AES Encrpytor

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 System.Security.Cryptography;
using System.IO;

namespace EncryptionSoftware
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        string file;


        private void button2_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "")
                MessageBox.Show("ERROR!");
            else
            {
                byte[] selectedFileBytes = File.ReadAllBytes(file);
                byte[] passwordBytes = System.Text.Encoding.UTF8.GetBytes(textBox1.Text);
                using (var aesProvider = new AesCryptoServiceProvider())
                {
                    aesProvider.KeySize = 256;
                    aesProvider.Key = System.Text.Encoding.UTF8.GetBytes(textBox1.Text);
                    aesProvider.GenerateIV();
                    aesProvider.Mode = CipherMode.CBC;
                    aesProvider.Padding = PaddingMode.PKCS7;
                    using (var aesEncryptor = aesProvider.CreateEncryptor(aesProvider.Key, aesProvider.IV))
                    {
                        using (var fstream = new FileStream(file+".crypt",FileMode.Create))
                        {
                            //algoritmul foloseste un vector de initializare (IV) pe 16 bytes
                            //retinem IV generat automat pentru o mai buna securitate si posibilitatea decryptari fisierului
                            fstream.Write(aesProvider.IV, 0, 16);
                            using (CryptoStream cs = new CryptoStream(fstream, aesEncryptor, CryptoStreamMode.Write))
                            {
                                cs.Write(selectedFileBytes, 0, selectedFileBytes.Length);
                                cs.FlushFinalBlock();
                                //Flush final block method indica CryptoStream-ului ca nu mai urmeaza sa apara alte date si trebuie sa introduca padding-ul specific algoritmului

                            }

                        }
                    }
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            openFileDialog1.ShowDialog();
            file = openFileDialog1.FileName.ToString();
            label1.Text = file;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "")
                MessageBox.Show("ERROR!");
            else
            {
                FileStream fsread = new FileStream(file, FileMode.Open, FileAccess.Read);
                using (var aesProvider = new AesCryptoServiceProvider())
                {
                    aesProvider.KeySize = 256;
                    aesProvider.Key = System.Text.Encoding.UTF8.GetBytes(textBox1.Text);
                    aesProvider.Mode = CipherMode.CBC;
                    aesProvider.Padding = PaddingMode.PKCS7;
                    using (var fostream = new FileStream(file + ".decrypt", FileMode.Create,FileAccess.Write))
                    {
                        byte[] buffer=new byte[33];
                        var ms = new FileStream(file, FileMode.Open, FileAccess.Read);
                        ms.Read(buffer, 0, 16);
                        aesProvider.IV=buffer;
                        var aesDecryptor = aesProvider.CreateDecryptor(aesProvider.Key, aesProvider.IV);
                        using (CryptoStream cs = new CryptoStream(fostream, aesDecryptor, CryptoStreamMode.Write))
                        {
                            byte[] bytearrayinput = new byte[fsread.Length - 17];
                            fsread.Read(bytearrayinput, 17, bytearrayinput.Length);
                            cs.Write(bytearrayinput, 0, bytearrayinput.Length);
                            cs.Close();
                            fsread.Close();
                            fostream.Close();

                        }
                    }

                }
            }
        }
    }
}