Blockchain technology has created an excitement that was last seen two decades ago when the Internet was entering the mainstream. An appealing feature of blockchain technology is smart contracts. A smart contract is an executable code. It runs on top of the blockchain facilitating an agreement between untrusted parties. These smart contracts have a major limitation, namely they cannot operate on information external to the blockchain. The inability to query such information has paved the need for trusted entities called “oracles.” These oracles attest to facts without the robust security guarantees that blockchains generally provide. This can potentially harm the integrity of the network and lead to centralized points-of-failure. To address this concern, this article proposes a decentralized oracle which is based on a voting-based game that decides the truth or falsity of queries. In the context of this article, we are only interested in binary markets, i.e., queries which can be ${\tt True}$ , ${\tt False}$ , or ${\tt Unknown}$ . When requesting facts from an oracle, a user submits binary queries. Reporters (or certifiers) respond to the queries by placing monetary stake. A formal analysis of the system parameters is presented, which shows that the proposed platform incentivizes a Nash equilibrium for truthful reporting. An extension to the base protocol is also described and profiled against the original framework. Finally, we discuss a prototype architecture, along with additional features to be considered during implementation.

The primary purpose of this paper is to bridge the technology gap between Blockchain and Fintech applications. Blockchain technology is already being explored in a wide number of Fintech sectors. After creating a unique taxonomy for Fintech ecosystems, this paper outlines a number of implementation scenarios. For each of the industries in which blockchain is already in use and has established itself as a complementary technology to traditional systems, we give a taxonomy of use cases. In this procedure, we cover both public and private blockchains. Because it is still believed to be in its infancy, especially when it comes to financial use cases, blockchain has both positive and negative aspects. As a result, it is critical to be aware of all of the open research issues in this field. Our goal is to compile a list of open research challenges related to various aspects of the blockchain’s protocol and application layers. Finally, we will provide a clear understanding of the applications for which blockchain can be valuable, as well as the risks associated with its use in parallel.

Blockchain-based smart contracts enable the creation of decentralized applications, which often handle assets of considerable value. While the underlying platforms guarantee the correctness of smart-contract execution, they cannot ensure that the code of a contract is correct. Today, as evidenced by a number of recent security breaches, developers still have a hard time making contracts that work properly.Even though these incidents often exploit contract interaction, prior work on smart-contract verification, vulnerability discovery, and secure development typically considers only individual contracts in isolation. To address this gap, we introduce the VeriSolid framework for the formal verification of contracts that are specified using a abstract state machine based model with rigorous operational semantics. Our model-based approach allows developers to reason about and verify the behavior of a set of interacting contracts at a high level of abstraction. VeriSolid allows the generation of Solidity code that is functionally and behaviorally equivalent to verified models, which enables the creation of correct-by-design smart contracts. We additionally introduce a graphical notation (called deployment diagrams) for specifying possible interactions between contract types. Based on this notation, we present a framework for the automated verification, generation, and deployment of contracts that conform to a deployment diagram. To demonstrate the applicability of VeriSolid, we translate existing Ethereum Improvement Proposal (EIP) specifications to temporal properties for two of the most popular contract interfaces: ERC20 and ERC721. We also show you how to write code for the ERC20 and ERC721 interfaces in a way that is safe, and we do this by using VeriSolid. We evaluate our framework on 726 contracts that are currently deployed on the Ethereum blockchain, which include 267 ERC20 and 459 ERC721 contracts. Our experiments indicate that 18% of ERC20 contracts and 4% of ERC721 contracts fail to satisfy the EIP specifications.