Practically every platform that emerges these days claims to have come up with a new and unique consensus model that solves all the problems of its predecessors. Undeniably, proof-of-work (PoW) has issues, including speed and scalability, which were known since the beginning of Bitcoin. The extreme energy consumption is a problem that emerged later, as mining became a more lucrative proposition.
Proof-of-stake (PoS) emerged as an elegant solution that could address some of these challenges. When combined with other innovations such as a multi-chain architecture and transaction pruning, pretty much all of the challenges of a linear PoW blockchain can be overcome.
PoS Attacks – Theoretical, But Not Practical
The major arguments that people use against PoS are based on theoretical scenarios that have never come to fruition on any PoS blockchain. Nxt was among the first PoS blockchain, and in the 6.5 years it has been in operation, nobody has ever executed a successful nothing-at-stake attack.
There are two reasons for this. Firstly, any would-be attacker would need to successfully override the underlying software, which force-selects the best fork based on the stake invested.
Secondly, even if this could be overridden, the attacker would need to control over 50% of the network tokens. Only then would they stand a good enough chance of being picked to forge the next block for long enough to execute a double-spend successfully.
Similar software-based controls can be put in place against long-range attacks. For example, creating a checkpoint every x blocks can reconcile any fork against the current state of the blockchain and reject it if it contains discrepancies.
In the case of either a nothing-at-stake attack or a long-range attack,