feature request: biometric authentication

[khimaros]

similar to FIDO, but unlock the key using fingerprint or other biometric offered by the operating system?

[vicajilau]

Thanks for the feature request!

While biometric authentication is a great user experience feature, we think this is better implemented at the application level rather than in the SSH library itself.

Here's why:

1. Platform-specific: Biometric APIs vary significantly across platforms (Windows Hello, Touch ID, Android Biometric API, etc.). Adding this to dartssh2 would create OS-specific dependencies, breaking the cross-platform purity of the library.

2. Separation of concerns: Your app should handle the UI flow: "user enables biometric → key is unlocked locally → dartssh2 uses the unlocked key". The library should remain stateless about how keys are obtained.

3. Existing standards: If you're interested in hardware security keys (FIDO2/U2F), that's a different and more standardized approach. OpenSSH already supports ssh-sk-* formats (security keys), which dartssh2 could potentially support in the future. That would be a more aligned feature request.

Recommendation: Implement biometric unlock in your client app (using platform-specific biometric APIs), then pass the decrypted key to dartssh2 as normal.