diff --git a/Realtime/Internal/Controller/LCIMConversationController.cs b/Realtime/Internal/Controller/LCIMConversationController.cs
index caee6fe..79c9f71 100644
--- a/Realtime/Internal/Controller/LCIMConversationController.cs
+++ b/Realtime/Internal/Controller/LCIMConversationController.cs
@@ -57,7 +57,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
                 };
             }
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateStartConversationSignature(Client.Id, members);
+                LCIMSignature signature = await Client.SignatureFactory.CreateStartConversationSignature(Client.Id, members);
                 conv.S = signature.Signature;
                 conv.T = signature.Timestamp;
                 conv.N = signature.Nonce;
@@ -145,7 +145,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
             conv.M.AddRange(clientIds);
             // 签名参数
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateConversationSignature(convId,
+                LCIMSignature signature = await Client.SignatureFactory.CreateConversationSignature(convId,
                     Client.Id,
                     clientIds,
                     LCIMSignatureAction.Invite);
@@ -175,7 +175,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
             conv.M.AddRange(removeIds);
             // 签名参数
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateConversationSignature(convId,
+                LCIMSignature signature = await Client.SignatureFactory.CreateConversationSignature(convId,
                     Client.Id,
                     removeIds,
                     LCIMSignatureAction.Kick);
@@ -271,7 +271,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
             };
             blacklist.ToPids.AddRange(clientIds);
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateBlacklistSignature(convId,
+                LCIMSignature signature = await Client.SignatureFactory.CreateBlacklistSignature(convId,
                     Client.Id,
                     clientIds,
                     LCIMSignatureAction.ConversationBlockClients);
@@ -298,7 +298,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
             };
             blacklist.ToPids.AddRange(clientIds);
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateBlacklistSignature(convId,
+                LCIMSignature signature = await Client.SignatureFactory.CreateBlacklistSignature(convId,
                     Client.Id,
                     clientIds,
                     LCIMSignatureAction.ConversationUnblockClients);
diff --git a/Realtime/Internal/Controller/LCIMSessionController.cs b/Realtime/Internal/Controller/LCIMSessionController.cs
index 336dbb9..6017ca6 100644
--- a/Realtime/Internal/Controller/LCIMSessionController.cs
+++ b/Realtime/Internal/Controller/LCIMSessionController.cs
@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
+using LeanCloud.Storage;
 using LeanCloud.Realtime.Protocol;
 
 namespace LeanCloud.Realtime.Internal.Controller {
@@ -19,7 +21,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
         /// </summary>
         /// <returns></returns>
         internal async Task Open(bool force) {
-            SessionCommand session = NewSessionCommand();
+            SessionCommand session = await NewSessionCommand();
             session.R = !force;
             GenericCommand request = NewCommand(CommandType.Session, OpType.Open);
             request.SessionMessage = session;
@@ -32,7 +34,7 @@ namespace LeanCloud.Realtime.Internal.Controller {
         /// </summary>
         /// <returns></returns>
         internal async Task Reopen() {
-            SessionCommand session = NewSessionCommand();
+            SessionCommand session = await NewSessionCommand();
             session.R = true;
             GenericCommand request = NewCommand(CommandType.Session, OpType.Open);
             request.SessionMessage = session;
@@ -67,14 +69,14 @@ namespace LeanCloud.Realtime.Internal.Controller {
         #endregion
 
         private async Task Refresh() {
-            SessionCommand session = NewSessionCommand();
+            SessionCommand session = await NewSessionCommand();
             GenericCommand request = NewCommand(CommandType.Session, OpType.Refresh);
             request.SessionMessage = session;
             GenericCommand response = await Client.Connection.SendRequest(request);
             UpdateSession(response.SessionMessage);
         }
 
-        private SessionCommand NewSessionCommand() {
+        private async Task<SessionCommand> NewSessionCommand() {
             SessionCommand session = new SessionCommand();
             if (Client.Tag != null) {
                 session.Tag = Client.Tag;
@@ -82,8 +84,21 @@ namespace LeanCloud.Realtime.Internal.Controller {
             if (Client.DeviceId != null) {
                 session.DeviceId = Client.DeviceId;
             }
+            LCIMSignature signature = null;
             if (Client.SignatureFactory != null) {
-                LCIMSignature signature = Client.SignatureFactory.CreateConnectSignature(Client.Id);
+                signature = await Client.SignatureFactory.CreateConnectSignature(Client.Id);
+            }
+            if (signature == null && !string.IsNullOrEmpty(Client.SessionToken)) {
+                Dictionary<string, object> ret = await LCApplication.HttpClient.Post<Dictionary<string, object>>("rtm/sign", data: new Dictionary<string, object> {
+                    { "session_token", Client.SessionToken }
+                });
+                signature = new LCIMSignature {
+                    Signature = ret["signature"] as string,
+                    Timestamp = (long)ret["timestamp"],
+                    Nonce = ret["nonce"] as string
+                };
+            }
+            if (signature != null) {
                 session.S = signature.Signature;
                 session.T = signature.Timestamp;
                 session.N = signature.Nonce;
diff --git a/Realtime/LCIMClient.cs b/Realtime/LCIMClient.cs
index be282b3..6e87afd 100644
--- a/Realtime/LCIMClient.cs
+++ b/Realtime/LCIMClient.cs
@@ -4,6 +4,7 @@ using System.Threading.Tasks;
 using System.Linq;
 using System.Collections.ObjectModel;
 using LeanCloud.Common;
+using LeanCloud.Storage;
 using LeanCloud.Realtime.Protocol;
 using LeanCloud.Realtime.Internal.Controller;
 using LeanCloud.Realtime.Internal.Connection;
@@ -27,6 +28,10 @@ namespace LeanCloud.Realtime {
             get; private set;
         }
 
