Flutter has no native way to generate a cryptographic key inside the device's hardware security chip and sign something with it. You can store keys in the Secure Enclave on iOS or StrongBox on Android, but you have to write Swift and Kotlin yourself, bridge it through method channels, handle the three different signature formats each platform returns, and then figure out how to make the result usable for Ethereum's account abstraction standards. I spent 8 weeks doing exactly that, and the result is chainkey .

The actual problem

I was building a Web3 authentication flow in Flutter. The requirement: seedless wallets. No mnemonic phrase, no "write down these 12 words." The private key lives in the Secure Enclave (iOS) or StrongBox (Android) and never leaves the chip. Every signature requires biometric presence: Face ID, Touch ID, or fingerprint.

No Flutter package did this. The closest options handled key storage in software (Dart-side, exportable) or wrapped a single platform.…