identity tokens on the first packet to request a new session. A corresponding gateway appliance in the cloud enforces security policy, blocking unauthorized access at or below the transport layer. Results of penetration testing a sample Hyperledger 1.0 application are discussed. We also demonstrate network segmentation and traffic separation, which allows multiple organizations to share blockchain infrastructure and facilitates compliance auditing.
Yi Deng, Xuyang Song, Jingyue Yu, Yu Chen
No abstract is available for this record.
Kexin Hu, Zhenfeng Zhang
No abstract is available for this record.
Claude Crépeau, Nan Yang
The existing multi-prover interactive proof framework suffers from incompleteness in terms of soundness and zero-knowledge that is not completely addressed in the literature. The problem is that the existing definitions of what is local, entangled and no-signalling are not rich enough to capture the full generality of multi-prover interaction. In general, existing proofs do not take into account possible changes in locality either during a protocol's execution or when protocols are composed together. This is especially problematic for zero-knowledge, as composing commitments is the only known way of achieving zero-knowledge outside of some NP-intermediate languages. In this work, we introduce the locality hierarchy for multiparty (multi-round) interaction, and for the first time a complete definition of multi-round multiparty no-signalling distributions and strategies. Within this framework, we define the locality of a protocol which involves the provers, verifiers, simulators and distinguishers. We show that an existing protocol for NEXP [BFL90] and a zero-knowledge variant we introduce are sound in a local sense, but are zero-knowledge in a sense that is even stronger than usually understood. All prior claims of zero-knowledge proofs in the multi-prover model were actually incorrect. Finally, we present similar constructions for entangled and no-signalling prover sets for NEXP and EXP based on [IV12] and [KRR14] using new multi-prover commitment schemes.
Ayad Al-Adhami
Radio Frequency Identification (RFID) technology has been expanded to be used in different fields that need automatic identifying and verifying of tagged objects without human intervention. RFID technology offers a great advantage in comparison with barcodes by providing accurate information, ease of use and reducing of labour cost. These advantages have been utilised by using passive RFID tags. Although RFID technology can enhance the efficiency of different RFID applications systems, researchers have reported issues regarding the use of RFID technology. These issues are making the technology vulnerable to many threats in terms of security and privacy. Different RFID solutions, based on different cryptography primitives, have been developed. Most of these protocols focus on the use of passive RFID tags. However, due to the computation feasibility in passive RFID tags, these tags might be vulnerable to some of the security and privacy threats. , e.g. unauthorised reader can read the information inside tags, illegitimate tags or cloned tags can be accessed by a reader. Moreover, most consideration of reserchers is focus on single tag authentication and mostly do not consider scenarios that need multi-tag such as supply chain management and healthcare management. Secret sharing schemes have been also proposed to overcome the key management problem in supply chain management. However, secret sharing schemes have some scalability limitations when applied with high numbers of RFID tags. This work is mainly focused on solving the problem of the security and privacy in multi-tag RFID based system. In this work firstly, we studied different RFID protocols such as symmetric key authentication protocols, authentication protocols based on elliptic curve cryptography, secret sharing schemes and multi-tag authentication protocols. Secondly, we consider the significant research into the mutual authentication of passive RFID tags. Therefore, a mutual authentication scheme that is based on zero-knowledge proof have been proposed . The main object of this work is to develop an ECC- RFID based system that enables multi-RFID tags to be authenticated with one reader by using different versions of ECC public key encryption schemes. The protocol are relied on using threshold cryptosystems that operate ECC to generate secret keys then distribute and stored secret keys among multi RFID tags. Finally, we provide performance measurement for the implementation of the proposed protocols.
Zhiguo Wan, Zhangshuang Guan, Zhuo Feng, Hequn Xian
No abstract is available for this record.
Neeraj Samtani
No abstract is available for this record.
Darlene Godfrey-Welch, Remy Lagrois, Jared Law, Russell Scott Anderwald · 5 authors
Payment cards (e.g., credit and debit cards) are the most frequent form of payment in use today. A payment card transaction entails many verification information exchanges between the cardholder, merchant, issuing bank, a merchant bank, and third-party payment card processors. Today, a record of the payment transaction often records to multiple ledgers. Merchant’s incur fees for both accepting and processing payment cards. The payment card industry is in dire need of technology which removes the need for third-party verification and records transaction details to a single tamper-resistant digital ledger. The private blockchain is that technology. Private blockchain provides a linked list built with hash pointers used to record encrypted transactions in a structured manner. It is a decentralized and distributed and available to all participants involved in the transaction. Private blockchain removes the need for third-party validators, thereby reducing fees and increasing the Merchant’s overall transaction value.
Francesco Buccafurri, Gianluca Lax, Antonia Russo, Guillaume Zunino
No abstract is available for this record.
Ben Berger, Zvika Brakerski
We consider natural ways to extend the notion of Zero-Knowledge (ZK) Proofs beyond decision problems. Specifically, we consider search problems, and define zero-knowledge proofs in this context as interactive protocols in which the prover can establish the correctness of a solution to a given instance without the verifier learning anything beyond the intended solution, even if it deviates from the protocol. The goal of this work is to initiate a study of Search Zero-Knowledge (search-ZK), the class of search problems for which such systems exist. This class trivially contains search problems where the validity of a solution can be efficiently verified (using a single message proof containing only the solution). A slightly less obvious, but still straightforward, way to obtain zero-knowledge proofs for search problems is to let the prover send a solution and prove in zero-knowledge that the instance-solution pair is valid. However, there may be other ways to obtain such zero-knowledge proofs, and they may be more advantageous. In fact, we prove that there are search problems for which the aforementioned approach fails, but still search zero-knowledge protocols exist. On the other hand, we show sufficient conditions for search problems under which some form of zero-knowledge can be obtained using the straightforward way.
Jan Hajný, Petr Dzurenda, Lukáš Malina
Card‐based physical access control systems are used by most people on a daily basis, for example, at work, in public transportation, or at hotels. Yet these systems have often very poor cryptographic protection. User identifiers and keys can be easily eavesdropped on and counterfeited. The privacy‐preserving features are almost missing in these systems. To improve this state, we propose a novel cryptographic scheme based on efficient zero‐knowledge proofs and Boneh‐Boyen signatures. The proposed scheme is provably secure and provides the full set of privacy‐enhancing features, that is, the anonymity, untraceability, and unlinkability of users. Furthermore, our scheme supports distributed multidevice authentication with multiple RFID (Radio‐Frequency IDentification) user devices. This feature is particularly important in applications for controlling access to dangerous sites where the presence of protective equipment is checked during each access control session. Besides the full cryptographic specification, we also show the results of our implementation on devices commonly used in access control applications, particularly the smart cards and embedded verification terminals. By avoiding costly operations on user devices, such as bilinear pairings, we were able to achieve times comparable to existing systems (around 500 ms), while providing significantly higher security, privacy protection, and features for RFID multidevice authentication.
Matteo Campanelli, Rosario Gennaro
No abstract is available for this record.
Yuan Zhang, Xiaodong Lin, Chunxiang Xu
No abstract is available for this record.
Naif Alzahrani, Nirupama Bulusu
No abstract is available for this record.