diff --git a/build.gradle b/build.gradle
index c477816..5e05bce 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,7 +3,7 @@ plugins {
 }
 
 group 'com.valashko.xaapi'
-version '0.1'
+version '0.2'
 
 sourceCompatibility = 1.8
 
diff --git a/src/main/java/com/valashko/xaapi/command/WriteCommand.java b/src/main/java/com/valashko/xaapi/command/WriteCommand.java
new file mode 100644
index 0000000..cc1e771
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/command/WriteCommand.java
@@ -0,0 +1,23 @@
+package com.valashko.xaapi.command;
+
+import com.google.gson.JsonObject;
+import com.valashko.xaapi.device.SlaveDevice;
+
+import java.nio.charset.StandardCharsets;
+
+public class WriteCommand implements ICommand {
+    private SlaveDevice device;
+    private JsonObject data;
+
+    public WriteCommand(SlaveDevice device, JsonObject data, String key) {
+        this.device = device;
+        this.data = data;
+        data.addProperty("key", key);
+    }
+
+    @Override
+    public byte[] toBytes() {
+        String what = "{{\"cmd\":\"write\", \"sid\":\""+ device.getSid() +"\", \"data\":" + data + "}}";
+        return what.getBytes(StandardCharsets.US_ASCII);
+    }
+}
diff --git a/src/main/java/com/valashko/xaapi/device/BuiltinDevice.java b/src/main/java/com/valashko/xaapi/device/BuiltinDevice.java
index f1e33e5..a561a2f 100644
--- a/src/main/java/com/valashko/xaapi/device/BuiltinDevice.java
+++ b/src/main/java/com/valashko/xaapi/device/BuiltinDevice.java
@@ -2,7 +2,6 @@
 
 import com.google.gson.JsonParser;
 import com.valashko.xaapi.XaapiException;
-import sun.reflect.generics.reflectiveObjects.NotImplementedException;
 
 public abstract class BuiltinDevice {
 
diff --git a/src/main/java/com/valashko/xaapi/device/SlaveDevice.java b/src/main/java/com/valashko/xaapi/device/SlaveDevice.java
index a891495..e67c175 100644
--- a/src/main/java/com/valashko/xaapi/device/SlaveDevice.java
+++ b/src/main/java/com/valashko/xaapi/device/SlaveDevice.java
@@ -15,10 +15,12 @@ public enum Type {
     }
 
     protected static JsonParser JSON_PARSER = new JsonParser();
+    protected XiaomiGateway gateway;
     private String sid;
     private Type type;
 
-    public SlaveDevice(String sid, Type type) {
+    public SlaveDevice(XiaomiGateway gateway, String sid, Type type) {
+        this.gateway = gateway;
         this.sid = sid;
         this.type = type;
     }
diff --git a/src/main/java/com/valashko/xaapi/device/Utility.java b/src/main/java/com/valashko/xaapi/device/Utility.java
new file mode 100644
index 0000000..0170508
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/device/Utility.java
@@ -0,0 +1,12 @@
+package com.valashko.xaapi.device;
+
+public class Utility {
+
+    public static String toHexString(byte[] bytes) {
+        StringBuilder sb = new StringBuilder();
+        for (byte b : bytes) {
+            sb.append(String.format("%02X", b));
+        }
+        return sb.toString();
+    }
+}
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiCube.java b/src/main/java/com/valashko/xaapi/device/XiaomiCube.java
index ecebbe7..23daf90 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiCube.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiCube.java
@@ -29,8 +29,8 @@ public enum Action {
     private HashMap<SubscriptionToken, Consumer<String>> actionsCallbacks = new HashMap<>();
     private HashMap<SubscriptionToken, Consumer<Double>> rotationCallbacks = new HashMap<>();
 
-    public XiaomiCube(String sid) {
-        super(sid, Type.XiaomiCube);
+    public XiaomiCube(XiaomiGateway gateway, String sid) {
+        super(gateway, sid, Type.XiaomiCube);
     }
 
