reflection and private methods

[csharpuser]

Does anybody know how to disallow the direct invokation of a private method using reflection but still allow the invokation through reflection of a public method which uses the private method.

To be more explicit lets take an example. Having the following methods in a class:

public void UpdateMyStuff(string data)
{
//transform input data and call the private method
UpdatePrivately(transformedData);
}

private void UpdatePrivately(string transformedData)
{
//make the actual update operations
....................................
}

Basically I would like to be possible to invoke the UpdateMyStuff method through reflection but not to allow anybody to invoke the UpdatePrivatly method, not even through reflection. Maybe somehow the ReflectionPermission could solve this problem?

Thank you very much, any help would be appreciated!