Cryptography hang GUI loader

[xandros6]

Cryptography library not use Isolates so there are 2 points in the code of security1.dart :

line88 :await _generateKey();
line105 :final sharedKey = await x25519.sharedSecretKey;

that cause the hang of GUI loader for some seconds.

I try to add Isolate, but I'm unable to do it works.
Can you help me pelase?