     @Override
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiDoorWindowSensor.java b/src/main/java/com/valashko/xaapi/device/XiaomiDoorWindowSensor.java
index 7b0a087..6645667 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiDoorWindowSensor.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiDoorWindowSensor.java
@@ -13,8 +13,8 @@ public enum Status {
 
     private Status lastStatus;
 
-    public XiaomiDoorWindowSensor(String sid) {
-        super(sid, Type.XiaomiCube);
+    public XiaomiDoorWindowSensor(XiaomiGateway gateway, String sid) {
+        super(gateway, sid, Type.XiaomiCube);
     }
 
     @Override
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiGateway.java b/src/main/java/com/valashko/xaapi/device/XiaomiGateway.java
index d8f10ff..246189e 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiGateway.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiGateway.java
@@ -1,20 +1,27 @@
 package com.valashko.xaapi.device;
 
 import com.google.gson.Gson;
+import com.google.gson.JsonObject;
 import com.valashko.xaapi.XaapiException;
-import com.valashko.xaapi.channel.DirectChannel;
-import com.valashko.xaapi.channel.IncomingMulticastChannel;
-import com.valashko.xaapi.command.WhoisCommand;
-import com.valashko.xaapi.command.GetIdListCommand;
-import com.valashko.xaapi.command.ReadCommand;
-import com.valashko.xaapi.reply.GetIdListReply;
-import com.valashko.xaapi.reply.ReadReply;
-import com.valashko.xaapi.reply.WhoisReply;
+import com.valashko.xaapi.channel.*;
+import com.valashko.xaapi.command.*;
+import com.valashko.xaapi.reply.*;
 
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
 import java.io.IOException;
 import java.net.SocketTimeoutException;
+import java.nio.charset.StandardCharsets;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.Executor;
 
 public class XiaomiGateway {
@@ -22,10 +29,15 @@ public class XiaomiGateway {
     private static final String GROUP = "224.0.0.50";
     private static final int PORT = 9898;
     private static final int PORT_DISCOVERY = 4321;
+    private static final byte[] IV =
+        {     0x17, (byte)0x99, 0x6d, 0x09, 0x3d, 0x28, (byte)0xdd, (byte)0xb3,
+        (byte)0xba,       0x69, 0x5a, 0x2e, 0x6f, 0x58,       0x56,       0x2e};
 
     private static final Gson GSON = new Gson();
 
     private String sid;
+    private Optional<String> key = Optional.empty();
+    private Cipher cipher;
     private IncomingMulticastChannel incomingMulticastChannel;
     private DirectChannel directChannel;
     private XiaomiGatewayLight builtinLight;
@@ -51,12 +63,33 @@ public XiaomiGateway(String ip) throws IOException, XaapiException {
         configureBuiltinDevices();
         queryDevices();
     }
+    public XiaomiGateway(String ip, String password) throws IOException, XaapiException {
+        this(ip);
+        configureCipher(password);
+    }
 
     private void configureBuiltinDevices() {
         builtinLight = new XiaomiGatewayLight();
         builtinIlluminationSensor = new XiaomiGatewayIlluminationSensor();
     }
 
+    private void configureCipher(String password) throws XaapiException {
+        try {
+            cipher = Cipher.getInstance("AES/CBC/NoPadding");
+            final SecretKeySpec keySpec = new SecretKeySpec(password.getBytes(), "AES");
+            final IvParameterSpec ivSpec = new IvParameterSpec(IV);
+            cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
+        } catch (NoSuchAlgorithmException e) {
+            throw new XaapiException("Cipher error: " + e.getMessage());
+        } catch (NoSuchPaddingException e) {
+            throw new XaapiException("Cipher error: " + e.getMessage());
+        } catch (InvalidAlgorithmParameterException e) {
+            throw new XaapiException("Cipher error: " + e.getMessage());
+        } catch (InvalidKeyException e) {
+            throw new XaapiException("Cipher error: " + e.getMessage());
+        }
+    }
+
     private void queryDevices() throws XaapiException {
         try {
             directChannel.send(new GetIdListCommand().toBytes());
@@ -93,6 +126,34 @@ private boolean isMyself(String sid) {
         return sid.equals(this.sid);
     }
 
