The PoC consensus of MASS
The stability of Bitcoin proves that a practical, internet-scale, Byzantine faulttolerant system is feasible, and the reliability of the system is guaranteed through its consensus protocol. However, the Bitcoin system's use of a Proof-of-Work (PoW) algorithm has raised serious concerns about the expansion of its network. Those concerns include: (1) Since PoW algorithm cannot decouple the selection process of the submitted block from the block building protocol, meaning the hash power cannot be reused for consensus in multiple chains. (2) The PoW algorithm that Bitcoin uses is at risk of descending into a game between an increasingly centralised network and a handful of oligarchs who have successfully monopolised computing resources. (3) With the network’s incredible growth, vast amounts of energy are being continually expended solely for the purpose of sustaining it. (4) The dominance of ASICs among miners has raised massive barriers to entry and put mining beyond the means of ordinary users.
In this work, we propose MASS PoC algorithm, a consensus mechanism based on providing proof of storage space instead of wasteful proofs of work. In a PoC consensus algorithm, when a node submits a block to the network, it must also provide a valid proof of capacity. It is very difficult for a node to generate a valid capacity proof without having the corresponding storage size, and any node in the network can verify the proof. If both the block data and the proof are valid, the block will be accepted by the rest of the network.
The earliest cryptocurrency of which we are aware that uses disk space as the primary mining resource is Burstcoin. And most of the PoC’s blockchain systems use Burstcoin consensus algorithm. However, the most notable security issue with Burstcoin is time-memory tradeoffs: a miner doing just a little extra computation can mine at the same rate as an honest miner, while using just a small fraction of the space. In terms of efficiency, a major issue with Burstcoin is that a constant fraction (0.024%) of dedicated disk space must be read every time a block is mined. Finally, verification in Burstcoin is also problematic: a miner has to hash over 8 million 256-bit blocks to verify another miner’s claim. In summary, Burstcoin's consensus algorithm will lead to many security risks, such as the risk of unfair mining, the risk of ASIC being stored, the high fork rate, and the full node being easily vulnerable to DDoS. Therefore, we propose MASS PoC algorithm, a new proof of capacity consensus protocol different from Burstcoin consensus algorithm can solve the above problems.
The basic principle behind how a proof is provided is as follows: during the initialisation phase, a series of data is generated according to the protocol and is saved in the storage capacity. When a new block is to be generated, a part of this stored data is revealed based on the value of a random number. This data is then used to generate a proof, and the node is able to compete for the next block. The process consists of five stages: initialisation, block building, block reception, main chain selection, and punishment mechanism.