This article briefly recaps the contents of MASS whitepaper. For further learning, it is recommenged to read the original whitepaper.
Background and Philosophy
Before the birth of Bitcoin, people did not believe that thousands of computing nodes in the world could be connected by Internet and maintain a database together. The appearance of Bitcoin had proved that a practical and Internet-level Byzantine fault-tolerant system was feasible, on which the first digital currency in human history had been issued democratically. However, the Proof-of-Work (PoW) consensus algorithm adopted by Bitcoin system has a strong dependence on computing resources, causing Bitcoin and other PoW blockchain systems gradually become a centralized network and a game with only resource oligarchs.
MASS believes that to promote the blockchain maintenance and realize the vision of network decentralization, the real solution should be a more advanced consensus algorithm, which is more democratic, fair, energy-efficient, safe, highly scalable and universal. Basing on this score, MASS community has developed MASS proof-of-capacity consensus protocol with various advantages such as low entry barrier, no permission required, 51% Byzantine fault-tolerance, natural decentralization and parallel support for multiple blockchain instances.
Basing on the protocol, MASS community has developed an innovative blockchain system MASS Net with a novel design and robust economy mechanism, which can help the consensus engine network with the cold start.
Principles of Proof of Capacity
In the PoC consensus algorithm, a node must provide a valid proof of capacity when it submits a block to the network. It is difficult for a node to generate a valid proof of capacity without a corresponding storage size, and at the same time all nodes in the network can verify the proof. If the block data and the proof are valid, the block will be accepted by the rest of the network.
The process of providing proof is shown as follows: In the phase of initialization, a serios of hash data is generated according to the protocol and is stored in the storage capacity. When a new block is to be generated, the data will be searched in the capacity according to the value of the random number, which will be used to generate the proof and participate in the competition to generate the next block.
The whole process includes five phases: Initialization, block construction, block reception, main chain selection and penalty mechanism.
Initialization: Miners need to initialize the hard disk and generate two HashMaps first and save them to the hard disk.
Block construction: After verifying the latest block timestamp, miners obtain the challenge parameters from the latest block, search for the data that meets the conditions in the HashMaps and generate a proof of capacity. If the quality of the capacity proof is greater than the difficulty of the net, the miner wins the right to block. Then the miner signs the block Hash and broadcasts the block to other nodes.
Block reception: When receiving the latest block, the node will conduct a series of verifications such as timestamp, public key, signature, proof of capacity, proof quality, transaction legality and so on.
Strategy of main chain selection: When more than one blocks that meet the rules above are received in the network, it needs to select the main chain block according to some certain rules: to select by the largest cumulated difficulty, the smallest timestamp and the best proof quality in turn.
Penalty mechanism: In the MASS proof-of-capacity consensus protocol, multi-mining attacks are resisted by the multi-mining penalty mechanism. If the node receives two different Header with the same proof, the miner of the block is proved to be double mining, and the node is able to construct a penalty transaction so that the Pk of the multi-miner is added to the blacklist and no longer capable to block.
Economy Mechanism
Any consensus mechanism needs an effective incentive mechanism to achieve growth and sustainable development. The incentive mechanism makes the rational interests pursued by each participant consistent with the interest of the entire system, and finally realizes a highly decentralized and stable consensus network.
The maximum supply of MASS Net cryptocurrency MASS is 206,438,400 (about 200 million), which will be issued within 15 periods. When a new period begins, the reward for each block will be halved and the length of the period will be doubled from the previous one.
The block heights of halving are as follows:
13440, 40320, 94080, 201600, 416640, 846720, 1706880, 3427200, 6867840, 13749120, 27511680, 55036800, 110087040, 220187520.
The distribution of block rewards is as follows:
Hard disk mining (18.75%): Hard disk mining means that miners invest hard disk resources and run mining software to participate in maintaining the network consensus. If a block is mined, the miner will obtain 18.75% of the block reward.
