Cycle Network TCCP: Universal for EVM and Non-EVM chains

The Cross-Chain Message

A cross-chain protocol is a set of rules and procedures that enable communication and interaction between different blockchain networks. The primary purpose of cross-chain protocols is to facilitate interoperability, allowing assets, data, or transactions to be transferred or shared seamlessly between disparate blockchain ecosystems.

Cross-chain protocols are crucial for achieving the vision of a decentralized and interconnected blockchain ecosystem. These protocols can take various forms. Atomic swaps like HTLC ( hash time lock contract ) allow users to exchange cryptocurrencies directly between different blockchains without the need for an intermediary. The protocols based on a bridge facilitate the transfer of assets or data between different blockchains by locking assets on one chain and issuing corresponding tokens or representations on another chain. Some projects, like IBC, TON and XCMP, focus on developing interoperability standards that multiple blockchain networks can adopt to ensure seamless communication and compatibility.

Cycle Network imposes TCCP ( Trustless Cross Chain Protocol ) to support interoperability among separate blockchains or layer2s. TCCP employs a trustless scheme for the highest-level security and efficient. So, why is trustless protocol important? We explain that by comparing it with other cross-chain protocols.

Security Level of Cross-Chain

Security is of paramount importance in cross-chain protocols to protect assets, promote interoperability, maintain trust and reliability, preserve decentralization, and ensure economic stability in the blockchain ecosystem. Based on the security level, cross-chain protocols can be classified into three broad categories: centralized, federated, and trustless.

In centralized cross-chain protocols, there is a central authority or intermediary that facilitates the communication and transfer of assets between different blockchains. Users have to trust this central entity to manage the cross-chain transactions securely.

Cross-chain protocols based on multi signatures or aggregator signatures involve a consortium or federation of multiple entities that cooperate to enable interoperability between blockchains. While they are more decentralized than purely centralized solutions, they still require users to trust the federation members to operate the cross-chain protocol fairly and securely.

Trustless cross-chain protocols aim to achieve interoperability without relying on centralized or federated entities. They typically leverage cryptographic techniques ( like zero-knowledge proof ) and decentralized consensus mechanisms ( like SPV ) to ensure the security and integrity of cross-chain transactions. Users do not need to trust any single entity; instead, they rely on the security guarantees provided by the underlying blockchain protocols.

For highest-level security, the cross-chain protocol prefers the trustless way. For example, some cross-chain protocols utilize SPV to verify whether the cross-chain data has reached an agreement on-chain. However, it is an very gas consuming scheme for the on-chain contracts. To tackle this problem, the zero-knowledge proof emerges as an efficient and secure way, which is also employed by Cycle Network’s TCCP.

TCCP: Trustless Interoperability

Trustless Cross Chain Protocol (TCCP) is a protocol used by Omni Distributed Ledger technology to enable interoperability with other blockchains or layer2s. TCCP consists of two core interfaces, Rollin and Rollout. Rollin is used to transfer assets or messages into the Cycle Network, while Rollout is used to transfer assets and messages out of the Cycle Network. By integrating these interfaces, application developers can securely combine assets and data for omni-chain programming. TCCP ensures trustless two-way communication between different blockchains, allowing for seamless cross-chain transactions.

TCCP ensures trustless cross-chain interoperability and security in Cycle Network through various mechanisms:

• Firstly, TCCP incorporates the Bridge Module, which implements cross-chain transactions, locked asset management, and wrapped asset management. It organizes and records cross-chain messages into a Merkle tree, providing proof of existence. Users can withdraw their assets or execute global state changes by submitting appropriate parameters to the Merkel Proof.
• Secondly, TCCP includes the Verify Module, which verifies the proof submitted by the Prover from the execution layer. This verification process ensures the validity of the Cycle Network’s world state.
• Thirdly, TCCP leverages the ZK Prover Module to construct polynomial constraints that are verified if and only if the execution trace is valid. This zero-knowledge verification enhances the security and privacy of transactions in Cycle Network.
• Additionally, Cycle Network ensures the completeness and security of its data through the Data Availability feature. Raw transaction data is stored on the Security Layer through batch submissions, forming a virtual blockchain. This ensures the immutability and security of Cycle Network’s data.

Overall, TCCP combines these mechanisms to achieve trustless cross-chain communication, secure data storage, and efficient on-chain verification in Cycle Network.

TCCP: universal for EVM and Non-EVM chains

The blockchains based on Ethereum Virtual Machine (EVM) play important roles in the multi-blockchain ecosystem. Therefore, how to interoperate among EVM chains, or between EVM and Non-EVM chains, is an very critical issue to solve. Next, we will talk about some popular cross-chain schemes which aim to interoperate among EVM chains, or between EVM and Non-EVM chains. Moreover, the universal solution, Cycle’s TCCP, whose interoperability is compatible with EVM and Non-EVM chains, is also explained.

