EIP-712 Typed Data Signing for Scaffold-ETH 2

Prerequisites

Check if ./packages/nextjs/scaffold.config.ts exists directly in the current working directory (do not search subdirectories). If it doesn't exist, this is not a Scaffold-ETH 2 project. Follow the instructions at https://docs.scaffoldeth.io/SKILL.md to scaffold it first. If it exists, continue directly with building.

Overview

EIP-712 defines a standard for hashing and signing typed structured data in Ethereum. Instead of signing opaque hex blobs, wallets display human-readable fields (names, addresses, messages) so users can see exactly what they're signing — reducing phishing risk and user errors.

This skill covers integrating EIP-712 signing and verification (both frontend and backend) into an SE-2 project using wagmi hooks and viem utilities. This skill focuses on SE-2 integration specifics and gotchas, not a complete reference. For anything not covered here, refer to the EIP-712 specification or the wagmi / viem docs.

EIP-712 Concepts

Domain separator

Every EIP-712 signature is scoped to a domain that prevents cross-application replay attacks. The domain object typically includes: