diff --git a/binary/utils.go b/binary/utils.go
index 9267fff3..2c3895d0 100644
--- a/binary/utils.go
+++ b/binary/utils.go
@@ -20,9 +20,15 @@ func ZlibUncompress(src []byte) []byte {
 
 func CalculateImageResourceId(md5 []byte) string {
 	return strings.ToUpper(fmt.Sprintf(
-		"{%s-%s-%s-%s-%s}.png",
-		hex.EncodeToString(md5[0:4]), hex.EncodeToString(md5[4:6]), hex.EncodeToString(md5[6:8]),
-		hex.EncodeToString(md5[8:10]), hex.EncodeToString(md5[10:]),
+		"{%s}.png", GenUUID(md5),
+	))
+}
+
+func GenUUID(h []byte) string {
+	return strings.ToUpper(fmt.Sprintf(
+		"%s-%s-%s-%s-%s",
+		hex.EncodeToString(h[0:4]), hex.EncodeToString(h[4:6]), hex.EncodeToString(h[6:8]),
+		hex.EncodeToString(h[8:10]), hex.EncodeToString(h[10:]),
 	))
 }
 
diff --git a/client/global.go b/client/global.go
index cc251295..3ab40f74 100644
--- a/client/global.go
+++ b/client/global.go
@@ -2,10 +2,12 @@ package client
 
 import (
 	"crypto/md5"
+	"encoding/json"
 	"github.com/Mrs4s/MiraiGo/binary"
 	devinfo "github.com/Mrs4s/MiraiGo/client/pb"
 	"github.com/Mrs4s/MiraiGo/client/pb/msg"
 	"github.com/Mrs4s/MiraiGo/message"
+	"github.com/Mrs4s/MiraiGo/utils"
 	"google.golang.org/protobuf/proto"
 	"math/rand"
 	"sort"
@@ -45,12 +47,21 @@ type Version struct {
 	Sdk         uint32
 }
 
+type DeviceInfoFile struct {
+	Display     string `json:"display"`
+	FingerPrint string `json:"finger_print"`
+	BootId      string `json:"boot_id"`
+	ProcVersion string `json:"proc_version"`
+	IMEI        string `json:"imei"`
+}
+
 type groupMessageBuilder struct {
 	MessageSeq    int32
 	MessageCount  int32
 	MessageSlices []*msg.Message
 }
 
+// default
 var SystemDeviceInfo = &DeviceInfo{
 	Display:     []byte("MIRAI.123456.001"),
 	Product:     []byte("mirai"),
@@ -81,6 +92,7 @@ var SystemDeviceInfo = &DeviceInfo{
 }
 
 var EmptyBytes = []byte{}
+var NumberRange = "0123456789"
 
 func init() {
 	r := make([]byte, 16)
@@ -91,6 +103,50 @@ func init() {
 	SystemDeviceInfo.GenNewTgtgtKey()
 }
 
+func GenRandomDevice() {
+	r := make([]byte, 16)
+	rand.Read(r)
+	SystemDeviceInfo.Display = []byte("MIRAI." + utils.RandomStringRange(6, NumberRange) + ".001")
+	SystemDeviceInfo.FingerPrint = []byte("mamoe/mirai/mirai:10/MIRAI.200122.001/" + utils.RandomStringRange(7, NumberRange) + ":user/release-keys")
+	SystemDeviceInfo.BootId = []byte(binary.GenUUID(r))
+	SystemDeviceInfo.ProcVersion = []byte("Linux version 3.0.31-" + utils.RandomString(8) + " (android-build@xxx.xxx.xxx.xxx.com)")
+	rand.Read(r)
+	t := md5.Sum(r)
+	SystemDeviceInfo.IMSIMd5 = t[:]
+	SystemDeviceInfo.IMEI = utils.RandomStringRange(15, NumberRange)
+	SystemDeviceInfo.AndroidId = SystemDeviceInfo.Display
+	SystemDeviceInfo.GenNewGuid()
+	SystemDeviceInfo.GenNewTgtgtKey()
+}
+
+func (info *DeviceInfo) ToJson() []byte {
+	f := &DeviceInfoFile{
+		Display:     string(info.Display),
+		FingerPrint: string(info.FingerPrint),
+		BootId:      string(info.BootId),
+		ProcVersion: string(info.ProcVersion),
+		IMEI:        info.IMEI,
+	}
+	d, _ := json.Marshal(f)
+	return d
+}
+
+func (info *DeviceInfo) ReadJson(d []byte) error {
+	var f DeviceInfoFile
+	if err := json.Unmarshal(d, &f); err != nil {
+		return err
+	}
+	info.Display = []byte(f.Display)
+	info.FingerPrint = []byte(f.FingerPrint)
+	info.BootId = []byte(f.BootId)
+	info.ProcVersion = []byte(f.ProcVersion)
+	info.IMEI = f.IMEI
+	info.AndroidId = SystemDeviceInfo.Display
+	SystemDeviceInfo.GenNewGuid()
+	SystemDeviceInfo.GenNewTgtgtKey()
+	return nil
+}
+
 func (info *DeviceInfo) GenNewGuid() {
 	t := md5.Sum(append(info.AndroidId, info.MacAddress...))
 	info.Guid = t[:]
diff --git a/message/elements.go b/message/elements.go
index 670a0b0b..294cede0 100644
--- a/message/elements.go
+++ b/message/elements.go
@@ -41,12 +41,6 @@ func NewText(s string) *TextElement {
 	return &TextElement{Content: s}
 }
 
-func NewImage(data []byte) *ImageElement {
-	return &ImageElement{
-		Data: data,
-	}
-}
-
 func NewGroupImage(id string, md5 []byte) *GroupImageElement {
 	return &GroupImageElement{
 		ImageId: id,
diff --git a/utils/string.go b/utils/string.go
index ea6de605..f4bd74dc 100644
--- a/utils/string.go
+++ b/utils/string.go
@@ -7,8 +7,11 @@ import (
 )
 
 func RandomString(len int) string {
+	return RandomStringRange(len, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
+}
+
+func RandomStringRange(len int, str string) string {
 	var res string
-	var str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
 	b := bytes.NewBufferString(str)
 	length := b.Len()
 	bigInt := big.NewInt(int64(length))