ECDH P521 UnimplementedError

[a7mdragab]

Hello, I am using ECDHP521 https://pub.dev/documentation/cryptography/latest/cryptography/ecdhP521-constant.html

When trying final localKeyPair = ecdhP521.newKeyPairSync(); or final localKeyPair = await ecdhP521.newKeyPair();

I got the error

ERROR:flutter/lib/ui/ui_dart_state.cc(171)] Unhandled Exception: UnimplementedError

Can you help? Thanks

[mariganesh555]

I have the same issue . Any solution is there?

final algorithm = Ecdh.p256(length: 32);

[xal]

The documentation says it is implemented only for web builds (mobile not implemented yet)

[tutti]

Where does it say that? The closest I've been able to find is "We don't have implementations of these in pure Dart", which doesn't mean "only on web" at all.

[terrier989]

ECDH and ECDSA are supported only in the browser at the moment.

[tutti]

Yes, I know that (now). But I'm referring to this (emphasis mine):

The documentation says it is implemented only for web builds (mobile not implemented yet)

Where?

[krille-chan]

In the past you were able to use the webcrypto package for ECDH on Android and iOS but this is no longer working since Flutter 2.5. Is there a chance that this can be implemented in this package now? Otherwise I see no way to use ECDH anymore with Flutter at all :-( Would a bounty help here?

[FlutterCrypto]

@krillefear: When using web crypto with actual Dart (Dart version 2.14.4) I ran into the same issue (error: "package:webcrypto failed to attached finalizer").

This message is thrown in impl_ffi.utils.dart and in this routine web crypto tries to let the Dart GC delete the no longer used key as fast as possible. I temporary solved this problem by commenting out the line "throw AssertionError('package:webcrypto failed to attached finalizer');".

I already know that this is a security feature (leave a less cryptographic footprint in the memory) but the GC will delete the key when it is not longer in use.

You can follow a possible solution here: https://github.com/google/webcrypto.dart/issues/10

Kind Regards Michael

[PwS]

any update for this ?

[terrier989]

This package supports ECDH and ECDSA on:

• Browsers
• Apple operating systems (iOS, Mac OS X)
• Android

[terrier989]

I close the ticket as P521 is now supported on the main platforms (browser, iOS, Android).

It would be nice if we had supported the ECDH/ECDSA on Windows and Linux too. I guess the easiest way to accomplish this would be BoringSSL. Feel free to create a ticket for that. :)

[romgrm]

If anyone comes across this, the Ecdsa generation does not work on simulator/emulator, only on real devices :)