Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Siguri_Projekti2;
using DataSecurity_pr2.Models;
using System.Text.RegularExpressions;

namespace DataSecurity_pr2
{
    public partial class Form1 : Form
    {
        public static ClientSide client;
        public Form1()
        {
            InitializeComponent();
            //ServerSide.serverConn();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            client = new ClientSide();
        }
        public static bool is_Valid_Email(String email)
        {
            String regex = "^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+@[a-zA-Z0-9.-]+$";
            //Compile regular expression to get the pattern
            Regex pattern = new Regex(regex);
            if (pattern.IsMatch(email))
            {
                return true;
            }
            return false;
        }
        public static bool is_Valid_Password(String password)
        {

            if (password.Length < 8)
            {
                return false;
            }
            else
            {
                return true;
            }

        }

        private void button1_Click_1(object sender, EventArgs e)
        {
            // validimet
            if (textBox1.Text != "" && textBox2.Text != "" && is_Valid_Email(textBox1.Text) && is_Valid_Password(textBox2.Text))
            {
                client.requestToServer("login*" + textBox1.Text + ">" + textBox2.Text);
                string response = client.responseFromServer();

                response = Regex.Replace(response, @"[\0]+", "");
                if (response == "ERROR")
                {
                    MessageBox.Show("You should sign up first!", "Alert");
                }
                else if (response == "invalidCredentials")
                {
                    MessageBox.Show("Invalid credentials", "Alert");
                }
                else
                {
                    string payload = ClientSide.getJwtPayload(response);

                    if (payload == "invalidSignature")
                    {
                        MessageBox.Show("Invalid Signature", "Error");
                    }
                    else
                    {
                        string keyValPwd = payload.Split(',')[4];
                        string password = keyValPwd.Split(':')[1];
                        password = password.Substring(1, password.Length - 2);
                        string keyValSlt = payload.Split(',')[5];
                        string salt = keyValSlt.Split(':')[1];
                        salt = salt.Substring(1, salt.Length - 3);
                        if (ClientSide.computeHash(textBox2.Text + salt) == password)
                        {
                            this.Hide();
                            Form3 form = new Form3(payload);
                            form.ShowDialog();
                            this.Close();
                        }
                        else
                        {
                            MessageBox.Show("Invalid Credentials", "Error");
                        }
                    }
                }
            }
            else {
                MessageBox.Show("Password or email is written wrong(password must have 8 characters and email must have @ contained)!", "Error");
            }
        }

        private void label2_Click(object sender, EventArgs e)
        {
            this.Hide();
            Form2 form = new Form2();
            form.ShowDialog();
            this.Close();
        }
 
    }
}