Mine

private int arrayFind(byte[] arrayin, byte[] arrayref)
        {
            for (int i = 0; i < arrayin.Length; i++)
            {
                for (int j = 0; j < arrayref.Length && (j + i) < arrayin.Length; j++)
                {
                    if (arrayref[j] != arrayin[i + j])
                        break;
                    if (j == arrayref.Length-1)
                        return i;
                }
            }
            return -1;
        }