.NET Core 2.0 RSA PlatformNotSupportedException

.Net Core don't have the toXmlString() and fromXmlString method. but you can use an extension

Workarounds: #874, #23686

Update:

Added ToXmlString and FromXmlString implementations to RSA and DSA in .NET Core 3.0

RSA & DSA examples.

Looks like it's finally been implemented in .NET Core 3.0: https://github.com/dotnet/corefx/pull/37593