Sunny King’s Supernode Proof of Stake Consensus Complete Guide by MoonKing9998

By Community Staking Professional —Moonking9998

1. Basic introduction

Supernode Proof of Stake (SPoS) is a blockchain consensus mechanism designed by Sunny King, the creator of Proof of Stake (PoS) consensus, in June 2018. It is an extension to many core concepts of PoS, including Stake as Power, decentralization, high scalability and more. Compared to the new generation of mechanisms inspired by PoS, such as Casper, hybrid PoS, and DPoS, which is sometimes not considered as PoS, SPoS is a true and faithful continuation to the original PoS fundamentals.

Released in 2013, PoS was designed to resolve several key issues associated with Bitcoin’s Proof of Work (PoW) consensus mechanism, including energy inefficiency, centralization of mining pools and lack of scalability. Since its creation, many cryptocurrencies have been inspired by PoS and adopted the algorithm, such as Dash, Cardano, and Sunny King’s own creation Peercoin.

However, PoS consensus mechanism carries certain shortcomings, and is unable to meet the requirements of the current blockchain field for the development and application of a single public chain platform. On December 31th 2016, therefore, Sunny King started a new thing, this thing will change the history again.

In November 2018, Sunny King launched the first native blockchain platform V SYSTEMS (https://www.v.systems/) based on his SPoS consensus mechanism. The project aims to deliver a blockchain database and cloud platform, with the vision to bring forward a new economic era consisting of hundreds of millions of blockchain applications.

2. Summary of PoS

Since SPoS is an extension to PoS’ original ideologies, it is crucial to learn the key technical features of PoS before fully understanding the concept of SPoS.

1. Almost no energy consumption

PoS does not rely on electricity nor computational power as the basis for block validation, thereby consuming almost no energy.

2. Unlimited level of scalability

As the validation process is not restricted by hardware or electricity constraints, in theory, the blockchain carries an unlimited level of scalability. This paves the way for large scale blockchain technology applications.

3. Coin utility determines coin value

The coin value is not reliant on the intrinsic value nor the equivalence of other types of goods (e.g. the cost of mining). Instead, the coin value is determined by the coin utility.

4. Stake is power

Block validation and rewards are both based upon stake.

5. Decentralization

Without mining pools, there will be no giant and centralized institutions to dominate the blockchain.

6. Random block production

PoS uses the design of random block production, and only the average block interval can be observed.

3. Criticisms for PoS

SPoS is designed to tackle the issues of PoS. It is therefore also important to learn the key criticisms faced by PoS in order to fully understand the rationale behind SPoS.

1. Nothing-at-stake

Nothing-at-stake is one of the major concerns on PoS. The argument suggests that because block validation does not involve computational power or energy consumption, coin minters will try to mint on all block trees in order to prevent himself from not minting on the winning chain, therefore avoiding any potential loss and maximizing the gain.

2. Stake liquidity limited by coin age

PoS imposes many restrictions on the movement of stake after participating in coin minting. On a technical level, this design prevents frequent attacks (i.e. the holder of the coin can “vote more than once” and one stake gains multiple benefits).

From the perspective of PoS, one stake should not be allowed to claim multiple minting rights. However, one might be able to take advantage of stake liquidity and attempt to quickly move the stake around to claim more minting rights than it should. This type of attack is referred to as “busy contention attack”.

Even though the restrictions on movement may be of good reasons from a technical point of view, economically it is a barrier of entry for users to participate in minting. Coin holders are often concerned on how long their coins will be locked for the minting process.

Under SPoS, however, the number of stakes participating in minting is directly related to the level of security for the mechanism, similar to how computing power determines bitcoin security level. In this sense, not putting any restrictions on movement of stake is in fact beneficial to network security.

3. Coin age cannot accurately reflect contribution

As a proof of the stake value in minting opportunity, coin age shows a high level of stability and a wide range of advantages.

However, since it is a transaction-based measurement, the computational complexity is correlated with the number of transactions executed in a given time. Also, coin age is not an accurate indicator of the stake owner’s contribution to the community.

4. Minting security

Since PoS requires minter to sign the block, the private key must remain online, which poses a potential huge risk to the minter.

5. Inability to support large scale adoption

Under PoS, not all nodes receive enough incentives to undergo hardware upgrade. Moreover, if a random block production is adopted like in Bitcoin or other PoS blockchain, the actual production interval may sometimes far exceed the average time.

These issues create a huge concern for the efficiency of the blockchain, as systems usually prefer a constant response time over a random one.

4. Evolution from PoS to SPoS

1. Nothing-at-stake

The concern on nothing-at-stake is in fact unnecessary, as it ignores the fact that when a person owns a certain amount of stake in the ecosystem, the person is motivated to maximize the interest of the community instead of initiating attacks.

Coin owners who seek to maximize profits use the exchange value of the coin as a measurement of the coin value. Minting on all branches of block tree will be contradictory to his self interest, as it is considered a type of attack and the action will lead to a drop in the exchange value.

Considering the negative impact on the coin value, the potential loss on not minting on all branches is far less than the potential loss on coin value. Rational coin owners will always choose to uphold the protocol and ideologies of the consensus mechanism in order to maximize the interest.

