A Random Password Generator in C Sharp with code explanation

Below is a C# Random Password Generator program that allows users to create strong passwords with customizable options, such as the length of the password and the inclusion of special characters, numbers, and uppercase/lowercase letters.

Full Code

using System;
using System.Text;

class PasswordGenerator
{
    static void Main(string[] args)
    {
        Console.WriteLine("Welcome to the Random Password Generator!");

        while (true)
        {
            Console.WriteLine("\nChoose an option:");
            Console.WriteLine("1. Generate a Random Password");
            Console.WriteLine("2. Exit");
            Console.Write("Enter your choice: ");

            string choice = Console.ReadLine();

            switch (choice)
            {
                case "1":
                    GeneratePassword();
                    break;
                case "2":
                    Console.WriteLine("Goodbye!");
                    return;
                default:
                    Console.WriteLine("Invalid choice. Please try again.");
                    break;
            }
        }
    }

    static void GeneratePassword()
    {
        // Ask the user for the password length
        Console.Write("Enter the desired password length (minimum 6): ");
        if (!int.TryParse(Console.ReadLine(), out int length) || length < 6)
        {
            Console.WriteLine("Invalid input. Password length must be at least 6.");
            return;
        }

        // Ask the user if they want specific character types in the password
        Console.Write("Include uppercase letters? (y/n): ");
        bool includeUppercase = Console.ReadLine().Trim().ToLower() == "y";

        Console.Write("Include lowercase letters? (y/n): ");
        bool includeLowercase = Console.ReadLine().Trim().ToLower() == "y";

        Console.Write("Include numbers? (y/n): ");
        bool includeNumbers = Console.ReadLine().Trim().ToLower() == "y";

        Console.Write("Include special characters? (y/n): ");
        bool includeSpecial = Console.ReadLine().Trim().ToLower() == "y";

        // Generate the password
        string password = GenerateRandomPassword(length, includeUppercase, includeLowercase, includeNumbers, includeSpecial);
        if (string.IsNullOrEmpty(password))
        {
            Console.WriteLine("No character types were selected. Unable to generate a password.");
        }
        else
        {
            Console.WriteLine($"Generated Password: {password}");
        }
    }

    static string GenerateRandomPassword(int length, bool includeUppercase, bool includeLowercase, bool includeNumbers, bool includeSpecial)
    {
        // Define character pools
        string upperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        string lowerCaseLetters = "abcdefghijklmnopqrstuvwxyz";
        string numbers = "0123456789";
        string specialCharacters = "!@#$%^&*()-_=+[]{}|;:,.<>?";

        // Build the character pool based on user preferences
        StringBuilder characterPool = new StringBuilder();
        if (includeUppercase) characterPool.Append(upperCaseLetters);
        if (includeLowercase) characterPool.Append(lowerCaseLetters);
        if (includeNumbers) characterPool.Append(numbers);
        if (includeSpecial) characterPool.Append(specialCharacters);

        // If no character types were selected, return an empty string
        if (characterPool.Length == 0) return string.Empty;

        // Generate the password
        StringBuilder password = new StringBuilder();
        Random random = new Random();
        for (int i = 0; i < length; i++)
        {
            int index = random.Next(0, characterPool.Length);
            password.Append(characterPool[index]);
        }

        return password.ToString();
    }
}

Explanation

1. Main Menu:
   • Displays a menu for the user to choose between generating a password or exiting the program.
   • Handles user input using a switch statement.
   • Ensures the program keeps running until the user selects the “Exit” option.

   Console.WriteLine("1. Generate a Random Password");
   Console.WriteLine("2. Exit");
   

2. Input Validation:
   • Validates the password length entered by the user (minimum of 6 characters).
   • Prompts the user to choose whether to include uppercase, lowercase, numbers, and special characters in the password.

   Console.Write("Include uppercase letters? (y/n): ");
   bool includeUppercase = Console.ReadLine().Trim().ToLower() == "y";
   

3. Password Generation:
   • Builds a character pool based on the user’s choices. Each selected category (uppercase, lowercase, numbers, special characters) adds characters to the pool.
   • If no character types are selected, the method returns an empty string, and the program informs the user.

   if (includeUppercase) characterPool.Append(upperCaseLetters);
   if (includeLowercase) characterPool.Append(lowerCaseLetters);
   if (includeNumbers) characterPool.Append(numbers);
   if (includeSpecial) characterPool.Append(specialCharacters);
   

4. Random Password Construction:
   • Uses the Random class to select random characters from the built character pool.
   • Appends these characters to a StringBuilder to construct the password.

   for (int i = 0; i < length; i++)
   {
       int index = random.Next(0, characterPool.Length);
       password.Append(characterPool[index]);
   }
   

5. Output:
   • Displays the generated password or an error message if no valid character pool was selected.

   Console.WriteLine($"Generated Password: {password}");
   

Sample Run

Run the program:

Welcome to the Random Password Generator!

Choose an option:
1. Generate a Random Password
2. Exit
Enter your choice: 1

Enter the desired password length (minimum 6): 12
Include uppercase letters? (y/n): y
Include lowercase letters? (y/n): y
Include numbers? (y/n): y
Include special characters? (y/n): n

Generated Password: Aa1lZ9kR5tPq

Validation and Edge Cases

1. Minimum Length:
   • Ensures the password length is at least 6 characters. If not, the user is prompted to enter a valid length.
2. No Character Types Selected:
   • If the user doesn’t select any character types, the program cannot generate a password and informs the user.
3. Randomness:
   • The Random class ensures the generated password is sufficiently random.

Features

1. Customizable Passwords:
   • Users can specify password length and choose which character types to include.
2. Validation:
   • Ensures valid input for password length and character type selection.
3. Strong Passwords:
   • Generates strong passwords with combinations of uppercase, lowercase, numbers, and special characters.
4. Reusable Method:
   • The GenerateRandomPassword method can be reused in other programs.

Ideas for Enhancement

1. Ensure Balanced Composition:
   • Modify the program to ensure that at least one character from each selected type (e.g., uppercase, numbers) appears in the password.
2. Add Clipboard Copying:
   • Automatically copy the generated password to the clipboard.
3. Save Passwords:
   • Store the generated passwords in a secure file or password manager.
4. GUI Version:
   • Use Windows Forms or WPF to create a graphical user interface for the password generator.