What Is Blockchain?

Known by many as the technology underpinning the bitcoin digital currency, blockchain has acquired a new identity in the enterprise. At a time when companies face new challenges in data management and security, it’s emerging as a way to let companies make and verify transactions on a network instantaneously without a central authority. Today, more than 40 top financial institutions and a growing number of firms across industries are experimenting with distributed ledger technology as a secure and transparent way to digitally track the ownership of assets, a move that could speed up transactions and cut costs while lowering the risk of fraud. Some companies see an opportunity to use blockchain to track the movement of assets throughout their supply chains or electronically initiate and enforce contracts.

Blockchain remains in the experimental phase inside many large firms and there are few tested use cases, experts and analysts caution. Here’s a look at how this emerging technology works:

What is blockchain?

A blockchain is a data structure that makes it possible to create a digital ledger of transactions and share it among a distributed network of computers. It uses cryptography to allow each participant on the network to manipulate the ledger in a secure way without the need for a central authority.

Once a block of data is recorded on the blockchain ledger, it’s extremely difficult to change or remove. When someone wants to add to it, participants in the network — all of which have copies of the existing blockchain — run algorithms to evaluate and verify the proposed transaction. If a majority of nodes agree that the transaction looks valid — that is, identifying information matches the blockchain’s history — then the new transaction will be approved and a new block added to the chain.

The term blockchain today usually describes a version of this distributed ledger structure and distributed consensus process. There are different blockchain configurations that use different consensus mechanisms, depending on the type and size of the network and the use case of a particular company. The bitcoin blockchain, for example, is public and “permissionless”, meaning anyone can participate and contribute to the ledger. Many firms also are exploring private or “permissioned” blockchains whose network is made up only of known participants. Each of these blockchain implementations operate in different ways.

Guardtime, a company that sells blockchain-based products and services to enterprises and governments including Ericsson AB and the country of Estonia, explained its approach like this:

Assume an organization has 10 transactions per second. Each of those transactions receives its own digital signature. Using a tree structure, those signatures are combined and given a single digital fingerprint — a unique representation of those transactions at a specific time. That fingerprint is sent up the tree to the next layer of infrastructure, such as a service provider or telecom company. This process happens for every organization in the network until there is a single digital fingerprint that encompasses all the transactions as they existed during that particular second. Once validated, that fingerprint is stored in a blockchain that all the participants can see. A copy of that ledger is also sent back to each organization to store locally. Those signatures can be continuously verified against what is in the blockchain, giving companies a way to monitor the state and integrity of a particular asset or transaction.

Anytime a change to data or an asset is proposed, a new, unique digital fingerprint is created, Guardtime said. That fingerprint is sent to each client node for validation. If the fingerprints don’t match, or if the change to the data doesn’t fit with the network’s agreed-upon rules, the transaction may not be validated. This setup means the entire network, rather than a central authority, is responsible for ensuring the validity of each transaction.

by Arvind Krishna, WSJ |  Read more:

Image: Oliver Wyman