🌐 Overview

Welcome to the technical documentation for Hemi, a Layer-2 solution for Bitcoin and Ethereum blockchains that offers true scalability and interoperability.

This documentation is designed to guide builders and enthusiasts in understanding and utilizing the Hemi Virtual Machine (hVM). The hVM is Hemi's modular protocol that provides developers with a familiar programming interface.

✈️ Navigating the Docs

Our documentation is organized into the following sections to help you find relevant information quickly:

⚡ Quickstart: Whether you plan to develop, explore, or mine on Hemi, we have identified some crucial resources to quickstart your journey.

⚡ Foundational Topics: Learn about the architecture, sequencer consensus, PoP consensus & Bitcoin finality, tunneling, and more.

⚡ How-To Tutorials: Whether you are using or developing on Hemi, these basics will get you started! Set up your MetaMask Wallet, tunnel ETH and BTC to Hemi, start with Remix IDE, deploy an ERC-20 token and run a PoP miner.

⚡ Tooling: Understand and access the tools required to build on Hemi.

⚡Incentives: Check out our points, grants, retroactive funding, and one-off spends.

⚡ Additional Resources: Partners inquiry, FAQ, official links, and our brand kit.

⚡ Send Feedback: We'd love to hear from you, good or bad! Found a bug? Got a hackathon coming up? Slide into our DMs.

🏁 Getting Started

Whether you're a developer, miner, or explorer, we've got a path for you!

👇 Select Your Role

🌐 Welcome to the Hemi Developer Quickstart Guide!

This guide provides an overview of the essential steps and resources to get you started navigating Hemi’s ecosystem and leveraging its full potential.

1️⃣ Explore the Hemi Network

Begin by familiarizing yourself with the Hemi network’s architecture, key features, and its unique approach to interoperability and scalability.

• What are Hemi ?

• How does secure Hemi?

• What is the ?

• Which does Hemi currently support?

2️⃣ Set Up Your Wallets

Prepare your various wallets to start exploring Hemi by setting up an EVM and BTC wallet. This step ensures you have everything in place to interact with the Hemi network effectively.

• and

• .

• Join our and collaborate with the community.

3️⃣ Interact with Hemi Apps

Dive into the Hemi ecosystem by exploring and interacting with decentralized applications (dApps) built on the network. This hands-on approach helps you understand Hemi’s functionality and how dApps operate within the blockchain environment.

• Visit and see how we interact with Hemi Network endpoints.

• Start PoP mining using the .

• to Hemi.

• to Hemi.

❓ What Now?

Congratulations on getting started with Hemi! 🎉

Now that you’ve set up your environment, explored various apps, and begun building on the network, here are the next steps to deepen your engagement and maximize the potential of your journey on Hemi.

• Learn about and our rewards .

• with Hemi assets.

• on Hemi.

• to Hemi!

📐Troubleshooting

If you encounter any issues or need assistance at any step, the following resources are available to help:

• Email

Hemi Mainnet

Additional Mainnet Public RPC Endpoints

• BFG (for PoP Mining): wss://rpc.hemi.network/v1/ws/public

• Explorer:

• Explorer documentation:

Code Snippets

Example HTTP request:

Hemi Testnet

Additional Testnet Public RPC Endpoints

• BFG (for PoP Miner): wss://testnet.rpc.hemi.network/v1/ws/public

• Explorer:

• Explorer documentation:

Code Snippets

Example HTTP request:

Third-Party Providers

We partner with leading node providers to help you seamlessly integrate your dApps with the Hemi network. These providers offer reliable and scalable API access to Hemi nodes, allowing you to concentrate on development while they handle the infrastructure management.

$HEMI Contract Details

🌐 Overview

The Hemi Network utilizes the Bitcoin-Secure Sequencer (BSS), a type of Proof-of-Stake (PoS) node, to achieve consensus, or agreement, on the network’s status. By leveraging the Bitcoin blockchain, the Hemi Network decentralizes its security measures, reducing reliance on internal network validators.

🛠️ How?

⛓️ It incorporates state proofs from the Bitcoin network to validate the Hemi blockchain, ensuring the network's history cannot be easily altered or falsified.

🛡️ The hybrid model provides a unique defense against majority stake attacks, a common vulnerability in pure PoS networks.

🔐 In the event of an overwhelming attack, the network can offload transactions to the Bitcoin network, ensuring continuous operation and security.

Coming Soon (Join Discord to See Updates)

🔒 Network Security and Finality

• To inherit Bitcoin security, a new type of miner (a “PoP Miner”) publishes Hemi consensus information to the Bitcoin blockchain.

• After a state publication to Bitcoin, the Hemi Network’s consensus layer incorporates cryptographic proofs of these publications, with PoP Miners receiving a reward in the protocol’s native token. The network uses these proofs during fork resolution to prevent reorganizations with the full force of Bitcoin’s security.

• As they are produced, the Hemi Network’s chain segments initially receive Bitcoin confirmations, which means an attacker would have to control increasingly large ratios of staking power to successfully affect a reorganization.

At this point, it is mathematically impossible for anyone to reorganize the network without 51% attacking Bitcoin itself.

🌐 Overview

• The Hemi Network connects to both the Bitcoin and Ethereum networks, allowing asset portability across both, enabling a third-party cross-chain ecosystem. To create this highly secure multichain ecosystem, the Hemi Network operates several kinds of decentralized nodes: Bitcoin finality governors, Bitcoin-secure sequencers, Proof-of-Proof miners, and a modified Geth node.

🛡️ Bitcoin Finality Governors (BFGs)

• Regulate the network's security status by analyzing Bitcoin blocks for Hemi Network state proofs.

• Determine the network's finality status, ensuring security.

• Coordinate with Bitcoin-secure sequencers and proof-of-proof miners.

