Yellowpaper Summary丨MultiVAC: The World’s First All-dimensional Sharding Solution

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Dear MultiVAC community members and blockchain enthusiasts,

We are proud to announce that MultiVAC, the world’s first fully sharded public blockchain, has published its Sharding Yellowpaper on 26 September at 14:00 (UTC+8). This publication signifies an important milestone for MultiVAC since the publication of our whitepaper: MultiVAC has stepped far beyond the cradle of design onto the launchpad, and is ready to be launched into space.

MultiVAC’s Yellowpaper is the result of our core algorithm team’s months of effort into exploring base-layer blockchain architectures and verification mechanisms. In light of our detailed and comprehensive implementation plan and multiple technological innovations, we are very proud of our dedicated MultiVAC engineers and are extremely grateful to them for their hard work over these past few months. We are gradually moving towards making our technical solutions open-sourced and contributable by all.

MultiVAC is a next-generation public blockchain platform designed for complex and large-scale decentralized applications, developing the world’s first fast, efficient, and fully sharded blockchain with parallelization for computation, storage and transmission. Our Yellowpaper exemplifies MultiVAC’s innovative sharding solution, emphasizing MultiVAC’s unique edge account, storage and transmission sharding. If you are interested in MultiVAC’s technical solutions, please do take a glance at the summary below:

MultiVAC Sharding At A Glance

Sharding is essentially the division of the network into smaller fragments and managing transactions from those fragments in parallel, so as to increase the system’s overall throughput. Within each shard, there are a certain number of miners that participate in consensus. If miners know that they were to be selected for consensus beforehand, there exists a certain risk for collusion by miners to undermine the system. We thus require a mechanism to find suitable miners without leaking their identities beforehand.

Let’s now take a look at MultiVAC’s unique miner selection methodology.MultiVAC’s Verifiable Random Function (VRF) miner selection makes the result of miner selection entirely random and uncontrollable, which in turn, prevents the early revelation of miner selection, ensuring the reliability of results. Bitcoin utilizes the Proof of Work (POW) algorithm to select miners. Although this mechanism can guarantee random selection to a certain extent, it consumes an incredible amount of electricity and wastes an immense amount of resources. MultiVAC’s VRF, on the other hand, incorporates both mathematical rigour and mathematical elegance without the wasteful expenditure of electricity, fully guaranteeing the randomness of our selection results while lowering transmission costs and enhancing efficiency. Algorand, Dfinity, and Cardano’s Ouroboros Praos all use or will use VRF-based consensus solutions, a testament to the method’s power and versatility.

Einstein once remarked that mathematics has earned the respect of many because of its reliability and indisputability. A firm believer in this statement, MultiVAC strives to maximize the benefits that mathematical elegance can provide.

Through an innovative POS mechanism, MultiVAC effectively prevents Sybil attacks, ensuring the smooth functioning of our network. As mentioned in our Yellowpaper, the POS mechanism requires each node to turn in a pre-determined deposit in order to be selected into a shard as a miner; the higher the value of deposit placed, the more likely one is selected. It is worthy to note that after shard selection, each miner has an equal say within the shard in the block voting process. Some of you may wonder how one can increase the mining profits in such a mechanism. The answer is simple; by increasing the amount of deposit placed, you can become a miner within multiple shards, and thus, increase your overall revenue.

Dynamic Miner Sharding Flow Diagram

By utilizing the innovative POS+VRF miner selection mechanism, MultiVAC prevents miners with high stake deposits from dominating a shard with high voting power. In turn, this fully ensures that miner selection is democratic and fair, allowing ordinary miners to gain access to block production and enhancing the stability and safety of the network. MultiVAC employs a dynamic re-sharding mechanism to ensure system security. The system adjusts the combination of miners allocate to each shard every few minutes. As the composition of miners within each shard constantly changes, hacking a shard is no easier than hacking the entire network. Finally, MultiVAC assesses the transaction volume of each shard to make sure that the shard is balanced. If the transaction volume is too high within one shard, MultiVAC will dynamically split it into two independent shards, increasing its the transaction speed and ensuring that no part of the network is clogged for any length of time.

What do you think of our dynamic sharding design?

Account Sharding

It is inevitable that challenges arise when we use sharding technologies to tackle scalability, and such challenges include how transactions are distributed among shards,. In particular, cross-sharding design is a wicked problem in sharding solutions, because most implementations of sharding require a huge number of cross-shard transmissions that make them extremely unwieldy. In light of this, MultiVAC has pioneered and adopted the world’s first asynchronous transmission model; through transaction shards that are based on payment addresses, MultiVAC makes it possible for all transactions to be confirmed by account in a single location, preventing double spending and complex cross-shard communication.

Perhaps it’s easier to explain MultiVAC’s thought process with the following example: Suppose there are two users, Lily and Ava, and Lily has to pay Ava 10MTV. For simplicity, let us assume that the network only consists of two shards, which we denote as A and B. Now, it is obvious that one transaction cannot be simultaneously carried out in two shards, so the issue at stake is whether Lily’s transaction should be distributed to A or B for processing.

