diff --git a/api/system-current.txt b/api/system-current.txt
index 98c6fcad17d76..4c86e57b5be4e 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -5092,7 +5092,9 @@ package android.media.tv.tuner {
     field public static final int INVALID_FILTER_ID = -1; // 0xffffffff
     field public static final long INVALID_FILTER_ID_64BIT = -1L; // 0xffffffffffffffffL
     field public static final int INVALID_FIRST_MACROBLOCK_IN_SLICE = -1; // 0xffffffff
+    field public static final int INVALID_FRONTEND_ID = -1; // 0xffffffff
     field public static final int INVALID_FRONTEND_SETTING_FREQUENCY = -1; // 0xffffffff
+    field @NonNull public static final byte[] INVALID_KEYTOKEN;
     field public static final int INVALID_LTS_ID = -1; // 0xffffffff
     field public static final int INVALID_MMTP_RECORD_EVENT_MPT_SEQUENCE_NUM = -1; // 0xffffffff
     field public static final int INVALID_STREAM_ID = 65535; // 0xffff
diff --git a/core/api/system-current.txt b/core/api/system-current.txt
index 4cc4b1664cf22..f172dc2695f66 100644
--- a/core/api/system-current.txt
+++ b/core/api/system-current.txt
@@ -5032,7 +5032,9 @@ package android.media.tv.tuner {
     field public static final int INVALID_FILTER_ID = -1; // 0xffffffff
     field public static final long INVALID_FILTER_ID_64BIT = -1L; // 0xffffffffffffffffL
     field public static final int INVALID_FIRST_MACROBLOCK_IN_SLICE = -1; // 0xffffffff
+    field public static final int INVALID_FRONTEND_ID = -1; // 0xffffffff
     field public static final int INVALID_FRONTEND_SETTING_FREQUENCY = -1; // 0xffffffff
+    field @NonNull public static final byte[] INVALID_KEYTOKEN;
     field public static final int INVALID_LTS_ID = -1; // 0xffffffff
     field public static final int INVALID_MMTP_RECORD_EVENT_MPT_SEQUENCE_NUM = -1; // 0xffffffff
     field public static final int INVALID_STREAM_ID = 65535; // 0xffff
diff --git a/media/java/android/media/tv/tuner/Descrambler.java b/media/java/android/media/tv/tuner/Descrambler.java
index 7b58bfc30b241..5f79dc52a2f1b 100644
--- a/media/java/android/media/tv/tuner/Descrambler.java
+++ b/media/java/android/media/tv/tuner/Descrambler.java
@@ -111,10 +111,13 @@ public class Descrambler implements AutoCloseable {
     /**
      * Set a key token to link descrambler to a key slot
      *
-     * A descrambler instance can have only one key slot to link, but a key slot can hold a few
+     * <p>A descrambler instance can have only one key slot to link, but a key slot can hold a few
      * keys for different purposes.
      *
-     * @param keyToken the token to be used to link the key slot.
+     * @param keyToken the token to be used to link the key slot. Use {@link Tuner.INVALID_KEYTOKEN}
+     *        to remove the to remove the current key from descrambler. If the current keyToken
+     *        comes from MediaCas session, use {@link Tuner.INVALID_KEYTOKEN} to remove current key
+     *        before close MediaCas session.
      * @return result status of the operation.
      */
     @Result
diff --git a/media/java/android/media/tv/tuner/Tuner.java b/media/java/android/media/tv/tuner/Tuner.java
index 5a578ddcdc253..aa3143fafd88d 100644
--- a/media/java/android/media/tv/tuner/Tuner.java
+++ b/media/java/android/media/tv/tuner/Tuner.java
@@ -152,6 +152,27 @@ public class Tuner implements AutoCloseable  {
      */
     public static final int INVALID_FRONTEND_SETTING_FREQUENCY =
             android.hardware.tv.tuner.V1_1.Constants.Constant.INVALID_FRONTEND_SETTING_FREQUENCY;
+    /**
+     * Invalid frontend id.
+     */
+    public static final int INVALID_FRONTEND_ID =
+            android.hardware.tv.tuner.V1_1.Constants.Constant.INVALID_FRONTEND_ID;
+    /**
+     * Invalid LNB id.
+     *
+     * @hide
+     */
+    public static final int INVALID_LNB_ID =
+            android.hardware.tv.tuner.V1_1.Constants.Constant.INVALID_LNB_ID;
+    /**
+     * Invalid key token. It is used to remove the current key from descrambler.
+     *
+     * <p>If the current keyToken comes from a MediaCas session, App is recommended to
+     * to use this constant to remove current key before closing MediaCas session.
+     */
+    @NonNull
+    public static final byte[] INVALID_KEYTOKEN =
+            {android.hardware.tv.tuner.V1_1.Constants.Constant.INVALID_KEYTOKEN};
 
     /** @hide */
     @IntDef(prefix = "SCAN_TYPE_", value = {SCAN_TYPE_UNDEFINED, SCAN_TYPE_AUTO, SCAN_TYPE_BLIND})
diff --git a/media/java/android/media/tv/tuner/frontend/FrontendInfo.java b/media/java/android/media/tv/tuner/frontend/FrontendInfo.java
index 334900ba705a6..68c0c9659cb9e 100644
--- a/media/java/android/media/tv/tuner/frontend/FrontendInfo.java
+++ b/media/java/android/media/tv/tuner/frontend/FrontendInfo.java
@@ -53,6 +53,9 @@ public class FrontendInfo {
 
     /**
      * Gets frontend ID.
+     *
+     * @return the frontend ID or {@link android.media.tv.tuner.Tuner.INVALID_FRONTEND_ID}
+     *         if invalid
      */
     public int getId() {
         return mId;