+        internal string SessionToken {
+            get; private set;
+        }
+
         #region 事件
 
         #region 连接状态事件
@@ -248,6 +253,31 @@ namespace LeanCloud.Realtime {
             string tag = null,
             string deviceId = null,
             ILCIMSignatureFactory signatureFactory = null) {
+            if (string.IsNullOrEmpty(clientId)) {
+                throw new ArgumentNullException(nameof(clientId));
+            }
+            SetUpClient(clientId, tag, deviceId, signatureFactory);
+        }
+
+        public LCIMClient(LCUser user,
+            string tag = null,
+            string deviceId = null,
+            ILCIMSignatureFactory signatureFactory = null) {
+            if (user == null) {
+                throw new ArgumentNullException(nameof(user));
+            }
+            if (string.IsNullOrEmpty(user.ObjectId) ||
+                string.IsNullOrEmpty(user.SessionToken)) {
+                throw new ArgumentException("User must be authenticacted.");
+            }
+            SetUpClient(user.ObjectId, tag, deviceId, signatureFactory);
+            SessionToken = user.SessionToken;
+        }
+
+        private void SetUpClient(string clientId,
+            string tag,
+            string deviceId,
+            ILCIMSignatureFactory signatureFactory) {
             Id = clientId;
             Tag = tag;
             DeviceId = deviceId;
diff --git a/Realtime/Signature/ILCIMSignatureFactory.cs b/Realtime/Signature/ILCIMSignatureFactory.cs
index 3f4d845..7b62de6 100644
--- a/Realtime/Signature/ILCIMSignatureFactory.cs
+++ b/Realtime/Signature/ILCIMSignatureFactory.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Threading.Tasks;
 
 namespace LeanCloud.Realtime {
     public interface ILCIMSignatureFactory {
@@ -7,13 +8,13 @@ namespace LeanCloud.Realtime {
         /// </summary>
         /// <param name="clientId"></param>
         /// <returns></returns>
-        LCIMSignature CreateConnectSignature(string clientId);
+        Task<LCIMSignature> CreateConnectSignature(string clientId);
 
         /// <summary>
         /// 创建开启对话签名
         /// </summary>
         /// <returns></returns>
-        LCIMSignature CreateStartConversationSignature(string clientId, IEnumerable<string> memberIds);
+        Task<LCIMSignature> CreateStartConversationSignature(string clientId, IEnumerable<string> memberIds);
 
         /// <summary>
         /// 创建会话相关签名
@@ -23,7 +24,7 @@ namespace LeanCloud.Realtime {
         /// <param name="memberIds"></param>
         /// <param name="action"></param>
         /// <returns></returns>
-        LCIMSignature CreateConversationSignature(string conversationId, string clientId, IEnumerable<string> memberIds, string action);
+        Task<LCIMSignature> CreateConversationSignature(string conversationId, string clientId, IEnumerable<string> memberIds, string action);
 
         /// <summary>
         /// 创建黑名单相关签名
@@ -33,6 +34,6 @@ namespace LeanCloud.Realtime {
         /// <param name="memberIds"></param>
         /// <param name="action"></param>
         /// <returns></returns>
-        LCIMSignature CreateBlacklistSignature(string conversationId, string clientId, IEnumerable<string> memberIds, string action);
+        Task<LCIMSignature> CreateBlacklistSignature(string conversationId, string clientId, IEnumerable<string> memberIds, string action);
     }
 }
diff --git a/Test/Realtime.Test/Client.cs b/Test/Realtime.Test/Client.cs
new file mode 100644
index 0000000..07823d2
--- /dev/null
+++ b/Test/Realtime.Test/Client.cs
@@ -0,0 +1,7 @@
+using System;
+namespace Realtime.Test {
+    public class Client {
+        public Client() {
+        }
+    }
+}
diff --git a/Test/Realtime.Test/ConversationQuery.cs b/Test/Realtime.Test/ConversationQuery.cs
new file mode 100644
index 0000000..f30a23b
--- /dev/null
+++ b/Test/Realtime.Test/ConversationQuery.cs
@@ -0,0 +1,7 @@
+using System;
+namespace Realtime.Test {
+    public class ConversationQuery {
+        public ConversationQuery() {
+        }
+    }
+}