diff --git a/security.go b/security.go
index fa8357b..86eb989 100644
--- a/security.go
+++ b/security.go
@@ -13,6 +13,8 @@ const (
 	SecTypeUnknown  = SecurityType(0)
 	SecTypeNone     = SecurityType(1)
 	SecTypeVNC      = SecurityType(2)
+	SecTypeTight    = SecurityType(16)
+	SecTypeATEN     = SecurityType(16)
 	SecTypeVeNCrypt = SecurityType(19)
 )
 
@@ -75,6 +77,96 @@ func (*ServerAuthNone) Auth(c Conn) error {
 	return nil
 }
 
+type ClientAuthATEN struct {
+	Username []byte
+	Password []byte
+}
+
+func readTightTunnels(c Conn) (uint32, error) {
+	var n uint32
+	if err := binary.Read(c, binary.BigEndian, &n); err != nil {
+		return 0, err
+	}
+	return n, nil
+}
+
+func (*ClientAuthATEN) Type() SecurityType {
+	return SecTypeATEN
+}
+
+func (*ClientAuthATEN) SubType() SecuritySubType {
+	return SecSubTypeUnknown
+}
+
+func charCodeAt(s string, n int) rune {
+	for i, r := range s {
+		if i == n {
+			return r
+		}
+	}
+	return 0
+}
+
+func (auth *ClientAuthATEN) Auth(c Conn) error {
+	var definedAuthLen = 24
+
+	nt, err := readTightTunnels(c)
+	if err != nil {
+		return err
+	}
+	if (nt&0xffff0ff0)>>0 == 0xaff90fb0 {
+		fmt.Printf("aten\n")
+		var skip [20]byte
+		binary.Read(c, binary.BigEndian, &skip)
+		fmt.Printf("skip %s\n", skip)
+	}
+	/*
+		if len(auth.Username) > 24 || len(auth.Password) > 24 {
+			return fmt.Errorf("username/password > 24")
+		}
+
+		username := make([]byte, 24-len(auth.Username)+1)
+		password := make([]byte, 24-len(auth.Password)+1)
+		copy(username, auth.Username)
+		copy(password, auth.Password)
+		username = append(username, []byte("\x00")...)
+		password = append(password, []byte("\x00")...)
+		challenge := bytes.Join([][]byte{username, password}, []byte(":"))
+		if err := binary.Write(c, binary.BigEndian, challenge); err != nil {
+			return err
+		}
+
+		if err := c.Flush(); err != nil {
+			return err
+		}
+	*/
+	sendUsername := make([]byte, definedAuthLen)
+	for i := 0; i < definedAuthLen; i++ {
+		if i < len(auth.Username) {
+			sendUsername[i] = byte(charCodeAt(string(auth.Username), i))
+		} else {
+			sendUsername[i] = 0
+		}
+	}
+
+	sendPassword := make([]byte, definedAuthLen)
+
+	for i := 0; i < definedAuthLen; i++ {
+		if i < len(auth.Password) {
+			sendPassword[i] = byte(charCodeAt(string(auth.Password), i))
+		} else {
+			sendPassword[i] = 0
+		}
+	}
+	if err := binary.Write(c, binary.BigEndian, sendUsername); err != nil {
+		return err
+	}
+	if err := binary.Write(c, binary.BigEndian, sendPassword); err != nil {
+		return err
+	}
+	return c.Flush()
+}
+
 func (*ClientAuthVeNCrypt02Plain) Type() SecurityType {
 	return SecTypeVeNCrypt
 }