Mainnet
OrdiVM builds upon the innovative concepts pioneered by SatoshiVM, creating a next-generation decentralized Bitcoin ZK Rollup Layer 2 solution. This powerful platform seamlessly integrates with the OrdiVM ecosystem, combining the security and value anchoring of Bitcoin with the programmability and versatility of OrdiVM.
Here's a breakdown of the core technologies powering OrdiVM:
ZK Rollup: OrdiVM leverages Rollup technology to efficiently process transactions. It bundles multiple transactions off-chain and submits them as a single batch for verification on the OrdiVM Rollup Node.
Enhanced ZK Verification: Inspired by BitVM, OrdiVM employs an advanced ZK verification scheme that eliminates the need for a challenge-response protocol. This method utilizes Taproot scripts to verify function execution within OrdiVM without altering Bitcoin's consensus rules. This ensures the secure and efficient validation of transactions on OrdiVM.
Data Availability: To maintain transparency, OrdiVM transmits block transaction data to the Bitcoin mainnet. This allows anyone to independently verify the accuracy of computations performed on the OrdiVM platform.
Native BTC Gas: Similar to how Ethereum Layer 2 solutions utilize ETH for gas fees, OrdiVM leverages native BTC as gas for transactions within the OrdiVM environment.
We'll delve deeper into the technical architecture of OrdiVM in the following sections. This will provide a comprehensive understanding of how these technologies work together to deliver a secure, scalable, and user-friendly platform.
OrdiVM: Sequencing Transactions Securely and Scalably
Similar to Ethereum's ZK Rollups, OrdiVM employs a layered architecture. The Sequencing Layer acts as the backbone of the network, analogous to the Execution Layer in Ethereum. This critical layer houses essential components for efficient transaction processing.
The Heart of Transaction Processing
Execution Module: This module resembles Ethereum Layer 2's Sequencer. It centrally receives and processes user transactions, generating new OrdiVM blocks or transaction batches.
Rollup Nodes: These nodes, further divided into ordinary full nodes and Proposers, play a crucial role in verification. Proposers collaborate with the Sequencer to synchronize transaction content.
Synchronized Transactions for Secure Verification
Inspired by Ethereum Layer 2 designs, OrdiVM utilizes a similar synchronization process between the Sequencer and Proposer. This synchronization can occur off-chain or after on-chain publication, ensuring both parties have the latest data. Importantly, both the Sequencer and Proposer run Bitcoin nodes for smooth network operation.
Sequencing Transactions for Efficient Processing
Before making transaction batches public, the OrdiVM Sequencer establishes their order. This process triggers a series of actions:
Transaction Execution: The Sequencer locally executes transactions and updates the state.
Data Packaging: Transaction data is assembled into a batch (txn batch) / Block and sent to the Prover (optional) and the Proposer.
Uploading to Bitcoin Chain: The Sequencer uploads the batch to the Bitcoin chain. The Proposer downloads this data and completes the state update locally.
State Commitment Publication: The Proposer publishes the updated State commitment (State root) to the Bitcoin chain.
Challenge Response: If challenged, the Proposer responds with the necessary proof.
Privacy-Preserving Mempool
Similar to most Layer 2 solutions, OrdiVM utilizes a private mempool, keeping transaction data within the pool confidential. This aligns with solutions like Arbitrum on Ethereum.
Guaranteed Block Generation
Regardless of new transactions, the OrdiVM Sequencer can ensure a new Block generation every 3 to 60 seconds off-chain.
Censorship-Resistant Transactions
Users have two ways to submit transactions:
Direct On-Chain Submission: Users can directly publish transaction data in a specific format on the Bitcoin chain. Layer 2 nodes monitor these transactions. If the Sequencer ignores valid user requests, the generated blocks will fail verification by Rollup nodes and Proposers, preventing censorship.
This breakdown clarifies the OrdiVM sequencing layer, highlighting its secure, scalable, and censorship-resistant transaction processing mechanisms.
OrdiVM: Transaction Submission and Verification
OrdiVM offers two methods for users to submit transactions, providing flexibility and security:
1. Direct Submission Within the Layer 2 Network (RPC Calls)
This is the more common approach, where users send transaction requests directly to designated OrdiVM nodes via Remote Procedure Calls (RPC). These nodes then forward the requests to the Sequencer for processing. Compared to on-chain submission, this method is significantly cheaper but could be susceptible to censorship or rejection by the Sequencer.
2. Direct On-Chain Submission
This method prioritizes censorship resistance. Users can directly publish their transaction data in a specific format on the Bitcoin chain. Layer 2 nodes constantly monitor these transactions. If the Sequencer ignores valid user requests submitted on-chain, the generated blocks will fail verification by OrdiVM full nodes and Proposers, preventing censorship.
Balancing Efficiency and Security
The ideal scenario would be replicating Layer 1's censorship resistance on Layer 2. However, due to Bitcoin's limitations with smart contracts, current Layer 2 solutions cannot directly embed user transactions within an on-chain Rollup contract like Ethereum Layer 2. While Ethereum allows deploying fixed Rollup contracts on Layer 1 to manage state data and integrate user transactions, this approach isn't feasible for Bitcoin Layer 2.
OrdiVM's approach, similar to other leading Bitcoin Layer 2 projects, achieves the highest level of censorship resistance possible within these constraints.
OrdiVM: Rollup Nodes and Proposers Revisited
As mentioned earlier, OrdiVM utilizes two key node types:
Rollup Nodes: These act as standard full nodes within the Layer 2 network.
