HMAC signature of a string: returns hex and base64. ?algo=sha256|sha512|sha1|md5|sha3-256&key=<secret>&input=<message>. Deterministic and independently verifiable.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.003000 USDC | 0xA437...5561 |
| Polygon | exact | $0.003000 USDC | 0xA437...5561 |
| Arbitrum One | exact | $0.003000 USDC | 0xA437...5561 |
| nano:mainnet | exact | 8628000000.000000 tokens | nano_3...z4ss |