Question

如何在本地数据库中保存变量值，这样当我再次启动程序时，我可以再次获取变量的值。

我希望允许用户在重新启动程序时更改其PIN码并使用新的PIN码。

这是一个Windows窗体应用程序，我有一个按钮来更改用于允许用户打开程序的密码

private void button17_Click(object sender, EventArgs e)
{
    /*
    The change PIN number has a problem and the pin number needs to be on a database or a text file in order to be updated correctly
    */
    if (message.TextLength != 0 && message.TextLength < 5)
    {
        message.Text = "Enter Your Current 4 digits PIN ";

        if (Convert.ToInt32(message.Text) == currentpinn)
        {
            message.Text = "Enter Your New 4 digits PIN ";
            currentpinn = Convert.ToInt32(message.Text);
            message.Text = " Your PIN has changed successfully  ";
        }

        message.Text = "The PIN you have entered is not correct please try again!  ";
    }
    else 
    { 
        message.Text = "Please enter a valied PIN "; 
    }
}

Answer 1

通常，您需要做的是拥有密码的系统：

存储密码

使用RNGCryptoServiceProvider Class生成长随机盐。
将salt添加到密码中，并使用标准加密哈希函数（例如SHA256Managed Class）对其进行哈希处理。
保存salt和hash。

验证密码

检索用户的盐和哈希。
将salt添加到给定的密码并使用相同的哈希函数对其进行哈希。
将给定密码的哈希值与存储中的哈希值进行比较。如果匹配，则密码正确。否则，密码不正确。


    private void buttonCreate_Click(object sender, EventArgs e)
    {
        using (var d = new GetNewPasswordDialog())
        {
            d.ShowDialog(this);
            if (d.DialogResult == DialogResult.OK)
            {
                var newPassword = d.Password;
                var salt = CreateRandomSalt(33);
                var hash = GeneratePasswordHash(newPassword, salt);

            System.Diagnostics.Debug.WriteLine(hash);
            System.Diagnostics.Debug.WriteLine(salt);

            // save the hash & salt
            // using application config as an example
            Properties.Settings.Default.Hash = hash;
            Properties.Settings.Default.Salt = salt;
            Properties.Settings.Default.Save();
        }
    }
}

private void buttonVerify_Click(object sender, EventArgs e)
{
    // The change PIN number has a problem and the pin number 
    // needs to be on a database or a text file in order to be updated correctly

    if (textBox1.TextLength != 0 && textBox1.TextLength < 5)
    {
        message.Text = Properties.Resources.EnterPin;

        // read in the current password hash and salt from storage
        var savedSalt = Properties.Settings.Default.Salt;
        var savedHash = Properties.Settings.Default.Hash;

        // get the pin number that was entered and generate a hash using the saved salt
        var currentPIN = textBox1.Text.Trim();
        var currentHash = GeneratePasswordHash(currentPIN, savedSalt);


        if (string.Compare(savedHash, currentHash) == 0)
        {
            message.Text = "Your PIN is correct";

            // TODO: Allow user to change PIN
            buttonCreate.Enabled = true;
        }
        else
        {
            message.Text = "The PIN you have entered is not correct please try again!  ";
        }
    }
    else
    {
        message.Text = "Please enter a valid PIN";
    }
}

private string CreateRandomSalt(int length)
{
    // Generate a random salt
    var salt = new byte[length];
    using (var csprng = new RNGCryptoServiceProvider())
    {
        csprng.GetBytes(salt);
    }
    return Convert.ToBase64String(salt);
}

private string GeneratePasswordHash(string password, string salt)
{
    using (var pbkdf2 = new Rfc2898DeriveBytes(password, Convert.FromBase64String(salt)))
    {
        pbkdf2.IterationCount = 1000;
        var hash = pbkdf2.GetBytes(50);
        return Convert.ToBase64String(hash);
    }
}

Answer 2

Settings.settings在磁盘上存储首选项。当程序退出时将设置写入磁盘，然后在程序再次启动时将其读回，这很麻烦。我们可以使用Settings.settings文件。

双击Visual Studio文件资源管理器中的Settings.settings文件，您应该看到一个设置表。接下来，在最左侧的列中键入变量的名称。在当前情况下，我使用了PinNumber。确保范围是用户。

然后在Code Behind中你可以像这样使用那个变量

//Put all validations here like 4 digit, IsNumber etc...
Properties.Settings.Default.PinNumber = CurrentPin; // Assign Value
Properties.Settings.Default.Save(); // Saving the Value
CurrentPin = Properties.Settings.Default.PinNumber; //Getting the last value

C＃本地数据库

2 个答案: