scholarly journals An Oracle-Based On-Chain Privacy

Computers ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 69
Author(s):  
Yu-Jen Chen ◽  
Ja-Ling Wu ◽  
Yung-Chen Hsieh ◽  
Chih-Wen Hsueh
Keyword(s):  
Homomorphic Encryption ◽  
Distributed Database ◽  
Smart Contracts ◽  
Logic Function ◽  
Sensitive Data ◽  
Privacy Issue ◽  
The Public ◽  
Smart Contract ◽  
Privacy Issues ◽  
Real Assets

In this work, we demonstrate how the blockchain and the off-chain storage interact via Oracle-based mechanisms, which build an effective connection between a distributed database and real assets. For demonstration purposes, smart contracts were drawn up to deal with two different applications. Due to the characteristics of the blockchain, we may still encounter severe privacy issues, since the data stored on the blockchain are exposed to the public. The proposed scheme provides a general solution for resolving the above-mentioned privacy issue; that is, we try to protect the on-chain privacy of the sensitive data by using homomorphic encryption techniques. Specifically, we constructed a secure comparison protocol that can check the correctness of a logic function directly in the encrypted domain. By using the proposed access control contract and the secure comparison protocol, one can carry out sensitive data-dependent smart contract operations without revealing the data themselves.

scholarly journals Logistic Regression on Homomorphic Encrypted Data at Scale

2019 ◽  
Vol 33 ◽  
pp. 9466-9471 ◽  
Author(s):  
Kyoohyung Han ◽  
Seungwan Hong ◽  
Jung Hee Cheon ◽  
Daejun Park
Keyword(s):  
Logistic Regression ◽  
Data Privacy ◽  
Homomorphic Encryption ◽  
Training Data ◽  
Sensitive Data ◽  
Encrypted Data ◽  
The Public ◽  
Private Data ◽  
First Time ◽  
Practical Feasibility

Machine learning on (homomorphic) encrypted data is a cryptographic method for analyzing private and/or sensitive data while keeping privacy. In the training phase, it takes as input an encrypted training data and outputs an encrypted model without ever decrypting. In the prediction phase, it uses the encrypted model to predict results on new encrypted data. In each phase, no decryption key is needed, and thus the data privacy is ultimately guaranteed. It has many applications in various areas such as finance, education, genomics, and medical field that have sensitive private data. While several studies have been reported on the prediction phase, few studies have been conducted on the training phase.In this paper, we present an efficient algorithm for logistic regression on homomorphic encrypted data, and evaluate our algorithm on real financial data consisting of 422,108 samples over 200 features. Our experiment shows that an encrypted model with a sufficient Kolmogorov Smirnow statistic value can be obtained in ∼17 hours in a single machine. We also evaluate our algorithm on the public MNIST dataset, and it takes ∼2 hours to learn an encrypted model with 96.4% accuracy. Considering the inefficiency of homomorphic encryption, our result is encouraging and demonstrates the practical feasibility of the logistic regression training on large encrypted data, for the first time to the best of our knowledge.

scholarly journals Prototyping a Smart Contract Based Public Procurement to Fight Corruption

Computers ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 85
Author(s):  
Tim Weingärtner ◽  
Danielle Batista ◽  
Sandro Köchli ◽  
Gilles Voutat
Keyword(s):  
Information Disclosure ◽  
Public Procurement ◽  
Smart Contracts ◽  
The Public ◽  
Blockchain Technology ◽  
Smart Contract ◽  
Sample Data ◽  
Procurement Procedure ◽  
Delivery Verification ◽  
Bidding Process

Corruption in public procurement is a worldwide appearance that causes immense financial and reputational damages. Especially in developing countries, corruption is a widespread issue due to secrecy and lack of transparency. An important instrument for transparency and accountability assurance is the record which is managed and controlled by recordkeeping systems. Blockchain technology and more precisely blockchain-based smart contracts are emerging technological tools that can be used as recordkeeping systems and a tool to mitigate some of the fraud involving public procurement records. Immutability, transparency, distribution and automation are some of the features of smart contracts already implemented in several applications to avoid malicious human interference. In this paper, we discuss some of the frauds in public procurement, and we propose smart contracts to automatize different stages of the public procurement procedure attempting to fix their biggest current weaknesses. The processes we have focused on include the bidding process, supplier habilitation and delivery verification. In the three subprocesses, common irregularities include human fallibility, improper information disclosure and hidden agreements which concern not only governments but also civil society. To show the feasibility and usability of our proposal, we have implemented a prototype that demonstrates the process using sample data.

scholarly journals Transforming Public Procurement Contracts Into Smart Contracts

2021 ◽  
pp. 1380-1394
Author(s):  
Pauline Debono
Keyword(s):  
Public Administration ◽  
Public Procurement ◽  
Smart Contracts ◽  
Procurement Process ◽  
The Public ◽  
Smart Contract ◽  
Procurement Contracts ◽  
Public Contract

The terms governing the provision of supplies, services, or works by an economic operator to a governmental entity are set into a public contract that is signed, following a procurement process. This article explores whether the public administration can utilise smart contracts to incorporate the terms governing the provision of supplies, services, or works. The fundamental elements of a contract are assessed, in order to determine whether a smart contract can be considered as fulfilling these requirements. Following this assessment, the main hurdles to the use of smart contracting are examined and a possible solution proposed. The case for utilising smart contracting within the realm of public procurement is finally advocated.

scholarly journals Smart Contracts as a New Technology in the Digital Economy

2018 ◽  
Vol 18(33) (4) ◽  
pp. 146-151
Author(s):  
Irina Glazkova ◽  
Dorota Kozioł-Kaczorek ◽  
Sergey Shmatko
Keyword(s):  
Business Processes ◽  
New Technology ◽  
Digital Technologies ◽  
Distributed Database ◽  
Smart Contracts ◽  
Government Organization ◽  
Storage Devices ◽  
Smart Contract ◽  
Wide Range ◽  
Reducing Costs

Digital technologies have a number of advantages that contribute to the development of the economy and make it more transparent. Some of the main features of modern digital technologies are speeding up business processes, reducing costs, eliminating the possibility of fraud, ensuring the transparency of the system and the ability to check and analyze the system. Regardless of whether a commercial or government organization uses the technology, in any case, there is a wide range of possibilities of its application. One of these technologies is blockchain. A blockchain is a distributed database in which storage devices are not connected to a shared server. This database stores an ever-growing list of ordered records called blocks. Each block contains a timestamp and a link to the previous block. The article defines a smart contract, describes the main areas of its application and provides processes similar to smart contracts, but working outside the blockchain. We also consider some of the risks that arise when working with smart contracts.

scholarly journals Transforming Public Procurement Contracts Into Smart Contracts

2019 ◽  
Vol 10 (2) ◽  
pp. 16-28 ◽  
Author(s):  
Pauline Debono
Keyword(s):  
Public Administration ◽  
Public Procurement ◽  
Smart Contracts ◽  
Procurement Process ◽  
The Public ◽  
Smart Contract ◽  
Procurement Contracts ◽  
Public Contract

The terms governing the provision of supplies, services, or works by an economic operator to a governmental entity are set into a public contract that is signed, following a procurement process. This article explores whether the public administration can utilise smart contracts to incorporate the terms governing the provision of supplies, services, or works. The fundamental elements of a contract are assessed, in order to determine whether a smart contract can be considered as fulfilling these requirements. Following this assessment, the main hurdles to the use of smart contracting are examined and a possible solution proposed. The case for utilising smart contracting within the realm of public procurement is finally advocated.

