Think about the many times you might have tried to make one firm, near flawless decision. For most rational individuals, this mental battle begins with the process of placing all possible options side by side. Thereafter, the pros and cons of these are studied with one resultant effect weighted against the other, usually in terms of desirability. In the end, the option that is most likely to yield the most befitting and desired result (often benefitting) is selected.
All of this seems very clear cut. Now envision a scenario involving decision making whereby several variables are involved and intricately enmeshed. Having too much of A (which is on its own advantageous), destabilizes the balance and intrinsic usefulness of B. A and B are a great combination and a force to be reckoned with but how to balance this with C?
Such is the case of the scalability trilemma. "Scalability, Decentralization and Security" has been identified by Vitalik buterin as the tri-dilemmatic puzzle that needs to be solved simultaneously in order to deal with the ethereum scalability issue. The scalability trilemma is made evident by events such as the inundation and clogging up of the ethereum network by the cryptokitties game which led to greatly reduced speeds and lower transaction times in December, the year 2017.
In 2019, the depth and extent of the effects of the trilemma is clearly evinced by the effects of a rise in the presence of decentralized finance projects on the ethereum blockchain. This recent development has only served to magnify the inefficiencies of the network while the Defi industry continues to emerge. The trilemma is not peculiar to the ethereum blockchain, more relatable effects include the slothful transaction speed I.e 7 transactions per seconds and particularly exorbitant transaction fees of the bitcoin blockchain.
The extent of difficulties caused by the trilemma spans across blockchains and consensus mechanisms employed to solve this three way puzzle. It has led to the existence of de facto centralized systems, Centralized systems brought forth by a supposedly decentralized technology. It Is the reason for fewer, truly interactive fair games and lesser high volume exchanges on familiar blockchain networks.
The scalability trilemma is a major hindrance, which when solved, will truly refine the blockchain technology allowing for greater ease in IOT transactions, large scale payment processing as well as the seamless Integration of traditional operations onto the blockchain.
Introducing the Harmony blockchain the ONE true solution that efficiently solves and harmonizes the scalability trilemma.
What makes the harmony network a fully scalable, provably secure and energy efficient blockchain? Why is it described as the Open Consensus for 10 billion people? Most importantly, how is it able to solve the scalability trilemma, thereby harmonising decentralization, security and scalability all at once?
Exploring the features of the Harmony blockchain.
Consensus mechanism :-Fast Byzantine Fault Tolerance(FBFT)
A consensus mechanism describes the process by which an agreement is reached amongst validators on the next block. Harmony's consensus protocol is an improvement on the complex practical Byzantine fault tolerance ( which consists of a specific process of vote rebroadcasting during validation), which would be inefficient for a network with a large number of nodes such as harmony. The Harmony network is made up of 4 shards and 400 nodes.
The FBFT makes use of the multi signature signing process to collect and broadcast votes, thereby reducing the complexity of the PBFT and rendering it more scalable. The FBFT also smartly precludes the "secret commitment round" peculiar to the schnorr signature.
This is subverted by way of the Boneh Lynn -Shacham which only requires one round trip I.e one round trip for a multi signature.
Picture a scenario wherein an individual’s decision on a specific menu can be easily accessed in a restaurant. E.g via a voting board on the restaurant’s mobile application. Then, the waiter doesn’t have to make a return trip each and every time, acknowledging each and every one’s menu decisions before deciding to take the orders. Since the voting board already reveals each customers menu interests, all that’s left to do is serve.
Sharding as a tool to ensure scalability.
THE NORM
Proof of work (as an ID registration Process)
Transaction Sharding
Network Sharding (Multiple shard committee)
The Harmony Network
Proof of stake (as validator registration process/Sybil attack preventer)
Beacon chain (Randomness beacon and Identity register)
Scalable Randomness generator (Verifiable Random Function(VRF) and Verifiable delay function(VDF)
Multiple shard chains that store separate blockchain states and process transactions concurrently.
Sharding creates multiple groups of validators and lets them process transactions concurrently. The Harmony network sharding is also firmly built on the proof of stake consensus model. I.e stake based sharding, Shifting the security requirements from minimum amount of nodes to minimum amount of voting shares.
