Zero-Knowledge Proofs (ZKPs) have evolved rapidly in the blockchain space, expanding from initial privacy applications to enabling verifiable general-purpose computation. The emergence of Zero-Knowledge Virtual Machines (zkVMs) has significantly broadened the applicability of ZK technology.
This guide provides a systematic overview of zkVM core concepts, mainstream technical approaches, application scenarios, and how to choose the right zkVM tools for your needs.
What Is a zkVM?
A Zero-Knowledge Virtual Machine (zkVM) is a computational system capable of running programs and generating zero-knowledge proofs of their execution. It enables verification that "a specific program produced a specific output from specific inputs" while preserving computational privacy or compressing the computation process.
In simple terms, zkVM transforms program execution into a mathematically verifiable fact.
The Motivation Behind zkVMs
Traditional blockchain systems face two core challenges:
- Poor Scalability: Every node must execute all transactions, leading to high computational costs and low throughput.
- Limited Privacy: All operations and state are public, making it difficult to support business logic involving private data.
zkVMs emerged to address these problems:
By combining circuit execution with zero-knowledge proofs, zkVMs enable computations to be performed off-chain. Only a small proof must be verified on-chain, improving both performance and privacy.
Main Types of zkVMs
As zero-knowledge proof technology has advanced, developers have explored multiple zkVM approaches based on different circuit designs and virtual machine architectures. These can be broadly categorized into three types:
zkWASM / zkLLVM: Compiling High-Level Languages to ZK Circuits
Representative Projects: zkWASM (Delphinus), RISC Zero, SP1, Jolt
- Programming Languages: Rust, C/C++, Go, etc.
- Implementation: Source code is compiled to an intermediate language (e.g., WASM or LLVM IR), which is then translated into a ZK circuit.
- Advantages: Low development barrier, mature ecosystems, suitable for web and AI developers.
- Use Cases: Off-chain computation, ZK coprocessors, privacy-preserving dApps, ZK oracles.
zkEVM: Ethereum Virtual Machine Compatibility
Representative Projects: Polygon zkEVM, zkSync Era, Scroll, Taiko, Kakarot
- Programming Languages: Solidity / Vyper
- Implementation: The Ethereum Virtual Machine (EVM) environment is simulated, with circuits designed for each instruction.
- Advantages: 100% compatibility with Ethereum, allowing existing smart contracts to migrate seamlessly.
- Use Cases: Layer 2 zkRollups, smart contract privacy protection.
zkRISC / Instruction Set Simulators
Representative Projects: RISC Zero, SP1, Jolt, ZK-MIPS, Valida
- Implementation: Simulates a CPU-level instruction set (e.g., RISC-V, MIPS).
- Programming Languages: Rust or C, compiled for execution.
- Advantages: Highly general-purpose and flexible, capable of running arbitrary programs.
- Use Cases: AI inference, cross-chain verification, large-scale trusted off-chain computation.
The zkVM Application Landscape
zkVMs enable more than just Rollups; they can help build an entire trusted off-chain world. Below is a simplified map of zkVM applications:
| Application Direction | Example Scenarios | Description |
|---|---|---|
| ✅ zkRollup Execution Engine | zkSync, Polygon zkEVM, Scroll | Executes transactions or contracts in a Rollup, generating state transition proofs. |
| ✅ Privacy-Preserving Computation | Identity verification, anonymous voting, healthcare data sharing | Uses zkVM to protect input privacy while ensuring correct execution. |
| ✅ ZK Coprocessor / Off-Chain AI | Running AI models, complex off-chain computations | zkVM runs programs off-chain and generates ZK proofs for rapid on-chain verification. |
| ✅ ZK Oracle | Verifying real-world data (e.g., weather, prices) | Eliminates the need to trust intermediaries; only the zkVM proof is trusted. |
| ✅ Cross-Chain Verification / Light Clients | Cross-chain state sync, verifying foreign chain headers | zkVM executes light node logic, generating validity proofs for cross-chain operations. |
| ✅ ZK Data Markets / DA Applications | Private file uploads, ZK proof of ownership | zkVM verifies file integrity or processes data without revealing content. |
The Relationship Between zkVM and zkRollup
zkVMs and zkRollups are often conflated, but they serve distinct yet highly related roles:
zkRollup is a scaling architecture; zkVM is one of its key components.
| Component | Definition | Role |
|---|---|---|
| zkRollup | Executes batches of transactions off-chain, submitting only a state proof to the chain. | Provides the scaling structure. |
| zkVM | Transforms program execution into a verifiable zero-knowledge proof. | Serves as the verifiable computation engine. |
In other words:
zkRollup is the highway.
zkVM is the computation engine running on that highway.