Among EVM chains

Among these EVM compatible chains, several cross-chain protocols and solutions have been developed to enable interoperability and asset transfers between different Ethereum-based networks. Some of the notable ones include:

• Wrapped Tokens (WETH). Wrapped tokens are tokens that represent assets from one blockchain network on another blockchain. For example, Wrapped Ether (WETH) is an ERC-20 token that represents Ether (ETH) on the Ethereum blockchain, allowing it to be traded on decentralized exchanges (DEXs) and used in Ethereum-based smart contracts.
• Atomic Swaps: Atomic swaps, like HTLC, allow users to exchange tokens directly between different blockchain networks without the need for intermediaries. Several projects have implemented atomic swap protocols for EVM-compatible chains, enabling trustless and secure token swaps between Ethereum and other compatible networks.
• Cross-Chain Bridges on Layer 2 Solutions: Layer 2 scaling solutions for Ethereum, such as Optimistic Rollups and zk-Rollups, also provide opportunities for cross-chain interoperability. Projects like Arbitrum and zkSync are implementing cross-chain bridges to connect Layer 2 solutions with Ethereum mainnet and potentially other EVM-compatible chains.

Among Non-EVM chains

Some projects focus on building interoperability protocols specifically for EVM and Non-EVM chains, like Wormhole, Axelar, Multichain and so on. These protocols aim to enable seamless communication and asset transfers between Ethereum-based networks and other blockchain platforms.

Some other cross-chain projects pay more attention to the interoperability ecosystem which are built from their custom blockchains, like Cosmos, Polkadot. However, to expand their ecosystems, they also provide interoperability for EVM chains. The famous sub-projects include Gravity Bridge and XCM.

The TON blockchain introduces decentralized cross-chain bridge, which allows users to transfer assets from TON Blockchain to other blockchains and vice versa. Up to now, the TON bridge managed by decentralized oracles supports interoperability two-way from TON blockchain to Ethereum, Polygon and BSC. It can also work with any other EVM-compatible network without modifications and with other networks with minimal modifications.

Above blockchains are with a common feature which is the ability for smart contracts. By implementing the interoperability logic within contracts, the cross-chain functions work fine. However, the most famous Bitcoin lacks this important feature, which makes interoperability a hard problem. Even though EthRelay ( a famous cross-chain project implementing value transfer from Bitcoin to Ethereum ) could transfer Bitcoin to ETH, it is a one-way solution limiting more cross-chain functions.

Fortunately, recent projects, like Stacks, Rootstock and MAP protocol, provide programmability through implementation of complex smart contract functionality in Layer2. With help of Bitcoin layers, the hope of interoperability emerges.

TCCP: A universal cross-chain protocol for EVM and Non-EVM chains

From above analysis, we can know that it is a critical issue to support interoperability between EVM and Non-EVM chains simultaneously. Cycle’s TCCP achieve that by the following designs.

Firstly, Cycle Network works as a layer2 blockchain, which means it can become any layer1 blockchain’s rollup. It brings possibility to act as a Bitcoin’s layer2 to expand its interoperability with other blockchains using TCCP. Bitcoin, as the special Non-EVM blockchain, is very hard to break itself through to cross-chain with other blockchains with or without smart contracts. Therefore, because of the Cycle Network’s natural feature, TCCP could achieve the interoperability between Bitcoin and other blockchains.

As for details, When interoperating with non-Ethereum blockchains, especially Bitcoin, the Cycle network will use the Ethereum as a trust layer, publishing batch transactions in the Ethereum network, executing them off-chain, and recording verifiable results on the chain. The verification results can be recognized by users or other organizations and forwarded to Bitcoin for completion. Specifically: 1. Sequencer initiates task submission to Task Manager Contract. The task manager contract is deployed on Ethereum and responsible for record task submissions from sequencers on Cycle Network. It could be listened by some off-chain networks, like Eigenlayer. 2. Operators validate the task. Operators refer to nodes in the off-chain networks. They account for listening and validating the submissions in the task manager contract. 3. Upon validation, the task is signed. Once successful validation for the submission, the operators sign it and send the signatures to aggregator server. 4. Signatures are aggregated. Once receving enough signatures, the server aggregates them and send the aggregated signature back to Ethereum. 5. Task execution. The user could validate the aggregated signature and execute the task on Bitcoin network.

Secondly, as for the EVM chains, TCCP utilizes the Access Module and the Execution Module. The access layer presents a simple means for developers to access. With JSON-RPC. developers can access the nodes to construct EVM-compatible applications by leveraging Cycle Network’s complete EVM (Ethernet Virtual Machine) compatibility. Execution layer adopts ZK-EVM to ensure EVM compatibility, allowing users to build omni-chain applications using EVM for cross chain interaction and data processing.

In conclusion, Cycle Network’s TCCP stands out as a trustless and universal cross-chain protocol that supports interoperability between EVM and Non-EVM chains. With its innovative design and focus on security, user experience, and scalability, TCCP is poised to play a significant role in the future development of the blockchain ecosystem.