Sharding as a concept manages to efficiently tackle decentralization and security. The fast Byzantine fault tolerance consensus mechanism, has 50% more speed than an average blockchain network employing the use of the default Byzantine fault tolerance. Also, by the fact that throughput predictably increases linearly with the additional nodes in a sharded blockchain network, Harmony is rendered highly scalable.
Scalable distributed randomness generation and the proof of stake consensus.
One major advantage of the proof of stake consensus mechanism is it's energy efficiency when compared to the proof of work. In the Harmony network, the distributed randomness generation is a potent combination of the secure and unexpected which assigns nodes to shards while preventing any form of maliciousness by the delayed revealing I.e Verifiable delay function of the "rnd" actual randomness. This form of randomness based sharding, "utilizes mutually agreed on random numbers to determine the Sharding assignment of each node" and is unpredictable, unbiaseable, verifiable and scalable.
As the pfnd( final randomness) is firmly established in the blockchain even before the actual randomness is known, malicious leaders are prevented from biasness. I.e selecting specific subsets from the VRF, random numbers.
Stake based Sharding.
Prospective validators are required to stake a certain amount of tokens to be eligible. The amount of staked tokens will translate to the amount of voting shares particular to each validator. Each voting share then gives a weight of one vote in the multi signature consensus described above. To a run a node, a minimum of 1 million one tokens (Harmony native tokens) are required.
"Harmony will adopt EPoS, a mechanism that elects the highest ranked validators based on stake as the committee. Specifically, for every epoch (~ 1 day), the top 1600 stakers will obtain the 1600 seats (4 shards * 400 seats) and become the validators across the shards".
Sharding by shares in the Harmony blockchain will prevent a validator with more than 1/4 of all staked tokens from been placed in a shard where it is most likely to possess at least 1/3 of the voting shares. This is a deterrent to large scale attacks. The validator who possesses the first voting share in the bucket I.e the number of shards in which voting shares are randomly distributed, is then referred as the leader.
The Harmony blockchain also employs the use of the adaptive thresholded proof of stake mechanism which ensures that the price of a voting share is set algorithmically such that it is small enough, rendering malicious stakers unable to concentrate their voting powers. Hence, malicious entities are unable to occupy more than 1/3 of the voting shares in a single shard, allowing for a more probably secure network.
Resharding.
Resharding is another sharding method that reinforces security by preventing malicious entities from taking over a single shard. Harmony, under the assumption of a slowly adaptive model of attack, subverts threat to a single shard by adopting the cuckoo rule which involves a strategic distribution of voting shares every epoch, based on the median of total voting shares. This resharding scheme has been proven to keep the voting shares in all shards balanced, as well as ensuring optimum security.
Epoch
Timeline of the Harmony blockchain.
The concept of the word "epoch" can be described as a timeline that governs the processes of consensus and Sharding. A reset button or default state just before a new epoch "e" e.g (24 hours that make a day) would require that a validator stake his/her tokens during epoch e-1.
The aforementioned distributed randomness generation generates a random number as stated. The Sharding structure is then formed based on such established randomness.
Fast state synchronization.
This enables easy synchronization of new validators in a shard by allowing for the current state (and not the entire blockchain history) to be downloaded. The Genesis block of an epoch would include additional hash pointers to the first block of the last epoch. This ease of affirming the validity of the current state of the blockchain with the use of cryptographic traces (pointers, signatures) in linking one epoch to another, can be likened to branches of family trees with easily identifiable tags which quickly reveal an individuals position amidst generations of seemingly unending history. The fast state synchronization is made better efficient by the trimming of the blockchain current state I.e further reducing its size and preventing replay attacks.
Beacon chain and Shard chain.
Shard chains allow for communication between themselves via cross shard communication. The beacon chain on the other hand has two functions that make it different from the shard chain which processes and validates its own transactions.
- Functions in generating the random number required for consensus.
- Accepts stakes.
The beacon chain also allows for increased security and affirms the validity of the shard chain state via cross shard communication. The beacon chain therefore functions as a form of check and balance for the simplest of transactions occurring in a shard chain by verifying the authenticity of each block header( by way of hash of the previous block and confirming that the multisignatures present correlate with the validators of the block). The beacon chain also serves to strengthen the shard chain by reducing the likelihood of maliciousness (as both chains have to be corrupted to "validate " the existence of an alternate block)
Networking
The Harmony network employs the use of:-
- The kademlia based routing which reduces the complexity of cross shard communication.
- The erasure code which sends messages in chunks of encoded messages thereby minimizing the network Load.
- FEC based unicast
- Support for locator mobility.
- support for home nodes.
Incentives.
Consensus rewards obtained by validators in connection to votes made on specific blocks translate to a "protocol defined number of tokens based on a validators stated voting share". Transaction fees are also rewarded to validators this same way.
Stake slashing.
This is required as it discourages dishonest behaviors by a leader or a validator. Events punishable by stake slashing include:-
- A case wherein a leader change is triggered for a shard. This would result in a slash in the amount of shares of such a "prior leader" in that shard.
- Two signed blocks that conflict each other.
Such misbehaviours can be reported with proof. I.e validators can report with proof of transaction to encourage more honest behaviours and if verified to be true, earn rewards in form of slashed tokens.
These characteristic features of Harmony meld to form a distinct, fully scalable, provably secure and energy efficient blockchain displaying innovativeness in areas such as:-
- Sharding I.e sharding of the current State and fast state synchronization.
- Secure Sharding which employs the use of the distributed randomness generation(VRF and VDF) as well as optimally secure resharding.
- Efficient and fast consensus. I.e Proof of stake and fast Byzantine fault tolerance.
- Adaptive thresholded Proof of stake which prevents malicious take over.
- Scalable networking infrastructure. I.e kaldemia routing, RaptorQ fountain code
- Consistent cross shard transactions.
The Harmony blockchain Use cases and recent developments.
The harmony mainnet was launched on June 28th I.e the first fully sharded proof of stake blockchain and with 600 nodes, remains a part of the top 15 decentralized networks. The mainnet phase two will include the addition of 4 shards (each with 400 nodes) to make a total of 1600 nodes. The second phase of the mainnet will also consist of a token swap to the native ONE token, as well as smart contract staking and token transfers.
The Harmony testnet boasts of a high transaction time of 118,000 tps which speaks volumes. Expect very many uses cases for the Harmony blockchain such as decentralized exchanges and industry use cases such as credit ratings and ad exchanges as well as decentralized finance projects (Defi’s) that intrinsically require high throughput.
The recent partnership between
Animoca (the company behind the Cryptokitty game) and harmony also sets in motion the possibility of other future collaborations between harmony and other blockchain based gaming companies. Animoca is said to have chosen to partner with Harmony in order to collaborate on the development of a new ecosystem for crypto collectibles.
Also, the recent partnering between Morpheus lab(a blockchain platform as a service) and harmony further emphasizes the importance of a more scalable, secure blockchain network. Morpheus labs rapid tooling can be employed by developers at large at much lower transaction fees. A great combination of rapid tooling on a scalable and low cost network.
The use-cases of Harmony are quite numerous and most certainly innovative. In fact, I find myself affirming that the "Open consensus for 10 billion" statement is far from being an exaggeration. Harmony was built by top level individuals who have worked with well know tech giants. The harmony team consists of dedicated and disciplined individuals who have come together to indeed make a difference. The experimental Zone Pangaea, was built with three phases, primarily for the purpose of interacting with the Harmony network. Within the first 24 hours, 138 Nodes were up & running and there were 1283 Signups across 77 countries with 356 Keys downloaded.
The great success of this atypical experimental blockchain zone juxtaposes the meaning of the word "pangaea", a name given to the earth’s first supercontinent, which takes one back to a time when our planet was one, to the core characteristic of the Harmony blockchain, the ability to truly harmonize “decentralization, security and scalability”, solving efficiently the trilemma, reaching a consensus and making them seem as ONE.
For more information on harmony,
https://harmony.one/
https://harmony.one/pdf/whitepaper.pdf
https://medium.com/harmony-one
https://t.me/harmony_one
https://twitter.com/harmonyprotocol