⚙️ Bitcoin-Secure Sequencers (BSS Nodes)

• Integrate Hemi Network transactions with Ethereum mainnet transactions.

• Maintain the network's consensus layer and manage staking, unstaking, and slashing operations.

• Ensure a seamless connection between the Hemi Network and Ethereum for asset transfers.

🛠️Modified Geth Node

• Operates as a customized Ethereum node, providing compatibility and connectivity between the Hemi Network and Ethereum.

• Ensures data synchronization and transaction processing within the Hemi Network ecosystem.

🔗 Proof-of-Proof Miners (PoP Miners)

• Secure the network by embedding state proofs into the Bitcoin blockchain.

• Hash network headers to create cryptographic proofs and publish these to Bitcoin.

• Receive tokens as rewards for their contributions.

⚡️ Achieving Decentralized Interoperability

This innovative approach ensures secure, decentralized interoperability among Bitcoin, Ethereum, the Hemi Network, and other EVM-compatible chains.

🚨 Weak Subjectivity

• This risk involves an attacker accumulating enough keys of old PoS miners to gain majority control at some point in the past. With this control, they could create a valid, alternative/competing version of the blockchain which would appear equally valid to a bootstrapping node attempting to sync the network for the first time, and could also be used to create seemingly valid zero-knowledge proofs of chain state that differs from the legitimate canonical chain.

• While Ethereum relies on community consensus to avoid long-range reorganizations of its chain, its PoS protocol doesn’t technically prevent this type of attack.

🚫 Censorship

• An attacker with current majority stake could potentially block or ignore certain transactions, exercising a form of majority control that undermines the network's decentralization and fairness.

❌ Lack of Protocol-Level Defenses

• Since PoS operates entirely within its network, it lacks protocol-level defenses against the types of attacks mentioned above.

• Among the vulnerabilities, the limitations are:

  • No External Correction Mechanism: If internal rules fail or are exploited, there's no external system to protect or correct the network.

🔄 Why Use a Third-Party Bridge?

Hemi’s native Tunnel supports tunneling BTC, however, some assets (e.g., pumpBTC, iBTC) are not yet integrated. In these cases, a third-party bridge provides:

• Fast bridging times.

• Established track record of security and reliability.

• Wide token support.

🤝 Supported Third-Party Bridges

Below is a list of third-party bridges you can use to transfer BTC assets to Hemi. Each bridge has its own UI, fees, and specific token support.

🛡️ Inherits Bitcoin's Security

• Hemi's network capitalizes on Bitcoin's formidable security through a mechanism known as Proof-of-Proof (PoP). This approach allows Hemi to inherit the solid Proof-of-Work (PoW) security of Bitcoin.

🔍 How?

• To achieve this, Hemi deploys specialized miners, referred to as PoP Miners. These miners are responsible for:

  • Gathering crucial network details and publishing them on Bitcoin's blockchain, thereby linking Hemi's security directly to Bitcoin's proven system.

  • Employing sophisticated algorithms to generate proofs that are vital for the network's security.

🏗️ Block Confirmations

• New segments in the Hemi chain receive confirmations from Bitcoin, significantly raising the barrier for potential attacks. These confirmations:

  • Serve as "security bricks," each one strengthening the network's defenses.

  • Ensure that any attempt to compromise the network requires substantial power, making unnoticed attacks virtually impossible.

  • As Bitcoin confirmations accumulate, the Hemi Network's "security wall" becomes increasingly formidable, creating an effective deterrent against malicious actors.

🔚 Conclusion

• The Proof-of-Proof (PoP) consensus mechanism uniquely positions the Hemi Network by:

  • Allowing Bitcoin miners to secure Hemi indirectly, without direct involvement in Hemi's consensus processes.

  • Facilitating scalable transaction throughput in the Hemi ecosystem without expanding its Bitcoin footprint significantly.

  • Setting a high barrier for network reorganizations, as disrupting Hemi would necessitate a highly improbable 51% attack on Bitcoin itself, a task too daunting even for nation-states.

🖥️ Nodes 101

• Cryptocurrency networks are powered by a distributed array of computers, each referred to as a node, functioning in a peer-to-peer manner where each holds equal standing. Nodes, depending on the client software they run, fulfill different roles within the network.

• For instance, in the Bitcoin network, full nodes store a complete history of transactions for verification purposes, offering high security, while light nodes, focusing on transaction capability, rely on full nodes for information about the network's current state. This setup allows for a flexible network structure where nodes can freely join or leave without disrupting the network's overall functionality.

🛠️ Hemi Node Structure

• In contrast, the Hemi Network employs a more specialized node architecture to optimize network performance and security. It includes:

  • Bitcoin Finality Governors: Ensures transactions achieve finality on the Bitcoin blockchain.

  • Bitcoin-Secure Sequencers: Orders transactions in a secure manner, leveraging Bitcoin's security.

Review Process

Once your submission is received, our team will review it within 2 business days. We take every inquiry seriously and evaluate each on its merits.

• If You Don't Hear From Us: Should 2 business days pass without a response, it might indicate that your proposal isn't the right fit for us at the moment. This doesn't reflect your proposal's value; rather, it might not align with our current needs or focus areas.

🌐 Overview

🌐 Overview

Oracles play a critical role in bridging the gap between blockchain and the external world, enabling smart contracts on Hemi to access trustworthy off-chain data necessary for various use cases.

The most common applications of oracles include:

• Providing up-to-date token prices for different pairs, which is essential for DeFi protocols and financial products.

• Enabling dynamic NFTs that can change their properties based on real-world events, adding a layer of interactivity and uniqueness.

Follow along with some of the tutorials to help you get a head start when building your first Hemi project.

General

Coming Soon (Join to See Updates)

🌐 Overview

extension for .

It includes:

• Chain definitions!

🌐 Overview

• A cryptocurrency transaction fundamentally represents an update to the network's decentralized ledger.