Staking mining (18.75%): Staking mining refers to the miners staking a certain amount of MASS cryptocurrency until it reaches a predetermined block height. A staking period is 61440 blocks (about 32 days) and the staking number is 2048 at least. Only the miners with top 30 staking amount will be rewarded, and 18.75% of the block reward will be equally distributed to the 30 staking miners according to the weight of staking amount and time.
Game mining (62.5%): Hard disk miners can bind a certain amount of MASS coin to the capacity space, and if the capacity space bursts, the miner will obtain 62.5% of the block reward. Otherwise, if the capacity space of the burst block is unbounded with MASS cryptocurrency, the 62.5% of the block rewards will go to the staking miners.
Whether it is binding mining or staking mining, it is a manifestation of miners’ confidence in the future of MASS network, which will help the network develop smoothly and is therefore motivated by the economy mechanism.
Transaction
There are mainly three types of transaction in MASS Net: ordinary transaction, staking transaction and binding transaction.
Ordinary transaction: The transfer transaction of MASS cryptocurrency.
Staking transaction: Freeze the trading right of MASS cryptocurrency to a certain block height, and unlock it only when the specific block height is reached.
Binding transaction: Bind the MASS cryptocurrency to the capacity space address, and the right of usage can be restored only after the unbinding transaction is submitted.
Advantages
Security: The PoC protocol adopts the principle of time-memory trade-off to ensure the unforgeability of the proof, and takes in a verifiable random function to make sure that the system is equipped with the ability of 51% Byzantine fault-tolerance. Besides, the fork detection and penalty scheme can protect the main chain from “Nothing at Stake” attacks which may split the main chain.
Fairness: The MASS PoC consensus protocol guarantees that the block generation probability of a node only depends on the proof of valid capacity provided by the node. In addition, the proof of valid capacity is independent from the storage media, therefore all nodes participating in MASS network have similar marginal costs.
Efficiency and energy saving: In MASS PoC protocol, computing resources are only required when initializing the storage capacity, and in the phase of block consensus, the data is visited only once with O(1) complexity. Therefore, it doesn’t require continuous power input consumption when using MASS PoC protocol for block negotiation. When MASS system executes the block consensus, the computing resources used are negligible and will not affect the normal use of the computer. When the storage capacity is no longer participateing in MASS network, it can be reformatted and used for other purposes.
General: In the process of consensus, a node only needs to perform access queries on the initialized capacity without any data operation on it. Therefore, the same storage space can provide multiple capacity consensus proofs and a node using MASS PoC protocol can simultaneously support multiple blockchains in parallel.
Conclusion and Outlook
The whitepaper introduces the principles and characteristics of MASS proof of capacity consensus protocol and the economy mechanism of MASS Net blockchain.
MASS consensus engine is encapsulated by the MASS proof of capacity consensus protocol, which aims to become the basic infrastructure of all blockchain consensus layer. The PoC consensus has a natural multi-chain feature, that is, the same hard disk space can provide space proof for multiple chains that meet the same PoC consensus standard. Therefore, MASS consensus engine is general and capable to provide consensus service for any blockchain. MASS consensus engine is fair and energy-efficient, which requires a very small amount of computing resources, and this means everyone has the opportunity to participate.
MASS Net blockchain system is the first public chain to utilize MASS consensus engine. MASS cryptocurrency is the store of value in MASS blockchain system, as well as the value anchor of MASS consensus engine.
The economy mechanism of MASS cryptocurrency will contribute to the growth of miner ecosystem on MASS consensus engine, thereby providing a solid underlying consensus for the blockchains to join MASS ecosystem in the future.
MASS consensus engine, MASS Net blockchain and MASS cryptocurrency are interdependent and are the three important forces in the initial stage of MASS ecological construction.
Since 2019, several projects have shifted from smart contracts to application chains, and in the future there will be hundreds of application chains to form the application chain ecology jointly, which requires the support of cross-chain technology. It is expected that MASS consensus engine can solve cross-chain technical problems from the perspective of the bottom layer of consensus, which may introduce blockchain to a new chapter.
