Darwinia: The Cross-Chain Bridge Hub|Polka World Interview

11 min readMar 1, 2021

Recently, leading crypto project reporter PolkaWorld interviewed Alex, co-founder of Darwinia Network, about their mission and plan for the upcoming parachain slot auction. Below is a transcription of the interview.

Darwinia Network is a cross-chain bridge protocol built on Substrate that intends to compete for a Polkadot parachain slot. Their focus is on connecting heterogeneous blockchains such as Ethereum and TRON and becoming the main cross-chain bridge hub of Polkadot, while empowering other parachains with the ability to communicate across multiple public chains, even if they exist outside the Polkadot ecosystem.

In this PolkaWorld interview, we spoke with Darwinia co-founder Alex and asked how far Darwinia is along the road towards achieving its goals and whether or not he can offer any insights regarding their participation and plans for the upcoming Polkadot parachain slot auctions.

Kiko: Will you please introduce yourself and the process of how you started Darwinia?

Alex: Hello, I’m Alex; Together with Denny Wang, we founded Darwinia Network.

Back in 2010 and 2011, Denny and I were inspired by Bitcoin and joined the blockchain industry. We participated in several open-source projects but started to get to know each other in 2013 when we worked on the BitShares project. Denny was one of the core developers, and I was contributing to the development of the front-end web wallet as a freelancer.

In 2013, BitShares was one of the earliest decentralized exchanges at a time when the concept of stablecoins and DeFi were new and evolving. These new ideas were complicated; but fascinating, and we had many discussions and interactions in the forum.

We got to know each other gradually as we worked together on various projects. In 2018, we decided to set up a small team to develop a cross-chain game called Evolution Land and the Darwinia network.

We have always shared the vision of building a “Decentralized Web,” which is in line with Web3.0’s vision. As a Web3.0 builder, Darwinia has been working hard to realize this goal.

Darwinia Network is a bridge-chain, allowing value transfer in a decentralized and trustless manner between heterogeneous chains, and we hope to build a central bridge hub so that assets can flow freely between any chain without having to trust any middleman.

At the same time, we are also an early participant in the Polkadot ecosystem, providing critical infrastructure, and hope to become a Polkadot parachain. In Polkadot’s parachain architecture, relay chains empower parachains with high-speed and efficient cross-chain interoperability within the Polkadot ecosystem while interacting with heterogeneous external chains through bridges.

We want to fulfill that role and become the main bridge parachain on Polkadot/Kusama. On the one hand, our parachain will connect to other parachains via the Polkadot/Kusama relay chain, and on the other hand, our bridge chain will connect all Polkadot and Kusama parachains to external blockchains such as Ethereum, BSC, EOS, TRON, etc. as infrastructure; without teams having to reinvent the wheel and build bridges on their own between external chains.

This is Darwinia Network’s value proposition for the industry and community.

Kiko: Darwinia is striving to become a “cross-chain transfer bridge hub,” which requires you to build bridges between Darwinia and many other blockchains. What bridges do you plan to develop, and which have you implemented so far?

Alex: The first Bridge was built to Ethereum because there’s no doubt; it’s the most popular cross-chain destination. EOS, TRON, BSC, and HECO are also on our list, which we will prioritize based on real ecosystem prosperity and user base, willingness to connect, and whether or not their consensus model is compatible with our bridge technology.

Once the bridge is launched between Ethereum and Darwinia, we will keep a close eye on its performance. If there are no new significant issues after a period of monitoring and testing, we will begin developing the next bridge.

Building on experience gained from constructing our first bridge and using modularized components and tools engineered during the development process, any new bridges’ development should progress at an accelerated pace.

Let’s imagine, for example, that Darwinia has bridged four heterogeneous blockchains. Any new chain that requires interoperability among the existing four chains would need only to connect to Darwinia, not build four bridges ad-hoc, which would be far less efficient. Darwinia as Infrastructure enables seamless cross-chain interoperability between all networks simultaneously for any newly connected chain.

As Darwinia bridges more and more blockchains, its role as infrastructure will become much more critical in the blockchain industry.

Kiko: The Polkadot official team is working on a Polkadot-Ethereum bridge. What is the difference between your solutions?

Alex: The official Ethereum bridge protocol designed by Polkadot adopts a GRANDPA consensus model based on Authority. In other words, it has a collection of Authorities on Ethereum, authorized by validators on Polkadot.

After the validator signs a transaction on Polkadot, the Ethereum side verifies the signature. This is similar to our own conceptual model for ​​implementing a bridge, but we engineered a light client of the GRANDPA protocol for our solution on Ethereum instead.

