Future Development Trends and Key Technologies of Cross-Chain Services

In recent years, the blockchain ecosystem has shown diversified development, with various independent public chains and Ethereum Layer 2 emerging one after another. Different chains have their own advantages in terms of security, transaction costs, processing speed, as well as developer and user communities, making it common for users to switch between multiple chains. Compared to the Ethereum mainnet, Layer 2 and other independent public chains typically offer lower fees and faster transaction speeds. Therefore, users inevitably need to use cross-chain bridges to reduce costs or utilize high-quality applications on other chains.

A cross-chain bridge can be likened to an "armored car," and its security is crucial. Every stage, from design and production to operation, must be error-free. However, many existing cross-chain solutions have more or less architectural design flaws, code vulnerabilities, or rely on specific trust assumptions in certain stages, all of which significantly reduce the security of cross-chain bridges.

As a bridge connecting various public chains, cross-chain technology not only addresses the issue of fragmented liquidity but also serves as an important solution for asset cross-chain transfer. However, users' needs for cross-chain go far beyond this. In the Web3.0 multi-chain ecosystem, users expect to achieve seamless interaction of assets and data with all mainstream public chains through a single application, without the need to frequently switch wallets and networks.

In the current landscape of "one dominant and many strong" public chains, what users truly need is a more secure, more universal, and more user-friendly cross-chain communication protocol.

Mainstream Cross-Chain Communication Modes

Native Verification Model

This model enables inter-chain communication by running lightweight clients in the virtual machines of the source and target chains, with the help of relayers. Its characteristic is that it does not require the operation of an intermediate chain. Some projects use zero-knowledge proof technology to eliminate trust assumptions that exist in certain solutions.

external verification mode

This model relies on one or more validators to monitor specific addresses on the source chain. When a user sends assets to that address, the assets are temporarily locked. After the validators verify the information and reach a consensus, the corresponding assets are generated on the target chain. However, this model has a "trust assumption" and is vulnerable to asset theft due to "single points of failure" or "local failures."

Local Verification Mode

Local verification is a peer-to-peer liquidity network where each node acts as a "router" providing the original assets of the target chain rather than derivative assets. However, this model lacks universality and is only applicable for asset cross-chain transfers, making it impossible to achieve inter-chain transfer of universal information and data.

upstream chain model

This model requires applications to deploy smart contracts on a specific chain to achieve message replication and state updates. Its main drawback on the commercial level is that the chain will compete with all Layer 1 public chains rather than collaborate, vying for application deployment.

zkRelayer: The Key to Inter-Chain Communication

An outstanding cross-chain communication solution should possess the following characteristics:

1. Trustless assumption, secure
2. Permissionless, decentralized
3. Universality
4. Scalability
5. High efficiency, low cost

However, not all cross-chain solutions can meet these conditions. Among them, the "trustless assumption" is the most urgent and important. Early external verification models used intermediary chains to solve communication issues between public chains, but this method is cumbersome and struggles to address the communication challenges between EVM and non-EVM, as well as PoW and PoS chains. At the same time, the intermediary chains themselves pose centralization risks, making it difficult to achieve decentralized security and trustless security.

Some solutions in the native verification model emphasize the roles of the sender and receiver clients, but still require users to trust that the relayers and oracles will not collude maliciously, as well as the honesty of the protocol itself in the relaying process. This means they still cannot achieve complete trustless security.

zkRelayer is an innovative zero-knowledge proof relay for cross-chain communication. Its advantage lies in the fact that users do not need to trust any external third party or the protocol itself. As long as the mathematical and cryptographic proof processes are complete and correct, this system can gain public recognition. Users trust "truth" rather than specific individuals or organizations. Throughout the communication link (Chain A → Sender → zkRelayer → ZK Verifier → Receiver → Chain B), the position of zkRelayer will transcend that of the light clients of the sender and receiver, becoming the core of the solution.

The core components of zkRelayer include the ZK Prover and Message Aggregator. Some projects adopt zero-knowledge proof methods that feature speed, recursion, and trustlessness, with linear proof times and sub-linear verification times reaching theoretical limits. This technology is applied in relays for cross-chain communication, ensuring that the entire communication process is trustless, efficient, and low-cost.

zkRelayer is expected to become a key technology for opening a new chapter in cross-chain communication. With its support, cross-chain communication will usher in a new stage of development, laying the foundation for further prosperity of the Web3 ecosystem.