Could you add Curve25519 sign algorithm?

[raqeta]

I found this implementation by k-s-t-i. It's works with Dart earlier version. Or I can create pull request later. Thanks :) https://github.com/k-s-t-i/curve25519-dart

[soatok]

Curve25519 is ECDH, not a signature algorithm.

You want Ed25519.