Our solution distinguishes itself through the addition of MMR data to the block header. MMR is a crypto algorithm known as Merkle Mountain Range, a variant of the Merkle tree.

The MMR digest summarizes all blocks from genesis to the current block and finger-prints the chain history right into the block header, a technique that is applied to the smart-contract on both source and target chains.

The advantage of using this method is that when we confirm a block on Ethereum, such as the 10,000th block, we immediately verify the data integrity in any block in between blocks 0–10,000. There is no need to relay/store/verify every block in the range; so efficiency is greatly improved. This technique is not only applied to the Ethereum to Substrate bridge but also other blockchain bridges.

The integration of MMR makes us unique among other light client-based solutions and allows Darwinia to execute trustless verification-on-demand while achieving sub-linear performance with lower costs and reduced storage requirements.

In addition to that, we have also introduced the Optimistic Verification Game sub-protocol to chains without deterministic irreversible finalities, such as Ethereum and Bitcoin based on Proof of Work (PoW) consensus chains.

Kiko: How have you made Darwinia’s bridge completely decentralized?

Alex: Darwinia light client is a sub-linear super-light client. We don’t store every block of the source chain; only the latest block header containing the chain-history MMR digest which we use to verify any block within the history. How do we verify the integrity of the latest block header containing that MMR digest? We introduce an Optimistic Verification Game sub-protocol to confirm with absolute certainty it’s the latest block. Allow me to explain how it works:

Anyone at all can be a Relayer and submit block headers they observe to the super light-client, so game theory plays an important role. If a Relayer submits wrong information either intentionally or unintentionally, they are challenged by others. If they lose the challenge for whatever reason, their stake may be slashed; while a successful challenger is rewarded. Relayers, therefore, receive economic incentives to monitor, report, and challenge the status of data submission in the light client.

If there is a conflict between two Relayers who submit differing block data, how do we resolve the conflict? We don’t rely on centralized committees to vote and resolve them; instead, the protocol initiates the Verification Game process to challenge the suspicious relayers, requesting additional header data from historical blocks determined by a “sampling function” for further verification.

While it is trivial for an honest relayer to submit the newly requested block header data, an adversary would have to fork the chain in advance and, even so, would find it extremely difficult to pass further stages of verification.

In the PoW protocol, the cost to forge a fake chain is equivalent to launching a 51% attack on the original chain; therefore, an attacker using this method will inevitably fail within 1–2 rounds of the Optimistic Verification Game challenge.

When verifying challenge data, the protocol checks the historical chain MMR summary in the block header and performs transition verification on the proof of work. It’s somewhat like a hash commit-reveal-verify process.

The decentralization of our bridge is based upon the following presumption: “anyone can submit data; anyone can challenge; conflict is resolved by protocol challenges derived from consensus rules; and no one has a superpower.”

Kiko: What would be Darwinia’s next focus?

Alex: We posted our development roadmap for 2021 in January and will focus on two primary objectives this year: First, on participation in the Kusama and Polkadot parachain slot auctions, where Crab and Darwinia Networks hope to become parachains;

And second, to build as many bridges as possible. Thus, once we become a parachain of Kusama and/or Polkadot we will be able to deliver greater and greater value via integration with additional chains, compounded through the power of the network effect.

At the same time, in terms of Darwinia ecosystem applications, we continue to upgrade our cross-chain game Evolution Land, an application designed to showcase our cross-chain technology innovations.

With each new bridge’s launch, we plan to deploy a matching new continent on the destination chain to demonstrate cross-chain interoperability, all while making the game more fun and adding additional value to our NFTs.

We are also working around the clock to bring true Gamefi (Defi+NFT with gameplay) into Evolution Land on the primary cross-chain layer, Darwinia.

Kiko: So Darwinia will first go for the Kusama parachain slot?

Alex: Yes, exactly. Crab Network (Darwinia’s canary network) will go for a Kusama Parachain, and Darwinia Mainnet will go for a Polkadot parachain.

Crab Network has been live for several months now; It’s a canary network with real economic value, and the native token is CRING. We conducted two airdrops to RING and Polkadot holders when Crab Network was first launched and reserved 2% of RING supply to support redeemability from CRING to RING at the ratio of 100:1.

You can imagine Crab Network as an extension of Darwinia Network’s mainnet, and soon tokens will be able to traverse these two networks via the Darwinia-Crab bridge. Once the bridge is online, users will be able to send RING to Crab Network and receive 100x the amount in CRING, and vice versa to receive 1/100 the amount of RING on Darwinia mainnet.

