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Four Arbitrum development specialists from Offchain Labs have disagreed with Vitalik Buterin’s stance on implementing the RISC-V instruction set architecture (ISA) for the Ethereum execution tier.

In their opinion, WASM seems to be a better long-term solution than RISC-V for Ethereum’s L1 smart contract format, or delivery ISA.

Offchain Labs, a key developer of Ethereum Arbitrum layer 2 solutions, has spoken out against Vitalik Buterin’s proposal to move Ethereum’s executive layer to RISC-V, publishing a detailed technical breakdown that argues for the superiority of WebAssembly (WASM) in the long term.

In a Nov. 20 post on Ethereum Research, four experts from Offchain Labs argue that while RISC-V is currently performing well in generating ZK confirmations, that does not make it the optimal choice for depositing and storing smart contracts on the Ethereum network.

Ethereum co-founder Buterin suggested in an April post on Ethereum Magicians that the Ethereum virtual machine bytecode be replaced by the open RISC-V instruction set architecture (ISA) (pronounced risk-five

), arguing that it could potentially reduce the cost of in-chain ZK proofs by up to a hundred times in some cases.

We share these goals, but question Vitalik’s unfounded conclusion that the same ISA can be ideal for both ZK evidence and smart contract delivery.

Mario Alvarez, Matteo Campanelli, Tzahi Siedenberg and Daniel Lumi note.

Separation of delivery and proof?

The team’s main thesis is that there should be a separation between the dISA (dISA) delivery ISA – the format for uploading contracts to the network – and the pISA (pISA) proof-of-concept ISA used by ZK virtual machines. They feel that these functions should not be combined.

Offchain Labs is already building a test case to support this idea: Arbitrum blocks, including WASM-based Stylus smart contracts, undergo ZK verification through compilation of WASM into RISC-V and subsequent proof-of-work on RISC-V.

We are able to conduct ZK proof-of-stake real blockchain proofs today on a blockchain that uses WASM as a dISA, using RISC-V-based ZK-VM as the server side,”

the publication said.

the team is skeptical about the prospect of RISC-V as the end point in ZK-VM’s development, pointing to the rapid changes in the evidence domain. The recent move from 32-bit to 64-bit versions of RISC-V underscores this uncertainty.

RISC-V’s fixation on L1 could tie Ethereum to a particular proof-of-concept technology while better alternatives emerge, they warn, while WASM-based ZK-VMs such as Ligero’s Ligetron are already demonstrating advantages that hardware-based ISAs may not be able to match.

Meanwhile, the cost of ZK proof-of-concept has dropped to around $0.025 per Ethereum block and continues to fall, making narrowly focused optimization for proof-of-concept efficiency less of a priority, researchers say.

“Even if L1 required multiple ZK proofs per block, these costs would be negligible compared to the gas and MEV fees a block builder might receive,”

, they write.

The team notes WASM’s structured design, which makes it easy to make changes and optimize code without breaking compatibility with existing contracts. In addition, WASM works well on standard hardware, whereas most Ethereum nodes lack RISC-V processors, requiring emulation.

WASM’s validation capabilities ensure type-safety and prevent vulnerabilities, and its mature toolkit has been tested in billions of execution scenarios.

“We believe that WASM can become a kind of Internet protocol for smart contracts, acting as an ideal intermediary between the various source code languages used to create smart contracts and the various server solutions used to execute and validate them.