The Ripple Voting Mechanism
In September 2014, Ripple has released a white paper which described their method to achieve fast consensus in a peer network without expensive (and slow) proof of work. This is not entirely new and here is an older video about their system where transactions take only 5 seconds. In the white paper they describe exactly how they achieve this.
They describe a mechanism called RPCA such that:
“Each server in the Ripple network is tasked with voting on a new batch of candidate transactions
during rounds that take place every few seconds. “
As a result, consensus is reached very quickly and transactions can be approved “in a matter of seconds”.
The RPCA mechanism attempts to solve the double spending problem by considering that all transactions on which 80% of nodes have agreed are “closed transactions” and they can no longer be changed or replaced by another transaction.
Later transactions are simply rejected which is almost the same as in our 20 second solution(s) for bitcoin.
The RCPA voting mechanism is expected to be deterministic and each honest node is expected to achieve the same result.
Future will show if Ripple get it right.