Book Image

Mastering Blockchain - Fourth Edition

By : Imran Bashir
5 (3)
Book Image

Mastering Blockchain - Fourth Edition

5 (3)
By: Imran Bashir

Overview of this book

Blockchain is the backbone of cryptocurrencies, it has had a massive impact in many sectors, including finance, supply chains, healthcare, government, and media. It’s also being used for cutting edge technologies such as AI and IoT. This new edition is thoroughly revised to offer a practical approach to using Ethereum, Hyperledger, Fabric, and Corda with step-by-step tutorials and real-world use-cases to help you understand everything you need to know about blockchain development and implementation. With new chapters on Decentralized Finance and solving privacy, identity, and security issues, as well as bonus online content exploring alternative blockchains, this is an unmissable read for everyone who wants to gain a deep understanding of blockchain. The book doesn’t shy away from advanced topics and practical expertise, such as decentralized application (DApp) development using smart contracts and oracles, and emerging trends in the blockchain space. Throughout the book, you’ll explore blockchain solutions beyond cryptocurrencies, such as the IoT with blockchain, enterprise blockchains, and tokenization, and gain insight into the future scope of this fascinating and disruptive technology. By the end of this blockchain book, you will have gained a thorough comprehension of the various facets of blockchain and understand the potential of this technology in diverse real-world scenarios.
Table of Contents (24 chapters)
23
Index

The DAO

The Decentralized Autonomous Organization (DAO), started in April 2016, was a smart contract written to provide a platform for investment. Due to a bug in the code, called the reentrancy bug, it was hacked in June 2016. An equivalent of approximately 3.6 million ether was siphoned out of the DAO into another account.

Even though the term “hacked” is used here, it was not really hacked. The smart contract did what it was asked to do but due to its vulnerabilities, the attacker was able to exploit it. It can be seen as an unintentional behavior (a bug) that the programmers of the DAO did not foresee. This incident resulted in a hard fork on the Ethereum blockchain, which was introduced to recover from the attack.

The DAO attack exploited a vulnerability (reentrancy bug) in the DAO code where it was possible to withdraw tokens from the DAO smart contract repeatedly before giving the DAO contract a chance to update its internal state, indicating how many...