Midpoint EOAs

All on-chain transactions come from a known EOA that your contract can verify.

// Checks that the caller is the known EOA. Ensures that your callback is only called when your midpoint returns a response.
require(tx.origin == 0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9, "Invalid EOA");

Live callback EOAs:

Chain	Address
Ethereum Goerli Testnet	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Optimism Goerli Testnet	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Arbitrum Goerli Testnet	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Polygon Mumbai Testnet	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Filecoin Hyperspace Testnet	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Ethereum	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Optimism	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Arbitrum	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9
Polygon	0xC0FFEE4a3A2D488B138d090b8112875B90b5e6D9

Look for 0xC0FFEE when checking an address.