public Task<byte[]> GetEntropy1(int length)
{
    RNGCryptoServiceProvider entropyGen = new RNGCryptoServiceProvider();
    byte[] entropyBuffer = new byte[2048];

    try
    {
        semaphore.Wait();

        Task t = Task.Run(() =>
        {
            /* gather entropy from sensors */
        });

        if (!t.Wait(5000))
        {
            entropyGen.GetBytes(entropyBuffer);
        }
        return entropyBuffer;
    }
    catch (Exception)
    {
        return entropyBuffer;
    }
    finally
    {
        this.semaphore.Release();
    }
}