Book Image

Ethereum Smart Contract Development

By : Mayukh Mukhopadhyay
Book Image

Ethereum Smart Contract Development

By: Mayukh Mukhopadhyay

Overview of this book

Ethereum is a public, blockchain-based distributed computing platform featuring smart contract functionality. This book is your one-stop guide to blockchain and Ethereum smart contract development. We start by introducing you to the basics of blockchain. You'll learn about hash functions, Merkle trees, forking, mining, and much more. Then you'll learn about Ethereum and smart contracts, and we'll cover Ethereum virtual machine (EVM) in detail. Next, you'll get acquainted with DApps and DAOs and see how they work. We'll also delve into the mechanisms of advanced smart contracts, taking a practical approach. You'll also learn how to develop your own cryptocurrency from scratch in order to understand the business behind ICO. Further on, you'll get to know the key concepts of the Solidity programming language, enabling you to build decentralized blockchain-based applications. We'll also look at enterprise use cases, where you'll build a decentralized microblogging site. At the end of this book, we discuss blockchain-as-a-service, the dark web marketplace, and various advanced topics so you can get well versed with the blockchain principles and ecosystem.
Table of Contents (18 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Index

Parity hack returns


In the previous chapter on solidity, we discussed the parity hack by the multi-signature wallet in the library contract. After that hack, the parity team had changed the library contract with the necessary fix. However, in doing so, they forgot to audit the other sections of the library smart contract, which had a new vulnerability.

Figure 8.10 shows the portion of the self-destruct code, which was available to outside users. A rookie developer with the alias name devops199 accessed this function and accidentally executed it. Hence, the entire library contract self-destructed and took itself off the blockchain.

The impact was realized much later when the wallets calling this library became meaningless and the tokens worth multimillion USD remained trapped forever in these dangling wallet contracts. Such hack stories make us realize the importance of peer review on any open source code and demonstrate why we should use hard wallets in place of a hot wallet.

Figure 8.10: Suicide...