diff --git a/core/java/android/service/trust/TrustAgentService.java b/core/java/android/service/trust/TrustAgentService.java
index 559313a30dfaa..41345e0154eef 100644
--- a/core/java/android/service/trust/TrustAgentService.java
+++ b/core/java/android/service/trust/TrustAgentService.java
@@ -141,7 +141,9 @@ public class TrustAgentService extends Service {
      *
      * Without this flag, the message passed to {@code grantTrust} is only used for debugging
      * purposes. With the flag, it may be displayed to the user as the reason why the device is
-     * unlocked.
+     * unlocked. If this flag isn't set OR the message is set to null, the device will display
+     * its own default message for trust granted. If the TrustAgent intentionally doesn't want to
+     * show any message, then it can set this flag AND set the message to an empty string.
      */
     public static final int FLAG_GRANT_TRUST_DISPLAY_MESSAGE = 1 << 3;
 
diff --git a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
index 167d8af5ce795..01375cb489bb9 100644
--- a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
+++ b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
@@ -440,8 +440,8 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
             final boolean userHasTrust = getUserHasTrust(userId);
             if (userHasTrust && trustGrantedMessages != null) {
                 for (String msg : trustGrantedMessages) {
-                    if (!TextUtils.isEmpty(msg)) {
-                        message = msg;
+                    message = msg;
+                    if (!TextUtils.isEmpty(message)) {
                         break;
                     }
                 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/KeyguardIndicationController.java b/packages/SystemUI/src/com/android/systemui/statusbar/KeyguardIndicationController.java
index 47dc5c2a5513e..2bf1800311250 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/KeyguardIndicationController.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/KeyguardIndicationController.java
@@ -687,11 +687,11 @@ public class KeyguardIndicationController {
     /**
      * Returns the indication text indicating that trust has been granted.
      *
-     * @return {@code null} or an empty string if a trust indication text should not be shown.
+     * @return an empty string if a trust indication text should not be shown.
      */
     @VisibleForTesting
     String getTrustGrantedIndication() {
-        return TextUtils.isEmpty(mTrustGrantedIndication)
+        return mTrustGrantedIndication == null
                 ? mContext.getString(R.string.keyguard_indication_trust_unlocked)
                 : mTrustGrantedIndication.toString();
     }
diff --git a/packages/SystemUI/tests/src/com/android/systemui/statusbar/KeyguardIndicationControllerTest.java b/packages/SystemUI/tests/src/com/android/systemui/statusbar/KeyguardIndicationControllerTest.java
index 798f47d2d6cbd..433c3b2cf06c9 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/statusbar/KeyguardIndicationControllerTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/statusbar/KeyguardIndicationControllerTest.java
@@ -994,14 +994,14 @@ public class KeyguardIndicationControllerTest extends SysuiTestCase {
     }
 
     @Test
-    public void onTrustGrantedMessageDoesShowsOnTrustGranted() {
+    public void onTrustGrantedMessageShowsOnTrustGranted() {
         createController();
         mController.setVisible(true);
 
         // GIVEN trust is granted
         when(mKeyguardUpdateMonitor.getUserHasTrust(anyInt())).thenReturn(true);
 
-        // WHEN the showTrustGranted message is called
+        // WHEN the showTrustGranted method is called
         final String trustGrantedMsg = "testing trust granted message";
         mController.getKeyguardCallback().showTrustGrantedMessage(trustGrantedMsg);
 
@@ -1011,6 +1011,38 @@ public class KeyguardIndicationControllerTest extends SysuiTestCase {
                 trustGrantedMsg);
     }
 
+    @Test
+    public void onTrustGrantedMessage_nullMessage_showsDefaultMessage() {
+        createController();
+        mController.setVisible(true);
+
+        // GIVEN trust is granted
+        when(mKeyguardUpdateMonitor.getUserHasTrust(anyInt())).thenReturn(true);
+
+        // WHEN the showTrustGranted method is called with a null message
+        mController.getKeyguardCallback().showTrustGrantedMessage(null);
+
+        // THEN verify the default trust granted message shows
+        verifyIndicationMessage(
+                INDICATION_TYPE_TRUST,
+                getContext().getString(R.string.keyguard_indication_trust_unlocked));
+    }
+
+    @Test
+    public void onTrustGrantedMessage_emptyString_showsNoMessage() {
+        createController();
+        mController.setVisible(true);
+
+        // GIVEN trust is granted
+        when(mKeyguardUpdateMonitor.getUserHasTrust(anyInt())).thenReturn(true);
+
+        // WHEN the showTrustGranted method is called with an EMPTY string
+        mController.getKeyguardCallback().showTrustGrantedMessage("");
+
+        // THEN verify NO trust message is shown
+        verifyNoMessage(INDICATION_TYPE_TRUST);
+    }
+
     @Test
     public void coEx_faceSuccess_showsPressToOpen() {
         // GIVEN bouncer isn't showing, can skip bouncer, udfps is supported, no a11y enabled
diff --git a/services/core/java/com/android/server/trust/TrustManagerService.java b/services/core/java/com/android/server/trust/TrustManagerService.java
index 80ce70de2138c..3707c8e42e048 100644
--- a/services/core/java/com/android/server/trust/TrustManagerService.java
+++ b/services/core/java/com/android/server/trust/TrustManagerService.java
@@ -1211,7 +1211,7 @@ public class TrustManagerService extends SystemService {
             if (info.userId == userId
                     && info.agent.isTrusted()
                     && info.agent.shouldDisplayTrustGrantedMessage()
-                    && !TextUtils.isEmpty(info.agent.getMessage())) {
+                    && info.agent.getMessage() != null) {
                 trustGrantedMessages.add(info.agent.getMessage().toString());
             }
         }