SubArray

private static byte[] SubArray(byte[] arr, int start, int count = 0, bool maintainKeys = false)
{
    if (count == 0)
    {
        count = arr.Length - start;
    }

    byte[] result = new byte[count];

    for (int i = start, j = 0; j < count; i++, j++)
    {
        result[maintainKeys ? i : j] = arr[i];
    }
    return result;
}