diff --git a/communication/protocol.go b/communication/protocol.go
index f9bf42a..eeab517 100644
--- a/communication/protocol.go
+++ b/communication/protocol.go
@@ -2,46 +2,59 @@ package communication
 
 import (
 	"bytes"
+	"crypto/rand"
 	"encoding/gob"
+
+	"git.qowevisa.me/Qowevisa/gotell/gmyerr"
 )
 
-const (
-	SERVER_COMMAND = 1 + iota
-	SERVER_MESSAGE
-	CLIENT_RESPONSE
-	P2P_MESSAGE
-)
-
+// VERSION field
 const (
 	V1 = 1 + iota
 )
 
+// FROM field
 const (
-	NICKNAME = 1
+	FROM_SERVER = 1 + iota
+	FROM_CLIENT
+	FROM_MY_ID
 )
 
-type communicationMessage struct {
-	Type uint8
-	Data []byte
+// FROM_ID is 2 bytes
+
+// TO_ID is 2 bytes
+
+// ACTION field
+const (
+	ACTION_ASK = 1 + iota
+	ACTION_SEND
+)
+
+// ABOUT field
+const (
+	ABOUT_NICKNAME = 1 + iota
+	ABOUT_ID
+	ABOUT_LINK
+	ABOUT_ECDH_PUB_KEY
+	ABOUT_CBES_SPECS
+	ABOUT_MKLG_FGPRINT
+	ABOUT_MESSAGE
+)
+
+// DATA_LEN is 2 bytes
+
+type Message struct {
+	Version uint8
+	From    uint8
+	FromID  uint16
+	ToID    uint16
+	Action  uint8
+	About   uint8
+	DataLen uint16
+	Data    []byte
 }
 
-func AskClientNickname() ([]byte, error) {
-	c := communicationMessage{
-		Type: SERVER_COMMAND,
-		Data: []byte{NICKNAME},
-	}
-	return c.Bytes()
-}
-
-func JustGetMessage(msg []byte) ([]byte, error) {
-	c := communicationMessage{
-		Type: SERVER_MESSAGE,
-		Data: msg,
-	}
-	return c.Bytes()
-}
-
-func (c *communicationMessage) Bytes() ([]byte, error) {
+func (c *Message) Bytes() ([]byte, error) {
 	var buf bytes.Buffer
 	encoder := gob.NewEncoder(&buf)
 	err := encoder.Encode(c)
@@ -51,14 +64,143 @@ func (c *communicationMessage) Bytes() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
-func Decode(serverBytes []byte) (*communicationMessage, error) {
-	var c communicationMessage
+func Decode(serverBytes []byte) (*Message, error) {
+	var c Message
 	buf := bytes.NewBuffer(serverBytes)
 	decoder := gob.NewDecoder(buf)
 	err := decoder.Decode(&c)
 	if err != nil {
 		return nil, err
 	}
-
 	return &c, nil
 }
+
+func ServerAskClientAboutNickname() ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_SERVER,
+		FromID:  0,
+		ToID:    0,
+		Action:  ACTION_ASK,
+		About:   ABOUT_NICKNAME,
+		DataLen: 0,
+		Data:    []byte{},
+	}
+	return c.Bytes()
+}
+
+func ClientSendServerNickname(nickname []byte) ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_CLIENT,
+		FromID:  0,
+		ToID:    0,
+		Action:  ACTION_SEND,
+		About:   ABOUT_NICKNAME,
+		DataLen: uint16(len(nickname)),
+		Data:    nickname,
+	}
+	return c.Bytes()
+}
+
+func ServerSendClientHisID(id []byte) ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_SERVER,
+		FromID:  0,
+		ToID:    0,
+		Action:  ACTION_SEND,
+		About:   ABOUT_ID,
+		DataLen: uint16(len(id)),
+		Data:    id,
+	}
+	return c.Bytes()
+}
+
+func (r *RegisteredUser) GenerateLink(count uint32) (Link, error) {
+	var l Link
+	buf := make([]byte, LINK_LEN_V1)
+
+	_, err := rand.Read(buf)
+	if err != nil {
+		return Link{}, err
+	}
+	if count == 0 {
+		return Link{}, ERROR_LINK_ZERO_COUNT
+	}
+	l.Status = LINK_STATUS_CREATED
+	l.Data = buf
+	l.UseCount = count
+
+	return l, nil
+}
+
+func (l *Link) Bytes() ([]byte, error) {
+	var buf bytes.Buffer
+	encoder := gob.NewEncoder(&buf)
+	err := encoder.Encode(l)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func (r *RegisteredUser) GetIDFromLink(l Link) ([]byte, error) {
+	bb, err := l.Bytes()
+	if err != nil {
+		return nil, gmyerr.WrapPrefix("l.Bytes", err)
+	}
+	c := Message{
+		Version: V1,
+		From:    FROM_CLIENT,
+		FromID:  r.ID,
+		ToID:    0,
+		Action:  ACTION_ASK,
+		About:   ABOUT_LINK,
+		DataLen: uint16(len(bb)),
+		Data:    bb,
+	}
+	return c.Bytes()
+}
+
+func ServerSendClientIDFromLink(toID uint16, toName []byte) ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_SERVER,
+		FromID:  0,
+		ToID:    toID,
+		Action:  ACTION_SEND,
+		About:   ABOUT_LINK,
+		DataLen: uint16(len(toName)),
+		Data:    toName,
+	}
+	return c.Bytes()
+}
+
+func (r *RegisteredUser) ClientSendThroughServerCBESSpecs(to uint16, data []byte) ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_CLIENT,
+		FromID:  r.ID,
+		ToID:    to,
+		Action:  ACTION_SEND,
+		About:   ABOUT_CBES_SPECS,
+		DataLen: uint16(len(data)),
+		Data:    data,
+	}
+	return c.Bytes()
+}
+
+func (r *RegisteredUser) SendMessageToID(to uint16, msg []byte) ([]byte, error) {
+	c := Message{
+		Version: V1,
+		From:    FROM_CLIENT,
+		FromID:  r.ID,
+		ToID:    to,
+		Action:  ACTION_SEND,
+		About:   ABOUT_MESSAGE,
+		DataLen: uint16(len(msg)),
+		Data:    msg,
+	}
+	return c.Bytes()
+}