• Such a transaction mandates a cryptographic signature from the sender's wallet, serving as a verification mechanism to authorize the transaction. Within the Bitcoin ecosystem, scripting capabilities enable the execution of more complex transaction types.

• Conversely, Ethereum operates as a distributed virtual machine, allowing for the execution of sophisticated programs known as smart contracts. These contracts, embedded directly on the blockchain, can operate autonomously based on their programming.

⚖️ The Blockchain Trilemma and L1 Challenges

• L1 chains like Bitcoin and Ethereum typically have relatively slow transaction times—a problem commonly known as the blockchain trilemma.

• The process of improving transaction throughput on a blockchain necessitates an expansion of data storage capacity, as each transaction must be individually recorded on the ledger. This requirement potentially centralizes the operation of full nodes to entities possessing considerable computational and financial resources.

• In response, Layer 2 (L2) networks present a strategic solution by aggregating multiple transactions off-chain prior to their collective finalization on the primary Layer 1 (L1) blockchain. This methodology not only preserves the foundational security principles of the L1 blockchain but also contributes to a reduction in transaction fees and an acceleration of transaction processing times, thereby enhancing the efficiency and accessibility of blockchain technology. ⏩

🌉 Tunneling Ethereum & Bitcoin with Hemi

• The Hemi Network, as an EVM-compatible Layer 2 network built to bridge Ethereum and Bitcoin, enables rapid transaction settlement and finality. Transactions inherit the complex programming abilities of Ethereum and the robust security of Bitcoin. The Hemi Network’s design also encourages greater decentralization than typical L2 networks, preventing censorship and ensuring open access.

To contact the Hemi team, please use one of the following methods:

• E-mail [email protected]

• Join our Discord and send a message in the #help channel

We gotchyu! Let us know how we can help!

🌀 Conventional Rollups

💭 Things to Consider

Centralized Influence in a Decentralized Sequencing World

Within frameworks aiming for decentralized sequencing, the presence of a centralized proposer could wield significant influence, potentially disrupting their intended decentralized nature.

Such control might result in the withholding of valid state rollups from Ethereum, leading to coercion of decentralized sequencers into potential censorship or halting communication of specific chain segments back to Ethereum for settlement.

🟩 Verifiers and Challenges

Vulnerabilities in optimistic rollup networks pose risks of asset theft through forged L2 states. To address this, rollups introduce verifiers, but the lack of proper incentives for this role presents challenges.

These lack of incentives can lead to difficulties such as:

• 🔒 Securing a sufficient number of verifiers to perform the complex and expensive verification process required.

• 👥 Relying heavily on users or nodes funded by development teams resulting in centralization.

• 📣 Potential bias or influence.

• 🌎 Sustainability and scalability issues.

✋ Denial-of-Service Risks

L2 networks' reliance on centralized "batchers" can expose them to denial-of-service risks if batchers refuse to publish transactions back to Ethereum for data availability.

⛔️ The Trouble With Merged Mining

• Bitcoin miners must choose to participate by running nodes for the sidechain, which can curtail decentralization.

• This makes the sidechain more susceptible to attack, as Bitcoin miners can collude to attack the sidechain at no cost while reaping Bitcoin block rewards.

• Merged mining can introduce new security problems and issues with incentives.

🔍 How Proof-of-Proof Works

• Hemi uses a consensus protocol called Proof-of-Proof (PoP), which allows Hemi to exceed Bitcoin's security at scale.

• Bitcoin miners don’t need to participate in Hemi directly; they confirm blocks that include Hemi transactions and collect transaction fees for doing so.

• Users who do want to earn rewards in Hemi’s native token can run a super-lightweight PoP miner to publish Hemi consensus data to Bitcoin.

👉

• Each new Hemi block receives a Bitcoin confirmation, making reorganization increasingly unlikely until the block reaches finality.

• Bitcoin requires about 60 minutes to reach finality; Hemi takes nine Bitcoin blocks (about 90 minutes) to reach finality and achieves (WIP) in just two hours.

Thus, in the Proof-of-Proof protocol, unlike with merged mining, Bitcoin miners needn’t be active to benefit; they can’t collude to attack the chain, and superfinality comes fast.

🚧 Limitations of Existing Approaches

Various Bitcoin header relay systems have been available on Ethereum as a primitive Bitcoin interoperability technology for nearly a decade. This approach has third-party relayers communicate new Bitcoin headers to a smart contract which maintains a lightweight view of Bitcoin consensus. Smart contracts can then verify a Merkle proof to verify that a specific Bitcoin transaction exists in the canonical Bitcoin chain.

However, this approach has significant limitations:

• Relies on third-party relayers

• Requires large inclusion proofs with expensive validation

• Can only prove a transaction exists in Bitcoin (no UTXO set proofs, no balance proofs, etc.)

Recently, other protocols have designed alternate Bitcoin interoperability primitives like 3-way noncustodial escrow systems validated with zk proofs, or smart-contract-controlled wallets run by the network validator set where network Sequencers facilitate UTXO queries.

However, these other approaches are only designed to serve specific use cases, and still don't provide smart contracts with a complete view of Bitcoin's state. Developers building on these primitives are also forced to accept the governance/security models that these one-off primitives provide, such as trusting a Sequencer doesn't withhold data from a UTXO query.

💡 With hVM, we set out to create something much more powerful and flexible that enabled anyone to build custom Bitcoin interoperability infrastructure directly in the EVM with complete access to Bitcoin state.

🔍 How?

By embedding a full indexed Bitcoin node directly inside the EVM, hVM:

• Does not involve any relayer system or trust assumption

• Does not require validation of any expensive proofs

• Supports secure queries for Bitcoin information that requires processing the entire chain like UTXOs, balances, and eventually popular Bitcoin metaprotocols

🏗️ Use Cases

hVM enables dApp developers to build all kinds of Bitcoin-aware dApps and custom Bitcoin interoperability infrastructure which was previously infeasible or outright impossible on other networks.

