"All roads lead to Rome" — — Building a trustless traffic network

Source: kokii.eth X Account

Author: kokii.eth

Compiled by: Summer Ventures

Imagine living in an internet era where: friends in Singapore and the US have to deal with different network protocols to exchange messages; players in Korea and the UK face severe latency while competing in online gaming teams; transferring money from Brazil to Hong Kong requires multiple currency exchanges to complete the settlement --- --- this is a nightmarish experience. Fortunately, we do not have to overcome these difficulties today: thanks to communication protocols like TCP/IP, users on Facebook can share and interact with others at any time, generating billions of likes every day; due to low-latency UDP data exchange protocols, "League of Legends" can handle billions of commands and state synchronization requests daily; because of interbank protocols like SWIFT, payment institutions like Mastercard and Alipay can exceed 1 billion daily transactions, allowing users to complete transactions with a simple mobile app; and because of cloud service protocols, ChatGPT can handle over 10 million tasks every day.

Application scenarios are the driving force behind internet development. It is the demand and pain points that necessitate the establishment of simpler and more user-friendly interfaces and functions, hiding the complex technologies and integrating different protocols behind the scenes. Users engaging in high-frequency scenarios such as social networking, payments, gaming, and other financial applications do not need to consider the underlying infrastructure. This is "protocol abstraction," which fundamentally achieves user interconnectivity across different regions, ecosystems, and infrastructures, creating an efficient traffic network.

Web3 is still in a primitive era without a unified network protocol, or in other words, without an interoperable traffic network. As the ecosystem pushes for large-scale applications, it must achieve "protocol abstraction" to provide users with a smooth experience and offer applications efficient liquidity. If the traffic pool of the internet comes from users, then the traffic network of Web3 is more based on assets, data, and protocols.

Current State of Web3: A "Fragmented" Network

Compared to the internet, the technology stack of Web3 is inevitably becoming decentralized and complex: layers of networks, Rollups, sidechains, application chains, etc., are facing a situation of "rise and fall" after the initial "hundred schools of thought contending." The fundamental reason is that blockchain technology is still in a relatively early stage, lacking unified technical standards and traffic infrastructure. New blockchain projects continue to emerge to explore new application scenarios and technical possibilities, but each application has its own design philosophy and business considerations, gradually evolving into a situation where leading projects tend to rely on traffic and build their own infrastructure.

This decentralization and diversification have brought about a complexity boom, reflecting the essence of blockchain decentralization, but it has also increasingly fragmented users, developers, and liquidity --- ---

User transactions require interaction across different chains and middleware, facing high entry barriers and asset security risks:

• Entry Barrier: Making a simple interaction requires choosing a public chain protocol and the corresponding wallet, and while assets are cross-chain, users also need to obtain the transaction fees (Gas Fee) for the target chain first;
• Transaction Friction: Users need to manually manage multiple wallets, addresses, and private keys across multiple chains;
• Security Risks: Each transaction requires multiple signatures for authorization, constantly facing risks from phishing attacks and/or protocol failures, while the assets themselves do not receive the same protection as in traditional banking networks.

For developers, they need to prioritize ecosystem alignment and cannot focus on product design and user experience:

• Ecosystem Choice: Balancing permissions across protocol code, developer tools, community activity, and other directions;
• Liquidity Choice: Users and liquidity are dispersed across different ecosystems, but deploying across different ecosystems can dilute the team's focus, leading to liquidity fragmentation and low capital utilization;
• Product Isolation: Products cannot organically combine and switch smoothly with other products.

The current Web3 world presents a funnel for users to enter, with drop-offs occurring at every obstacle in the process. Whether due to excessive operational steps or the requirement for prior knowledge, potential users and developers are continuously filtered out. Despite rapid advancements in infrastructure development, progress in user experience and application layers remains sluggish. Ultimately, only a few applications can withstand such high interaction and development barriers, with the vast majority of active applications concentrated in leading decentralized finance scenarios.

Application-Driven Infrastructure Upgrade: Technical Abstraction

Early Web2 users also had to face complex underlying technologies, but with technological advancements, abstraction allows users to focus only on the front-end interface and interactions. Abstraction encapsulates modules, preventing users and developers from facing a chaotic array of modules and becoming confused.

This abstraction has created conditions for explosive growth in applications --- --- developers can focus on product design and user experience, while users can use applications without barriers; most importantly, any application and user can simultaneously enjoy the ecological interactions and traffic networks of the entire web. Users can quickly establish network connections, complete tasks through graphical interfaces, browse web pages by simply entering URLs in the address bar, and log into any application through unified authentication; application developers can focus on business logic without worrying about underlying browser compatibility and DOM manipulation, while cloud virtual servers have thoroughly connected the underlying infrastructure of all applications (including storage, computing, etc.). The work of focusing on the abstraction of blockchain infrastructure and application experience is just beginning, but Web3 can reuse some of Web2's mature abstraction frameworks, and its development speed may surpass that of the Web2 era.