Proposers: A select group of Rollup nodes with special permissions.
Data Synchronization: Two Methods
Rollup nodes and Proposers can synchronize newly added transaction data from the Sequencer through two methods:
P2P Network: Rollup nodes can form a peer-to-peer (P2P) network. Nodes can voluntarily request the latest transaction batches from their peers within this network. This method is faster but offers less censorship resistance. In a malicious scenario, the Sequencer or a majority of nodes could isolate certain nodes, hindering their ability to synchronize data.
Waiting for On-Chain Publication: Rollup nodes can wait for the Sequencer to publish the latest transaction batch on the Bitcoin chain. They can then parse the latest blocks from this data. This method is slower but more resistant to censorship. Even if isolated by other nodes, anyone can still download and synchronize data directly from the Bitcoin chain.
Proposers and State Commitments
After synchronizing a batch of ordered transactions, a Proposer node executes them sequentially and generates new state commitments (State root). These commitments are unique values that summarize the overall state of all accounts within the system. Any change in an account's status will trigger a corresponding change in the state commitment. Essentially, different state commitments represent the global state at different points in time.
The Proposer is responsible for publishing these commitments, derived from off-chain computations, onto the Bitcoin blockchain. (Refer to the L2BEAT website for a deeper dive into State root and Proposers).
In essence, OrdiVM utilizes designated Proposers within the Rollup node network to promptly publish commitments for each transaction batch onto the Bitcoin blockchain, ensuring transparency and verifiability.
OrdiVM: Settlement Layer - Ensuring Secure Transactions
The settlement layer plays a critical role in OrdiVM's modular architecture. Similar to Celestia's approach, this layer focuses on two core functions:
State Transition Verification: This ensures the validity of off-chain state updates within OrdiVM.
Bridging Components: These components facilitate secure asset transfers between the Bitcoin mainnet (Layer 1) and OrdiVM (Layer 2).
Some blockchain projects further divide the settlement layer into arbitration and bridging layers. The arbitration layer verifies state commitments, while the bridging layer handles asset transfers.
Commitments and Verifiable Proofs
As mentioned earlier, Proposer nodes in OrdiVM regularly submit State Commitments to the Bitcoin chain. These commitments represent the completion of a batch of off-chain transactions and the resulting new state within OrdiVM. Importantly, State Commitment publication happens concurrently with ZK proof generation. These proofs are then published as Taproot-locked UTXOs on the Bitcoin mainnet.
Non-Interactive On-Chain Verification
OrdiVM utilizes a non-interactive on-chain verification scheme. After a Proposer submits a Commitment on the Bitcoin chain, Verifier nodes on the network observe this value. These Verifier nodes then attempt to independently acquire the complete data set corresponding to the Commitment to verify its accuracy.
Error Detection and Dispute Resolution: If Verifiers detect discrepancies, they can initiate a one-time interaction with Bitcoin nodes directly. This interaction helps pinpoint specific errors within the original data set associated with the disputed Commitment. Subsequently, the Verifier can penalize the Proposer by transferring their Bitcoin UTXO.
This approach ensures the integrity of the system without requiring constant back-and-forth communication on the Bitcoin chain.
OrdiVM: Secure Verification and Finality
Simplifying Dispute Resolution
Unlike bitVM, OrdiVM's penalty mechanism for Proposer misconduct avoids a challenge-response process. Verifiers can determine and enforce penalties in a single interaction using the capabilities of Taproot scripts and time locks. External observers can also monitor specific UTXO movements on the Bitcoin chain to verify the validity of Commitments after they are finalized and become immutable. This approach inherits Bitcoin's finality for OrdiVM's Layer 2 ledger data.
Step-by-Step Verification
Imagine this scenario: The OrdiVM Sequencer broadcasts a message asking everyone to compute "1+1=?". Every Rollup Node independently calculates the answer, resulting in "1+1=2." Designated Proposers are then obligated to announce this new state ("2") on the Bitcoin chain.
The Proposer submits the hash of "2" to the Bitcoin chain, signifying the hashed representation of the current OrdiVM state. Additionally, the Proposer provides a ZK proof (in the form of Taproot-locked UTXOs) that verifies the computation process. Anyone can confirm the validity of the OrdiVM state by spending these UTXOs.
Removing the Proving Layer (Integrated Verification)
OrdiVM streamlines the verification process by integrating verification capabilities within the existing node structure. Unlike SatoshiVM's separate Proving Layer, Verifiers are embedded within OrdiVM nodes, ensuring the system's security and preventing malicious behavior by the Sequencer.
The Sequencer transmits Layer 2 blocks directly to Proposers, who then generate ZK proofs and submit them for inclusion in the final submission.
Synchronized Nodes for Efficient Verification
In parallel, the Sequencer and Rollup nodes maintain local copies of the complete OrdiVM ledger data and global state. This synchronized information allows Provers to generate accurate ZK proofs reflecting the latest state changes.
Verification and Dispute Resolution
Once ZK proofs are received, Proposers perform verification. The corresponding Commitment for the verification process is then published on the Bitcoin mainnet. Verifiers can download this Commitment for local verification. If discrepancies are found, Verifiers can initiate challenges using OrdiVM's adaptations of bit commitment Taproot and verification Taproot.
This revised explanation removes the separate Proving Layer concept in SatoshiVM and integrates verification within the existing OrdiVM node structure for a more streamlined and efficient approach.