Some use cases of hVM include:

• Non-custodial BTC<->ETH asset exchanges

• Bitcoin MEV marketplaces

• Bitcoin lending markets

• Bitcoin staking systems

🚊 How Bitcoin Tunnels Work

The Bitcoin Tunnels allow Bitcoin assets to move between Bitcoin and Hemi by locking assets in custodial vaults and minting representative tokens on Hemi. Users can freely use these tokens on Hemi, and eventually, tunnel them to Ethereum or other EVM-compatible networks.

Deposit to Hemi

1. Users generate a deposit transaction by sending Bitcoin (or Bitcoin-native assets) to the selected custodianship vault’s Bitcoin address, managed by the multisig.

2. Once sent, the Bitcoin assets are locked in the custodianship vault.

3. Hemi’s Bitcoin Tunnel verifies the successful deposit on the Bitcoin network by monitoring the UTXO table for the corresponding deposit. If the deposit is successfully verified, the system moves to the next step.

4. Upon verification, Hemi mints representative tokens equivalent to the deposited Bitcoin assets. These tokens are sent to the user’s Hemi address. Hemi mints the representative tokens after 6 Bitcoin confirmations, or approximately

Withdrawal to Bitcoin

1. The user on Hemi initiates a withdrawal transaction by selecting the amount of representative tokens they want to convert back to Bitcoin.

2. These representative tokens are burned on the Hemi network, signaling the system that the user intends to withdraw the corresponding amount of Bitcoin from the custodianship vault.

3. Hemi’s Bitcoin Tunnel updates the rollup state root with the details of the withdrawal transaction. This state root is submitted to Bitcoin by a Publisher to ensure that the withdrawal is accurately recorded.

4. Hemi’s Bitcoin Tunnel verifies the correct burning of tokens and prepares the custodianship system for withdrawal.

🔍 Comparison to Other Bitcoin Interoperability Solutions

• Hemi’s Bitcoin Tunnels leverage the power of hVM (Hemi Virtual Machine) to monitor and secure Bitcoin-based asset transfers.

• The Bitcoin Tunnel contract uses hVM to track Bitcoin addresses and outputs tied to custodianship vaults, ensuring efficient and secure asset management.

• In hVM Phase 0, an externally owned account (EOA) is required to notify the contract of any irregular withdrawals. Once flagged, hVM can verify the offending transaction and respond by slashing misbehaving custodians.

• This contrasts with BTC interoperability solutions like BTC header relay, where users must manually construct cryptographic proofs of misbehavior and relay them to the contract for validation, introducing higher costs and risks of error.

🌐 Overview

• Hemi’s hVM is an EVM upgraded with Bitcoin awareness via new precompile contracts that smart contracts can call to get data from the Bitcoin node embedded in the EVM.

🔍 Tiny Bitcoin Daemon (TBC)

• The Hemi network maintains an EVM-visible Bitcoin node using Hemi’s custom “Tiny Bitcoin” (TBC) daemon. TBC syncs with the regular Bitcoin network over P2P and indexes Bitcoin blocks up to the height specified by the protocol.

• When a Hemi Sequencer creates a block, they can optionally include an additional “Bitcoin Attributes Deposited” transaction communicating one or more new Bitcoin headers to the Hemi protocol.

🎚️ Processed Bitcoin View

• When these transactions occur, all nodes on the Hemi network process these Bitcoin blocks at the same Hemi block height creating a “Processed Bitcoin View” synchronized across all Hemi nodes as part of the EVM state transition.

• This synchronization ensures execution of all Bitcoin-aware smart contracts are deterministic across all nodes.

To expose Bitcoin data to smart contracts, hVM introduces a number of new precompile contracts accessible in the EVM which fetch the latest data from the Processed Bitcoin View maintained by the embedded TBC node at the time the request is made.

🏁 Prerequisites

1. Add the UniSat Chrome extension

Navigate to the and click 'Add to Chrome.'

Click 'Add extension.'

📚 Tutorial

Video

1. Open the UniSat Chrome extension

Open the UniSat extension and click 'Create new wallet.'

2. Create a password

3. Copy your secret recovery phrase

After you have saved your private key in a secure area, click 'Continue.'

4. Select address type

Hemi currently uses two primary address types:

• Legacy (P2PKH): PoP mining currently requires a P2PKH address, although this may change at some point in the future.

• Native SegWit (P2WPKH): For everything else on Hemi (i.e., Bitcoin tunneling), any address type can be used but P2WPKH will (generally) be the cheapest fee-wise.

After you have selected your address type, click 'Continue.'

5. Your UniSat wallet setup is complete! 🎉

🌐Overview

Prior to TGE, users who engage in securing Hemi (mainnet) to Bitcoin will receive PoPPoints tokens, which are distributed based on how many other users are actively PoP Mining. These PoPPoints tokens are initially non-transferrable. During the initial mainnet release, all miners who get a PoP publication for a keystone into Bitcoin within ~1.6 hours will share 100 PoPPoints for that keystone round.

As mainnet evolves, this payout algorithm will be adjusted.

📚 Tutorial

Video

1. Open MetaMask

2. Access Token Selection

• Navigate to Tokens

• Click on the three vertical dots on the right of the token menu

• Import tokens

3. Enter the Contract Address

• Type in the tHEMI token contract address 0xC5D2E164601c59c2cD760669e849BFe498003e21 into the Token Contract Address field.

• If the address is recognized, MetaMask will automatically populate the Token Symbol and Token Decimal fields. For PoPPoints, you should see a symbol POPand 18 decimals.

4. Import

• Confirm the accuracy of the provided information, and then click on Next.

• If successful, you should see your PoPPoints tokens in your wallet's token list:

For now, these tokens are non-transferrable.

