CngKey.Create throws "The requested operation is not supported." during key import from Blob

HI,

I try to import key from blob using "Microsoft Software Key Storage Provider". This is my code:

byte[] keyBlob = File.ReadAllBytes("c:\\privkey.der");

string container = "MyContainer";
CngProvider myKSP = new CngProvider("Microsoft Software Key Storage Provider");
if (!CngKey.Exists(container, myKSP))
{

    CngKeyCreationParameters keyParams = new CngKeyCreationParameters();

    //Will allow export of full keypair to the file later on
    keyParams.ExportPolicy = CngExportPolicies.AllowPlaintextExport;

    keyParams.KeyCreationOptions = CngKeyCreationOptions.None;

    //Set the Key Storage Provider
    keyParams.Provider = myKSP;
    keyParams.KeyUsage = CngKeyUsages.Signing;

    //Set the RSA keysize to 2048
    CngProperty keySizeProperty = new CngProperty("Length", BitConverter.GetBytes(2048), CngPropertyOptions.None);
    keyParams.Parameters.Add(keySizeProperty);

    //Most important step -> import the keyblob as byte[]
    CngProperty keyBlobProperty = new CngProperty(CngKeyBlobFormat.Pkcs8PrivateBlob.Format, keyBlob, CngPropertyOptions.None);
    keyParams.Parameters.Add(keyBlobProperty);

    CngKey myCNGKey = CngKey.Create(new CngAlgorithm("RSA"), container, keyParams);
}

Create operation throws an exception:

System.Security.Cryptography.CryptographicException was unhandled
  HResult=-2146893783
  Message=The requested operation is not supported.

  Source=System.Core
  StackTrace:
       at System.Security.Cryptography.NCryptNative.SetProperty(SafeNCryptHandle ncryptObject, String propertyName, Byte[] value, CngPropertyOptions propertyOptions)
       at System.Security.Cryptography.CngKey.SetKeyProperties(SafeNCryptKeyHandle keyHandle, CngKeyCreationParameters creationParameters)
       at System.Security.Cryptography.CngKey.Create(CngAlgorithm algorithm, String keyName, CngKeyCreationParameters creationParameters)
       at ConsoleApplication4.Program.Main(String[] args) in c:\Users\mkaszubs\Documents\Visual Studio 2012\Projects\ConsoleApplication1\ConsoleApplication4\Program.cs:line 48
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

 

This code comes from different post on this forum. Interesting part is that I was able to Import this key using 

CngKey key = CngKey.Import(keyBlob, CngKeyBlobFormat.Pkcs8PrivateBlob, myKSP);

So it looks like blob is formated correctly.

My OS: Windows Server 2008 R2 Enterpriese

.Net: Framework 4.5

Any suggestion what can be wrong here?

Regards,

Marcin