Offchain Labs Criticizes Buterin’s Proposal to Transition EVM to RISC-V

Offchain Labs proposes WASM over RISC-V for Ethereum's EVM modernization.

The primary developer of the L2 network Arbitrum, Offchain Labs, has introduced its own approach to modernizing the Ethereum Virtual Machine (EVM).

The research team proposed transitioning Ethereum to WASM instead of the RISC-V architecture suggested by Vitalik Buterin. In their view, RISC-V is well-suited for generating zero-knowledge proofs, but is not the optimal choice for executing and storing the platform’s smart contracts.

Previously, Buterin stated that RISC-V would solve several first-layer blockchain scaling issues and reduce ZK costs by 100 times.

“We support these goals but question Vitalik’s assumption that a single instruction set architecture can optimally serve both zero-knowledge proofs and smart contract execution,” wrote Mario Alvarez, Matteo Campanelli, Tsachi Zidenberg, and Daniel Lumi.

The developers highlighted several fundamental advantages of the WebAssembly architecture:

• Modular design — allows for the modernization and optimization of executable code while maintaining full backward compatibility with existing contracts;
• Cross-chain efficiency — operates on standard server hardware, unlike RISC-V, which requires emulation on most Ethereum nodes;
• Strict validation — built-in type safety prevents a whole class of vulnerabilities at the execution level;
• Production readiness — the tool ecosystem has been tested in billions of real-world execution environments.

“WASM can become a universal protocol for smart contracts — an ideal intermediate standard that links a variety of programming languages with different execution and verification systems,” the team emphasized.

Arguments Against

The researchers’ key argument is the distinction between “executable” (dISA) and “proving ISA” (pISA). Experts believe that unifying these architectures is not necessary, as they address different tasks.

Offchain Labs is developing a model oriented towards this approach. Arbitrum blocks with Stylus smart contracts based on WASM undergo ZK verification through a two-step process:

1. Compilation of WASM into RISC-V.
2. Generation of RISC-V execution proofs.

“We are already capable of verifying real blockchain blocks through ZK proofs, where WASM is used as the executable architecture, and a RISC-V-based ZK-VM functions as the computational backend,” the experts explained.

The team also pointed to the rapidly changing landscape of proof technologies, questioning whether RISC-V is the final point in the evolution of ZK-VM. As an example, they cited the recent transition from 32- to 64-bit RISC-V implementations, demonstrating that standards continue to evolve.

According to the researchers, fixing the architecture at L1 could limit Ethereum’s flexibility in the future, preventing adaptation to more advanced proof technologies that will inevitably emerge.

WASM-based ZK-VMs like Ligetron from Ligero already demonstrate functional advantages potentially unattainable for hardware-oriented models.

The cost of zero-knowledge proofs has decreased to approximately $0.025 per block and continues to fall.

“Even if multiple ZK proofs per block are required, these costs will remain insignificant compared to gas fees and MEV revenues received by the validator,” the experts clarified.

In April, Cardano founder Charles Hoskinson positively assessed Buterin’s proposal to replace EVM with the RISC-V architecture.