🏁 Prerequisites

• - Set up your EVM wallet and add the Hemi Network before interacting with any Hemi application.

📚 Tutorial

1. Visit the Stargate bridge

Navigate to the to tunnel your ERC20 asset from Ethereum to the Hemi network.

2. Connect wallet

Click 'Connect Wallet' in the top-right corner.

3. Select the asset and confirm networks

Using the token dropdown, select the asset you wish to bridge to Hemi.

4. Enter the amount to bridge

Input the amount of asset you wish to bridge to Hemi.

When you are satisfied with your transaction, click 'Transfer'.

5. Approve and sign the transaction

From your connected wallet, approve the asset spend and sign the transaction.

6. You have successfully tunneled to Hemi! 🎉

After signing the transaction, look for the pending transaction bar at the top of the screen. It may take a few minutes to confirm the transaction.

🏁 Prerequisites

• - Set up your EVM wallet and add the Hemi Network before interacting with any Hemi application.

📚 Tutorial

Video

1. Visit the Hemi Portal

Go to to tunnel your ERC20 asset from Ethereum to the Hemi network.

2. Connect wallet

Click 'Connect Wallets' in the top-right corner of the Hemi Portal.

3. Connect your EVM wallet

Currently, MetaMask and Rabby are the only EVM wallets Hemi supports. Our team is working to add support for additional wallets.

4. Connect to the Ethereum Network

Ensure that you are connected to the Ethereum Network. If you are not connected, the Portal will prompt you to connect.

5. Select asset and enter the amount to tunnel

Use the token dropdown to select the asset you wish to tunnel. After selecting the asset, input the amount of the asset you wish to move to Hemi.

After you have confirmed the gas fee and wish to proceed with the deposit, click 'Deposit.'

6. Confirm the deposit

Sign and confirm your deposit transaction in your connected wallet.

7. You have successfully tunneled to Hemi! 🎉

Your transaction should now be complete! You can check the status and view the transaction in the 'Transaction History' tab.

🌐 Overview

• Smart contracts on Hemi can access Bitcoin data by calling the hVM precompile contract addresses, which query the deterministic TBC node running inside the EVM.

• Future protocol upgrades will add additional precompile calls to provide additional information like Bitcoin fee levels, Bitcoin block construction information, and popular metaprotocols like Ordinals, BRC-20s, and Runes.

ℹ️ "Phase 0" Precompile Summary

🏁 Prerequisites

To follow along, you’ll need:

• Metamask (or another Remix-supported web wallet) connected to Hemi testnet as a custom network;

• A nonzero ETH balance tunneled over to a Hemi address in your wallet you want to deploy the demo contract with to pay deployment gas fees.

📚 Tutorial

1. Create Contract

• To start, open Remix, delete any existing contracts in the “contracts” folder,.

• Create a new contract file, which for our example we’ll call “BitcoinBalDemo.sol”.

• Paste in the following code:

You can now compile and deploy this contract, and try out calling it with a Bitcoin address string to see the address's balance (in satoshis) returned by hVM.

Proof-of-Proof Miners (PoP Miners)

🌐 Overview

🚊 How Ethereum Tunnels Work

The Ethereum Tunnel process involves locking assets on one network while minting corresponding representative tokens on the other network. For Ethereum-native assets, tokens are minted on Hemi once the assets are locked in a Hemi validation contract on Ethereum.

This allows seamless asset transfers across chains, enabling users to leverage the strengths of both networks while minimizing the friction of cross-chain operations.

Deposit to Hemi

1. The process begins with the user initiating a deposit transaction on Ethereum. This deposit locks up Ethereum-native tokens in a Hemi validation contract on Ethereum. The validation contract plays a critical role by securing the assets and ensuring they remain locked throughout the tunneling process.

2. Once the deposit is secured in an Ethereum block, Hemi’s block derivation protocol kicks in. The Sequencer, responsible for ordering and generating Hemi blocks, is required to include the deposit in the first Hemi block derived from the Ethereum block that contains the deposit transaction. This ensures that the deposit is acknowledged in Hemi’s L2 environment almost immediately after its validation on Ethereum.

3. After the deposit is included, Hemi mints a representative token on the Hemi Network, which serves as the equivalent of the locked asset on Ethereum. This token can now be freely used within the Hemi ecosystem, allowing users to engage with dApps or perform any transaction that requires the asset. You should receive your deposit within 0-2 minutes.

Withdrawal to Ethereum

1. To return the assets back to Ethereum, the user submits a withdrawal transaction on Hemi. When the withdrawal request is submitted, the representative tokens on Hemi are burned, which signals the user’s intent to withdraw their corresponding Ethereum-native assets.

2. Hemi’s state transition system updates its rollup state root, which is then submitted to Ethereum by a Publisher. The state root acts as a cryptographic proof of the transactions that occurred on Hemi, including the user’s withdrawal request.

3. The key to finalizing the withdrawal lies in Hemi’s use of Bitcoin finality, which is a significant differentiator from other optimistic rollup bridges. (In traditional optimistic rollups, the finality of cross-chain transactions is delayed by a dispute window, during which fraud proofs can be raised. Hemi accelerates this process by leveraging Bitcoin’s highly secure Proof-of-Work consensus mechanism to finalize the state root on Ethereum.) This process takes roughly 40 minutes.

🔄 Tunneling Hemi-Native and Bitcoin-Native Assets to Ethereum

Hemi’s tunneling process is not limited to Ethereum-native assets. Phase 2 of Hemi's Ethereum Tunnel will support Hemi-native and Bitcoin-native assets, extending the functionality of the tunnels to a broader range of assets. This capability is crucial for enabling the use of Bitcoin within Ethereum’s extensive decentralized finance (DeFi) ecosystem, which traditionally lacks native Bitcoin interoperability.

