diff --git a/proxy/vmess/user.go b/proxy/vmess/user.go
index 7c234d08..fe64339c 100644
--- a/proxy/vmess/user.go
+++ b/proxy/vmess/user.go
@@ -1,5 +1,9 @@
 package vmess
 
+import (
+	"time"
+)
+
 type UserLevel int
 
 const (
@@ -12,6 +16,11 @@ type User interface {
 	Level() UserLevel
 }
 
+type SecondaryID interface {
+	ID() *ID
+	ValidUntil() time.Time
+}
+
 type UserSettings struct {
 	PayloadReadTimeout int
 }