In fact, the issue of nothing-at-stake has yet to be observed in a real scenario.

2. Stake liquidity

With a high level of stake liquidity, minters can spend or transfer their stake at any time. Coin leasers can also withdraw their lease, spend, or transfer their stake at any moment. This freedom of movement helps safeguard the blockchain. Take an extreme example of when supernodes are under attack — under SPoS mechanism, a coin holder can immediately withdraw the lease and switch to a secure backup supernode. This will render the attack meaningless, and also make it difficult to attack the blockchain as a whole, as in theory the hacker will have to attack an unlimited amount of supernodes.

Although there is a concern of busy contention attacks due to stake liquidity as mentioned in previous section, SPoS is well adapt to counter the situation. The mechanism introduces a unique measurement of account balance, similar to the accumulative average measurement during minting contention. The idea is that the stake must remain in the account for a period of time and wait for the metric to return to full. This design helps eliminate the concerns on frequent attacks.

3. Coin age

A minting balance mechanism is introduced for coin age measurement in the SPoS mechanism. The idea is that when a stake is withdrawn from the supernode, the total amount of stake on the supernode is immediately reduced. However, when a stake is leased to the supernode, the total amount of stake on the supernode is not immediately increased.

Whether the supernode wins the minting right depends on the minting balance. This minting balance, on the other hand, is dependent on whether the leased stake has been placed for a sufficient period of time. Yet, the length of the stake placement time and minting rewards are not correlated.

4. Minting security

To raise the level of security, SPoS mechanism separates the roles of minter and spender. That is, the private key of the coin holder can be different from the private key of the coin minter. With this design, all private keys of the stake can be put in offline storage.

This naturally allows the emergence of minting pools — the supernodes in SPoS. It is a similar concept to mining pools in Bitcoin.

Sunny King has also introduced a balanced minting right to prevent centralization of supernodes. This will be further explored in later sections.

5. Supporting large scale decentralized applications

The introduction of supernodes provides sufficient incentives to ensure that the supernodes continuously upgrade the hardware to support the blockchain expansion.

Also, the fixed block production sequence and production interval allows the supernode local clock to synchronize with the Internet time protocol. This ensures a high efficiency of block production as well as improves the security and predictability.

5. Technical and economical features of SPoS

Key technical features of SPoS:

1. Fixed block production sequence and constant block interval

2. Cold minting

3. Supernodes

Key economical features of SPoS:

1. Both stake owners and supernodes receive incentives for block production

Minting rewards are shared by supernodes and stake owners. The reward sharing ratio is determined by the supernode. Currently, there are 15 supernodes running on the V SYSTEMS mainnet. Coin holders (stake owners) can lease their coins to the supernode in order to earn the minting rewards. Each supernode takes turn to generate blocks in a minute, with each block bringing 36 VSYS Coins as rewards.

Based on the current number of supernodes, each supernode will generate 51,840 VSYS coins per day. After deducting around 20% of the reward for hardware upgrade and other operational costs, the remaining 80% will be proportionately distributed to coin holders who leased their coins to the supernode.

More information can be found on https://vsysrate.com/

2. Minting right and minting rewards are distributed in a fair manner, thus eliminating the risk of minting pool centralization

Equal minting right for each minting slot gives supernodes an equal standing and minting output. This is contrary to the design of Bitcoin, where no built-in mechanism is put in place to prevent the domination of mining pools. SPoS eliminates this major barrier that hinders the goal of decentralization.

The equal minting right of minting slot plays an important role in the minting economy. Supernodes form a market of minting pools. The minting market will then form an interest rate for leasing. Since stake owners have a reasonable preference to lease to a supernode paying higher lease rate, and the additional lease to a high paying supernode will lower its lease rate due to the constant minting output of the supernode, an equilibrium exists as a built-in force to equalize the lease rates of supernodes.

6. Advancements of SPoS

1. Superior version of PoS, following the stake-as-power philosophy
2. The only everyone can easy minting and easy out consensus.
3. Performance-oriented, support large scale decentralized applications
4. Most resistant consensus mechanism to 51% attack
5. Highly secure of minting progress for all ecosystem participants
6. Decentralized supernodes
7. Simplify the consensus using a mathematical approach just like bitcoin & PoW did

References:

Bitcoin: A Peer-to-Peer Electronic Cash System

https://bitcoin.org/bitcoin.pdf

PPCoin: Peer-to-Peer Crypto-Currency with Proof-of-Stake

https://peercoin.net/whitepapers/peercoin-paper.pdf

Evolution of Energy-Free Consensus: From POS to SPOS

https://www.v.systems/pdf/sposwhitepaper.pdf

Casper Proof of Stake compendium

https://github.com/ethereum/wiki/wiki/Casper-Proof-of-Stake-compendium

Delegated Proof of Stake

http://docs.bitshares.org/bitshares/dpos.html

EOS — An Introduction

https://eos.io/documents/EOS_An_Introduction.pdf

Decred Documentation — Proof-of-Stake Voting and Proof-of-Work Mining

https://docs.decred.org/research/overview/

Dash: A Payments-Focused Cryptocurrency

https://github.com/dashpay/dash/wiki/Whitepaper