Withdrawal to Ethereum

1. The process for tunneling Hemi-native assets begins with the user submitting a deposit transaction on Hemi, locking their native assets within Hemi’s native asset tunnel contract.

2. Similar to Ethereum-native asset transfers, the state root containing this deposit transaction is published to Ethereum.

3. Once the rollup state root is confirmed (following Bitcoin finality and the absence of any disputes), the user submits a deposit proof on Ethereum to claim the corresponding representative tokens. These tokens represent the Hemi-native assets within the Ethereum ecosystem and can be used in Ethereum dApps or traded just like any other Ethereum-based token.

Deposit to Hemi

1. Moving Hemi-native assets back to Hemi from Ethereum involves a similar process. The user initiates a withdrawal on Ethereum, burning the representative tokens.

2. This triggers Hemi’s block derivation protocol to include the withdrawal in the next Hemi block derived from the corresponding Ethereum block.

3. Once the withdrawal is processed, the Hemi-native assets are transferred from Hemi’s native asset tunnel contract back to the user, completing the return to Hemi’s L2 environment.

One of the core advantages of this system is its flexibility. It allows Bitcoin-native assets, which are traditionally siloed on the Bitcoin network, to be tunneled through Hemi and into Ethereum. This enables Bitcoin to participate in Ethereum’s DeFi ecosystem while maintaining the security and decentralization that Bitcoin’s Proof-of-Work consensus provides.

🔍 Comparison to Standard Ethereum Bridges

While Hemi’s Ethereum Tunnels share the foundational principles of traditional bridges like the Standard Bridge, there are several critical distinctions:

• The primary distinction between Hemi’s Tunnels and standard bridges lies in the finality model and security architecture. Standard bridges depend on an optimistic model with a delayed dispute window. The withdrawal process on these bridges typically takes a week or longer, as they await the potential for fraud proofs before finalizing the transaction.

• Hemi Tunnels enhance this process by incorporating Bitcoin finality. Instead of relying solely on an Ethereum-based dispute window, Hemi uses Bitcoin’s Proof-of-Work consensus as an additional layer of security. This allows Hemi to finalize transactions more quickly, as the Bitcoin network’s finality period is shorter and more secure than the traditional dispute windows of optimistic rollups.

• Hemi will decentralize the dispute process by distributing the Challenger role across a wider set of participants. This decentralization mitigates the risk of collusion or centralization of power within the bridging system, offering a more secure alternative to centralized or semi-centralized dispute mechanisms found in standard bridges.

🏁 Prerequisites

• Acquire BTC - BTC can be purchased on any number of exchanges and on-ramps.

• - Set up your EVM wallet and add Hemi Network.

• - Set up your BTC wallet.

📚 Tutorial

1. Visit the Hemi Portal

Go to to access the Hemi Portal.

2. Connect wallet

Click 'Connect Wallets' in the top-right corner of the Hemi Portal.

3. Connect your EVM wallet

Currently, MetaMask and Rabby are the only EVM wallets Hemi supports. Our team is working to add support for additional wallets.

4. Connect your BTC wallet

Connect your BTC wallet (currently only UniSat supported). If you do not have a UniSat wallet, you can view our to create and set one up.

5. Select 'Bitcoin' as the 'From Network'

Ensure that you are connected to the Bitcoin network.

6. Enter the amount of BTC to tunnel

Input the amount of BTC you wish to tunnel to Hemi. There is a minimum amount of 0.0001 BTC to deposit and withdrawal.

After you have confirmed the gas fee and wish to proceed with the deposit, click 'Deposit.'

7. Confirm the deposit in UniSat

Confirm your BTC deposit in the UniSat browser extension.

8. You have successfully tunneled BTC to Hemi! 🎉

Your transaction has been initiated and must go through two confirmation periods to confirm your deposit:

1. Withdrawal from BTC address (~1hr) - When you initiate a deposit request, a transaction is signed from your BTC address to transfer the specified amount into a secure vault on the Bitcoin network. This deposit requires six block confirmations, which generally takes about one hour to complete.

2. Deposit into EVM Hemi address - Once the deposit is fully confirmed on the Bitcoin network, the Hemi Network validates the transaction and mints a corresponding token receipt (hemiBTC) on the Hemi blockchain, ensuring a seamless transition of assets.

You can check the status and view the transaction in the 'Transaction History' tab.

Manual confirmation of deposit

After six confirmations, Hemi can confirm a successful deposit from the Bitcoin network and deposit the funds to your address. Occasionally, the vault operator will require a manual confirmation in order to complete the deposit.

🏁 Prerequisites

• Hemi RPC URL and deployed contract address.

• Contract source code available (flattened only if verifying manually via the Hemi Blockscout UI).

🖥️ Blockscout UI Verification

1. Flatten the contract

Flattening a contract is necessary when verifying through the UI.

For Hardhat:

For Foundry:

2. Access Hemi Blockscout

Go to Hemi Blockscout Explorer and navigate to the page.

3. Input contract information

• Smart contract / Address: Paste the address that your smart contract was deployed to.

• Contract license: Select 'No License' unless otherwise specified.

• Verification method: Choose Solidity (Flattened source code).

Copy and paste the entire flattened contract code into the Contract code field and click 'Verify & publish'.

4. Submit for verification 🎉

Once all required details are entered, submit the form. BlockScout will compare the uploaded source code with the deployed bytecode. If they match, your contract will be verified.

🚧 Hardhat Verification

1. Install dependencies

If you haven't already installed Hardhat and the verification plugin (adapted for Blockscout), run the following:

2. Configure Hardhat for Hemi

In your `hardhat.config.js`, set up the Hemi network and include Blockscout API information for contract verification:

3. Verify the contract

Once deployed, you can verify the contract using Hardhat’s `verify` command. Make sure to include any constructor arguments if necessary:

4. Verification successful! 🎉

🌐 Overview

• Mining within the Hemi Network involves a specialized process designed to intertwine the security of the Hemi Network with that of the Bitcoin blockchain.

