diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index 70b38a4..15ad226 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -79,6 +79,7 @@
     ],
     defaults: ["TetheringExternalLibs"],
     libs: [
+        "framework-annotations-lib",
         "framework-tethering.impl",
     ],
     manifest: "AndroidManifestBase.xml",
diff --git a/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java b/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
index 21e55b4..1d5df61 100644
--- a/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
@@ -28,8 +28,6 @@
 
 import static java.util.Arrays.asList;
 
-import android.content.Context;
-import android.net.ConnectivityManager;
 import android.net.IpPrefix;
 import android.net.LinkAddress;
 import android.net.LinkProperties;
@@ -53,6 +51,7 @@
 import java.util.List;
 import java.util.Random;
 import java.util.Set;
+import java.util.function.Supplier;
 
 /**
  * This class coordinate IP addresses conflict problem.
@@ -65,6 +64,7 @@
  * @hide
  */
 public class PrivateAddressCoordinator {
+    // WARNING: Keep in sync with chooseDownstreamAddress
     public static final int PREFIX_LENGTH = 24;
 
     // Upstream monitor would be stopped when tethering is down. When tethering restart, downstream
@@ -77,19 +77,20 @@
     private static final String LEGACY_WIFI_P2P_IFACE_ADDRESS = "192.168.49.1/24";
     private static final String LEGACY_BLUETOOTH_IFACE_ADDRESS = "192.168.44.1/24";
     private final List<IpPrefix> mTetheringPrefixes;
-    private final ConnectivityManager mConnectivityMgr;
+    // A supplier that returns ConnectivityManager#getAllNetworks.
+    private final Supplier<Network[]> mGetAllNetworksSupplier;
     private final boolean mIsRandomPrefixBaseEnabled;
     private final boolean mShouldEnableWifiP2pDedicatedIp;
     // keyed by downstream type(TetheringManager.TETHERING_*).
     private final ArrayMap<AddressKey, LinkAddress> mCachedAddresses;
     private final Random mRandom;
 
-    public PrivateAddressCoordinator(Context context, boolean isRandomPrefixBase,
-                                     boolean shouldEnableWifiP2pDedicatedIp) {
+    public PrivateAddressCoordinator(Supplier<Network[]> getAllNetworksSupplier,
+            boolean isRandomPrefixBase,
+            boolean shouldEnableWifiP2pDedicatedIp) {
         mDownstreams = new ArraySet<>();
         mUpstreamPrefixMap = new ArrayMap<>();
-        mConnectivityMgr = (ConnectivityManager) context.getSystemService(
-                Context.CONNECTIVITY_SERVICE);
+        mGetAllNetworksSupplier = getAllNetworksSupplier;
         mIsRandomPrefixBaseEnabled = isRandomPrefixBase;
         mShouldEnableWifiP2pDedicatedIp = shouldEnableWifiP2pDedicatedIp;
         mCachedAddresses = new ArrayMap<AddressKey, LinkAddress>();
@@ -166,7 +167,7 @@
 
         // Remove all upstreams that are no longer valid networks
         final Set<Network> toBeRemoved = new HashSet<>(mUpstreamPrefixMap.keySet());
-        toBeRemoved.removeAll(asList(mConnectivityMgr.getAllNetworks()));
+        toBeRemoved.removeAll(asList(mGetAllNetworksSupplier.get()));
 
         mUpstreamPrefixMap.removeAll(toBeRemoved);
     }
@@ -194,7 +195,7 @@
             return cachedAddress;
         }
 
-        final int prefixIndex = getStartedPrefixIndex();
+        final int prefixIndex = getRandomPrefixIndex();
         for (int i = 0; i < mTetheringPrefixes.size(); i++) {
             final IpPrefix prefixRange = mTetheringPrefixes.get(
                     (prefixIndex + i) % mTetheringPrefixes.size());
@@ -210,7 +211,7 @@
         return null;
     }
 
-    private int getStartedPrefixIndex() {
+    private int getRandomPrefixIndex() {
         if (!mIsRandomPrefixBaseEnabled) return 0;
 
         final int random = getRandomInt() & 0xffffff;
@@ -247,123 +248,62 @@
         return getInUseDownstreamPrefix(prefix);
     }
 
-    // Get the next non-conflict sub prefix. E.g: To get next sub prefix from 10.0.0.0/8, if the
-    // previously selected prefix is 10.20.42.0/24(subPrefix: 0.20.42.0) and the conflicting prefix
-    // is 10.16.0.0/20 (10.16.0.0 ~ 10.16.15.255), then the max address under subPrefix is
-    // 0.16.15.255 and the next subPrefix is 0.16.16.255/24 (0.16.15.255 + 0.0.1.0).
-    // Note: the sub address 0.0.0.255 here is fine to be any value that it will be replaced as
-    // selected random sub address later.
-    private int getNextSubPrefix(final IpPrefix conflictPrefix, final int prefixRangeMask) {
-        final int suffixMask = ~prefixLengthToV4NetmaskIntHTH(conflictPrefix.getPrefixLength());
-        // The largest offset within the prefix assignment block that still conflicts with
-        // conflictPrefix.
-        final int maxConflict =
-                (getPrefixBaseAddress(conflictPrefix) | suffixMask) & ~prefixRangeMask;
-
-        final int prefixMask = prefixLengthToV4NetmaskIntHTH(PREFIX_LENGTH);
-        // Pick a sub prefix a full prefix (1 << (32 - PREFIX_LENGTH) addresses) greater than
-        // maxConflict. This ensures that the selected prefix never overlaps with conflictPrefix.
-        // There is no need to mask the result with PREFIX_LENGTH bits because this is done by
-        // findAvailablePrefixFromRange when it constructs the prefix.
-        return maxConflict + (1 << (32 - PREFIX_LENGTH));
-    }
-
-    private LinkAddress chooseDownstreamAddress(final IpPrefix prefixRange) {
+    @VisibleForTesting
+    public LinkAddress chooseDownstreamAddress(final IpPrefix prefixRange) {
         // The netmask of the prefix assignment block (e.g., 0xfff00000 for 172.16.0.0/12).
         final int prefixRangeMask = prefixLengthToV4NetmaskIntHTH(prefixRange.getPrefixLength());
 
         // The zero address in the block (e.g., 0xac100000 for 172.16.0.0/12).
         final int baseAddress = getPrefixBaseAddress(prefixRange);
 
-        // The subnet mask corresponding to PREFIX_LENGTH.
-        final int prefixMask = prefixLengthToV4NetmaskIntHTH(PREFIX_LENGTH);
+        // Try to get an address within the given prefix that does not conflict with any other
+        // prefix in the system.
+        for (int i = 0; i < 20; ++i) {
+            final int randomSuffix = mRandom.nextInt() & ~prefixRangeMask;
+            final int randomAddress = baseAddress | randomSuffix;
 
-        // The offset within prefixRange of a randomly-selected prefix of length PREFIX_LENGTH.
-        // This may not be the prefix of the address returned by this method:
-        // - If it is already in use, the method will return an address in another prefix.
-        // - If all prefixes within prefixRange are in use, the method will return null. For
-        // example, for a /24 prefix within 172.26.0.0/12, this will be a multiple of 256 in
-        // [0, 1048576). In other words, a random 32-bit number with mask 0x000fff00.
-        //
-        // prefixRangeMask is required to ensure no wrapping. For example, consider:
-        // - prefixRange 127.0.0.0/8
-        // - randomPrefixStart 127.255.255.0
-        // - A conflicting prefix of 127.255.254.0/23
-        // In this case without prefixRangeMask, getNextSubPrefix would return 128.0.0.0, which
-        // means the "start < end" check in findAvailablePrefixFromRange would not reject the prefix
-        // because Java doesn't have unsigned integers, so 128.0.0.0 = 0x80000000 = -2147483648
-        // is less than 127.0.0.0 = 0x7f000000 = 2130706432.
-        //
-        // Additionally, it makes debug output easier to read by making the numbers smaller.
-        final int randomInt = getRandomInt();
-        final int randomPrefixStart = randomInt & ~prefixRangeMask & prefixMask;
+            // Avoid selecting x.x.x.[0, 1, 255] addresses.
+            switch (randomAddress & 0xFF) {
+                case 0:
+                case 1:
+                case 255:
+                    // Try selecting a different address
+                    continue;
+            }
 
-        // A random offset within the prefix. Used to determine the local address once the prefix
-        // is selected. It does not result in an IPv4 address ending in .0, .1, or .255
-        // For a PREFIX_LENGTH of 24, this is a number between 2 and 254.
-        final int subAddress = getSanitizedSubAddr(randomInt, ~prefixMask);
+            // Avoid selecting commonly used subnets.
+            switch (randomAddress & 0xFFFFFF00) {
+                case 0xC0A80000: // 192.168.0.0/24
+                case 0xC0A80100: // 192.168.1.0/24
+                case 0xC0A85800: // 192.168.88.0/24
+                case 0xC0A86400: // 192.168.100.0/24
+                    continue;
+            }
 
-        // Find a prefix length PREFIX_LENGTH between randomPrefixStart and the end of the block,
-        // such that the prefix does not conflict with any upstream.
-        IpPrefix downstreamPrefix = findAvailablePrefixFromRange(
-                 randomPrefixStart, (~prefixRangeMask) + 1, baseAddress, prefixRangeMask);
-        if (downstreamPrefix != null) return getLinkAddress(downstreamPrefix, subAddress);
+            // Avoid 10.0.0.0 - 10.10.255.255
+            if (randomAddress >= 0x0A000000 && randomAddress <= 0x0A0AFFFF) {
+                continue;
+            }
 
-        // If that failed, do the same, but between 0 and randomPrefixStart.
-        downstreamPrefix = findAvailablePrefixFromRange(
-                0, randomPrefixStart, baseAddress, prefixRangeMask);
-
-        return getLinkAddress(downstreamPrefix, subAddress);
-    }
-
-    private LinkAddress getLinkAddress(final IpPrefix prefix, final int subAddress) {
-        if (prefix == null) return null;
-
-        final InetAddress address = intToInet4AddressHTH(getPrefixBaseAddress(prefix) | subAddress);
-        return new LinkAddress(address, PREFIX_LENGTH);
-    }
-
-    private IpPrefix findAvailablePrefixFromRange(final int start, final int end,
-            final int baseAddress, final int prefixRangeMask) {
-        int newSubPrefix = start;
-        while (newSubPrefix < end) {
-            final InetAddress address = intToInet4AddressHTH(baseAddress | newSubPrefix);
+            final InetAddress address = intToInet4AddressHTH(randomAddress);
             final IpPrefix prefix = new IpPrefix(address, PREFIX_LENGTH);
-
-            final IpPrefix conflictPrefix = getConflictPrefix(prefix);
-
-            if (conflictPrefix == null) return prefix;
-
-            newSubPrefix = getNextSubPrefix(conflictPrefix, prefixRangeMask);
+            if (getConflictPrefix(prefix) != null) {
+                // Prefix is conflicting with another prefix used in the system, find another one.
+                continue;
+            }
+            return new LinkAddress(address, PREFIX_LENGTH);
         }
-
+        // Could not find a prefix, return null and let caller try another range.
         return null;
     }
 
     /** Get random int which could be used to generate random address. */
+    // TODO: get rid of this function and mock getRandomPrefixIndex in tests.
     @VisibleForTesting
     public int getRandomInt() {
         return mRandom.nextInt();
     }
 
-    /** Get random subAddress and avoid selecting x.x.x.0, x.x.x.1 and x.x.x.255 address. */
-    private int getSanitizedSubAddr(final int randomInt, final int subAddrMask) {
-        final int randomSubAddr = randomInt & subAddrMask;
-        // If prefix length > 30, the selecting speace would be less than 4 which may be hard to
-        // avoid 3 consecutive address.
-        if (PREFIX_LENGTH > 30) return randomSubAddr;
-
-        // TODO: maybe it is not necessary to avoid .0, .1 and .255 address because tethering
-        // address would not be conflicted. This code only works because PREFIX_LENGTH is not longer
-        // than 24
-        final int candidate = randomSubAddr & 0xff;
-        if (candidate == 0 || candidate == 1 || candidate == 255) {
-            return (randomSubAddr & 0xfffffffc) + 2;
-        }
-
-        return randomSubAddr;
-    }
-
     /** Release downstream record for IpServer. */
     public void releaseDownstream(final IpServer ipServer) {
         mDownstreams.remove(ipServer);
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index 5bb1694..81f057c 100644
--- a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -21,6 +21,7 @@
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothPan;
 import android.content.Context;
+import android.net.ConnectivityManager;
 import android.net.INetd;
 import android.net.connectivity.ConnectivityInternalApiUtil;
 import android.net.ip.IpServer;
@@ -176,9 +177,12 @@
     /**
      * Make PrivateAddressCoordinator to be used by Tethering.
      */
-    public PrivateAddressCoordinator makePrivateAddressCoordinator(Context ctx,
-            TetheringConfiguration cfg) {
-        return new PrivateAddressCoordinator(ctx, cfg.isRandomPrefixBaseEnabled(),
+    public PrivateAddressCoordinator makePrivateAddressCoordinator(
+            Context ctx, TetheringConfiguration cfg) {
+        final ConnectivityManager cm = ctx.getSystemService(ConnectivityManager.class);
+        return new PrivateAddressCoordinator(
+                cm::getAllNetworks,
+                cfg.isRandomPrefixBaseEnabled(),
                 cfg.shouldEnableWifiP2pDedicatedIp());
     }
 
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/PrivateAddressCoordinatorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/PrivateAddressCoordinatorTest.java
index 148787f..a5c06f3 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/PrivateAddressCoordinatorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/PrivateAddressCoordinatorTest.java
@@ -16,7 +16,6 @@
 package com.android.networkstack.tethering;
 
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
-import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 import static android.net.NetworkCapabilities.TRANSPORT_VPN;
 import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
 import static android.net.TetheringManager.CONNECTIVITY_SCOPE_GLOBAL;
@@ -29,9 +28,11 @@
 import static com.android.networkstack.tethering.util.PrefixUtils.asIpPrefix;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
@@ -103,6 +104,7 @@
         MockitoAnnotations.initMocks(this);
 
         when(mContext.getSystemService(Context.CONNECTIVITY_SERVICE)).thenReturn(mConnectivityMgr);
+        when(mContext.getSystemService(ConnectivityManager.class)).thenReturn(mConnectivityMgr);
         when(mConnectivityMgr.getAllNetworks()).thenReturn(mAllNetworks);
         when(mConfig.shouldEnableWifiP2pDedicatedIp()).thenReturn(false);
         when(mConfig.isRandomPrefixBaseEnabled()).thenReturn(false);
@@ -110,7 +112,7 @@
         mPrivateAddressCoordinator =
                 spy(
                         new PrivateAddressCoordinator(
-                                mContext,
+                                mConnectivityMgr::getAllNetworks,
                                 mConfig.isRandomPrefixBaseEnabled(),
                                 mConfig.shouldEnableWifiP2pDedicatedIp()));
     }
@@ -153,37 +155,6 @@
     }
 
     @Test
-    public void testSanitizedAddress() throws Exception {
-        int fakeSubAddr = 0x2b00; // 43.0.
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeSubAddr);
-        LinkAddress actualAddress = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, false /* useLastAddress */);
-        assertEquals(new LinkAddress("192.168.43.2/24"), actualAddress);
-        mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
-
-        fakeSubAddr = 0x2d01; // 45.1.
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeSubAddr);
-        actualAddress = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, false /* useLastAddress */);
-        assertEquals(new LinkAddress("192.168.45.2/24"), actualAddress);
-        mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
-
-        fakeSubAddr = 0x2eff; // 46.255.
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeSubAddr);
-        actualAddress = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, false /* useLastAddress */);
-        assertEquals(new LinkAddress("192.168.46.254/24"), actualAddress);
-        mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
-
-        fakeSubAddr = 0x2f05; // 47.5.
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeSubAddr);
-        actualAddress = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, false /* useLastAddress */);
-        assertEquals(new LinkAddress("192.168.47.5/24"), actualAddress);
-        mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
-    }
-
-    @Test
     public void testReservedPrefix() throws Exception {
         // - Test bluetooth prefix is reserved.
         when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(
@@ -218,22 +189,15 @@
 
     @Test
     public void testRequestLastDownstreamAddress() throws Exception {
-        final int fakeHotspotSubAddr = 0x2b05; // 43.5
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeHotspotSubAddr);
         final LinkAddress hotspotAddress = requestDownstreamAddress(mHotspotIpServer,
                 CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong wifi prefix: ", new LinkAddress("192.168.43.5/24"), hotspotAddress);
 
         final LinkAddress usbAddress = requestDownstreamAddress(mUsbIpServer,
                 CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong wifi prefix: ", new LinkAddress("192.168.45.5/24"), usbAddress);
 
         mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
         mPrivateAddressCoordinator.releaseDownstream(mUsbIpServer);
 
-        final int newFakeSubAddr = 0x3c05;
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeHotspotSubAddr);
-
         final LinkAddress newHotspotAddress = requestDownstreamAddress(mHotspotIpServer,
                 CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
         assertEquals(hotspotAddress, newHotspotAddress);
@@ -271,262 +235,27 @@
     }
 
     @Test
-    public void testNoConflictUpstreamPrefix() throws Exception {
-        final int fakeHotspotSubAddr = 0x2b05; // 43.5
-        final IpPrefix predefinedPrefix = new IpPrefix("192.168.43.0/24");
-        // Force always get subAddress "43.5" for conflict testing.
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(fakeHotspotSubAddr);
-        // - Enable hotspot with prefix 192.168.43.0/24
-        final LinkAddress hotspotAddr = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        final IpPrefix hotspotPrefix = asIpPrefix(hotspotAddr);
-        assertEquals("Wrong wifi prefix: ", predefinedPrefix, hotspotPrefix);
-        // - test mobile network with null NetworkCapabilities. Ideally this should not happen
-        // because NetworkCapabilities update should always happen before LinkProperties update
-        // and the UpstreamNetworkState update, just make sure no crash in this case.
-        final UpstreamNetworkState noCapUpstream = buildUpstreamNetworkState(mMobileNetwork,
-                new LinkAddress("10.0.0.8/24"), null, null);
-        updateUpstreamPrefix(noCapUpstream);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - test mobile upstream with no address.
-        final UpstreamNetworkState noAddress = buildUpstreamNetworkState(mMobileNetwork,
-                null, null, makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(noCapUpstream);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - Update v6 only mobile network, hotspot prefix should not be removed.
-        final UpstreamNetworkState v6OnlyMobile = buildUpstreamNetworkState(mMobileNetwork,
-                null, new LinkAddress("2001:db8::/64"),
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(v6OnlyMobile);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        mPrivateAddressCoordinator.removeUpstreamPrefix(mMobileNetwork);
-        // - Update v4 only mobile network, hotspot prefix should not be removed.
-        final UpstreamNetworkState v4OnlyMobile = buildUpstreamNetworkState(mMobileNetwork,
-                new LinkAddress("10.0.0.8/24"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(v4OnlyMobile);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - Update v4v6 mobile network, hotspot prefix should not be removed.
-        final UpstreamNetworkState v4v6Mobile = buildUpstreamNetworkState(mMobileNetwork,
-                new LinkAddress("10.0.0.8/24"), new LinkAddress("2001:db8::/64"),
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(v4v6Mobile);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - Update v6 only wifi network, hotspot prefix should not be removed.
-        final UpstreamNetworkState v6OnlyWifi = buildUpstreamNetworkState(mWifiNetwork,
-                null, new LinkAddress("2001:db8::/64"), makeNetworkCapabilities(TRANSPORT_WIFI));
-        updateUpstreamPrefix(v6OnlyWifi);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        mPrivateAddressCoordinator.removeUpstreamPrefix(mWifiNetwork);
-        // - Update vpn network, it conflict with hotspot prefix but VPN networks are ignored.
-        final UpstreamNetworkState v4OnlyVpn = buildUpstreamNetworkState(mVpnNetwork,
-                new LinkAddress("192.168.43.5/24"), null, makeNetworkCapabilities(TRANSPORT_VPN));
-        updateUpstreamPrefix(v4OnlyVpn);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - Update v4 only wifi network, it conflict with hotspot prefix.
-        final UpstreamNetworkState v4OnlyWifi = buildUpstreamNetworkState(mWifiNetwork,
-                new LinkAddress("192.168.43.5/24"), null, makeNetworkCapabilities(TRANSPORT_WIFI));
-        updateUpstreamPrefix(v4OnlyWifi);
-        verify(mHotspotIpServer).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        reset(mHotspotIpServer);
-        // - Restart hotspot again and its prefix is different previous.
-        mPrivateAddressCoordinator.releaseDownstream(mHotspotIpServer);
-        final LinkAddress hotspotAddr2 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        final IpPrefix hotspotPrefix2 = asIpPrefix(hotspotAddr2);
-        assertNotEquals(hotspotPrefix, hotspotPrefix2);
-        updateUpstreamPrefix(v4OnlyWifi);
-        verify(mHotspotIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-        // - Usb tethering can be enabled and its prefix is different with conflict one.
-        final LinkAddress usbAddr = requestDownstreamAddress(mUsbIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        final IpPrefix usbPrefix = asIpPrefix(usbAddr);
-        assertNotEquals(predefinedPrefix, usbPrefix);
-        assertNotEquals(hotspotPrefix2, usbPrefix);
-        // - Disable wifi upstream, then wifi's prefix can be selected again.
-        mPrivateAddressCoordinator.removeUpstreamPrefix(mWifiNetwork);
-        final LinkAddress ethAddr = requestDownstreamAddress(mEthernetIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        final IpPrefix ethPrefix = asIpPrefix(ethAddr);
-        assertEquals(predefinedPrefix, ethPrefix);
+    public void testChooseDownstreamAddress_noUpstreamConflicts() throws Exception {
+        LinkAddress address = new LinkAddress("192.168.42.42/24");
+        UpstreamNetworkState ns = buildUpstreamNetworkState(mMobileNetwork, address, null, null);
+        updateUpstreamPrefix(ns);
+        // try to look for a /24 in upstream that does not conflict with upstream -> impossible.
+        assertNull(mPrivateAddressCoordinator.chooseDownstreamAddress(asIpPrefix(address)));
+
+        IpPrefix prefix = new IpPrefix("192.168.0.0/16");
+        LinkAddress chosenAddress = mPrivateAddressCoordinator.chooseDownstreamAddress(prefix);
+        assertNotNull(chosenAddress);
+        assertTrue(prefix.containsPrefix(asIpPrefix(chosenAddress)));
     }
 
     @Test
-    public void testChooseAvailablePrefix() throws Exception {
-        final int randomAddress = 0x8605; // 134.5
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(randomAddress);
-        final LinkAddress addr0 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        // Check whether return address is prefix 192.168.0.0/16 + subAddress 0.0.134.5.
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.134.5/24"), addr0);
-        final UpstreamNetworkState wifiUpstream = buildUpstreamNetworkState(mWifiNetwork,
-                new LinkAddress("192.168.134.13/26"), null,
-                makeNetworkCapabilities(TRANSPORT_WIFI));
-        updateUpstreamPrefix(wifiUpstream);
-
-        // Check whether return address is next prefix of 192.168.134.0/24.
-        final LinkAddress addr1 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.135.5/24"), addr1);
-        final UpstreamNetworkState wifiUpstream2 = buildUpstreamNetworkState(mWifiNetwork,
-                new LinkAddress("192.168.149.16/19"), null,
-                makeNetworkCapabilities(TRANSPORT_WIFI));
-        updateUpstreamPrefix(wifiUpstream2);
-
-
-        // The conflict range is 128 ~ 159, so the address is 192.168.160.5/24.
-        final LinkAddress addr2 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.160.5/24"), addr2);
-        final UpstreamNetworkState mobileUpstream = buildUpstreamNetworkState(mMobileNetwork,
-                new LinkAddress("192.168.129.53/18"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        // Update another conflict upstream which is covered by the previous one (but not the first
-        // one) and verify whether this would affect the result.
-        final UpstreamNetworkState mobileUpstream2 = buildUpstreamNetworkState(mMobileNetwork2,
-                new LinkAddress("192.168.170.7/19"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream);
-        updateUpstreamPrefix(mobileUpstream2);
-
-        // The conflict range are 128 ~ 159 and 159 ~ 191, so the address is 192.168.192.5/24.
-        final LinkAddress addr3 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.192.5/24"), addr3);
-        final UpstreamNetworkState mobileUpstream3 = buildUpstreamNetworkState(mMobileNetwork3,
-                new LinkAddress("192.168.188.133/17"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream3);
-
-        // Conflict range: 128 ~ 255. The next available address is 192.168.0.5 because
-        // 192.168.134/24 ~ 192.168.255.255/24 is not available.
-        final LinkAddress addr4 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.0.5/24"), addr4);
-        final UpstreamNetworkState mobileUpstream4 = buildUpstreamNetworkState(mMobileNetwork4,
-                new LinkAddress("192.168.3.59/21"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream4);
-
-        // Conflict ranges: 128 ~ 255 and 0 ~ 7, so the address is 192.168.8.5/24.
-        final LinkAddress addr5 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.8.5/24"), addr5);
-        final UpstreamNetworkState mobileUpstream5 = buildUpstreamNetworkState(mMobileNetwork5,
-                new LinkAddress("192.168.68.43/21"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream5);
-
-        // Update an upstream that does *not* conflict, check whether return the same address
-        // 192.168.5/24.
-        final LinkAddress addr6 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.8.5/24"), addr6);
-        final UpstreamNetworkState mobileUpstream6 = buildUpstreamNetworkState(mMobileNetwork6,
-                new LinkAddress("192.168.10.97/21"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream6);
-
-        // Conflict ranges: 0 ~ 15 and 128 ~ 255, so the address is 192.168.16.5/24.
-        final LinkAddress addr7 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.16.5/24"), addr7);
-        final UpstreamNetworkState mobileUpstream7 = buildUpstreamNetworkState(mMobileNetwork6,
-                new LinkAddress("192.168.0.0/17"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream7);
-
-        // Choose prefix from next range(172.16.0.0/12) when no available prefix in 192.168.0.0/16.
-        final LinkAddress addr8 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.16.134.5/24"), addr8);
-    }
-
-    @Test
-    public void testChoosePrefixFromDifferentRanges() throws Exception {
-        final int randomAddress = 0x1f2b2a; // 31.43.42
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(randomAddress);
-        final LinkAddress classC1 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        // Check whether return address is prefix 192.168.0.0/16 + subAddress 0.0.43.42.
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.43.42/24"), classC1);
-        final UpstreamNetworkState wifiUpstream = buildUpstreamNetworkState(mWifiNetwork,
-                new LinkAddress("192.168.88.23/17"), null,
-                makeNetworkCapabilities(TRANSPORT_WIFI));
-        updateUpstreamPrefix(wifiUpstream);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-
-        // Check whether return address is next address of prefix 192.168.128.0/17.
-        final LinkAddress classC2 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("192.168.128.42/24"), classC2);
-        final UpstreamNetworkState mobileUpstream = buildUpstreamNetworkState(mMobileNetwork,
-                new LinkAddress("192.1.2.3/8"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-
-        // Check whether return address is under prefix 172.16.0.0/12.
-        final LinkAddress classB1 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.31.43.42/24"), classB1);
-        final UpstreamNetworkState mobileUpstream2 = buildUpstreamNetworkState(mMobileNetwork2,
-                new LinkAddress("172.28.123.100/14"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream2);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-
-        // 172.28.0.0 ~ 172.31.255.255 is not available.
-        // Check whether return address is next address of prefix 172.16.0.0/14.
-        final LinkAddress classB2 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.16.0.42/24"), classB2);
-
-        // Check whether new downstream is next address of address 172.16.0.42/24.
-        final LinkAddress classB3 = requestDownstreamAddress(mUsbIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.16.1.42/24"), classB3);
-        final UpstreamNetworkState mobileUpstream3 = buildUpstreamNetworkState(mMobileNetwork3,
-                new LinkAddress("172.16.0.1/24"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream3);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-        verify(mUsbIpServer, never()).sendMessage(IpServer.CMD_NOTIFY_PREFIX_CONFLICT);
-
-        // Check whether return address is next address of prefix 172.16.1.42/24.
-        final LinkAddress classB4 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.16.2.42/24"), classB4);
-        final UpstreamNetworkState mobileUpstream4 = buildUpstreamNetworkState(mMobileNetwork4,
-                new LinkAddress("172.16.0.1/13"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream4);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-        verifyNotifyConflictAndRelease(mUsbIpServer);
-
-        // Check whether return address is next address of prefix 172.16.0.1/13.
-        final LinkAddress classB5 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.24.0.42/24"), classB5);
-        // Check whether return address is next address of prefix 172.24.0.42/24.
-        final LinkAddress classB6 = requestDownstreamAddress(mUsbIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("172.24.1.42/24"), classB6);
-        final UpstreamNetworkState mobileUpstream5 = buildUpstreamNetworkState(mMobileNetwork5,
-                new LinkAddress("172.24.0.1/12"), null,
-                makeNetworkCapabilities(TRANSPORT_CELLULAR));
-        updateUpstreamPrefix(mobileUpstream5);
-        verifyNotifyConflictAndRelease(mHotspotIpServer);
-        verifyNotifyConflictAndRelease(mUsbIpServer);
-
-        // Check whether return address is prefix 10.0.0.0/8 + subAddress 0.31.43.42.
-        final LinkAddress classA1 = requestDownstreamAddress(mHotspotIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("10.31.43.42/24"), classA1);
-        // Check whether new downstream is next address of address 10.31.43.42/24.
-        final LinkAddress classA2 = requestDownstreamAddress(mUsbIpServer,
-                CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong prefix: ", new LinkAddress("10.31.44.42/24"), classA2);
+    public void testChooseDownstreamAddress_excludesWellKnownPrefixes() throws Exception {
+        IpPrefix prefix = new IpPrefix("192.168.0.0/24");
+        assertNull(mPrivateAddressCoordinator.chooseDownstreamAddress(prefix));
+        prefix = new IpPrefix("192.168.100.0/24");
+        assertNull(mPrivateAddressCoordinator.chooseDownstreamAddress(prefix));
+        prefix = new IpPrefix("10.3.0.0/16");
+        assertNull(mPrivateAddressCoordinator.chooseDownstreamAddress(prefix));
     }
 
     private void verifyNotifyConflictAndRelease(final IpServer ipServer) throws Exception {
@@ -572,17 +301,18 @@
 
     @Test
     public void testEnableSapAndLohsConcurrently() throws Exception {
-        // 0x2b05 -> 43.5, 0x8605 -> 134.5
-        when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(0x2b05, 0x8605);
-
         final LinkAddress hotspotAddress = requestDownstreamAddress(mHotspotIpServer,
                 CONNECTIVITY_SCOPE_GLOBAL, true /* useLastAddress */);
-        assertEquals("Wrong hotspot prefix: ", new LinkAddress("192.168.43.5/24"), hotspotAddress);
+        assertNotNull(hotspotAddress);
 
         final LinkAddress localHotspotAddress = requestDownstreamAddress(mLocalHotspotIpServer,
                 CONNECTIVITY_SCOPE_LOCAL, true /* useLastAddress */);
-        assertEquals("Wrong local hotspot prefix: ", new LinkAddress("192.168.134.5/24"),
-                localHotspotAddress);
+        assertNotNull(localHotspotAddress);
+
+        final IpPrefix hotspotPrefix = asIpPrefix(hotspotAddress);
+        final IpPrefix localHotspotPrefix = asIpPrefix(localHotspotAddress);
+        assertFalse(hotspotPrefix.containsPrefix(localHotspotPrefix));
+        assertFalse(localHotspotPrefix.containsPrefix(hotspotPrefix));
     }
 
     @Test
@@ -615,7 +345,7 @@
         mPrivateAddressCoordinator =
                 spy(
                         new PrivateAddressCoordinator(
-                                mContext,
+                                mConnectivityMgr::getAllNetworks,
                                 mConfig.isRandomPrefixBaseEnabled(),
                                 mConfig.shouldEnableWifiP2pDedicatedIp()));
         when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(randomIntForPrefixBase);
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 6ba5d48..9a4945e 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -124,6 +124,7 @@
 import android.content.res.Resources;
 import android.database.ContentObserver;
 import android.hardware.usb.UsbManager;
+import android.net.ConnectivityManager;
 import android.net.ConnectivityManager.NetworkCallback;
 import android.net.EthernetManager;
 import android.net.EthernetManager.TetheredInterfaceCallback;
@@ -374,6 +375,7 @@
         @Override
         public String getSystemServiceName(Class<?> serviceClass) {
             if (TelephonyManager.class.equals(serviceClass)) return Context.TELEPHONY_SERVICE;
+            if (ConnectivityManager.class.equals(serviceClass)) return Context.CONNECTIVITY_SERVICE;
             return super.getSystemServiceName(serviceClass);
         }
     }
diff --git a/DnsResolver/Android.bp b/bpf/dns_helper/Android.bp
similarity index 100%
rename from DnsResolver/Android.bp
rename to bpf/dns_helper/Android.bp
diff --git a/DnsResolver/DnsBpfHelper.cpp b/bpf/dns_helper/DnsBpfHelper.cpp
similarity index 100%
rename from DnsResolver/DnsBpfHelper.cpp
rename to bpf/dns_helper/DnsBpfHelper.cpp
diff --git a/DnsResolver/DnsBpfHelper.h b/bpf/dns_helper/DnsBpfHelper.h
similarity index 100%
rename from DnsResolver/DnsBpfHelper.h
rename to bpf/dns_helper/DnsBpfHelper.h
diff --git a/DnsResolver/DnsBpfHelperTest.cpp b/bpf/dns_helper/DnsBpfHelperTest.cpp
similarity index 100%
rename from DnsResolver/DnsBpfHelperTest.cpp
rename to bpf/dns_helper/DnsBpfHelperTest.cpp
diff --git a/DnsResolver/DnsHelper.cpp b/bpf/dns_helper/DnsHelper.cpp
similarity index 100%
rename from DnsResolver/DnsHelper.cpp
rename to bpf/dns_helper/DnsHelper.cpp
diff --git a/DnsResolver/include/DnsHelperPublic.h b/bpf/dns_helper/include/DnsHelperPublic.h
similarity index 100%
rename from DnsResolver/include/DnsHelperPublic.h
rename to bpf/dns_helper/include/DnsHelperPublic.h
diff --git a/DnsResolver/libcom.android.tethering.dns_helper.map.txt b/bpf/dns_helper/libcom.android.tethering.dns_helper.map.txt
similarity index 100%
rename from DnsResolver/libcom.android.tethering.dns_helper.map.txt
rename to bpf/dns_helper/libcom.android.tethering.dns_helper.map.txt
diff --git a/bpf/headers/include/bpf/KernelUtils.h b/bpf/headers/include/bpf/KernelUtils.h
index 417a5c4..68bc607 100644
--- a/bpf/headers/include/bpf/KernelUtils.h
+++ b/bpf/headers/include/bpf/KernelUtils.h
@@ -55,11 +55,12 @@
            isKernelVersion(4,  9) ||  // minimum for Android S & T
            isKernelVersion(4, 14) ||  // minimum for Android U
            isKernelVersion(4, 19) ||  // minimum for Android V
-           isKernelVersion(5,  4) ||  // first supported in Android R
+           isKernelVersion(5,  4) ||  // first supported in Android R, min for W
            isKernelVersion(5, 10) ||  // first supported in Android S
            isKernelVersion(5, 15) ||  // first supported in Android T
            isKernelVersion(6,  1) ||  // first supported in Android U
-           isKernelVersion(6,  6);    // first supported in Android V
+           isKernelVersion(6,  6) ||  // first supported in Android V
+           isKernelVersion(6, 12);    // first supported in Android W
 }
 
 // Figure out the bitness of userspace.
diff --git a/bpf/progs/Android.bp b/bpf/progs/Android.bp
index 52eb1b3..20d194c 100644
--- a/bpf/progs/Android.bp
+++ b/bpf/progs/Android.bp
@@ -47,8 +47,8 @@
         "com.android.tethering",
     ],
     visibility: [
+        "//packages/modules/Connectivity/bpf/dns_helper",
         "//packages/modules/Connectivity/bpf/netd",
-        "//packages/modules/Connectivity/DnsResolver",
         "//packages/modules/Connectivity/service",
         "//packages/modules/Connectivity/service/native/libs/libclat",
         "//packages/modules/Connectivity/Tethering",
diff --git a/common/thread_flags.aconfig b/common/thread_flags.aconfig
index c11c6c0..14b70d0 100644
--- a/common/thread_flags.aconfig
+++ b/common/thread_flags.aconfig
@@ -26,3 +26,12 @@
     description: "Controls whether the Android Thread setting max power of channel feature is enabled"
     bug: "346686506"
 }
+
+flag {
+    name: "epskc_enabled"
+    is_exported: true
+    is_fixed_read_only: true
+    namespace: "thread_network"
+    description: "Controls whether the Android Thread Ephemeral Key feature is enabled"
+    bug: "348323500"
+}
diff --git a/framework-t/api/system-current.txt b/framework-t/api/system-current.txt
index 9f26bcf..09a3681 100644
--- a/framework-t/api/system-current.txt
+++ b/framework-t/api/system-current.txt
@@ -507,7 +507,10 @@
   }
 
   @FlaggedApi("com.android.net.thread.flags.thread_enabled") public final class ThreadNetworkController {
+    method @FlaggedApi("com.android.net.thread.flags.epskc_enabled") @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED") public void activateEphemeralKeyMode(@NonNull java.time.Duration, @NonNull java.util.concurrent.Executor, @NonNull android.os.OutcomeReceiver<java.lang.Void,android.net.thread.ThreadNetworkException>);
     method public void createRandomizedDataset(@NonNull String, @NonNull java.util.concurrent.Executor, @NonNull android.os.OutcomeReceiver<android.net.thread.ActiveOperationalDataset,android.net.thread.ThreadNetworkException>);
+    method @FlaggedApi("com.android.net.thread.flags.epskc_enabled") @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED") public void deactivateEphemeralKeyMode(@NonNull java.util.concurrent.Executor, @NonNull android.os.OutcomeReceiver<java.lang.Void,android.net.thread.ThreadNetworkException>);
+    method @FlaggedApi("com.android.net.thread.flags.epskc_enabled") @NonNull public java.time.Duration getMaxEphemeralKeyLifetime();
     method public int getThreadVersion();
     method public static boolean isAttached(int);
     method @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED") public void join(@NonNull android.net.thread.ActiveOperationalDataset, @NonNull java.util.concurrent.Executor, @NonNull android.os.OutcomeReceiver<java.lang.Void,android.net.thread.ThreadNetworkException>);
@@ -526,6 +529,9 @@
     field public static final int DEVICE_ROLE_LEADER = 4; // 0x4
     field public static final int DEVICE_ROLE_ROUTER = 3; // 0x3
     field public static final int DEVICE_ROLE_STOPPED = 0; // 0x0
+    field @FlaggedApi("com.android.net.thread.flags.epskc_enabled") public static final int EPHEMERAL_KEY_DISABLED = 0; // 0x0
+    field @FlaggedApi("com.android.net.thread.flags.epskc_enabled") public static final int EPHEMERAL_KEY_ENABLED = 1; // 0x1
+    field @FlaggedApi("com.android.net.thread.flags.epskc_enabled") public static final int EPHEMERAL_KEY_IN_USE = 2; // 0x2
     field public static final int MAX_POWER_CHANNEL_DISABLED = -2147483648; // 0x80000000
     field public static final int STATE_DISABLED = 0; // 0x0
     field public static final int STATE_DISABLING = 2; // 0x2
@@ -540,6 +546,7 @@
 
   public static interface ThreadNetworkController.StateCallback {
     method public void onDeviceRoleChanged(int);
+    method @FlaggedApi("com.android.net.thread.flags.epskc_enabled") @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED") public default void onEphemeralKeyStateChanged(int, @Nullable String, @Nullable java.time.Instant);
     method public default void onPartitionIdChanged(long);
     method public default void onThreadEnableStateChanged(int);
   }
diff --git a/thread/framework/java/android/net/thread/IStateCallback.aidl b/thread/framework/java/android/net/thread/IStateCallback.aidl
index 9d0a571..57c365b 100644
--- a/thread/framework/java/android/net/thread/IStateCallback.aidl
+++ b/thread/framework/java/android/net/thread/IStateCallback.aidl
@@ -23,4 +23,6 @@
     void onDeviceRoleChanged(int deviceRole);
     void onPartitionIdChanged(long partitionId);
     void onThreadEnableStateChanged(int enabledState);
+    void onEphemeralKeyStateChanged(
+            int ephemeralKeyState, @nullable String ephemeralKey, long expiryMillis);
 }
diff --git a/thread/framework/java/android/net/thread/IThreadNetworkController.aidl b/thread/framework/java/android/net/thread/IThreadNetworkController.aidl
index b7f68c9..e9cbb83 100644
--- a/thread/framework/java/android/net/thread/IThreadNetworkController.aidl
+++ b/thread/framework/java/android/net/thread/IThreadNetworkController.aidl
@@ -53,4 +53,7 @@
     void setConfiguration(in ThreadConfiguration config, in IOperationReceiver receiver);
     void registerConfigurationCallback(in IConfigurationReceiver receiver);
     void unregisterConfigurationCallback(in IConfigurationReceiver receiver);
+
+    void activateEphemeralKeyMode(long lifetimeMillis, in IOperationReceiver receiver);
+    void deactivateEphemeralKeyMode(in IOperationReceiver receiver);
 }
diff --git a/thread/framework/java/android/net/thread/ThreadNetworkController.java b/thread/framework/java/android/net/thread/ThreadNetworkController.java
index cb4e8de..1222398 100644
--- a/thread/framework/java/android/net/thread/ThreadNetworkController.java
+++ b/thread/framework/java/android/net/thread/ThreadNetworkController.java
@@ -40,6 +40,7 @@
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.time.Duration;
+import java.time.Instant;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.Executor;
@@ -82,6 +83,25 @@
     /** The Thread radio is being disabled. */
     public static final int STATE_DISABLING = 2;
 
+    /** The ephemeral key mode is disabled. */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    public static final int EPHEMERAL_KEY_DISABLED = 0;
+
+    /**
+     * The ephemeral key mode is enabled, an external commissioner candidate can use the ephemeral
+     * key to connect to this device and get Thread credential shared.
+     */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    public static final int EPHEMERAL_KEY_ENABLED = 1;
+
+    /**
+     * The ephemeral key is in use. This state means there is already an active secure session
+     * connected to this device with the ephemeral key, it's not possible to use the ephemeral key
+     * for new connections in this state.
+     */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    public static final int EPHEMERAL_KEY_IN_USE = 2;
+
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({
@@ -100,6 +120,13 @@
             value = {STATE_DISABLED, STATE_ENABLED, STATE_DISABLING})
     public @interface EnabledState {}
 
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(
+            prefix = {"EPHEMERAL_KEY_"},
+            value = {EPHEMERAL_KEY_DISABLED, EPHEMERAL_KEY_ENABLED, EPHEMERAL_KEY_IN_USE})
+    public @interface EphemeralKeyState {}
+
     /** Thread standard version 1.3. */
     public static final int THREAD_VERSION_1_3 = 4;
 
@@ -110,6 +137,9 @@
     @SuppressLint("MinMaxConstant")
     public static final int MAX_POWER_CHANNEL_DISABLED = Integer.MIN_VALUE;
 
+    /** The maximum lifetime of an ephemeral key. @hide */
+    @NonNull private static final Duration EPHEMERAL_KEY_LIFETIME_MAX = Duration.ofMinutes(10);
+
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({THREAD_VERSION_1_3})
@@ -174,6 +204,87 @@
         }
     }
 
+    /** Returns the maximum lifetime allowed when activating ephemeral key mode. */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    @NonNull
+    public Duration getMaxEphemeralKeyLifetime() {
+        return EPHEMERAL_KEY_LIFETIME_MAX;
+    }
+
+    /**
+     * Activates ephemeral key mode with a given {@code lifetime}. The ephemeral key is a temporary,
+     * single-use numeric code that is used for Thread Administration Sharing. After activation, the
+     * mode may expire or get deactivated, caller to this method should subscribe to the ephemeral
+     * key state updates with {@link #registerStateCallback} to get notified when the ephemeral key
+     * state changes.
+     *
+     * <p>On success, {@link OutcomeReceiver#onResult} of {@code receiver} is called. The ephemeral
+     * key string contains a sequence of numeric digits 0-9 of user-input friendly length (typically
+     * 9). Subscribers to ephemeral key state updates with {@link #registerStateCallback} will be
+     * notified with a call to {@link #onEphemeralKeyStateChanged}.
+     *
+     * <p>On failure, {@link OutcomeReceiver#onError} of {@code receiver} will be invoked with a
+     * specific error:
+     *
+     * <ul>
+     *   <li>{@link ThreadNetworkException#ERROR_FAILED_PRECONDITION} when this device is not
+     *       attached to Thread network
+     *   <li>{@link ThreadNetworkException#ERROR_BUSY} when ephemeral key mode is already activated
+     *       on the device, caller can recover from this error when the ephemeral key mode gets
+     *       deactivated
+     * </ul>
+     *
+     * @param lifetime valid lifetime of the generated ephemeral key, should be larger than {@link
+     *     Duration#ZERO} and at most the duration returned by {@link #getMaxEphemeralKeyLifetime}.
+     * @param executor the executor on which to execute {@code receiver}
+     * @param receiver the receiver to receive the result of this operation
+     * @throws IllegalArgumentException if the {@code lifetime} exceeds the allowed range
+     */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED")
+    public void activateEphemeralKeyMode(
+            @NonNull Duration lifetime,
+            @NonNull @CallbackExecutor Executor executor,
+            @NonNull OutcomeReceiver<Void, ThreadNetworkException> receiver) {
+        if (lifetime.compareTo(Duration.ZERO) <= 0
+                || lifetime.compareTo(EPHEMERAL_KEY_LIFETIME_MAX) > 0) {
+            throw new IllegalArgumentException(
+                    "Invalid ephemeral key lifetime: the value must be in range of (0, "
+                            + EPHEMERAL_KEY_LIFETIME_MAX
+                            + "]");
+        }
+        long lifetimeMillis = lifetime.toMillis();
+        try {
+            mControllerService.activateEphemeralKeyMode(
+                    lifetimeMillis, new OperationReceiverProxy(executor, receiver));
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Deactivates ephemeral key mode. If there is an active connection with the ephemeral key, the
+     * connection will be terminated.
+     *
+     * <p>On success, {@link OutcomeReceiver#onResult} of {@code receiver} is called. The call will
+     * always succeed if the device is not in ephemeral key mode.
+     *
+     * @param executor the executor to execute {@code receiver}
+     * @param receiver the receiver to receive the result of this operation
+     */
+    @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+    @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED")
+    public void deactivateEphemeralKeyMode(
+            @NonNull @CallbackExecutor Executor executor,
+            @NonNull OutcomeReceiver<Void, ThreadNetworkException> receiver) {
+        try {
+            mControllerService.deactivateEphemeralKeyMode(
+                    new OperationReceiverProxy(executor, receiver));
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
     /** Returns the Thread version this device is operating on. */
     @ThreadVersion
     public int getThreadVersion() {
@@ -248,6 +359,24 @@
          * @param enabledState the new Thread enabled state
          */
         default void onThreadEnableStateChanged(@EnabledState int enabledState) {}
+
+        /**
+         * The ephemeral key state has changed.
+         *
+         * @param ephemeralKeyState the ephemeral key state
+         * @param ephemeralKey the ephemeral key string which contains a sequence of numeric digits
+         *     0-9 of user-input friendly length (typically 9), or {@code null} if {@code
+         *     ephemeralKeyState} is {@link #EPHEMERAL_KEY_DISABLED} or the caller doesn't have the
+         *     permission {@link android.permission.THREAD_NETWORK_PRIVILEGED}
+         * @param expiry a timestamp of when the ephemeral key will expireor {@code null} if {@code
+         *     ephemeralKeyState} is {@link #EPHEMERAL_KEY_DISABLED}
+         */
+        @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)
+        @RequiresPermission("android.permission.THREAD_NETWORK_PRIVILEGED")
+        default void onEphemeralKeyStateChanged(
+                @EphemeralKeyState int ephemeralKeyState,
+                @Nullable String ephemeralKey,
+                @Nullable Instant expiry) {}
     }
 
     private static final class StateCallbackProxy extends IStateCallback.Stub {
@@ -288,13 +417,37 @@
                 Binder.restoreCallingIdentity(identity);
             }
         }
+
+        @Override
+        public void onEphemeralKeyStateChanged(
+                @EphemeralKeyState int ephemeralKeyState, String ephemeralKey, long expiryMillis) {
+            if (!Flags.epskcEnabled()) {
+                throw new IllegalStateException(
+                        "This should not be called when Ephemeral key API is disabled");
+            }
+
+            final long identity = Binder.clearCallingIdentity();
+            final Instant expiry =
+                    ephemeralKeyState == EPHEMERAL_KEY_DISABLED
+                            ? null
+                            : Instant.ofEpochMilli(expiryMillis);
+
+            try {
+                mExecutor.execute(
+                        () ->
+                                mCallback.onEphemeralKeyStateChanged(
+                                        ephemeralKeyState, ephemeralKey, expiry));
+            } finally {
+                Binder.restoreCallingIdentity(identity);
+            }
+        }
     }
 
     /**
      * Registers a callback to be called when Thread network states are changed.
      *
-     * <p>Upon return of this method, methods of {@code callback} will be invoked immediately with
-     * existing states.
+     * <p>Upon return of this method, all methods of {@code callback} will be invoked immediately
+     * with existing states. The order of the invoked callbacks is not guaranteed.
      *
      * @param executor the executor to execute the {@code callback}
      * @param callback the callback to receive Thread network state changes
diff --git a/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java b/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
index 57fea34..3d854d7 100644
--- a/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
+++ b/thread/service/java/com/android/server/thread/ThreadNetworkControllerService.java
@@ -15,6 +15,7 @@
 package com.android.server.thread;
 
 import static android.Manifest.permission.NETWORK_SETTINGS;
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.MulticastRoutingConfig.CONFIG_FORWARD_NONE;
 import static android.net.MulticastRoutingConfig.FORWARD_SELECTED;
 import static android.net.MulticastRoutingConfig.FORWARD_WITH_MIN_SCOPE;
@@ -26,6 +27,7 @@
 import static android.net.thread.ActiveOperationalDataset.MESH_LOCAL_PREFIX_FIRST_BYTE;
 import static android.net.thread.ActiveOperationalDataset.SecurityPolicy.DEFAULT_ROTATION_TIME_HOURS;
 import static android.net.thread.ThreadNetworkController.DEVICE_ROLE_DETACHED;
+import static android.net.thread.ThreadNetworkController.EPHEMERAL_KEY_DISABLED;
 import static android.net.thread.ThreadNetworkController.STATE_DISABLED;
 import static android.net.thread.ThreadNetworkController.STATE_DISABLING;
 import static android.net.thread.ThreadNetworkController.STATE_ENABLED;
@@ -855,6 +857,47 @@
     }
 
