private void btnEncrypt_Click(object sender, EventArgs e)
{
dt = MD5.HashMd5(DateTime.Now.ToString());
string valuePadding = paddingData().ToString();
string encryptedText = Encrypted(txtPadding.Text, txtKey.Text, dt);
string MD5encryptedText = MD5.HashMd5(encryptedText);
txtEncrypted.Text = encryptedText + ";" + dt + ";" + MD5encryptedText + ";" + txtKey.Text + ";" + valuePadding;
}
private void btnSend_Click(object sender, EventArgs e)
{
string text = txtEncrypted.Text;
byte[] data = new byte[1024 * 24];
data = Encoding.ASCII.GetBytes(text);
listBox1.Items.Add("You : " + txtMessage.Text);
txtMessage.Text = "";
KhoiTaoTimer();
client.Send(data);
data = new byte[1024];
client.Receive(data);
string s = Encoding.ASCII.GetString(data);
string[] arraystring = s.Split(';');
string encryptedText = arraystring[0];
string dt = arraystring[1];
string md5EncryptedText = arraystring[2];
txtKey.Text = arraystring[3];
string paddingValue = arraystring[4];
string hashEncryptedText = MD5.HashMd5(encryptedText);
if (md5EncryptedText == hashEncryptedText)
{
txtMessaged_Receive.Text = encryptedText;
string rawText = Decrypted(txtMessaged_Receive.Text, dt);
txtDecrypted.Text = rawText.Substring(0, rawText.Length - int.Parse(paddingValue));
listBox1.Items.Add("Him :" + txtDecrypted.Text);
}
else
{
listBox1.Invoke((MethodInvoker) delegate()
{
listBox1.Items.Add("Error: Noi dung da bi thay doi.");
});
}
IPEndPoint ip = (IPEndPoint)client.RemoteEndPoint;
txtIP.Text = ip.Address.ToString();
}
private int paddingData()
{
string Timestamp = new DateTimeOffset(DateTime.UtcNow).ToUniversalTime().ToString("yyyyMMddHHmmss");
string MHtimeStamp = MD5.HashMd5(Timestamp);
int soByteCuaChuoi = UTF8Encoding.UTF8.GetByteCount(txtMessage.Text);
int lengthNeed = 32 - soByteCuaChuoi;
int i = 0;
string tmpTime = string.Empty;
if (soByteCuaChuoi % 16 != 0)
{
i = 1;
int length = soByteCuaChuoi;
while (length % 16 != 0)
{
tmpTime = MHtimeStamp.Substring(0, i);
length = length + 1;
i++;
}
}
txtPadding.Text = txtMessage.Text + tmpTime;
return(i - 1);
}