• This is achieved through the operation of the PoP Miner application, which plays a pivotal role in this symbiotic security mechanism.

🛠️ How It Works

1. Fetching Headers: The PoP Miner retrieves network headers from the Bitcoin Finality Governor for Bitcoin blockchain publication.

2. Transaction Construction: The miner constructs Bitcoin transactions embedding aforementioned Hemi Network headers.

3. Proof of Publication: Miners broadcast transactions through the Governor. These transactions are then integrated into Hemi’s consensus layer after being validated via the Bitcoin network, resulting in miner rewards.

⛏️ Run a PoP Miner

The (Command Line Interface) version of PoP mining is designed for long-term, continuous operation. It requires some technical knowledge for setup and maintenance but provides robust security and operational efficiency.

💸 Earning Rewards

🕵️ Behind the Scenes

• A Bitcoin Secure Sequencer (BSS) generates and broadcasts a new block.

• BSS nodes send the block header to Bitcoin Finality Governor (BFG) nodes.

• BFG nodes direct the header to PoP Miners.

• Miners create and send back signed Bitcoin transactions containing the header.

🔵 EVM Wallets

Key Terms and Concepts

• A decentralized computing platform that allows developers to build and deploy smart contracts. MetaMask is an EVM wallet, meaning it can interact with any blockchain compatible with the EVM, not just Ethereum.

• Private Key: A secret code that allows you to access and control your cryptocurrency in your wallet. It is crucial never to share your private key with anyone, as it grants complete control over your funds.

• Public Address: An address that you can share with others to receive funds. It is a string of alphanumeric characters that acts like an account number on the blockchain.

Ethereum Explorer: Etherscan

is the primary blockchain explorer for Ethereum, providing a comprehensive interface to view transaction details, address balances, token transfers, and smart contract interactions. It’s an invaluable tool for MetaMask users to verify transaction status, track gas fees, and explore the Ethereum blockchain in depth.

• To view transaction details, address balances, token transfers, and smart contract interactions on the Hemi Network, visit the .

Ethereum Networks

The Ethereum network currently comprises a variety of networks with varying functionality, however Hemi build primarily on only two:

• Ethereum Mainnet: The primary Ethereum network where real ETH transactions occur. It is the live network that supports the Ethereum economy and decentralized applications (dApps), with transactions being irreversible and involving real value and fees.

• Sepolia Testnet: A testing environment for Ethereum that mimics the Mainnet but uses testnet ETH with no real value. It allows developers and users to test applications, transactions, and upgrades without risking real funds, providing a stable and efficient testing ground for Ethereum-based projects.

🟠 BTC Wallets

Key Terms and Concepts

• Private Key: A secret code that allows you to access and control your cryptocurrency in your wallet. It is crucial never to share your private key with anyone, as it grants complete control over your funds.

• Public Address: An address that you can share with others to receive funds. It is a string of alphanumeric characters that acts like an account number on the blockchain.

• Seed Phrase: A series of 12 or 24 words that serve as a backup to restore access to your wallet. This phrase should be stored securely and privately; if lost or compromised, you could lose access to your funds.

Bitcoin Address Types

Bitcoin addresses are the unique identifiers used to send and receive Bitcoin. Over time, several address types have been introduced to improve Bitcoin’s efficiency, security, and scalability.

Types of Bitcoin Addresses:

• Legacy (P2PKH): This is the original and most widely recognized address format.

• Nested SegWit (P2SH-P2WPKH): An interim solution that allows the benefits of SegWit while maintaining compatibility with Legacy wallets.

• Native SegWit (bech32): Native SegWit, also known as bech32, introduces significant improvements in transaction efficiency and scalability.

• Taproot:

Bitcoin Explorer: Mempool.space

• is a blockchain explorer for Bitcoin that visualizes the current state of the mempool, the pool of unconfirmed transactions, and provides insights into transaction fees and block confirmations. It is particularly useful for BTC wallet users to check the status of their transactions and understand current network congestion.

• To view transaction details, address balances, token transfers, and smart contract interactions on the Hemi network, visit the .

Bitcoin Networks

The Bitcoin network currently comprises a variety of networks with varying functionality, however Hemi build primarily on only two:

• Bitcoin Mainnet: The primary Bitcoin network where real BTC transactions occur. It is the live network that supports the Bitcoin economy and has actual value, with transactions being irreversible and fees applying.

• Bitcoin Testnet: A testing environment for Bitcoin that mimics the Mainnet but uses test BTC with no real value. Developers and users can test applications, transactions, and upgrades without risking real funds. (Not to be confused with Bitcoin Testnet4, a version of Bitcoin Testnet with updated configurations and more stability for testing purposes. It offers an alternative and more reliable test environment compared to the older Testnet3, with no real value attached to the test BTC.

💼 Hardware Wallets

If you use a hardware wallet and want to interact with Hemi, you can connect it through MetaMask to manage your assets securely. This approach allows you to maintain control of your private keys while accessing the Hemi network. For a step-by-step guide on connecting MetaMask with a hardware wallet, please refer to .

🌐 Overview

• Blockchain networks typically operate as independent systems with no knowledge of other networks, creating a siloed environment. This isolation makes it impossible to transfer assets directly from one chain to another.

• Bridges are developed to address this issue, enabling asset transfers between different blockchains. They function by accepting a token from one blockchain (chain A) and issuing a corresponding placeholder or wrapped token on another blockchain (chain B). This wrapped token represents the original token and can be redeemed for it.

🖼️ Example

• To illustrate, consider the process of transferring bitcoin to Ethereum. A user sends bitcoin to a bridge connecting to the Ethereum network. This bridge then issues a wrapped Ethereum token representing the bitcoin.

