private void MainForm_Load(object sender, EventArgs e)
        {
            InitializeGenericButtons();
            InitializeTextBoxes();

            ofd              = new OpenFileDialog();
            sfd              = new SaveFileDialog();
            cryptoAES        = new CryptoAES();
            cryptoRSA        = new CryptoRSA();
            cryptoSHA2       = new CryptoSHA2();
            cryptoSHA2Manual = new CryptoSHA2Manual();
            cryptoEnvelope   = new CryptoEnvelope(cryptoAES, cryptoRSA);
            cryptoSignature  = new CryptoSignature(cryptoSHA2, cryptoRSA);

            cbAESKeySize.SelectedIndex
                  = cbSHA2Size.SelectedIndex
                  = 0;
            cbRSAKeySize.SelectedIndex = 2;

            ofd.Filter = sfd.Filter =
                "txt files (*.txt)|*.txt|" +
                "pdf files (*.pdf)|*.pdf|" +
                "All files (*.*)|*.*";
        }
 public CryptoSignature(CryptoSHA2 cryptoSHA2, CryptoRSA cryptoRSA)
 {
     this.cryptoSHA2 = cryptoSHA2;
     this.cryptoRSA  = cryptoRSA;
 }