We believe that to achieve true large-scale applications in Web3, it is necessary to build infrastructure and innovative technologies for super applications and diverse user scenarios, just like the internet. We have observed that the rise and flourishing of many public chain infrastructures are driven by some "super applications" on the user side, such as Binance / Trust Wallet --- BSC, Coinbase --- Base, OKX / OK Wallet --- X Layer, Telegram --- TON, Metamask --- Linea, Tether --- Tron, Axie Infinity --- Ronin, etc.

Chain Abstraction: Hiding Blockchain Complexity

Chain abstraction aims to shield users from the complexities of blockchain technology, presenting only a simple and friendly front-end interface. Its ultimate goal is to seamlessly integrate various modules in a composable manner, creating a smooth experience for developers and users. It will enable end users to browse and use Web3 applications without barriers, without needing to focus on the chains used, cross-chain operations, Gas payments, and other tedious details.

Chain abstraction is not a specific technology but a design philosophy that requires combining various solutions to cover different aspects of user interaction with blockchains. The Access Layer is the front-end interface for users interacting with the blockchain, responsible for providing an intuitive and user-friendly UI and UX for users to interact with multiple chains. The Interface Layer is where users truly connect with applications built on the chain, providing secure and reliable access channels. The Functional Layer connects decentralized applications (Dapps) and blockchains and is key to achieving interoperability (Interoperability) in Web3 across protocols, users, assets, and liquidity.

It seems that multi-chain development is inevitable, and multi-chain communication is key to the functional layer of chain abstraction. Early cross-chain bridges could achieve cross-chain token transfers, but they were cumbersome for users and could only meet asset transfer needs. The ability to transmit messages between chains is crucial for building cross-chain Dapps to enable more complex use cases, facilitate cross-chain governance, token asset interactions, contract calls, and enhance user experience. Currently, there are over 100 bridges connecting various homogenous or heterogeneous chains, rooted in the interoperability trilemma:

• Trustlessness: Equivalent to the security of the underlying blockchain;
• Scalability: The ability to support any kind of asset and any blockchain;
• Universality: The ability to transmit any cross-chain data.

Based on trade-offs of speed, cost, and security, there are many cross-chain communication protocol designs with different architectures, characteristics, and validation methods. The core of multi-chain communication lies in the trust assumptions, how the target chain verifies information from the source chain (e.g., confirming that the required transaction has been completed), and the verification mechanism can be summarized as "who" confirms the transaction:

1. Centralized Model (Centralization): Relies on centralized external validators for verification, usually implemented using multi-signatures.

• Trust Assumption: Entities care about their reputation, so they will not act dishonestly;
• Examples: Centralized exchanges, cross-chain bridges (e.g., Wormhole with only 19 validators), etc.

1. Economic Model (Proof of Stake Economics) built on proof of stake: also implemented with multi-signatures but adds collateral guarantees.

• Trust Assumption: In addition to trusting entities that care about reputation, it also relies on slashing/forfeiting the staker's collateral to increase the cost of malicious actions;
• Examples: PoS has various design schemes, such as L1 implementations based on Cosmos that enable smart contract functionality (Axelar, Zetachain), secured by re-staked ETH (Omni Network), etc.

1. Game Theory Model (Multiparites under Game Theory): In addition to adding PoS guarantees, it decomposes the verification process into two (or more) independent tasks completed by two (or more) independent entities, ensuring security by suppressing coordination between entities.

• Trust Assumption: In addition to trusting external entities that care about their reputation and economic incentives, it also relies on different entities operating independently and not colluding;
• Examples: Delegating cross-chain message passing and verification to different roles, such as Layerzero (Oracle + Relayer); Connext (optimistic verification, introducing a Watchers reporting mechanism).

4. Mathematical Proof Model (Math Proof): Utilizes concise mathematical proofs for verification on the target chain.

• Trust Assumption: Cryptographic proof, relying on the security of both the target chain and the source chain;
• Examples: Hash time lock (BTC Lightning Network), light node verification (Cosmos IBC), ZK-Rollup bridges, etc.

Security is the foundation of user experience, but it is often sacrificed for scalability and universality. Theoretically, we hope to rely solely on mathematical verification to achieve high security, but such cross-chain communication protocols are difficult to scale for widespread deployment. However, frequent hacking incidents have reaffirmed the importance of security. Developers should provide security guarantees at the underlying architecture level and strive to solve issues of speed, cost, and ecosystem fragmentation, rather than simply shifting risks onto users.

