EIP-712 Typed Data Signing

Overview

What it means and why it exists

EIP-712 typed-data signing is an Ethereum signing method that structures a message into named, typed fields so wallets can display more meaningful authorization details than a raw unreadable string.

How it works

An application defines a domain, such as contract and chain, and a typed message schema. A wallet hashes the structured data according to EIP-712, signs it, and returns a signature that a contract or backend can verify. Applications use it for orders, permits and other off-chain authorizations that may later be submitted on chain.

Technical details worth understanding

The domain separator and exact field definitions are central to preventing signatures from being interpreted in the wrong context. EIP-712 alone does not guarantee one-time use or expiration; developers must include and enforce nonces, deadlines and appropriate authorization logic where needed. A displayed signature request should make the spender, asset, amount and action clear.

What can go wrong

Human-readable fields can still describe a malicious permission. Signing a typed message may authorize spending or a marketplace order without immediately sending an on-chain transaction. A user should not conclude 'no gas fee' means 'no financial risk'.

Practical checks

Inspect domain chainId and verifyingContract, then verify the operation type, token, spender, amount, nonce and deadline. A typed-data request can authorize future action even when the signer pays no gas now. Front ends should not hide critical fields under a generic 'Continue' button, especially for permits.

Related concepts

Crypto Wallet, Private Key, Non-Custodial Wallet.

Further reading

Ethereum EIP-712 — Typed Data Signing.