How to validate username and password from text file? | Winforms C#

Question

First I made textbox1(for username) , textbox2(for password) and button1(check). After:

private void button1_Click(object sender, EventArgs e)
{
    FileStream fs = new FileStream(@"D:\C#\test.txt", FileMode.Open, FileAccess.Read, FileShare.None);
    StreamReader sr = new StreamReader(fs);
}

I want to check username from the first line of test.txt (equals like added from me text in textbox1) and password from the second line.

Sorry for my bad english.

Answer 1

You could try something like this:

private void button1_Click(object sender, EventArgs e){
     string[] lines = System.IO.File.ReadAllLines(@"D:\C#\test.txt");
     String username = lines[0];
     String password = lines[1];
}

However, it's not a very good way to store your usernames and passwords. I'm assuming you're just testing something out.

Answer 2

The simplest answer to your question is to read the text-file line by line. I would however strongly suggest at least seeding and hashing the password.

This is a short example utilizing seeded SHA256 hashed passwords. It's just to show the concept and should not be used as is.

    void Test()
    {
        string pwd = "Testing1234";
        string user = "username";

        StorePassword(user, pwd);

        bool result = ValidatePassword(user, pwd);
        if (result == true) Console.WriteLine("Match!!");
    }

    private void StorePassword(string username, string password)
    {
        var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        var random = new Random();
        var salt = new string(
            Enumerable.Repeat(chars, 8)
                   .Select(s => s[random.Next(s.Length)])
                   .ToArray());

        string hash = GetHash(salt + password);
        string saltedHash = salt + ":" + hash;
        string[] credentials = new string[] { username, saltedHash };

        System.IO.File.WriteAllLines(@"D:\C#\test.txt",credentials);

    }

    bool ValidatePassword(string username, string password)
    {
        string[] content = System.IO.File.ReadAllLines(@"D:\C#\test.txt");

        if (username != content[0]) return false; //Wrong username

        string[] saltAndHash = content[1].Split(':'); //The salt will be stored att index 0 and the hash we are testing against will be stored at index 1.

        string hash = GetHash(saltAndHash[0] + password);

        if (hash == saltAndHash[1]) return true;
        else return false;

    }

    string GetHash(string input)
    {
        System.Security.Cryptography.SHA256Managed hasher = new System.Security.Cryptography.SHA256Managed();
        byte[] bytes = hasher.ComputeHash(Encoding.UTF8.GetBytes(input));

        return BitConverter.ToString(bytes).Replace("-", "");
    }