Here, the easiest method is to run hash algorithms for all of Lily’s transactions. If the hash function ends with ‘0’, then the transaction is carried out by A, and if the function ends with ‘1’, it is carried out by B. Nevertheless, another problem may arise if Lily only has 10MTV in her account, and on top of paying Ava 10MTV, she decides to give Ben 10MTV at the same time. As there is a 50% probability that the two transactions will not be processed by the same shard, there is a high chance of double payment. In order to prevent double payments, inter-shard communication is required to require only one of the transactions to go through, and this leads to high costs and low transaction efficiency. Thus, instead of distributing transactions according to hash functions, MultiVAC assesses the last digit of the sender’s address to distribute transactions, enabling MultiVAC to process all of Lily’s transactions within the same shard.

Storage Sharding

As we know, besides computation, safe and effective storage is also key to a safe and robust base-layer infrastructure. As our Yellowpaper notes, MultiVAC innovatively introduces a division of labor between miner nodes and storage nodes. With most of the data being stored by storage nodes and only verification data stored by miners, MultiVAC lowers the hardware requirements to be a system miner, allowing a large number of ordinary nodes machines to participate in the MultiVAC ecosystem. These machines all take part in consensus and validation, consequently making the MultiVAC ecosystem even safer and more decentralized. To put it another way, if you want to be part of the MultiVAC ecosystem, simply participate in mining and receive considerable revenues with just an ordinary personal computer. What more could you want?

Block Generation Flow Diagram

MultiVAC supports data extraction and indexing based on Hashes and Merkle Roots. MultiVAC uses a Merkle Root-based data storage, supporting indexing, segmenting, and comprehensive verification of data, and also allowing for flexible and efficient updates. Say you want to add your favorite movie to a MultiVAC-based DApp. A hash-based storage system would only allow you to search and index the whole movie, whereas a Merkle Root-based storage system like MultiVAC also enables saving, extracting and updating any part of the movie. Therefore, if there was one part of the movie that you would want to re-watch, our unique design allows you to do so quickly and easily.

It is worth noting that storage within the MultiVAC system is only provided as a base-layer service, similar to the internet infrastructure that all networks run on. Storage nodes do not have any ability to manipulate or generate data themselves and can only serve storage functions used by higher levels. All modifications to data must result from consensus, and all usages of data are first verified by the checking of cryptographic proofs. Moreover, all data is greatly duplicated and contain signatures of users’ private keys, making the data impossible to falsify or corrupt.

Transmission Sharding

When blockchain technology eventually becomes a key part of our daily lives, the volume of data that blockchains will process each day will be massive. According to estimates, when public blockchain systems are required to support millions of transactions per second (TPS), broadcasting block information to entire networks will take up at least 8Gbps of bandwidth. Obviously, such large network bandwidth cannot be supported by ordinary home computers. This in turn creates a barrier to node creation, which increases the risk of monopoly and node centralization and decreases transmission efficiency.

MultiVAC adopts a new in-shard broadcasting mechanism that confines data transmission within shards, and in turn, lowers the transmission pressure within the network and speeds up transactions. Once a miner completes block confirmation, information about the new block is broadcasted within the shard and only block headers are broadcasted to the entire system. As each header only takes up 400 bytes of space, even when MultiVAC reaches a TPS exceeding a million, it only requires 5–20Mbps of network bandwidth. This solution greatly reduces the hardware requirements on nodes, conserves transmission resources, and prevents the occurrence of network transmission storms that clog the network.

MultiVAC manages account state based on the classic UTXO transaction model, providing a capable solution to nasty cross-shard bottlenecks. The UTXO transaction model is a great invention. Invented and first applied to Bitcoin by Satoshi Nakamoto, UTXO abandons the concept of accounts and records Bitcoin assets owned by corresponding transaction addresses through the information of each individual transaction. Suppose you received three Bitcoin transactions of one, two and five Bitcoins respectively. Now, you have three transaction outputs (UTXO) that are not paid out yet. These three UTXO are like three coins, and each UTXO cannot be spent in smaller units. In other words, if you want to buy a pizza that is priced at four Bitcoins, you have to deduct five Bitcoins from your account first and return one remaining Bitcoin to your address. Therefore, if someone wants to verify your Bitcoin asset, he or she only needs to check your previous transaction records, as each input and output are traceable and should balance out. This is the UTXO transaction model.

In the MultiVAC system, each UTXO transaction input is either one or multiple confirmed transactions; no data exchange is required between the two involved parties. Since the same shard always processes an account’s transaction, shards never have to perform write operations on other shards, allowing inter-shard communication to be read-only. This drastically reduces the need for cross-shard communication. Sharding projects like Elastico and Zilliqa, while performing sharding, adopt a unified common ledger that all shards must sync with, incurring a high data syncing cost to maintain the common ledger. MultiVAC lowers such syncing costs with a much more fundamental and base-layer solution.

Concluding Remarks

Blockchain experts and scholars share the view that sharding is the only practical, manageable, and base-layer methodology to scale a blockchain to industrial-level capacity, while still maintaining a decentralized network with open participation. As the pioneer of the world’s fully-sharded blockchain solution that can fulfill the needs of the real economy, MultiVAC is immensely proud of its accomplishments thus far. This MultiVAC Yellowpaper aims to help more blockchain enthusiasts and MultiVAC community members better understand MultiVAC’s unique offerings and technological innovations, realizing a day when blockchain can create real value for us all.

In the future, MultiVAC will continue to build on our technological achievements, translate our innovative ideas into reality, and develop our ecosystem. We strive to make blockchain technology available to every household, and will play a key role in constructing a society characterized by harmony, security and trust.

Finally, the MultiVAC team wishes to express our heartfelt gratitude to all our community members and business partners. Your support has been essential to our achievements thus far and we could not thank you enough.

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