Know Your Customer (KYC) Implementation with Smart Contracts on a Privacy-Oriented Decentralized Architecture

2020 ◽  
Vol 12 (2) ◽  
pp. 41
Author(s):  
Nikolaos Kapsoulis ◽  
Alexandros Psychas ◽  
Georgios Palaiokrassas ◽  
Achilleas Marinakis ◽  
Antonios Litke ◽  
...  
Keyword(s):  
Privacy Protection ◽  
Smart Contracts ◽  
Expiration Date ◽  
User Privacy ◽  
Time Efficiency ◽  
Critical Part ◽  
The Public ◽  
Blockchain Technology ◽  
Smart Contract ◽  
Decentralized Architecture

Enterprise blockchain solutions attempt to solve the crucial matter of user privacy, albeit that blockchain was initially directed towards full transparency. In the context of Know Your Customer (KYC) standardization, a decentralized schema that enables user privacy protection on enterprise blockchains is proposed with two types of developed smart contracts. Through the public KYC smart contract, a user registers and uploads their KYC information to the exploited IPFS storage, actions interpreted in blockchain transactions on the permissioned blockchain of Alastria Network. Furthermore, through the public KYC smart contract, an admin user approves or rejects the validity and expiration date of the initial user’s KYC documents. Inside the private KYC smart contract, CRUD (Create, read, update and delete) operations for the KYC file repository occur. The presented system introduces effectiveness and time efficiency of operations through its schema simplicity and smart integration of the different technology modules and components. This developed scheme focuses on blockchain technology as the most important and critical part of the architecture and tends to accomplish an optimal schema clarity.

scholarly journals Blockchain Technology: The Essence and Prospects for Use in the Public Finance System of Ukraine

2021 ◽  
Vol 3 (518) ◽  
pp. 126-131
Author(s):  
O. O. Solodovnik ◽  
◽  
K. I. Dokunina ◽  
Keyword(s):  
Public Finance ◽  
Public Administration ◽  
Distributed Database ◽  
Smart Contracts ◽  
Information Transparency ◽  
Finance System ◽  
Investment Projects ◽  
The Public ◽  
Advantages And Disadvantages ◽  
Blockchain Technology

Historically, new investment projects, advanced technologies and financial innovations appear during the crisis period. However, the issues of using modern technologies in the public finance system are at the formation stage, which actualizes the task of arguing the use of innovative technologies that can provide simplicity, speed, and most importantly, the security of most financial transactions in the sphere of public finance. The article is aimed at researching and systematizing existing approaches to defining the essence of the concept of «blockchain» in order to substantiate the directions of improvement of the public administration system and the implementation of blockchain technology in the sphere of public finance. The definition of «blockchain» is studied and its interpretation is proposed as follows: this is a distributed database with registered and ordered economic transactions which, subject to certain conditions, can be connected and to which a specific transaction can be performed. The advantages and disadvantages of using blockchain technology are determined. It is established that blockchain has significant potential for use in various spheres of public life and, despite certain shortcomings, allows to improve the system of public administration. It is argued that to ensure the efficiency, information transparency and security of operations with budget funds, it is advisable to use innovative blockchain technology. It is proved that the implementation of this technology in the sphere of public finance will contribute to solving accumulated problems. It is determined that the modern paradigm of blockchain technology has become the basis for the implementation of smart contracts, but the issue of the use of this technology in such contracts is under formation and needs to be improved in terms of developing the conceptual basis for signing smart contracts by various economic entities.

scholarly journals Third Party Certification of Agri-Food Supply Chain Using Smart Contracts and Blockchain Tokens

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5307
Author(s):  
Ricardo Borges dos Santos ◽  
Nunzio Marco Torrisi ◽  
Rodrigo Palucci Pantoni
Keyword(s):  
Supply Chain ◽  
Mobile Application ◽  
Consumer Behaviour ◽  
Economic Incentives ◽  
Third Party ◽  
Smart Contracts ◽  
Proof Of Concept ◽  
Socially Responsible ◽  
The Public ◽  
Blockchain Technology

