RSA signature pem files

using System;
using System.IO;
using System.Windows.Forms;
using Chilkat;

namespace csharp_crypto_3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            algBox.SelectedIndex = 0;
        }

        private string SaveFile(string title, string filter)
        {
            var filePath = string.Empty;
            using (var dialog = new SaveFileDialog())
            {
                dialog.Filter = @filter;
                dialog.FilterIndex = 1;
                dialog.RestoreDirectory = true;
                dialog.Title = title;
                if (dialog.ShowDialog() == DialogResult.OK) filePath = dialog.FileName;
            }

            return filePath;
        }

        private string ReadFile(string title, string filter)
        {
            using (var dialog = new OpenFileDialog())
            {
                var content = string.Empty;
                dialog.Filter = @filter;
                dialog.FilterIndex = 1;
                dialog.RestoreDirectory = true;
                dialog.Title = @title;
                if (dialog.ShowDialog() != DialogResult.OK) return content;
                var fileStream = dialog.OpenFile();
                using (var reader = new StreamReader(fileStream))
                {
                    content = reader.ReadToEnd();
                }

                return content;
            }
        }

        // вывод лога в RichTextBox
        private void Log(string output)
        {
            logBox.AppendText(output + "\r\n");
            logBox.ScrollToCaret();
        }

        private void ActionButton_Click(object sender, EventArgs e)
        {
            logBox.Clear();
            var rsaLength = 0;
            var cont = true; // переменная, отвечающая за продолжение работы кода
            // проверка входных данных
            try
            {
                rsaLength = int.Parse(rsaLengthBox.Text);
            }
            catch (Exception ex)
            {
                Log(ex.Message);
                cont = false;
            }

            if (cont)
            {
                // проверяем длину ключа
                if (rsaLength < 512 || rsaLength > 8192)
                {
                    Log("Key length must be > 512 and < 8192");
                    cont = false;
                }
            }

            if (!cont) return; // завершаем работу функции при неверных входных данных
            // проверяем действие: подпись или проверка
            if (signRadioButton.Checked)
            {
                // подпись данных
                logBox.Clear();
                var rsa = new Rsa
                {
                    LittleEndian = false,
                    // порядок байтов
                    // big endian
                    // 0x1234 = 12 34
                    // litle endian
                    // 0x1234 = 34 12
                    EncodingMode = "hex"
                };
                var success = rsa.GenerateKey(rsaLength);
                // Log(rsa_length.ToString());
                // выводим лог об успешном или нет завершении функции
                var hashedAlg = algBox.SelectedItem.ToString();
                Log("selected hash alg: " + hashedAlg);
                Log(success ? "Key has been successfully generated!" : rsa.LastErrorText);

                Log("exporting private and public RSA keys...");

                var publicXml = rsa.ExportPublicKey();
                var privateXml = rsa.ExportPrivateKey();
                var privateKey = new PrivateKey();
                var publicKey = new PublicKey();

                // init savefiledialog
                // сохранение публичного и приватного ключа в pem file
                var privatePath = SaveFile("Save private key","PEM files (*.pem)|*.pem|All files (*.*)|*.*");
                var publicPath = SaveFile("Save public key", "PEM files (*.pem)|*.pem|All files (*.*)|*.*");
                success = privateKey.LoadXml(privateXml);
                Log(success? "private key has been loaded":"error while loading private key");
                success = publicKey.LoadXml(publicXml);
                Log(success ? "public key has been loaded" : "error while loading public key");
                // сохранения приватного и публичного ключа в отдельные файлы
                success = privateKey.SaveRsaPemFile(privatePath);
                if (!success)
                {
                    Log("error has occurred while saving the file");
                    return;
                }

                Log("Private Key has been successfully saved in: ");
                Log(privatePath);
                success = publicKey.SaveOpenSslPemFile(publicPath);
                if (!success)
                {
                    Log("error has occurred while saving the file");
                    return;
                }

                Log("Public Key has been successfully saved in: ");
                Log(publicPath);

                // чтение исходного файла, данного для подписывания
                string toSignFile = ReadFile("Open file to sign", "All files (*.*)|*.*");
                Log(toSignFile);

                // генерация подписи
                var hashed = rsa.SignStringENC(toSignFile, hashedAlg);
                var signed = SaveFile("Save signed doc", "All files (*.*)|*.*");

                File.WriteAllText(signed, hashed);
            }
            else
            {
                logBox.Clear();
                // проверка подписи
                var rsa2 = new Rsa
                {
                    LittleEndian = false
                }; // chilkat rsa
                var hashedAlg = algBox.SelectedItem.ToString();
                Log("selected hash alg: " + hashedAlg);
                var pubKey = new PublicKey();
                var toSignFile = ReadFile("Open file to sign", "All files (*.*)|*.*");
                var hashed = ReadFile("Open signed file","All files (*.*)|*.*");
                var filePublic = ReadFile("Open public key","PEM files (*.pem)|*.pem");
                var success = pubKey.LoadOpenSslPem(filePublic);
                Log(success ? "load public key file successfully" : "error");
                success = rsa2.ImportPublicKey(pubKey.GetXml());

                rsa2.EncodingMode = "hex";
                success = rsa2.VerifyStringENC(toSignFile, hashedAlg, hashed);
                Log(rsa2.LastErrorText);
                //Log(success ? "Successful verification!" : rsa2.LastErrorText);
            }
        }
    }
}