Blockchain Academy
We'll get together for networking with people interested in Blockchain including developers and anyone curious about Blockchain.

Finality

In a distributed network environment, the data shared by the nodes must be consistent. In addition, all nodes in the network must be able to share data. However, in the asynchronous distributed network environment, the concept of safety that the agreed values ​​always be the same between nodes, and the concept of liveness that all the nodes have to agree and synchronize are not always satisfied. This is called FLP Impossibility. Existing distributed networks have always prioritized sharing the same data, even if all nodes do not have the same data at the same time.

However, distributed networks that use the PoW consensus algorithm in the blockchain, that is, bitcoin and current Ethernet, have prioritize the Liveness that always comes to an consensus the network unless there is a problem with the object (block) that agrees with each node. Therefore, a block can occur at the same time, and the longest chain is regarded as the main chain in order to adopt one block. If the main chain is altered due to the generation of longer chain intentionally or accidentally in a branch of a block that occurs at the same time, the transaction in the previous block may not be processed and the balance may change. In other words, due to the possibility of change in the main chain, finalization of the transaction can’t be guaranteed completely. Currently, the Casper project to be implemented in Ethereum introduces a system that guarantees the finality based on PoS algorithm which is called Proof of Stake. This ensures that the previous block is not permanently altered by voting the validation nodes every 50 blocks. In other words, we are working to cover both liveness and safety.