Book Image

Building Blockchain Projects

By : Narayan Prusty
Book Image

Building Blockchain Projects

By: Narayan Prusty

Overview of this book

Blockchain is a decentralized ledger that maintains a continuously growing list of data records that are secured from tampering and revision. Every user is allowed to connect to the network, send new transactions to it, verify transactions, and create new blocks, making it permission-less. This book will teach you what blockchain is, how it maintains data integrity, and how to create real-world blockchain projects using Ethereum. With interesting real-world projects, you will learn how to write smart contracts which run exactly as programmed without any chance of fraud, censorship, or third-party interference, and build end-to-e applications for blockchain. You will learn about concepts such as cryptography in cryptocurrencies, ether security, mining, smart contracts, solidity, and more. You will also learn about web sockets, various API services for Ethereum, and much more. The blockchain is the main technical innovation of bitcoin, where it serves as the public ledger for bitcoin transactions.
Table of Contents (16 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback


Every system has some weaknesses. Similarly, Ethereum also has some weaknesses. Obviously, just like any other application, Ethereum source code can have bugs. And also just like any other network-based application, Ethereum is also exposed to DoS attacks. But let's see the unique and most important weaknesses of Ethereum.

Sybil attack

An attacker can attempt to fill the network with regular nodes controlled by him; you would then be very likely to connect only to the attacker nodes. Once you have connected to the attacker nodes, the attacker can refuse to relay blocks and transactions from everyone, thereby disconnecting you from the network. The attacker can relay only blocks that he creates, thereby putting you on a separate network, and so on.

51% attack

If the attacker controls more than half of the network hashrate, the attacker can generate blocks faster than the rest of the network. The attacker can simply preserve his private fork until it becomes longer than the branch built...