The Fundamental Layer provides blockchain technology at the lowest level, primarily involving how to design blockchain architecture to optimize stability, security, cost, and speed. After the relentless efforts of engineers, we believe that the performance of current monolithic chains has reached a sufficiently usable level, prompting some solutions to attempt to link multiple chains from the block construction level. The core of this layer of abstraction is scalability, and the directions for building at this level include:

• Shared Sequencer: Each L1/Rollup needs to maintain its own Sequencer, responsible for collecting transactions, packaging them, and reaching consensus/submitting them to the main chain. In a Shared Sequencer architecture, multiple chains share a set of Sequencers, supporting interoperability. Due to the consensus mechanisms of heterogeneous chains, the block structures vary significantly, and current Shared Sequencers focus on serving Ethereum Rollups (Espresso); Rome utilizes Solana as the execution layer for Shared Sequencer to achieve cross-chain liquidity between Solana and Ethereum Rollups.
• Aggregated Proofs: Unifying Rollup cross-chain bridge contracts on L1, constructing a dependency graph for different Rollup blocks at the aggregation layer, and using a zero-knowledge proof to aggregate cross-chain information from all chains to achieve atomic interoperability. Polygon AggLayer provides cross-chain infrastructure for L2 built using the Polygon CDK, aggregating ZK proofs from all connected Rollups and uploading them to the Ethereum mainnet.

Although different project teams share the same goal of providing users with a simple and intuitive way to manage multi-chain applications, they exhibit significant differences in focus and implementation paths. This stems from their unique technical challenges, functional requirements, cost-benefit trade-offs, and market considerations.

Users often express their needs straightforwardly, such as asking for "faster horses," but their real need is "to reach their destination faster." The advent of the automobile addressed this need, but its success relied on the combined push of the industrial revolution, infrastructure development, and legal environments. Therefore, solutions that truly address problems need to start from first principles, focusing on optimizing the lowest layers, and integrating support and efforts from multiple aspects to stack upwards, in order to truly land and achieve success.

Thus, we believe that the stack design of chain abstraction needs to follow these key points:

1. Prioritize Security: All solutions designed at the expense of security are merely stopgap measures that cannot reach the endpoint of achieving large-scale and substantial on-chain applications, and decentralization is the most important consideration for the security of blockchain protocols;
2. The stack should build from the bottom up starting from the Fundamental Layer: The upper layers of the stack depend on the design of the lower layers, and transitional solutions will be replaced as infrastructure iterates;
3. Aggregation of technologies at the same level: Due to the continuous iteration of infrastructure, different levels such as wallets, liquidity, and cross-chain communication protocols need further aggregation to provide simple solutions.

Liquidity Network Based on Chain Abstraction: Cycle Network

Based on the above points, Cycle Network uses ZK-Rollup technology to build a secure underlying communication infrastructure, achieving a seamless integrated experience of a full-chain ledger while greatly ensuring universality and scalability without sacrificing security. The name Cycle symbolizes the cyclical process of infrastructure development, ultimately leading to abstraction and integration, with application development becoming the core again. Cycle is accelerating this process, defining a new full-chain ledger paradigm for developers and users, rescuing them from the current fragmentation caused by multiple chains.

Imagine a future where users can manage all their assets within a single account (or more specifically, within a wallet address on a specific chain), and can pay the underlying chain's gas fees with any number of mainstream assets without awareness, interacting with applications across different chains, enjoying a smooth experience akin to Web2.

Developers can extend abstractions upward based on the SDK provided by Cycle, developing various applications based on the full chain. They can easily achieve asset circulation across multiple chains within their applications without deploying contracts separately on multiple chains, serving users across different chains.

Technical Architecture

To pursue extreme security and trustlessness, Cycle's cross-chain communication essentially deploys itself as a ZK-Rollup for all connected chains. The ZK-Rollup bridge is trustless and bi-directionally verified, and Cycle extends this feature from Ethereum to all external networks, simplifying state synchronization issues in distributed systems by anchoring multi-chain states with Cycle states through aggregated Sequencers, creating a decentralized super ledger and liquidity center for all blockchains.

The overall architecture of Cycle Network mainly consists of three components:

1. Cycle Layer is the core layer of Cycle, providing unified multi-chain state management as a ZK-Rollup for the Security Layer and Extend Layer. Core modules include:

• Verifiable Aggregate Sequencer is the core module for packaging Cycle transactions, relying on the Omni State Channel Indexer (OSCI) deployed on Ethereum to package all transactions;
• Omni-Ledger is the global ledger on Cycle, storing all transaction states on Cycle Network, including cross-chain transactions and internal transactions of the Cycle Layer;

2. Extend Layer connects other blockchains beyond Ethereum, including all L2s and other heterogeneous L1s (such as Solana, TON, and Bitcoin). Core modules include:

• Bridging contracts used to lock original chain assets in Rollup contracts;
• ZK Verifier verifies the ZK proofs generated by Cycle, proving the legitimacy of the Rollup state;
• Extend DA provides data availability, ensuring the immutability and security of data.

