For more details
https://www.tutorialspoint.com/cryptography/modern_cryptography.htm
https://www.youtube.com/watch?v=10BX3zOr7wk
https://www.youtube.com/watch?v=dmVwblN1Lz4

 Random r = new Random();
        char[] codes = "abcdefghijklmnopqrstuvwzyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToArray();
        string output;
        void generateKey(int gkey)
        {
            output = null;
            for (int x = 0; x < codes.Length; x++)
            {
              output += codes[r.Next(0, codes.Length)];
            }

            t1bx.Text = output;
        }

        private void B_generate_Click(object sender, RoutedEventArgs e)
        {
            generateKey(10);
        }

        static string ComputeSha256Hash(string rawData)
        {
            // Create a SHA256   
            using (SHA256 sha256Hash = SHA256.Create())
            {
                // ComputeHash - returns byte array  
                byte[] bytes = sha256Hash.ComputeHash(Encoding.UTF8.GetBytes(rawData));

                // Convert byte array to a string   
                StringBuilder builder = new StringBuilder();
                for (int i = 0; i < bytes.Length; i++)
                {
                    builder.Append(bytes[i].ToString("x2"));
                }
                return builder.ToString();
            }
        }


        private void B_hash_Click(object sender, RoutedEventArgs e)
        {
            txtbx_hash.Text = ComputeSha256Hash(output);
        }

    

public partial class MainWindow : Window
    {
        int tries = 0;
        int score = 0;
        int gameNumber = 0;
        string[] question = new string[10];
        string[] answer = new string[10];
        Question[] game = new Question[10];

        public MainWindow()
        {
            InitializeComponent();

            question[0] = "This is the general discussion about the bitcoin ecosystem " +
                "that doesn't fit better elsewhere. News, the Bitcoin community, innovations, the general environment, etc. Discussion of specific Bitcoin-related services usually belongs in other sections.";
            question[1] = "Allows you to post images even if you are a newbie, reduces the time-between-actions limit, and provides some of the same benefits as being of natural Member rank.";
            question[2] = "Discussion of sports games and other gambling-related topics which are separate from games and services themselves.";
            question[3] = "Button enables registered members to subscribe to email notification of replies to the topic.";
            question[4] = "Other topics that might be of interest to bitcoiners.";
            question[5] = "Discussion about the Bitcoin Forum.";
            question[6] = "This section is for topics about individual Bitcoin bonds, stocks, etc. Topics about exchange sites which deal in securities should go in the top-level Marketplace section.";
            question[7] = "The Administrator of the Bitcointalk.org";
            question[8] = "Longest Active Campaign";
            question[9] = "Thread that can share idea, knowledge, and skills with the use of your native language";


            string[] choices1 = { "A. Serious discussion", "B.Development & Technical Discussion", "C.Trading Discussion", "D. Bitcoin Discussion" };
            string[] choices2 = { "A.Member", "B. Hero Member", "C. Full Member", "D. Copper Member" };
            string[] choices3 = { "A.Games and rounds", "B.Gambling discussion", "C.Investor-based games", "D.Gambling" };
            string[] choices4 = { "A. Help", "B. +Merit", "C. Notify", "D. Print" };
            string[] choices5 = { "A. Serious Discussion", "B. Off-topic", "C. Politics & Society", "D. Mining" };
            string[] choices6 = { "A. Altcoin Discussion", "B. Development & Technical Discussion", "C. Serious discussion", "D. Meta" };
            string[] choices7 = { "A. Lending", "B. Securities", "C. Auctions", "D. Service Discussion" };
            string[] choices8 = { "A. Cyrus", "B. Theymos", "C. DdmrDdmr", "D. LoyceV" };
            string[] choices9 = { "A. Best Change", "B. Freebitco.io", "C. Yobit", "D. Chipmixer" };
            string[] choices10 = { "A. Bitcoin Discussion", "B. Local", "C. Marketplace (Altcoins)", "D. Meta" };

            answer[0] = choices1[3];
            answer[1] = choices2[3];
            answer[2] = choices3[1];
            answer[3] = choices4[2];
            answer[4] = choices5[1];
            answer[5] = choices6[3];
            answer[6] = choices7[1];
            answer[7] = choices8[1];
            answer[7] = choices8[0];
            answer[8] = choices9[3];
            answer[9] = choices10[1];

            game[0] = new Question(question[0], choices1, answer[0]);
            game[1] = new Question(question[1], choices2, answer[1]);
            game[2] = new Question(question[2], choices3, answer[2]);
            game[3] = new Question(question[3], choices4, answer[3]);
            game[4] = new Question(question[4], choices5, answer[4]);
            game[5] = new Question(question[5], choices6, answer[5]);
            game[6] = new Question(question[6], choices7, answer[6]);
            game[7] = new Question(question[7], choices8, answer[7]);
            game[8] = new Question(question[8], choices9, answer[8]);
            game[9] = new Question(question[9], choices10, answer[9]);
     
            display();
        }

        private void display()
        {
            txtScore.Text = score.ToString();
            txtTries.Text = tries.ToString();

            if (game.Length == gameNumber)
            {
                GameView.Visibility = Visibility.Collapsed;
                GameOverView.Visibility = Visibility.Visible;
                txtFinalScore.Text = score.ToString();
                return;
            } 

            RadioButton[] choices = { choices1, choices2, choices3, choices4 };
            txtQuestion.Text = game[gameNumber].question;
            for(int i = 0; i < 4; i++)
            {
                choices[i].Content = game[gameNumber].choices[i];
            }

            choices[0].IsChecked = true;
        }

        private void btnOkay_Click(object sender, RoutedEventArgs e)
        {
            RadioButton[] choices = { choices1, choices2, choices3, choices4 };
            for(int i = 0; i < choices.Length; i++)
            {
                if(choices[i].IsChecked == true)
                {
                    if((string)choices[i].Content == game[gameNumber].answer)
                    {
                        MessageBox.Show("Correct");
                        ++score;
                        ++gameNumber;
                        tries = 0;
                        display();
                    }
                    else
                    {
                        MessageBox.Show("Wrong");
                        ++tries;
                        txtTries.Text = tries.ToString();

                        if (tries == 2)
                        {
                            ++gameNumber;
                            tries = 0;
                            display();
                        }                       
                    }
                }
            }
        }

        private void btnTryAgain_Click(object sender, RoutedEventArgs e)
        {
            GameOverView.Visibility = Visibility.Collapsed;
            GameView.Visibility = Visibility.Visible;
            score = 0;
            tries = 0;
            gameNumber = 0;
            display();
        }
    }