Blockchain has taken the world by storm, but the technology is hardly without any flaws. The technology is facing a number of challenges, mostly related to the need to balance between security, scalability and decentralization. And while different blockchain protocols propose unique solutions, nonone has yet been able to solve these problems, which seem to be inherent to the core design of blockchain technology.
Meanwhile, other projects have gone a different route, looking for ways to advance distributed ledger technologies beyond blockchain. One of the most promising projects in that field is Hedera Hashgraph.
What is Hedera Hashgraph?
Hedera Hashgraph was born from the desire to find a better way to do distributed consensus at scale. This desire was what inspired Dr. Leemon Baird to get involved with the fledgling DLT space in 2012, when he began working on solving the scalability limitations associated with early DLT platforms. The result of these efforts, the hashgraph algorithm, laid the foundation for what eventually became Hedera Hashgraph.
Following the launch of the Hedera distributed ledger and the Hedera Governing Council, Hedera Hashgraph has become one of the most promising proof-of-stake DLT platforms. Hedera’s inventive design gives the network superior speed and scalability compared to traditional blockchain protocols. Hedera also boasts state-of-the-art security thanks to its asynchronous Bizantine Fault Tolerance algorithm. So let’s take a closer look at
How the Hedera Hashgraph algorithm works
Directed acyclic graphs
At the heart of Hedera sits the hashgraph algorithm, invented by Dr. Baird in 2015. Unlike traditional blockchain-based ledgers, which rely on cryptographically-chained data blocks, hashgraph utilizes a type of data structure called a directed acyclic graph (DAG).
In mathematics and computer science, a graph is a collection of points (typically called vertices or nodes) and edges (also known as arcs) that represent connections between points. A directed graph is then a graph whose arcs have a direction associated with them, while a DAG is a directed graph that does not form a closed loop (as shown below).
Hedera utilizes this type of data structure to build a powerful consensus mechanism for its network and power its distributed ledger technology.
Gossip about gossip
The description above gives us some idea about what makes DAGs so useful to decentralized systems. Comprising nodes and edges, these data structures are perfectly equipped for documenting the history of transactions between participants of a peer-to-peer network. Here’s how Hedera Hashgraph does it.
The Hashgraph consensus uses a so-called gossip protocol that facilitates the spreading and synchronization of transaction information across the Hedera network. Under the gossip protocol, when a member of the network becomes aware of new information, they relay that information to other, randomly chosen, network members. Every member that learns the new information starts relaying it to random members until the whole network knows about the transaction.
A ‘gossip’ between two nodes is an event that has an associated message containing: transaction information; a digital signature; a timestamp to ensure that all events are recorded in the proper order and two-parent hashes.
Now, if we use vertices to mark different events and edges to express how these events connect to one another through hashes, we’ll be able to represent the entire history of the network as one ever-growing graph of hashes, or in other words, a hashgraph. And not just the transactional history, but also a shared record of how network members have been talking to each other. A gossip about the gossip, stored on every computer participating in the network.
All this is important, because it not only allows us to have an accurate shared record of the network’s history, but it also enables virtual voting. This means that by looking at the recorded history, network members can deduce what information other members would have known at any given time.
Key properties oh Hedera Hashgraph
Speed and efficiency
Thanks to gossip about gossip and virtual voting, Hedera can support a much higher transaction throughput than traditional blockchain networks. Basically, because the network participants perform all necessary computations on their own, the computational load on the network is greatly reduced. According to Hedera, its proof-of-stake public network has the capacity to process over 10,000 transactions per second.
Hedera is able to achieve asynchronous Byzantine Fault Tolerance (aBFT), which is considered the gold standard when it comes to security of decentralized networks.
In general, Byzantine Fault Tolerance refers to the ability of distributed systems to function properly, even if some of its nodes have been compromised. In blockchain-based networks, consensus algorithms like proof-of-work are responsible for ensuring Byzantine Fault Tolerance. However they also typically have a limited tolerance for delayed messages, which makes them vulnerable to Distributed Denial of Service (DDoS) attacks.
In contrast, aBFT algorithms do not make timing assumptions. So aBFT means that finality of consensus will be reached with 100% probability if less than ⅓ of a network’s computational/voting power is controlled by attackers and messages from honest nodes get through, regardless of how long it takes them to do so.
Contrary to the popular belief, not all distributed ledger networks are highly decentralized. This is true for public, permissionless networks like Blockchain and Ethereum, but there are many platforms that do not support or, in fact, need such a high level of decentralization. Still, decentralization is one of the key elements of DLT’s value proposition and a highly desirable thing to have in any DLT platform. Most blockchain protocols only sacrifice decentralization to achieve gains in other areas, such as scalability (the so-called scalability trilema).
As mentioned above, Hedera Hashgraph has an impressive capacity for processing transactions, so how does the platform fare in terms of decentralization? Well, right now Hedera is a “public/permissioned” network, which means that it is open for anyone to deploy applications, but the nodes that constitute the network must be invited to join. In Hedera’s case, the nodes are operated by members of the Hedera Governing Council.
This model already provides some level of decentralization, but Hedera has plans to transition to a permissionless model in the future.
Key features of Hedera Hashgraph
Hedera Consensus Service
The Hedera Consensus Service (HCS) allows applications and permissioned networks to take advantage of the hashgraph consensus algorithm. Using the service, clients can submit messages to the Hedera public ledger for time-stamping and ordering. Messages can include important actionable information and can be encrypted to ensure user privacy. Essentially, the HCS acts as a trust layer for any application or permissioned network.
Hedera Token Service
Developed by LimeChain as part of an ongoing collaboration with Hedera, the Hedera Token Service (HTS) enables application to mint, configure and manage tokens on Hedera, without having to write and deploy smart contracts. Tokens created with the HTS can represent anything from stablecoins to in-game reward coins.
As mentioned above, Hedera is currently governed by the Hedera Governing Council, a body consisting of up to 39 leading businesses and organizations. The council makes decisions over software upgrades, network pricing, treasury management, and more. Council membership is term-based and members can serve up to two consecutive three-year terms.
The first fourteen Hedera Governing Council Members include Boeing, Deutsche Telekom, DLA Piper, FIS (WorldPay), Google, IBM, LG, Magalu, Nomura, Swirlds, Tata Communications, University College London (UCL), and Wipro.
The future of DLT
Looking at the current DLT landscape, it’s clear that the pursuit of greater scalability will continue to drive development in the sector in the coming years. Thanks to its clever design and robust consensus mechanism, Hedera Hashgraph is already capable of operating at an impressive scale, which puts the platform in a position to be a major part of the future of DLT.