//Nhận Key và check có Đúng Hay Không
public void Receive()
{
md5 md5 = new md5();
byte[] bytes = new byte[1024];
while (true)
{
int bytesRead = ns.Read(bytes, 0, bytes.Length);
string text = Encoding.UTF8.GetString(bytes, 0, bytesRead);
string[] s1 = text.Split(';');
switch (s1[0])
{
case "Send_Key":
send_key_public(s1);
break;
case "Receive_Key":
receive_key_public(s1);
break;
case "Receive":
if (check_md5(s1[1], s1[4]))
{
decrypt_mess(s1);
session = true;
dem = 0;
}
else
{
MessageList("Message da bi thay doi", "--");
}
break;
}
}
}
//ma hoa tin nhan
public void encryptmess(string mess)
{
md5 md5 = new md5();
Aes256 aes256 = new Aes256();
SHA256 sha256 = SHA256Managed.Create();
//array bytes message
byte[] mess1 = Encoding.UTF8.GetBytes(mess);
////array bytes key chung
byte[] key1 = sha256.ComputeHash(Encoding.ASCII.GetBytes(Convert.ToString(dh.Key_Chung)));
//get daytime
string ivc = getdatime();
//array bytes iv from daytime , start index 2
byte[] iv = create_init_vector(ivc);
txtiv.Text = Convert.ToBase64String(iv);
//get 32 byte from datime for padding
byte[] dayhash = sha256.ComputeHash(Encoding.ASCII.GetBytes(ivc));
//encrypt message
string encrypt = aes256.EncryptString(mess1, key1, iv, dayhash);
string[] enc1 = encrypt.Split(';');
string mess_md5 = md5.GetMD5(enc1[0] + Convert.ToString(dh.Key_Chung));
//byte[] enc = Encoding.ASCII.GetBytes(encrypt);
string messsend = "Receive;" + encrypt + ";" + ivc + ";" + mess_md5;
//string[] s1 = messsend.Split(';');
//textBoxmessnoise.Text = s1[1].ToString() + ";" + s1[2].ToString() + ";" + s1[3].ToString();
txtmessnoise.Text = messsend;
senddata(messsend);
}
//Check MD5,phat hien thay doi key
public bool check_md5(string encrypt, string md5_encrypt)
{
bool check = false;//sai hien thong bao.
md5 md5 = new md5();
string result = md5.GetMD5(encrypt + Convert.ToString(dh.Key_Chung));
if (result == md5_encrypt)
{
check = true;//dung tiep tuc gui.
}
return(check);
}
//Tính Padding
public string tinhpading(string text)
{
md5 hash = new md5();
string ivc = getdatime();
string chuoipading;
int i = 0;
int n = text.Length % 16;
if (n != 0)
{
string thempading = hash.GetMD5(ivc).Substring(0, 16 - n);
chuoipading = text + thempading;
}
else
{
chuoipading = text;
}
return(chuoipading);
}
