Liveness

What Is Liveness?

In cryptocurrency and blockchain, liveness is an assurance that a system will remain available to exchange messages amongst nodes without any impact from centralized authorities.

Most cryptocurrencies interact using consensus algorithms. Since blockchain is a distributed network, it has distributed nodes. These servers interact with each other to exchange messages about the working of the blockchain. The interacting systems must ensure their availability or “liveness” to respond to messages. This is necessary to assure quick operations of the blockchain. 

Why Liveness is Important 

Having liveness guaranteed is essential for systems working as nodes on the blockchain. These blockchains regularly determine the history, and details of transactions, checking for their accuracy. They also respond to messages. The issues of liveness and safety cover these two different aspects.  

For instance, the Bitcoin (BTC) network uses the Nakamoto Consensus, which relies on the Proof-of-Work algorithm to authenticate all its transactions. This Consensus uses Proof-of-Work mining in tandem with a metric commonly called the “longest chain wins” to determine the history of the block. 

If nodes are honest, the history and expected history will be the same. Since all nodes should be copies of each other, they shouldn’t have different records; if they do, there is a problem. Liveness is an assurance that the required operation will eventually take place without offering a time for it. The stop of a distributed computation is a part of liveness. It guarantees that all nodes or validating entities will agree on a computation. 

You can picture liveness as a group of nodes reaching an agreement about a computation. This means that all the nodes will agree on one value for the operation. There will be no dissent. 

Nodes have to reach a settlement on what information the next block should hold. The blockchain faces a problem if there is a disagreement between the nodes.