Every consumer’s buying decision at the supermarket influences food brands to make first party claims of sustainability and socially responsible farming methods on their agro-product labels. Fine wines are often subject to counterfeit along the supply chain to the consumer. This paper presents a method for efficient unrestricted publicity to third party certification (TPC) of plant agricultural products, starting at harvest, using smart contracts and blockchain tokens. The method is capable of providing economic incentives to the actors along the supply chain. A proof-of-concept using a modified Ethereum IGR token set of smart contracts using the ERC-1155 standard NFTs was deployed on the Rinkeby test net and evaluated. The main findings include (a) allowing immediate access to TPC by the public for any desired authority by using token smart contracts. (b) Food safety can be enhanced through TPC visible to consumers through mobile application and blockchain technology, thus reducing counterfeiting and green washing. (c) The framework is structured and maintained because participants obtain economical incentives thus leveraging it´s practical usage. In summary, this implementation of TPC broadcasting through tokens can improve transparency and sustainable conscientious consumer behaviour, thus enabling a more trustworthy supply chain transparency.

Legally Enforceable Smart-Contract Languages

2021 ◽  
Vol 54 (5) ◽  
pp. 1-34
Author(s):  
Vimal Dwivedi ◽  
Vishwajeet Pattanaik ◽  
Vipin Deval ◽  
Abhishek Dixit ◽  
Alex Norta ◽  
...  
Keyword(s):  
Literature Review ◽  
Systematic Literature Review ◽  
State Of The Art ◽  
Grey Literature ◽  
Smart Contracts ◽  
Smart Contract ◽  
Decentralized Autonomous Organizations

Smart contracts are a key component of today’s blockchains. They are critical in controlling decentralized autonomous organizations (DAO). However, smart contracts are not yet legally binding nor enforceable; this makes it difficult for businesses to adopt the DAO paradigm. Therefore, this study reviews existing Smart Contract Languages (SCL) and identifies properties that are critical to any future SCL for drafting legally binding contracts. This is achieved by conducting a Systematic Literature Review (SLR) of white- and grey literature published between 2015 and 2019. Using the SLR methodology, 45 Selected and 28 Supporting Studies detailing 45 state-of-the-art SCLs are selected. Finally, 10 SCL properties that enable legally compliant DAOs are discovered, and specifications for developing SCLs are explored.

Computing Blindfolded on Data Homomorphically Encrypted under Multiple Keys: A Survey

2022 ◽  
Vol 54 (9) ◽  
pp. 1-37
Author(s):  
Asma Aloufi ◽  
Peizhao Hu ◽  
Yongsoo Song ◽  
Kristin Lauter
Keyword(s):  
Homomorphic Encryption ◽  
Lessons Learned ◽  
Secret Key ◽  
Sensitive Data ◽  
Encrypted Data ◽  
Outsourced Computation ◽  
Secret Keys ◽  
Comprehensive Survey ◽  
Multiple Keys ◽  
Cryptographic Techniques

With capability of performing computations on encrypted data without needing the secret key, homomorphic encryption (HE) is a promising cryptographic technique that makes outsourced computations secure and privacy-preserving. A decade after Gentry’s breakthrough discovery of how we might support arbitrary computations on encrypted data, many studies followed and improved various aspects of HE, such as faster bootstrapping and ciphertext packing. However, the topic of how to support secure computations on ciphertexts encrypted under multiple keys does not receive enough attention. This capability is crucial in many application scenarios where data owners want to engage in joint computations and are preferred to protect their sensitive data under their own secret keys. Enabling this capability is a non-trivial task. In this article, we present a comprehensive survey of the state-of-the-art multi-key techniques and schemes that target different systems and threat models. In particular, we review recent constructions based on Threshold Homomorphic Encryption (ThHE) and Multi-Key Homomorphic Encryption (MKHE). We analyze these cryptographic techniques and schemes based on a new secure outsourced computation model and examine their complexities. We share lessons learned and draw observations for designing better schemes with reduced overheads.

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