• The user can utilize this wrapped bitcoin within the Ethereum network or return it to the bridge to reclaim the original bitcoin on the Bitcoin network.

🔍 Broader Applications & Limitations of Bridges

• Bridges are not limited to transferring assets between distinct blockchains. They can also facilitate transfers between different network layers, like connecting a Layer 1 (L1) blockchain like Ethereum to a Layer 2 (L2) rollup chain. This connection allows assets to benefit from the L2's lower fees and other features.

• However, bridges often rely on centralized infrastructure due to the lack of protocol-level awareness between the connected chains. For example, while an L2 might maintain the state of its corresponding L1, the L1 lacks inherent knowledge of the L2. This disconnect necessitates a centralized third party to maintain awareness of both chains.

🔒 Security and Efficiency

• The security model behind Hemi’s Ethereum Tunnels leverages the strengths of both Ethereum and Bitcoin. By integrating Bitcoin finality, Hemi ensures that cross-chain transactions achieve a level of finality backed by Bitcoin’s Proof-of-Work consensus, widely considered the most secure consensus mechanism in blockchain technology.

• This significantly reduces the time it takes to finalize cross-chain transactions and provides strong protection against censorship or fraud attempts during the tunneling process.

• The decentralized Challenger role also strengthens Hemi’s security. Rather than relying on a centralized entity to raise disputes, any participant in the Hemi ecosystem can act as a Challenger, further decentralizing the network and increasing its resistance to fraud.

🏗️ A Phased Approach

The phased approach to Hemi’s Ethereum and Bitcoin Tunnels aims to progressively enhance the security, decentralization, and asset support for cross-chain transfers. Each phase introduces key improvements to the settlement mechanisms and expands the range of assets that can be tunneled across Ethereum, Bitcoin, and Hemi, all while focusing on increasing trust minimization and reducing reliance on centralized actors.

🌐 Season 1: Testnet

🎯 Goal: To lay a solid foundation for the Hemi Network by engaging and incentivizing users, developers, and creators during the testnet phase.

Incentive Structure

• 🔗 On-chain Engagement: Points are allocated for transactions and other on-chain activities.

• 💬 Off-chain Participation: Points are also given for contributions to social platforms and community engagement that support network growth.

Rewards Focus

• Network Utilization and User Onboarding: Prioritizing actions that enhance network usage and integrate new participants effectively.

• Active Community Contributions: Recognizing significant community involvement and impactful contributions off-chain.

Strategic Initiatives

• Customized Financial Support: Crafting grants and investments specifically designed to align with strategic objectives of Hemi's ecosystem.

• Open Application for Innovation: Streamlining the process for developers to propose and deploy on-chain solutions, encouraging broad participation, and lowering barriers to entry.

🌐 Season 2: Mainnet + Token Generation Event (TGE)

🎯 Goal: To amplify network activity and ecosystem growth on the mainnet during the critical period following the TGE.

Incentive Structure

• 🔗 On-chain Engagement: Intensive rewards for activities that demonstrate substantial economic value, such as Total Value Locked (TVL) and transaction volume.

  • Drive substantial TVL growth through strategic protocol integrations.

  • Establish sustainable transaction volume via supported LSTs/LRTs on Hemi.

Rewards Focus

• Economic Contributions: Maximize network activity through strategic liquidity provision and trading.

• Ecosystem Growth: Onboard protocols to enhance the network activity targeting user base expansion.

Strategic Initiatives

• Push for Hemi-native Ecosystem: Promoting the development and integration of native applications though Hemi grants program.

• Support for Strategic Projects: Providing tailored support to projects that significantly contribute to network growth.

• Community-Driven Activities: Encouraging the community to participate in governance and decision-making processes.

🌐 Season 3 - N: Mainnet, Post-TGE

🎯 Objective: Consolidate network growth, enhance economic stability, and transition to decentralized governance on mainnet.

Incentive Structure

• 🔗 On-chain Engagement: Prioritizing liquidity provision, DEX trading volume, and supporting projects that significantly contribute to the network’s economic activity, such as AMM liquidity and Bitcoin DEX trading.

• 💬 Off-chain Participation: Maintaining engagement through community-building initiatives and continued support for established projects.

Rewards Focus

• Transition to Liquidity Mining: Points accumulated in Seasons 1 and 2 are carried over to the next season. Points will be rewarded for strategically interacting with the network.

Strategic Initiatives

• Retroactive Funding Implementation: Beginning to reward builders retroactively for their impactful contributions made in previous seasons.

• Continuation of Grant and Investment Programs: Focusing solely on bespoke agreements, moving away from open applications to more curated and strategic engagements that are aligned with network goals.

• New Inflationary $HEMI for Security: Introducing new $HEMI tokens specifically allocated to enhance network security and operational robustness.

Note: Points awarded by the Hemi Network are intended to encourage user activities that are beneficial to the network. Points are awarded solely to incentivize beneficial network activities and carry no monetary value, or financial rights. The exchange or conversion of points to rewards, if any, will be undertaken at the sole discretion of Hemi.

🏁 Getting Started

Are you building the next killer Hemi application (hApp) or a service that adds value to Hemi's ecosystem? Fill out the form below to let us know what you're building and apply for a grant!

Want some inspiration? Check out the lists below for some of the projects we're most excited about.

If you don't see your idea on this list, we'd still love to hear what you're interested in building!

🤖 Bitcoin-Aware hApps (Using hVM or hBK)

These are hApps that directly take advantage of Hemi's EVM-level Bitcoin awareness.

• Non-Custodial BTC / BTC Asset DEXes

  • A decentralized exchange to trade Bitcoin or Bitcoin-based assets without requiring users to give up custody of their funds.

• Non-Custodial Bitcoin Lending

  • A dApp to enable Bitcoin-based lending (either borrowing Bitcoin itself or using Bitcoin as collateral for other loans) without users giving up custody of their funds.

✨ AI hApps