Overview

Version 2.0.0 @Bitomni_Global (living document, last updated on August 30, 2024)

BitoBridge is an omnichain bridge that focuses on integrating Bitcoin and its tokens, such as Ordinals and BRC20, across multiple blockchains. BitoBridge is designed to be a trust-minimized, secure, decentralized, two-way pegged Bitcoin omnichain bridge achieved by leveraging Internet Computer (IC) technologies, including Chain Fusion, Bitcoin Integration, HTTP Outcalls, etc. It is intended to enhance Bitcoin and its tokens' utilities by incorporating them into diverse DeFi ecosystems. BitoBridge serves as a cornerstone in Bitomni’s suite of built-in BTCFi DApps. The governance of BitoBridge involves the Bitomni DAO, where BITO token holders democratically manage protocol changes and upgrades. This ensures transparency and community involvement, allowing users to actively influence the development and future direction of BitoBridge within the expanding BTCFi landscape.

Problem & Solution

Problem: It is challenging to move Bitcoin and its tokens across different blockchains, limiting their utility and accessibility.

Current solutions: Solutions such as centralized wrapped BTC, Cross-chain bridge, and Cross-chain swap exist in the market, which experiences trust, security vulnerabilities, user complexity, market volatility, and liquidity issues.

BitoBridge unique value proposition: A decentralized, secure, trust-minimized, two-way pegged omnichain bridge that supports BTC and its tokens. Such a solution enhances security, reduces reliance on intermediaries, and aligns with Bitcoin’s core principles and user sovereignty, making the process more resilient and trustful.

Core Principles

BitoBridge is designed with core principles that underpin its functionality and reliability:

Trust-minimized: The bridge's operation relies minimally on trust between parties. Instead of depending on a central authority or intermediary to verify transactions, BitoBridge utilizes IC's Chain-key Bitcoin (ckBTC) and Chain Fusion technologies [1,2], which rely on advanced cryptographic proofs and automated consensus mechanisms. These technologies ensure that transactions are valid and secure without requiring users to trust any single entity. This minimization of trust is crucial for maintaining security and integrity in BTCFi operations.

Decentralized: It refers to operating across a decentralized network of nodes within IC instead of a centralized server or platform. This structure ensures that no single point of failure can compromise the bridge’s functionality or the security of the assets it handles. Each node in the network participates in validating transactions and maintaining the bridge’s canisters, spreading risk and control evenly across the network. This helps to prevent potential attacks or fraud that are more feasible on centralized systems.

Two-way pegged: BitoBridge allows for the reversible exchange of Bitcoin and its tokens between Bitcoin native blockchain and other blockchains where it is used. Users can convert their Bitcoin to bitoBTC on IC or a wrapped version, bitoBTC.x, to interact with DeFi or BTCFi applications on blockchains like Ethereum (bitoBTC.eth), and vice versa, convert their wrapped tokens back into native Bitcoin. This functionality is critical for enabling liquidity and flexibility in using Bitcoin and its tokens across different blockchain ecosystems.

Omnichain: It refers to BitoBridge's comprehensive ability to unite various blockchain networks into a cohesive and interoperable ecosystem.

Tech Architecture

The overview of the BitoBridge structure is shown below:

This diagram provides an overview of the BitoBridge structure, illustrating the system's capacity to facilitate interoperability between blockchains, notably Bitcoin, Ethereum, etc, via the IC network. Supported tokens can be seamlessly bridged between any two supported blockchains; for example, Bitcoin <=> Ethereum, Ethereum <=> Solana, and Arbitrum <=> Ethereum.

At the heart of this structure is the BitoBridge Hub Canister, centrally positioned within the diagram. This canister serves as the primary coordinator for all activities across IC and the external blockchains. The Hub Canister is crucial in managing transactions and data flow between the IC and various connected networks, ensuring seamless operation across different environments.

Several key components are connected to the Hub Canister, each playing a specific role in the overall architecture. The BitoBridge Relayer Canister (R) acts as a bridge, facilitating communication and transaction relaying between the Hub and external blockchains. Meanwhile, the Chain-key Bitcoin (ckBTC) component allows for secure interactions with the Bitcoin blockchain, integrating it directly into the IC framework without compromising on decentralization or security.

Extending from the Hub Canister, the structure also includes peripheral components tailored to each supported blockchain, such as Ethereum, Solana, Aptos, and more. Each of these blockchains interacts with BitoBridge through dedicated contracts—namely, the Ledger Contract (L), responsible for managing token minting and recording transactions, and the Helper Contract (H), which handles auxiliary tasks such as token management and transaction verification.

Blockchain Integration

• Bitcoin Blockchain: The architecture includes direct integration with the Bitcoin network, facilitated through Chain-key Bitcoin (ckBTC). This allows native Bitcoin transactions to be managed within the BitoBridge system.

• EVM Blockchains: Integration with EVM blockchains is managed through BitoBridge’s specific ledger and helper contracts, enabling cross-chain transactions and asset management between EVM blockchains and other networks.

• Polkadot, Aptos, Solana, and Other Blockchains: Similar to EVM blockchains, these blockchains are integrated into the BitoBridge system via dedicated ledger and helper contracts. This design allows for seamless asset transfers and interoperability between various blockchain ecosystems.

bitoBTC

BitomniBTC (bitoBTC) is an ICRC-2 token issued on IC and backed 1:1 by Bitcoin (BTC) [3], so 1 bitoBTC can always be redeemed for 1 BTC and vice versa. It is the same as ckBTC and a critical component of the Bitomni ecosystem. It is designed as a twin of native BTC, enhancing its functionality in the IC ecosystem. bitoBTC enables BTC holders to participate in DeFi and BTCFi activities beyond the Bitcoin blockchain, maintaining their assets' inherent value and security while promoting interoperability and liquidity.

bitoBTC potentially facilitates various BTCFi services, including lending and borrowing, restaking, and cross-chain on-chain fund management. It mirrors the value of native BTC and is secured by advanced cryptographic methods and robust smart contracts to guarantee transaction integrity.

ICRC.xxx

ICRC.xxx tokens represent wrapped versions of ICRC-1 and ICRC-2 tokens on various blockchains, facilitating seamless interoperability across different blockchain ecosystems [3,4]. For instance, BITO.eth represents the wrapped BITO token, an ICRC-2 token, on the Ethereum blockchain, while bitoBTC.sol denotes the wrapped bitoBTC token on the Solana blockchain. This wrapping mechanism is fundamental to extending the utility of native ICRC tokens beyond IC, enabling them to engage in the broader DeFi landscape.

These wrapped tokens maintain a 1:1 value with their native counterparts, ensuring that each ICRC.xxx token can always be exchanged back to its original ICRC token. This functionality is crucial for maintaining value consistency and trust across different blockchains. By leveraging advanced cryptographic solutions and secure smart contract implementations, ICRC.xxx tokens uphold transaction integrity, providing a robust and decentralized method for users to participate in cross-chain DeFi activities, enhance liquidity, and access a broader range of blockchain applications.