This page demonstrates how to sign EIP712 typed data using MetaMask and verify it in Solidity. Feel free to learn from it and adapt it for your dApp and smart contracts.
Thank you to Christoph Mussenbrock for Solidity 0.5.0 and variable chain ID support, and Dan Finlay for EIP1102 support.
To use this demo, you need at least version 4.14.0 of MetaMask which supports eth_signTypedData_v3.
The signature generated by MetaMask, as well as your wallet address, has been inserted into the Solidity code above. The code hashes the data you just signed, runs ecrecover with yoour signature, and compares it with your wallet address.
If Remix displays
0: bool: truethat's great! Your wallet address was successfully authenticated against the signature.