diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 3ccb0c9..ab0d340 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -402,6 +402,7 @@
         // To avoid leaking stack in case that call never comes, and for tests,
         // initialize it here anyways.
         mInTouchMode(true),
+        mMaximumObscuringOpacityForTouch(1.0f),
         mFocusedDisplayId(ADISPLAY_ID_DEFAULT) {
     mLooper = new Looper(false);
     mReporter = createInputReporter();
@@ -1708,6 +1709,22 @@
             }
         }
 
+        // Drop events that can't be trusted due to occlusion
+        if (newTouchedWindowHandle != nullptr &&
+            mBlockUntrustedTouchesMode != BlockUntrustedTouchesMode::DISABLED) {
+            TouchOcclusionInfo occlusionInfo =
+                    computeTouchOcclusionInfoLocked(newTouchedWindowHandle, x, y);
+            // The order of the operands in the 'if' below is important because even if the feature
+            // is not BLOCK we want isTouchTrustedLocked() to execute in order to log details to
+            // logcat.
+            if (!isTouchTrustedLocked(occlusionInfo) &&
+                mBlockUntrustedTouchesMode == BlockUntrustedTouchesMode::BLOCK) {
+                ALOGW("Dropping untrusted touch event due to %s/%d",
+                      occlusionInfo.obscuringPackage.c_str(), occlusionInfo.obscuringUid);
+                newTouchedWindowHandle = nullptr;
+            }
+        }
+
         // Also don't send the new touch event to unresponsive gesture monitors
         newGestureMonitors = selectResponsiveMonitorsLocked(newGestureMonitors);
 
@@ -2121,6 +2138,84 @@
     return true;
 }
 
+/**
+ * Returns touch occlusion information in the form of TouchOcclusionInfo. To check if the touch is
+ * untrusted, one should check:
+ *
+ * 1. If result.hasBlockingOcclusion is true.
+ *    If it's, it means the touch should be blocked due to a window with occlusion mode of
+ *    BLOCK_UNTRUSTED.
+ *
+ * 2. If result.obscuringOpacity > mMaximumObscuringOpacityForTouch.
+ *    If it is (and 1 is false), then the touch should be blocked because a stack of windows
+ *    (possibly only one) with occlusion mode of USE_OPACITY from one UID resulted in a composed
+ *    obscuring opacity above the threshold. Note that if there was no window of occlusion mode
+ *    USE_OPACITY, result.obscuringOpacity would've been 0 and since
+ *    mMaximumObscuringOpacityForTouch >= 0, the condition above would never be true.
+ *
+ * If neither of those is true, then it means the touch can be allowed.
+ */
+InputDispatcher::TouchOcclusionInfo InputDispatcher::computeTouchOcclusionInfoLocked(
+        const sp<InputWindowHandle>& windowHandle, int32_t x, int32_t y) const {
+    int32_t displayId = windowHandle->getInfo()->displayId;
+    const std::vector<sp<InputWindowHandle>>& windowHandles = getWindowHandlesLocked(displayId);
+    TouchOcclusionInfo info;
+    info.hasBlockingOcclusion = false;
+    info.obscuringOpacity = 0;
+    info.obscuringUid = -1;
+    std::map<int32_t, float> opacityByUid;
+    for (const sp<InputWindowHandle>& otherHandle : windowHandles) {
+        if (windowHandle == otherHandle) {
+            break; // All future windows are below us. Exit early.
+        }
+        const InputWindowInfo* otherInfo = otherHandle->getInfo();
+        if (canBeObscuredBy(windowHandle, otherHandle) &&
+            windowHandle->getInfo()->ownerUid != otherInfo->ownerUid &&
+            otherInfo->frameContainsPoint(x, y)) {
+            // canBeObscuredBy() has returned true above, which means this window is untrusted, so
+            // we perform the checks below to see if the touch can be propagated or not based on the
+            // window's touch occlusion mode
+            if (otherInfo->touchOcclusionMode == TouchOcclusionMode::BLOCK_UNTRUSTED) {
+                info.hasBlockingOcclusion = true;
+                info.obscuringUid = otherInfo->ownerUid;
+                info.obscuringPackage = otherInfo->packageName;
+                break;
+            }
+            if (otherInfo->touchOcclusionMode == TouchOcclusionMode::USE_OPACITY) {
+                uint32_t uid = otherInfo->ownerUid;
+                float opacity =
+                        (opacityByUid.find(uid) == opacityByUid.end()) ? 0 : opacityByUid[uid];
+                // Given windows A and B:
+                // opacity(A, B) = 1 - [1 - opacity(A)] * [1 - opacity(B)]
+                opacity = 1 - (1 - opacity) * (1 - otherInfo->alpha);
+                opacityByUid[uid] = opacity;
+                if (opacity > info.obscuringOpacity) {
+                    info.obscuringOpacity = opacity;
+                    info.obscuringUid = uid;
+                    info.obscuringPackage = otherInfo->packageName;
+                }
+            }
+        }
+    }
+    return info;
+}
+
+bool InputDispatcher::isTouchTrustedLocked(const TouchOcclusionInfo& occlusionInfo) const {
+    if (occlusionInfo.hasBlockingOcclusion) {
+        ALOGW("Untrusted touch due to occlusion by %s/%d", occlusionInfo.obscuringPackage.c_str(),
+              occlusionInfo.obscuringUid);
+        return false;
+    }
+    if (occlusionInfo.obscuringOpacity > mMaximumObscuringOpacityForTouch) {
+        ALOGW("Untrusted touch due to occlusion by %s/%d (obscuring opacity = "
+              "%.2f, maximum allowed = %.2f)",
+              occlusionInfo.obscuringPackage.c_str(), occlusionInfo.obscuringUid,
+              occlusionInfo.obscuringOpacity, mMaximumObscuringOpacityForTouch);
+        return false;
+    }
+    return true;
+}
+
 bool InputDispatcher::isWindowObscuredAtPointLocked(const sp<InputWindowHandle>& windowHandle,
                                                     int32_t x, int32_t y) const {
     int32_t displayId = windowHandle->getInfo()->displayId;
@@ -4060,6 +4155,21 @@
     mInTouchMode = inTouchMode;
 }
 
+void InputDispatcher::setMaximumObscuringOpacityForTouch(float opacity) {
+    if (opacity < 0 || opacity > 1) {
+        LOG_ALWAYS_FATAL("Maximum obscuring opacity for touch should be >= 0 and <= 1");
+        return;
+    }
+
+    std::scoped_lock lock(mLock);
+    mMaximumObscuringOpacityForTouch = opacity;
+}
+
+void InputDispatcher::setBlockUntrustedTouchesMode(BlockUntrustedTouchesMode mode) {
+    std::scoped_lock lock(mLock);
+    mBlockUntrustedTouchesMode = mode;
+}
+
 bool InputDispatcher::transferTouchFocus(const sp<IBinder>& fromToken, const sp<IBinder>& toToken) {
     if (fromToken == toToken) {
         if (DEBUG_FOCUS) {