Kiko: When will Darwinia announce its parachain auction plan?

Alex: As a matter of fact, we have a PLO plan already but are still developing some critical product features to help support it. We want to ensure we are able to deliver first before making any additional promises. As we approach the auctions, we believe most of the components will be ready but will release our detailed PLO plan soon.

The bidding plan in general so far is to offer RING token rewards to our supporters based on the size of individual contributions, but we also want to do more:

For example, NFT airdrops such as premium land plots in the game Evolution Land; Apostles (characters that perform jobs such as mining or battle); or Mining Drills and other useful in-game implements, and users will be able to utilize these NFTs to enhance their Evolution Land GameFi experience.

In the final version of our NFT synthesis system Furnace that will launch soon, those rewards (Land, Drill, or Apostles) can be combined and fused in order to synthesize even more powerful NFTs that will further enhance the experience and rewards.

As I mentioned earlier, we will launch a new continent on Crab Network, and Darwinia PLO will reward users with NFTs that will be useful within the game. Presently, we have launched a DVM testnet called Pangolin on Crab Network to test its implementation and functioning.

DVM stands for Darwinia Virtual Machine, an EVM-compatible virtual machine that supports dApps currently running on Ethereum. Not only our game, Evolution Land, but also other dApps such as DEX and AMMs are all undergoing extensive testing on Pangolin right now.

We hope to introduce Crab Network with native support for NFTs, DeFi dApps, and Cross-chain interoperability features, all while keeping fees low.

Please stay tuned for our detailed PLO plan to be released in a few weeks.

Kiko: Is DVM developed based on Frontier? What optimization have you added to it?

Alex: Frontier provides a standard EVM core framework and executor while also offering a variety of adaptations for Substrate chain-level customization. The DVM optimizes the interfaces connecting existing infrastructure, provides an easy-to-use and barrier-free development platform for smart contract developers and offers a seamless experience for dApp users.

These optimizations include two-way mappings between Subkey and Ethereum addresses; deposit and withdrawal of system Currency precompiled contract; lossless, accurate two-way balance conversion between Substrate and Ethereum; as well as full compatibility with Metamask, and signature algorithm.

Let’s take lossless and accurate two-way balance conversion as an example. Conversion of balances with common tools within the existing Substrate-Ethereum framework often highlights compatibility issues between Polkadot.js (Substrate) and Metamask (EVM) based wallets. We have unified their interfaces to make user interaction smoother, especially when balances need to be credited or debited.

DVM also serves a critical function for Darwinia; it manages various cross-chain mapped assets. We know that as a cross-chain transfer bridge hub, various assets will need to be mapped to the Darwinia network, including ERC20 fungible tokens and ERC721 (and its variant) NFT non-fungible tokens, so it is crucial to manage these mapped assets effectively while maintaining the integrity of the decentralized ecosystem.

We use DVM to manage these mapped assets precisely because Ethereum’s asset standards have been so widely adopted, and so the mapped assets on DVM also adopt ERC20 and ERC721 token standards.

As a decentralized and open smart contract platform, Darwinia Virtual Machine allows unrestricted development and growth of dApps, including but not limited to DeFi, DEX, AMMs, and NFTs.

Kiko: How can users and developers from the Polkadot community participate in the Darwinia project?

Alex: We receive quite a bit of attention from followers in our community, general users, and developers, who participate actively in various ways.

Users can participate in staking on Crab or Darwinia mainnet, where yields have been relatively impressive, and can experience cross-chain transfer from Ethereum to Darwinia for the first time during the process. Staking rewards are often sent back to Ethereum through the bridge vis-a-vis on their way to a CEX or DEX.

We have airdropped Crab Network tokens to RING and DOT holders, allowing users to conduct various tests on Crab Network. We’ve also conducted RING airdrops to users via several marketing campaigns in the past.

Users can also play the game Evolution Land; participate in community events; join the Ambassador Program to become an advocate, or support our bids for parachain slots. As for developers, we have the Darwinia Builders Program to help support those who wish to learn and develop in our ecosystem.

Getting involved in the coming PLO on Kusama and Polkadot to indicate your support for Darwinia is welcome and encouraged; and it’s crucial for our long-term growth . With a bit of luck, our supporters will receive handsome rewards.

Join our community and visit our website to learn more about Darwinia Network

All you need to know about Darwinia

[Website] [Twitter] [Telegram] [GitHub] [Discord]




As an open cross-chain bridge protocol based on Substrate, Darwinia focuses on the construction of future Internet of Tokens. TG: http://t.me/DarwiniaNetwork