How to Authenticate Two Users at One Time using SQL Server and C#

Question

I am writing an unencryption program and the business requirement is that two users must login in order for it to work. How can I write program that in C# that attempts to log both users into SQL? The users are SQL Users and I can't figure out how to authenticate SQL Users in C#.

I imagined a login screen with two user name slots and two password slots and then a shared login button. On click, user authentication happens for each user. If both authentications are successful, the file is decrypted.

Any help, advice or direction would be greatly appreciated.

one idea is to use the TPL, create a task for each user credentials and run them at once in different threads https://msdn.microsoft.com/en-us/library/system.threading.tasks.task(v=vs.110).aspx — rmjoia, Sep 26 '17 at 11:48
Are you looking for this to work with both users at the same machine or remote to each other? — Simon Price, Sep 26 '17 at 11:51

rmjoia · Answer 1 · 2017-09-26T11:59:02.653

3

Something Like this can do the trick:

private async Task TestUserAuthAsync(){

    var task1 = Task.Run(AuthenticateUser("username1", "password1"));
    var task2 = Task.Run(AuthenticateUser("username2", "password2"));

    await Task.WhenAll(task1, task2);
}

You can do more, like return results log...

Something like Parallel.ForEach can also work.

edited Sep 26 '17 at 11:59

answered Sep 26 '17 at 11:56

rmjoia

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Is AuthenticateUser a built in SQL function? – Missy Sep 26 '17 at 11:58
No, I was making up some method. you'll need to write code for that.. maybe try using linq to sql for instance.. I thought you already had the code to authenticate one user – rmjoia Sep 26 '17 at 12:00
They want to use the users that you set up in SQL. Still upticked you for helping me :) – Missy Sep 26 '17 at 12:01
1

Sure, you can fetch all (filtered) users from SQL and then run the method. In that case I would get the users to a list, and then run a foreach. Check [Introduction to Entity Framework](https://msdn.microsoft.com/en-us/library/aa937723(v=vs.113).aspx) – rmjoia Sep 26 '17 at 12:03
Okay -- I'll check it out and see if it gets me enough information to authenticate them. – Missy Sep 26 '17 at 12:10
Awesome. Thank you. I will work this on my own as much as possible first. – Missy Sep 26 '17 at 12:30

Missy · Accepted Answer · 2017-09-26T15:19:56.647

The Authenticate User Method would look something like this - note that the connection strings need to be modified for the specific app and the MessageBox in the Catch statement is probably too much for the average user :)

 private bool AuthenticateUser() 
     {
        // rather than picking up variable names, I am picking up the information from the text boxes on the screen.
        bool retVal = false;
        string cs1 = "Data Source=yourdatasource;Initial Catalog=yourcat;Persist Security Info=True;User ID=" + txtLogin1.Text.Trim() + ";Password=" + txtPW1.Text.Trim() + ";";
        string cs2 = "Data Source=yourdatasource;Initial Catalog=yourcat;Persist Security Info=True;User ID=" + txtLogin2.Text.Trim() + ";Password=" + txtPW2.Text.Trim() + ";";
        try
        {
            using (var connection = new SqlConnection(cs1))
            {
                connection.Open();
                retVal = true;
            }
        }
        catch (SqlException e2)
        {
            MessageBox.Show("User 1 Failed " + e2.ToString());
        }

        try
        {
            using (var connection = new SqlConnection(cs2))
            {
                connection.Open();
                retVal = true;
            }
        }
        catch (SqlException ex)
        {
            MessageBox.Show("User 2 Failed "+ex.ToString());

        } 
        if (retVal)
            { MessageBox.Show("Passed"); }
        else
            { MessageBox.Show("Please Try"); }

        return retVal;
    }
}

How to Authenticate Two Users at One Time using SQL Server and C#

2 Answers2