In addition to scalability and privacy, what other application potential does ZKP have in the metaverse?

Original Title: 《Zero Knowledge Proofs and the Metaverse》

Original Author: Elan Neiger

Compiled by: Qianwen, ChainCatcher

In the first week of December 2022, the term "Metaverse" was chosen as the Oxford English Dictionary's word of the year, ranking second. In this vocabulary competition, over 300,000 people voted for words rich in long-lasting cultural significance to reflect the social atmosphere and public sentiment of the past year.

"Goblin Mode" (editor's note: literally translated as "Goblin Mode," referring to "self-indulgent, lazy, messy, or greedy behavior") won first place, which more explains the post-pandemic social atmosphere and the state of the surveyed population, rather than providing insights into global technological trends. Today, mainstream companies and celebrities, from Microsoft to Disney, from singer Elton John to rapper Snoop Dogg, have recognized the Metaverse as the next stage of the internet revolution and are making corresponding plans.

Mathew Ball defines the Metaverse in his book as "a massive, interoperable, real-time rendered network of 3D virtual worlds that can be simultaneously and persistently experienced by a practically unlimited number of users, providing a sense of presence with continuity across data such as identity, history, rights, items, communication, and payments."

Perhaps influenced by the shutdown of activities, enforced lockdowns, and social distancing during the pandemic in 2020, interest in collective virtual shared spaces has exploded, with over 500 companies claiming to be developing the Metaverse.

Although this widespread interest in the Metaverse has only recently emerged, the concept was invented earlier, with fictional works like "Snow Crash" and "Ready Player One" describing the Metaverse. One of the world's largest tech companies, Facebook, changed its name to Meta in 2021, intending to fully enter the Metaverse, marking the official emergence of the Metaverse concept as a trend of the times.

Clearly, due to a series of practical reasons, including limitations in networking, computing power, and interoperability standards, the Metaverse described by Ball has not yet become a reality. A fully realized Metaverse will ultimately protect data privacy, allow for necessary scalability, and enable participants to traverse the digital world with 3D avatars, digital assets, and various rights.

Despite numerous limitations at present, many stakeholders believe that the concept and demand for such virtual spaces will continue to grow. A mid-2022 survey by McKinsey of over 3,400 consumers and executives estimated that the Metaverse could reach a market value of $5 trillion by 2030. For many futurists, the Metaverse is envisioned as a parallel world for human leisure, labor, and existence.

Zero Knowledge Proofs

Zero Knowledge Proofs (ZKP) is another widely recognized term. With the zero-knowledge industry booming over the next 12 months, this term may win the "Word of the Year" in next year's Oxford English Dictionary.

The concept of zero knowledge was invented by three researchers at MIT in the 1980s, first described in their academic paper “The Knowledge Complexity of Interactive Proof Systems”.

Until the mid-2010s, zero-knowledge proofs were merely a term for a branch of cryptography, considered too theoretical and costly for practical applications. This situation has begun to change, largely thanks to companies and protocols in the cryptocurrency and blockchain space, collectively referred to as Web3.

A zero-knowledge proof is a protocol that allows one party, the "prover" (i.e., an individual or application connected to the network), to prove to another party, the "verifier," that they know certain information without revealing any details about that information. The key part is the origin of the "zero knowledge" concept, which means that no information other than the proof of knowledge is disclosed to the verifier.

Advancements in computing hardware, algorithms, and software have made ZKP more accessible than in its earlier purely theoretical era.

While there are many types of zero-knowledge proofs, all of their computations rely on processing large amounts of mathematical primitives in some combination, including multi-scalar multiplication (MSM), number-theoretic transforms (NTT), and hash functions.

Putting aside the mathematics, ZKP is a method of proving what you know, own, or have done without revealing any information about that item. ZKP has the potential to revolutionize several industries, particularly those requiring the sharing of private information online. It also allows for "yes/no" answers to complex questions involving private data.

Today, the zero-knowledge proof industry is dominated by companies in the Web3 space, with ZKP being developed and used in various use cases. For blockchain and the Metaverse, ZKP has two fundamental applications: scalability and privacy.

Web3, Metaverse, and ZKP

We can roughly summarize the history of internet development as:

• Web1: "Read-only" internet
• Web2: "Read-write" internet
• Web3: "Decentralized, user-owned" internet

Web2 is the most widely used iteration of the internet today. Web2 relies on centralized parties to gain access and content, meaning users do not own their data, and nearly every online interaction depends on another party to host their content, provide services, or store user information, assets, and value.

Web3 is a blockchain-based internet that emphasizes self-custody of digital assets and data. Users own their content and have control over their internet usage. The downside of Web3 is that almost all blockchains are transparent, with their ledgers being public data. The mechanisms that provide transparency to users also make privacy nearly non-existent.

Both the Metaverse and Web3 can be seen as successors to Web2. While the core of the Metaverse does not require blockchain, many interrelated technologies, including ownership of digital assets, will be utilized within the Metaverse, and the Metaverse economy will almost certainly be realized through digital currencies and NFTs.

Zero-knowledge proofs can facilitate private transactions in the Metaverse and blockchain, addressing the issues of open and transparent ledgers unique to Web3 while ensuring data privacy in the Metaverse. For example, users can provide ZKP to prove they have sufficient funds to complete a transaction with another entity without disclosing their account balance or transaction history.

When interacting with blockchains or using virtual identities in the Metaverse, zero-knowledge proofs can also enable the creation of anonymous accounts. Through zero-knowledge proofs, users can prove they are the owners of an account without revealing their identity or other personal information.

Additionally, zero-knowledge proofs can enable private communication. Both parties can use zero-knowledge proofs to demonstrate they are the intended recipients of information without disclosing the content of that information.

Both blockchain and the Metaverse rely on advancements in scalability. The space of blockchains is limited because they are designed to store data in a decentralized and distributed manner, with each network participant storing a copy of the entire blockchain. Therefore, the amount of data that can be stored on a blockchain is limited by the available storage space on the computers of network participants. Similarly, the Metaverse also requires a scalability solution to connect the many worlds and metaverses that make up the entire Metaverse.

Zero-knowledge proofs address the scalability issue of blockchains by allowing computations to occur in untrusted environments, as long as their solutions are placed on-chain and proven with ZKP that the computations were completed according to the rules of the blockchain. ZKP can achieve the same effect for the Metaverse, allowing Metaverse processing systems to delegate their computations to trusted environments and verify the accuracy of their results upon return.

Some aspects of Web3 already resemble the Metaverse. Concepts and structures like decentralized autonomous organizations (DAOs) facilitated by smart contracts give like-minded individuals wishing to join cooperative organizations transparent voting rights, ownership stakes, and digital sovereignty.

NFTs ensure that unique digital items are recorded and traded on the blockchain, with users of the accounts holding the NFTs retaining full ownership and control over them. NFTs may soon be used in the Metaverse to trade identities or items, such as identity skins, weapons, and clothing, or even access special events or areas, functioning as digital tickets.

Blockchain games utilize Web3 technologies like cryptocurrencies and NFTs, allowing players to buy, sell, or trade in-game assets, securely and transparently owning game assets.

A recent report predicts that the blockchain gaming market will reach $65.7 billion by 2027, up from $4.6 billion in 2022. The new investments and funding in blockchain gaming in 2021 and 2022 are considered the core driving forces behind this expected market growth.

Web3, the companies building Web3, and the tools enabling Web3 are likely to become the foundation for many protocols, facilitating the realization of an open, interconnected Metaverse. Similarly, the internet communication protocols that enable Web2 and Web3 may achieve scalability to establish global standards and protocol networks, managing long-term interoperable connections between three-dimensional worlds.

The Zero Knowledge Revolution

Accessible zero knowledge has the potential to radically transform several industries, some of which are related to the realization of a free and open Metaverse.

• Identity: People can verify their identity online to third parties, including service providers and governments, without taking on risks.
• Finance: Financial exchanges can verify users' creditworthiness without disclosing confidential and proprietary information.
• Voting: Voting in electronic elections can be verified while protecting voter privacy, ensuring election results cannot be tampered with.
• Cybersecurity: Users can log into platforms without revealing passwords to centralized verifiers.
• Anonymous Ownership: Digital assets, currencies, and other properties can be owned without disclosing the owner's identity.
• Machine Learning: Allows owners of machine learning algorithms to persuade others of the model's results without revealing any information about the machine learning model itself.
• Data Integrity: ZKP can prove the authenticity of images, videos, and datasets, helping to combat misinformation.

The Role of ZKP in the Metaverse

Currently, integrated virtual world platforms (IVWPs), such as "Fortnite," "Roblox," and "Minecraft," offer the closest experiences to the Metaverse. These IVWPs are the three largest virtual world platforms today, each with tens of millions of daily active players. However, due to the closed nature of their ecosystems, these games can be considered "metaverses" rather than the Metaverse.

Multiplayer games operate in two ways:

• Client-server (most games today, including "Fortnite," "Roblox," and "Minecraft").
• Peer-to-peer

The common client-server architecture requires the server to act as a centralized, authoritative service provider. Each player sends information to the server, which shares that information with all other players in the game.

The game design of the client-server model has several disadvantages that hinder its application in the Metaverse:

• Ownership: The server owns and maintains all assets in the game.
• Expenditure: Many powerful servers are needed to run complex multiplayer game engines.
• Scalability: There is a single relay point between the server and players, creating a scalability bottleneck as more players join the game.
• Privacy: The server is an untrusted third party that has knowledge of each player's actions.

Peer-to-peer game architecture addresses some of these issues but introduces another problem: cheating. Players can provide false information about their status in the game to circumvent the rules.

The Role of Zero Knowledge Proofs:

• ZKP can provide publicly verifiable proof for every action they take, signaling to all parties that the action complies with game rules.
• ZKP can also be used to prove ownership of digital assets in the game, eliminating the need for a server.
• Finally, ZKP can solve the scalability issue of games by allowing some actions or movements to be verified in the proof, reducing computational costs and enabling more players to participate in the game.

Introducing zero-knowledge proofs into peer-to-peer games could make them a core concept of the Metaverse, eliminating the need for expensive centralized servers and significantly reducing costs. This improvement allows for more participants in shared virtual spaces, with everyone acting as a server, verifying other players' actions with publicly verifiable ZKP.

By definition, the Metaverse will only be considered a "Metaverse" when it can support a large number of users experiencing the same events at the same time and in the same virtual location. While this vision of future game architecture in the Metaverse requires processing many ZKPs per second, advancements in zero-knowledge hardware are making these realities imminent.

Source: https://youtu.be/F-6jtETFkjg

Reflections on the Metaverse

Philosophically, the Metaverse can be likened to the ultimate expression of the three principles written by British philosopher John Locke in his 1689 work "Two Treatises of Government," which also form the legal foundation of the U.S. Constitution and other Western governments: life, liberty, and property.

While these concepts exist in the physical world, they are constrained by the realities of that world. Today, humanity lives in a material world, governed by natural laws that can broadly be described as physics. In the Metaverse, there are no physical limitations.

This raises the question of whether humans truly own and control their lives. If we violate social rules, the government can arrest us, or even take our lives for serious offenses. In the digital space, there is currently no offense that would cause a wrongdoer to lose their freedom in real life, unless a player is kicked out of the virtual world.

Liberty refers to the freedom to do or not do something. In the Western world, people have a certain degree of freedom. However, they are also constrained by laws and physical rules. For instance, without the support of external objects, we cannot live freely—most people need to work to make a living. Even participating in Metaverse games requires initial funding.

In the digital realm of the Metaverse, we will not be bound by social or physical laws. We will be able to experience infinite space and time, as there are no limits to the number of travels in the digital realm, and participants in the Metaverse can instantly reach any digital domain they wish to visit.

Broadly speaking, property refers to items. Humans must acquire and spend money to obtain items. While we can "own" items, we can only control certain aspects of our property. Laws are enforced by governments and police to protect property. Neglecting taxes and insurance can lead to the loss of your property. At the same time, fiat currency is controlled by the government, which may introduce further instability over time.

Zero-knowledge proofs can enhance another foundational structure of digital life: truth.

With zero-knowledge proofs, individuals can ensure their truth—identity, money, property, and freedom—by holding their private keys. Truth is the ultimate sovereign, as the universe is defined by it.

If a utopia does exist, it is unlikely to exist in physical space. When we think of the Metaverse, we tend to view it as a place. However, it is more likely to be an era when immersive digital worlds become the primary mode of our lives, and our beliefs in life, liberty, property, and truth can be fully realized.