Polkadot cross-chain bridge

Web 3.0, the next generation of the Internet, is envisioned as a fully functional, user-friendly web where our identities and data are our own — thanks to decentralized blockchain technology, they can be secured The land is protected and will not be attached to any centralized power subject. Polkadot was created in line with this vision: no single blockchain can do everything; that is, the future is multi-chain.

However, as the number (and often size) of blockchain networks continues to grow, Bridge Smart Contract Development Services they remain largely isolated from each other, like islands with their own communities and economies, unable to exchange information or value with the outside world. Today, the isolation of blockchain networks runs counter to the principles of decentralization and reflects the balkanization of the existing centralized Web 2.0 world (the fragmentation of Fragmentation under the system, i.e. “fragmentation”).

What is a bridge? Where is it important?

A blockchain bridge is a connection that allows tokens and arbitrary data to be transferred from one blockchain network to another. Two chains can have different protocols, rules, communities, and governance models, but bridges provide a compatible way to securely interoperate on both sides.

Bridges come in many different designs, but they generally fall into two camps: centralized bridges that rely on trust or federation, and more decentralized so-called “trusless” bridges. Centralized bridges rely on some type of central authority or system to operate, which means users need to trust an intermediary to use a given application or service.

By contrast, trustless bridges are those where the user does not have to trust a single entity or authority, but needs to trust the mathematical truth built into the code. Trustless interactions are enabled by the technology (and incentives) behind the system, not by commitments or legal agreements.

Polkadot is designed as an underlying infrastructure to enable the scalability, interoperability, and security required for future multi-chains, allowing different Layer 1 parachains to interact and communicate with each other in the ecosystem. But Polkadot also allows parachains to interoperate with external networks like Bitcoin and Ethereum via bridges. Some bridges have been developed or are under development to connect Polkadot with these external networks. Because Polkadot is designed to minimize intermediaries in digital systems, trustless bridges are often preferred in ecosystems.

An example of a bridge

A decentralized insurance market can be imagined as a practical example of a bridge. One way to create this marketplace on Polkadot is to deploy a specialized insurance parachain that acts as a marketplace for buyers and sellers of insurance. Suppose Polkadot also includes an oracle parachain that brings external data on-chain, and an Internet of Things (IoT) parachain that aggregates information from off-chain IoT devices.

In the case where you have purchased flight delay insurance, the payout policy may be set up so that if the oracle parachain confirms that your flight is delayed and the IoT parachain confirms that you arrived at the airport on time, the policy will pay out the compensation. On-chain, if the insurance parachain receives signals from both the oracle and the IoT parachain, it can use the Ethereum bridge to trigger a transaction to transfer a stablecoin (such as Dai) from the insurance company account to the policy holder account. This relatively simple example demonstrates the power of interoperability.

Polkadot is designed for a future where not only can we see applications primarily exist in one network, they can occasionally utilize other networks for simple transactions. Even these applications can go further than that, they can be deployed across multiple chains, each with varying degrees of customization. High-quality bridges bring us one step closer to this future.

Bridging Substrate-based chains

The Substrate blockchain building framework can be used to architect parachains with their own consensus and security (when combined with the Cumulus consensus engine) and blockchains that operate independently. While parachains connected and secured by Polkadot or Kusama Relay Chains are first-level citizens of the ecosystem, Cross chain bridge development Substrate-based standalone chains can also bridge and communicate with ecosystem parachains.

The Parity team is currently developing a generic bridge that can connect Substrate-based chains. This bridge consists of multiple components that together support bidirectional communication between a Substrate-based standalone chain and a Polkadot parachain, or two-way communication between two Substrate-based standalone chains. In particular, this bridge will enable the Polkadot and Kusama networks to interact with each other. You can view progress on Parity’s trustless bridges at the Parity Bridges repository page.

Bridge supported by Web3 Foundation grants

Web3 Foundation funding projects have supported the development of many bridges to the Polkadot ecosystem, including the following projects:

Interlay

Building a trustless bridge from Bitcoin to Polkadot. Currently in beta testing, it will allow users to mint PolkaBTC, a 1:1 Bitcoin reserve-backed asset, and bring it to Polkadot. PolkaBTC can be used with any application or parachain in the Polkadot ecosystem, just like a native asset, to unlock BTC liquidity for Polkadot DeFi. Internally, PolkaBTC implements the XCLAIM protocol, which makes the bridge financially trustless, permissionless, and censorship-resistant. PolkaBTC’s incentivized beta testnet went live at the end of February with significant improvements to the user experience. Meanwhile, PolkaBTC is being audited by the NCC, and Interlay has started integrating PolkaBTC with other parachains on Rococo.

Snowfork

A common functional bridge is being built between Ethereum and Polkadot. It can not only transfer ETH from Ethereum to Polkadot, but also transfer ERC20 assets and arbitrary data. In addition to asset transfers, the bridge can also be used for more complex interactions such as cross-chain invocation of smart contracts. For example, Build a cross chain bridge any application built on Polkadot can use the bridge to send Dai directly from one account on the Ethereum chain to another.

Darwinia

A permissionless non-custodial bridge protocol is being built that features efficient, low-cost cross-chain token decentralization and non-fungible token (NFT) transfers, as well as other cross-chain operations. The Darwinia bridge integrates technologies such as ultra-light clients, zero-knowledge and optimistic verification mechanisms. Darwinia has already launched a bridge with Ethereum, and plans to implement more bridges connecting important heterogeneous blockchains in the future, such as BSC, Tron, Filecoin, etc.

Centrifuge

Collaborated with ChainSafe to develop a modular, asset-agnostic, multi-directional bridge between Substrate-based blockchains and Ethereum. ChainBridge allows Centrifuge to transfer homogenized tokens and NFTs between chains, making it possible to finance real-world assets through various DeFi products. ChainBridge is open source, and it also allows other teams in the ecosystem to build bridges with their own projects.

Crypto Asset Gateway

ChainX

There are plans to connect multiple networks and a BTC to Substrate bridge has been implemented. In this design, the bridge is operated by validators, staked in ChainX’s proof-of-stake consensus to control the BTC multi-signature wallet.

Bifrost

An EOS network bridge was developed to implement on-chain light nodes by using merkle tree verification to enable trustless cross-chain asset transfer. The third version of their testnet, Bifrost Asgard CC3, was released recently. In the future, Bitfrost plans to work on interoperability with EOS contracts.

Bridging the Web 3.0 Future

The future of blockchain internet infrastructure lies in everyone working together in a spirit of cooperation. We want to connect diverse communities to the Substrate and Polkadot ecosystems and are committed to providing reusable development components that make it easy to develop and deploy bridges to other blockchains.