如何“取消模仿”(取消代表?)在Kerberos中

我有一门课:

public class ProcessIdentityScope : IDisposable
{
    private System.Security.Principal.WindowsImpersonationContext _impersonationContext;
    private bool _disposed;

    public ProcessIdentityScope()
    {
        _impersonationContext = System.Security.Principal.WindowsIdentity.Impersonate(IntPtr.Zero);
    }

    #region IDisposable Members

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!_disposed)
        {
            _impersonationContext.Undo();
            _impersonationContext.Dispose();
            _disposed = true;
        }
        else
            throw new ObjectDisposedException("ProcessIdentityScope");
    }

    #endregion
}

我是这样使用的:

using(ProcessIdentityScope identityScope = new ProcessIdentityScope())
{
    // Any code in here runs under the Process Identity.
}

此代码基于此msdn文章: http://msdn.microsoft.com/en-us/library/ms998351.aspx