+    private void updateKey(String token) throws XaapiException {
+        if(cipher != null) {
+            try {
+                String keyAsHexString = Utility.toHexString(cipher.doFinal(token.getBytes(StandardCharsets.US_ASCII)));
+                key = Optional.of(keyAsHexString);
+            } catch (IllegalBlockSizeException e) {
+                throw new XaapiException("Cipher error: " + e.getMessage());
+            } catch (BadPaddingException e) {
+                throw new XaapiException("Cipher error: " + e.getMessage());
+            }
+        } else {
+            throw new XaapiException("Unable to update key without a cipher. Did you forget to set a password?");
+        }
+    }
+
+    void sendDataToDevice(SlaveDevice device, JsonObject data) throws XaapiException {
+        if(key.isPresent()) {
+            try {
+                directChannel.send(new WriteCommand(device, data, key.get()).toBytes());
+                // TODO add handling for expired key
+            } catch (IOException e) {
+                throw new XaapiException("Network error: " + e.getMessage());
+            }
+        } else {
+            throw new XaapiException("Unable to control device without a key. Did you forget to set a password?");
+        }
+    }
+
     private SlaveDevice readDevice(String sid) throws XaapiException {
         try {
             directChannel.send(new ReadCommand(sid).toBytes());
@@ -101,23 +162,23 @@ private SlaveDevice readDevice(String sid) throws XaapiException {
 
             switch(reply.model) {
                 case "cube":
-                    XiaomiCube cube = new XiaomiCube(sid);
+                    XiaomiCube cube = new XiaomiCube(this, sid);
                     cube.update(reply.data);
                     return cube;
                 case "magnet":
-                    XiaomiDoorWindowSensor magnet = new XiaomiDoorWindowSensor(sid);
+                    XiaomiDoorWindowSensor magnet = new XiaomiDoorWindowSensor(this, sid);
                     magnet.update(reply.data);
                     return magnet;
                 case "plug":
-                    XiaomiSocket plug = new XiaomiSocket(sid);
+                    XiaomiSocket plug = new XiaomiSocket(this, sid);
                     plug.update(reply.data);
                     return plug;
                 case "motion":
-                    XiaomiMotionSensor motion = new XiaomiMotionSensor(sid);
+                    XiaomiMotionSensor motion = new XiaomiMotionSensor(this, sid);
                     motion.update(reply.data);
                     return motion;
                 case "switch":
-                    XiaomiSwitchButton button = new XiaomiSwitchButton(sid);
+                    XiaomiSwitchButton button = new XiaomiSwitchButton(this, sid);
                     button.update(reply.data);
                     return button;
                 default:
@@ -133,7 +194,8 @@ public void startReceivingUpdates(Executor executor) {
         executor.execute(() -> {
             while (continueReceivingUpdates) {
                 try {
-                    handleUpdate(GSON.fromJson(new String(incomingMulticastChannel.receive()), ReadReply.class));
+                    String received = new String(incomingMulticastChannel.receive());
+                    handleUpdate(GSON.fromJson(received, ReadReply.class), received);
                 } catch (SocketTimeoutException e) {
                     // ignore
                 } catch (IOException e) {
@@ -151,34 +213,46 @@ public void stopReceivingUpdates() {
         continueReceivingUpdates = false;
     }
 
-    private void handleUpdate(ReadReply update) throws XaapiException {
+    private void handleUpdate(Reply update, String received) throws XaapiException {
         switch(update.cmd) {
             case "report":
+                Report report = GSON.fromJson(received, Report.class);
                 if(isMyself(update.sid)) {
-                    handleBuiltinReport(update);
+                    handleBuiltinReport(report);
                 } else {
-                    handleReport(update);
+                    handleReport(report);
                 }
                 break;
             case "heartbeat":
-                handleHeartbeat(update);
+                if(isMyself(update.sid)) {
+                    GatewayHeartbeat gatewayHeartbeat = GSON.fromJson(received, GatewayHeartbeat.class);
+                    handleGatewayHeartbeat(gatewayHeartbeat);
+                } else {
+                    SlaveDeviceHeartbeat slaveDeviceHeartbeat = GSON.fromJson(received, SlaveDeviceHeartbeat.class);
+                    handleSlaveDeviceHeartbeat(slaveDeviceHeartbeat);
+                }
                 break;
             default:
                 throw new XaapiException("Unexpected update command: " + update.cmd);
         }
     }
 
