Book Image

Hands-On Blockchain with Hyperledger

By : Nitin Gaur, Luc Desrosiers, Venkatraman Ramakrishna, Petr Novotny, Salman A. Baset, Anthony O'Dowd
Book Image

Hands-On Blockchain with Hyperledger

By: Nitin Gaur, Luc Desrosiers, Venkatraman Ramakrishna, Petr Novotny, Salman A. Baset, Anthony O'Dowd

Overview of this book

Blockchain and Hyperledger technologies are hot topics today. Hyperledger Fabric and Hyperledger Composer are open source projects that help organizations create private, permissioned blockchain networks. These find application in finance, banking, supply chain, and IoT among several other sectors. This book will be an easy reference to explore and build blockchain networks using Hyperledger technologies. The book starts by outlining the evolution of blockchain, including an overview of relevant blockchain technologies. You will learn how to configure Hyperledger Fabric and become familiar with its architectural components. Using these components, you will learn to build private blockchain networks, along with the applications that connect to them. Starting from principles first, you’ll learn to design and launch a network, implement smart contracts in chaincode and much more. By the end of this book, you will be able to build and deploy your own decentralized applications, handling the key pain points encountered in the blockchain life cycle.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Packt Upsell

Fundamentals of the secure transaction processing protocol

We mentioned previously that cryptography is one of the core building blocks of a blockchain solution. The fundamental security of the bitcoin blockchain is the elegant cryptographical linkage of all major components of the ledger. Specifically, transactions are linked to each other, mainly through the Merkle tree.  A Merkle tree is based on the concept of a tree data structure where every leaf node has a hash calculated of its data and where the non-leaf node have a hash of all of their underlying child. This method provides a way to ensure the integrity of the data, but also provides privacy characteristics by allowing one to remove a leaf that is deemed private but leave the hash, thereby preserving the integrity of the tree. The Merkle tree has its roots incorporated into the block header. The block header includes a reference to the block headers that precede it.

That cryptographically enforced interconnectivity fosters the stability and security of distributed ledgers. At any point, if a link between any of the components is broken, it leaves them exposed to malicious attacks:

Transactions are also cryptographically connected to the rest of the blockchain structure, mainly through the Merkle tree. Once a transaction is modified within a block, with all other parts remaining stable, the link between all transactions of the block and its header are broken:

The new resulting Merkle tree root does not match the one already in the block header, hence providing no connectivity to the rest of the blockchain. If we proceed to change the Merkle tree root in the block's header, we will in turn break the chain of headers and thus the security model of the blockchain itself. Therefore, if we only change the contents of a block, the rest of the blockchain components remain stable and secure, especially as the block headers provide the connecting links by including a hash of the previous block header in the header of the next block.