<PackageReference Include="Microsoft.Bcl.Cryptography" Version="11.0.0-rc.1.26425.128" />

System.Security.Cryptography.RSAKeyFormatHelper

static class RSAKeyFormatHelper
namespace System.Security.Cryptography { internal static class RSAKeyFormatHelper { internal delegate TRet RSAParametersCallback<TRet> (RSAParameters parameters); } }