-    private void handleReport(ReadReply update) {
-        // TODO handle updates about gateway itself
-        getDevice(update.sid).update(update.data);
+    private void handleReport(Report report) {
+        getDevice(report.sid).update(report.data);
+    }
+
+    private void handleBuiltinReport(Report report) {
+        builtinLight.update(report.data);
+        builtinIlluminationSensor.update(report.data);
     }
 
-    private void handleBuiltinReport(ReadReply update) {
-        builtinLight.update(update.data);
-        builtinIlluminationSensor.update(update.data);
+    private void handleGatewayHeartbeat(GatewayHeartbeat gatewayHeartbeat) throws XaapiException {
+        if(cipher != null) {
+            updateKey(gatewayHeartbeat.token);
+        }
     }
 
-    private void handleHeartbeat(ReadReply update) {
+    private void handleSlaveDeviceHeartbeat(SlaveDeviceHeartbeat slaveDeviceHeartbeat) {
         // TODO implement
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiMotionSensor.java b/src/main/java/com/valashko/xaapi/device/XiaomiMotionSensor.java
index 268c106..19fada9 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiMotionSensor.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiMotionSensor.java
@@ -12,8 +12,8 @@ public enum Status {
 
     private Status lastStatus;
 
-    public XiaomiMotionSensor(String sid) {
-        super(sid, Type.XiaomiMotionSensor);
+    public XiaomiMotionSensor(XiaomiGateway gateway, String sid) {
+        super(gateway, sid, Type.XiaomiMotionSensor);
     }
 
     @Override
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiSocket.java b/src/main/java/com/valashko/xaapi/device/XiaomiSocket.java
index a6f12ab..cfb6ed9 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiSocket.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiSocket.java
@@ -14,8 +14,8 @@ public enum Status {
 
     private Status lastStatus;
 
-    public XiaomiSocket(String sid) {
-        super(sid, Type.XiaomiSocket);
+    public XiaomiSocket(XiaomiGateway gateway, String sid) {
+        super(gateway, sid, Type.XiaomiSocket);
     }
 
     @Override
@@ -48,4 +48,16 @@ void update(String data) {
     public Status getLastStatus() {
         return lastStatus;
     }
+
+    public void turnOn() throws XaapiException {
+        JsonObject on = new JsonObject();
+        on.addProperty("status", "on");
+        gateway.sendDataToDevice(this, on);
+    }
+
+    public void turnOff() throws XaapiException {
+        JsonObject off = new JsonObject();
+        off.addProperty("status", "off");
+        gateway.sendDataToDevice(this, off);
+    }
 }
diff --git a/src/main/java/com/valashko/xaapi/device/XiaomiSwitchButton.java b/src/main/java/com/valashko/xaapi/device/XiaomiSwitchButton.java
index 97e30cd..5f9230b 100644
--- a/src/main/java/com/valashko/xaapi/device/XiaomiSwitchButton.java
+++ b/src/main/java/com/valashko/xaapi/device/XiaomiSwitchButton.java
@@ -12,14 +12,16 @@ public class XiaomiSwitchButton extends SlaveDevice implements IInteractiveDevic
 
     public enum Action {
         Click,
-        DoubleClick
+        DoubleClick,
+        LongClickPress,
+        LongClickRelease
     }
 
     private Action lastAction;
     private HashMap<SubscriptionToken, Consumer<String>> actionsCallbacks = new HashMap<>();
 
-    public XiaomiSwitchButton(String sid) {
-        super(sid, Type.XiaomiSwitchButton);
+    public XiaomiSwitchButton(XiaomiGateway gateway, String sid) {
+        super(gateway, sid, Type.XiaomiSwitchButton);
     }
 