3. Security Layer is the blockchain layer that ensures the security of transaction states, selecting Ethereum as the most secure programmable network. Core modules include:

• Omni State Channel Indexer (OSCI) is a decentralized multi-chain indexer that records the rules for Sequencer packaging multi-chain Rollin and Rollout transactions;
• The Security Layer, as a special Extend Layer, also includes bridging contracts, ZK Verifier, and DA modules.

Cross-Chain Communication

The essence of Rollin is that Cycle reads and fixes the state updates of the connected chains through bridging contracts:

• Users initiate Rollin transactions on L1/LE, and the bridging contracts deployed on L1/LE execute the transactions, updating the Merkle tree root that records all cross-chain transactions between the source chain and Cycle, and emit relevant events;
• Cycle receives and records the emitted events, updating the Merkle tree in the bridging contracts when the next Batch is generated, confirming the Rollin transaction on Cycle.

The essence of Rollout is that the connected chains read Cycle's state updates by verifying the ZK Proof submitted by Cycle:

• Users initiate Rollout transactions on Cycle, which packages the transactions and submits them to L1/LE for data availability (DA), executing the transactions and generating ZK Proofs to submit to the bridging contracts on L1/LE for verification;
• Users send confirmation transaction verification proofs to the bridging contracts on L1/LE, which include Rollout metadata and Merkle proofs.

The following case illustrates how to use the Rollin and Rollout interfaces. Alice from Arbitrum transfers 2U to Bob from Optimism through Cycle, and their full-chain account state changes are shown in the upper right corner:

• Initially, Alice holds 5U on Arbitrum, and Bob holds 4U on Optimism, both Rollin into Cycle;
• After Cycle confirms the state update of the bridging contract, Alice and Bob can freely transfer and manage assets across multiple chains, with Alice transferring 2U to Bob;
• Bob Rollouts 3U from Cycle back to Optimism, and after this transaction is verified, he can withdraw the assets on Optimism.

Performance Advantages

By achieving secure full-chain state synchronization, developers can easily integrate their applications with cross-chain functionalities using the SDK and API provided by Cycle Network, retaining maximum flexibility in application design while integrating multi-chain liquidity and application interactivity in the trend of multi-chain and multi-application chains.

• Security: Cycle approaches from the lowest level of block construction, using mathematical proofs to verify cross-chain communication on the target chain, ultimately verifying on Ethereum, without relying on any trusted third parties;
• Scalability: Cycle can serve as a Rollup for any Layer1 blockchain;
• Programmability: Cycle itself is a Turing-complete Rollup, allowing developers to directly deploy full-chain Dapps;
• Low Latency: Built on ZK-Rollup, ensuring instant finality and improving cross-chain communication speed and user experience;
• High Capital Efficiency: No need for wrapping or preparing liquidity pools, real-time burning and minting improve capital efficiency.

Final Goal

Cycle provides application developers with a Core SDK that includes Rollin and Rollout interfaces. Based on the Core SDK, Cycle has also developed application-specific SDKs like Liquid Faucet. Dapps can access liquidity and users across all chains connected to Cycle by integrating these SDKs.

Based on Cycle Network as the foundational layer, components for achieving chain abstraction can be stacked on top:

• Full-Chain Accounts: Cycle has successfully deployed a full-chain yield protocol Piggy Bank, allowing users to create full-chain assets (e.g., PiggyBox) and interact across any network, achieving multi-chain asset aggregation, generation, purchasing, and paying gas fees;
• Liquidity Aggregation: Cycle can issue native tokens on any target chain. Dapps can quickly deploy on Cycle, reaching full-chain liquidity, increasing market depth, enhancing trading opportunities, and reducing trading costs. Liquidity providers integrate their liquidity into Cycle's unified liquidity pool and seamlessly distribute their liquidity across all chains.
• Multi-Chain Gaming/Investment Trading: TapUP is a GameFi on Telegram developed based on Cycle, establishing a full-chain DeFi bot in a gamified manner, allowing users to trade assets from different chains within the game, and in the future, participate in gaming asset trading on TON and other ecosystems on different original chains;
• Other Applications: Cycle can support any scenario requiring full-chain data, such as AI, DePIN, payments, etc.**

The ultimate goal of Cycle Network is to become a trustless liquidity infrastructure for all public chain infrastructures and applications, ensuring asset security, protocol security, and governance security, and to facilitate the mass adoption of over 1 billion users in the Web3 ecosystem.