Most zkRollups integrate a zkVM or zkEVM circuit implementation. For example, zkSync uses a custom zkLLVM compiler with a zkEVM, Scroll uses a zkEVM simulator, and RISC Zero supports generating execution proofs for zkRollups.
How zkVMs Work: A Technical Overview
The core mechanism of a zkVM involves transforming program execution → mathematical constraint system → zero-knowledge proof:
From a Developer's Perspective:
- Write a standard program (in Rust, Solidity, C, etc.).
- The zkVM compiler converts it into a circuit (composed of gates and constraints).
- The circuit is executed, generating a witness.
- A proof system (e.g., STARK, Plonk) generates a succinct proof.
- An on-chain verifier checks the proof without re-executing the program.
The design of the circuit and the performance of the proof system are critical factors determining a zkVM's competitiveness.
Comparison of Mainstream zkVM Frameworks
| Framework | Programming Language | Technical Highlights | Proof System | Primary Application Scenarios |
|---|---|---|---|---|
| RISC Zero | Rust | RISC-V VM, off-chain proof, on-chain verification | zk-STARK | General computation, AI, zkOracle |
| SP1 | Rust | Faster RISC VM alternative | STARK | zkAI, off-chain computation |
| zkSync VM | Solidity | Highly optimized zkEVM | zk-SNARK | zkRollup |
| Scroll zkEVM | Solidity | High EVM compatibility | zk-SNARK | Ethereum scaling |
| Delphinus zkWASM | WASM / C / Rust | Compiles to zkWASM | zk-SNARK | Web ZK applications |
| Jolt / Valida | TBD | High-speed proof generation | STARK + FRI | Emerging zkVM use cases |
How to Choose a zkVM
| Your Requirement | Recommended Solution | Reason |
|---|---|---|
| Building an EVM-compatible Rollup | zkSync / Polygon zkEVM / Scroll | Supports Solidity, mature ecosystem. |
| General computation, AI inference | RISC Zero / SP1 | Write in Rust, strong general-purpose execution capability. |
| Cross-chain verification / light clients | Valida / ZK-MIPS | Simulates various CPU environments. |
| Building ZK privacy web applications | zkWASM / Delphinus | WASM ecosystem, simple web integration. |
👉 Explore advanced zkVM development tools
Conclusion: The Future of zkVMs
zkVMs are emerging as a "new computational paradigm" for building trusted systems.
From cryptocurrency to off-chain AI, and from privacy protection to cross-chain interoperability, zkVMs represent a unified paradigm of program + proof:
"You don't need to re-run the computation; just verify that I ran it correctly."
—This is the core value proposition of zkVMs.
As the technology matures, we can expect zkVMs to become the "trusted computation engine" within Web3 infrastructure, enabling a new generation of applications.
Frequently Asked Questions
What is the main difference between a zkVM and a traditional VM?
A traditional Virtual Machine (VM) simply executes code. A zkVM not only executes code but also generates a zero-knowledge proof that the execution was performed correctly, without revealing the underlying data or requiring others to re-execute it.
Do I need to be a cryptography expert to use a zkVM?
No. Many modern zkVM frameworks are designed for software developers. You can write programs in familiar languages like Rust or Solidity, and the framework handles the complex process of proof generation.
Are zkRollups and zkVMs the same thing?
No. A zkRollup is a scaling solution that batches transactions. A zkVM is the engine inside a zkRollup that generates proofs for those batched transactions. A zkRollup uses a zkVM, but a zkVM can be used for many other applications beyond Rollups.
What are the current limitations of zkVM technology?
Key challenges include the computational overhead of proof generation (prover time), the cost of verification, and the complexity of circuit design for certain operations. However, these are active areas of research and rapid improvement.
Can zkVMs be used for artificial intelligence (AI)?
Yes. This is a major use case. A zkVM can run an AI model on private data off-chain, generate a proof that it was done correctly, and only submit the proof and result on-chain. This enables verifiable AI without compromising data privacy.
How do I get started building with a zkVM?
The best way to start is to choose a framework based on your preferred language (e.g., RISC Zero for Rust) and work through their tutorials to understand how to compile a simple program and generate a proof.