     @Override
@@ -53,6 +55,12 @@ private void updateWithAction(String action) throws XaapiException {
             case "double_click":
                 lastAction = Action.DoubleClick;
                 break;
+            case "long_click_press":
+                lastAction = Action.LongClickPress;
+                break;
+            case "long_click_release":
+                lastAction = Action.LongClickRelease;
+                break;
             default:
                 throw new XaapiException("Unknown action: " + action);
         }
diff --git a/src/main/java/com/valashko/xaapi/reply/GatewayHeartbeat.java b/src/main/java/com/valashko/xaapi/reply/GatewayHeartbeat.java
new file mode 100644
index 0000000..75b094b
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/reply/GatewayHeartbeat.java
@@ -0,0 +1,8 @@
+package com.valashko.xaapi.reply;
+
+public class GatewayHeartbeat extends Reply {
+    public String model;
+    public String short_id; // NB: sometimes it is a string and sometimes a number
+    public String token;
+    public String data;
+}
diff --git a/src/main/java/com/valashko/xaapi/reply/GetIdListReply.java b/src/main/java/com/valashko/xaapi/reply/GetIdListReply.java
index 780949b..67ef137 100644
--- a/src/main/java/com/valashko/xaapi/reply/GetIdListReply.java
+++ b/src/main/java/com/valashko/xaapi/reply/GetIdListReply.java
@@ -1,8 +1,6 @@
 package com.valashko.xaapi.reply;
 
-public class GetIdListReply {
-    public String cmd;
-    public String sid;
-    public String token;
+public class GetIdListReply extends Reply {
     public String data;
+    public String token;
 }
diff --git a/src/main/java/com/valashko/xaapi/reply/ReadReply.java b/src/main/java/com/valashko/xaapi/reply/ReadReply.java
index 11c34c6..64995c1 100644
--- a/src/main/java/com/valashko/xaapi/reply/ReadReply.java
+++ b/src/main/java/com/valashko/xaapi/reply/ReadReply.java
@@ -1,9 +1,7 @@
 package com.valashko.xaapi.reply;
 
-public class ReadReply {
-    public String cmd;
+public class ReadReply extends Reply {
     public String model;
-    public String sid;
-    public short short_id;
+    public String short_id;
     public String data;
 }
diff --git a/src/main/java/com/valashko/xaapi/reply/Reply.java b/src/main/java/com/valashko/xaapi/reply/Reply.java
new file mode 100644
index 0000000..e50cb6d
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/reply/Reply.java
@@ -0,0 +1,6 @@
+package com.valashko.xaapi.reply;
+
+public class Reply {
+    public String cmd;
+    public String sid;
+}
diff --git a/src/main/java/com/valashko/xaapi/reply/Report.java b/src/main/java/com/valashko/xaapi/reply/Report.java
new file mode 100644
index 0000000..e32d445
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/reply/Report.java
@@ -0,0 +1,7 @@
+package com.valashko.xaapi.reply;
+
+public class Report extends Reply {
+    public String model;
+    public short short_id; // NB: sometimes it is a string and sometimes a number
+    public String data;
+}
diff --git a/src/main/java/com/valashko/xaapi/reply/SlaveDeviceHeartbeat.java b/src/main/java/com/valashko/xaapi/reply/SlaveDeviceHeartbeat.java
new file mode 100644
index 0000000..dae662c
--- /dev/null
+++ b/src/main/java/com/valashko/xaapi/reply/SlaveDeviceHeartbeat.java
@@ -0,0 +1,5 @@
+package com.valashko.xaapi.reply;
+
+public class SlaveDeviceHeartbeat extends Reply {
+    // TODO implement
+}
diff --git a/src/main/java/com/valashko/xaapi/reply/WhoisReply.java b/src/main/java/com/valashko/xaapi/reply/WhoisReply.java
index 2fcedcf..dbcee29 100644
--- a/src/main/java/com/valashko/xaapi/reply/WhoisReply.java
+++ b/src/main/java/com/valashko/xaapi/reply/WhoisReply.java
@@ -1,9 +1,7 @@
 package com.valashko.xaapi.reply;
 
-public class WhoisReply {
-    public String cmd;
+public class WhoisReply extends Reply {
     public String port;
-    public String sid;
     public String model;
     public String proto_version;
     public String ip;