记一次代码学习记录

    场景：生成6位验证码


    public int ComputeTotp(/*HashAlgorithm hashAlgorithm, ulong timestepNumber, string modifier = null*/)
    {
        var hashAlgorithm = new HMACSHA1();
        var timestepNumber = (ulong)DateTime.UtcNow.Ticks;

        byte[] bytes = BitConverter.GetBytes(IPAddress.HostToNetworkOrder((long)timestepNumber));
        var steam = new MemoryStream(bytes);
        byte[] array = hashAlgorithm.ComputeHash(/*Rfc6238AuthenticationService.ApplyModifier(bytes, modifier)*/steam);
        int num = (int)(array[array.Length - 1] & 15);
        int num2 = (int)(array[num] & 127) << 24 | (int)(array[num + 1] & 255) << 16 | (int)(array[num + 2] & 255) << 8 | (int)(array[num + 3] & 255);
        return num2 % 1000000;
    }