     @Override
+    public void activateEphemeralKeyMode(long lifetimeMillis, IOperationReceiver receiver) {
+        enforceAllPermissionsGranted(PERMISSION_THREAD_NETWORK_PRIVILEGED);
+
+        mHandler.post(
+                () ->
+                        activateEphemeralKeyModeInternal(
+                                lifetimeMillis, new OperationReceiverWrapper(receiver)));
+    }
+
+    private void activateEphemeralKeyModeInternal(
+            long lifetimeMillis, OperationReceiverWrapper receiver) {
+        checkOnHandlerThread();
+
+        try {
+            getOtDaemon().activateEphemeralKeyMode(lifetimeMillis, newOtStatusReceiver(receiver));
+        } catch (RemoteException | ThreadNetworkException e) {
+            LOG.e("otDaemon.activateEphemeralKeyMode failed", e);
+            receiver.onError(e);
+        }
+    }
+
+    @Override
+    public void deactivateEphemeralKeyMode(IOperationReceiver receiver) {
+        enforceAllPermissionsGranted(PERMISSION_THREAD_NETWORK_PRIVILEGED);
+
+        mHandler.post(
+                () -> deactivateEphemeralKeyModeInternal(new OperationReceiverWrapper(receiver)));
+    }
+
+    private void deactivateEphemeralKeyModeInternal(OperationReceiverWrapper receiver) {
+        checkOnHandlerThread();
+
+        try {
+            getOtDaemon().deactivateEphemeralKeyMode(newOtStatusReceiver(receiver));
+        } catch (RemoteException | ThreadNetworkException e) {
+            LOG.e("otDaemon.deactivateEphemeralKeyMode failed", e);
+            receiver.onError(e);
+        }
+    }
+
+    @Override
     public void createRandomizedDataset(
             String networkName, IActiveOperationalDatasetReceiver receiver) {
         ActiveOperationalDatasetReceiverWrapper receiverWrapper =
@@ -1003,7 +1046,14 @@
     @Override
     public void registerStateCallback(IStateCallback stateCallback) throws RemoteException {
         enforceAllPermissionsGranted(permission.ACCESS_NETWORK_STATE);
-        mHandler.post(() -> mOtDaemonCallbackProxy.registerStateCallback(stateCallback));
+        boolean hasThreadPrivilegedPermission =
+                (mContext.checkCallingOrSelfPermission(PERMISSION_THREAD_NETWORK_PRIVILEGED)
+                        == PERMISSION_GRANTED);
+
+        mHandler.post(
+                () ->
+                        mOtDaemonCallbackProxy.registerStateCallback(
+                                stateCallback, hasThreadPrivilegedPermission));
     }
 
     @Override
@@ -1458,9 +1508,13 @@
 
         final IBinder.DeathRecipient deathRecipient;
 
-        CallbackMetadata(IBinder.DeathRecipient deathRecipient) {
+        final boolean hasThreadPrivilegedPermission;
+
+        CallbackMetadata(
+                IBinder.DeathRecipient deathRecipient, boolean hasThreadPrivilegedPermission) {
             this.id = allocId();
             this.deathRecipient = deathRecipient;
+            this.hasThreadPrivilegedPermission = hasThreadPrivilegedPermission;
         }
 
         private static long allocId() {
@@ -1502,7 +1556,8 @@
         private ActiveOperationalDataset mActiveDataset;
         private PendingOperationalDataset mPendingDataset;
 
-        public void registerStateCallback(IStateCallback callback) {
+        public void registerStateCallback(
+                IStateCallback callback, boolean hasThreadPrivilegedPermission) {
             checkOnHandlerThread();
             if (mStateCallbacks.containsKey(callback)) {
                 throw new IllegalStateException("Registering the same IStateCallback twice");
@@ -1510,7 +1565,8 @@
 
             IBinder.DeathRecipient deathRecipient =
                     () -> mHandler.post(() -> unregisterStateCallback(callback));
-            CallbackMetadata callbackMetadata = new CallbackMetadata(deathRecipient);
+            CallbackMetadata callbackMetadata =
+                    new CallbackMetadata(deathRecipient, hasThreadPrivilegedPermission);
             mStateCallbacks.put(callback, callbackMetadata);
             try {
                 callback.asBinder().linkToDeath(deathRecipient, 0);
@@ -1543,7 +1599,8 @@
 
             IBinder.DeathRecipient deathRecipient =
                     () -> mHandler.post(() -> unregisterDatasetCallback(callback));
-            CallbackMetadata callbackMetadata = new CallbackMetadata(deathRecipient);
+            CallbackMetadata callbackMetadata =
+                    new CallbackMetadata(deathRecipient, true /* hasThreadPrivilegedPermission */);
             mOpDatasetCallbacks.put(callback, callbackMetadata);
             try {
                 callback.asBinder().linkToDeath(deathRecipient, 0);
@@ -1622,16 +1679,18 @@
         }
 
         @Override
-        public void onStateChanged(OtDaemonState newState, long listenerId) {
+        public void onStateChanged(@NonNull OtDaemonState newState, long listenerId) {
             mHandler.post(() -> onStateChangedInternal(newState, listenerId));
         }
 
         private void onStateChangedInternal(OtDaemonState newState, long listenerId) {
             checkOnHandlerThread();
+
             onInterfaceStateChanged(newState.isInterfaceUp);
             onDeviceRoleChanged(newState.deviceRole, listenerId);
             onPartitionIdChanged(newState.partitionId, listenerId);
             onThreadEnabledChanged(newState.threadEnabled, listenerId);
+            onEphemeralKeyStateChanged(newState, listenerId);
             mState = newState;
 
             ActiveOperationalDataset newActiveDataset;
@@ -1707,6 +1766,43 @@
             }
         }
 
+        private void onEphemeralKeyStateChanged(OtDaemonState newState, long listenerId) {
+            checkOnHandlerThread();
+            boolean hasChange = isEphemeralKeyStateChanged(mState, newState);
+
+            for (var callbackEntry : mStateCallbacks.entrySet()) {
+                if (!hasChange && callbackEntry.getValue().id != listenerId) {
+                    continue;
+                }
+                String passcode =
+                        callbackEntry.getValue().hasThreadPrivilegedPermission
+                                ? newState.ephemeralKeyPasscode
+                                : null;
+                if (newState.ephemeralKeyState == EPHEMERAL_KEY_DISABLED) {
+                    passcode = null;
+                }
+                try {
+                    callbackEntry
+                            .getKey()
+                            .onEphemeralKeyStateChanged(
+                                    newState.ephemeralKeyState,
+                                    passcode,
+                                    newState.ephemeralKeyExpiryMillis);
+                } catch (RemoteException ignored) {
+                    // do nothing if the client is dead
+                }
+            }
+        }
+
+        private static boolean isEphemeralKeyStateChanged(
+                OtDaemonState oldState, @NonNull OtDaemonState newState) {
+            if (oldState == null) return true;
+            if (oldState.ephemeralKeyState != newState.ephemeralKeyState) return true;
+            if (oldState.ephemeralKeyState == EPHEMERAL_KEY_DISABLED) return false;
+            return (!Objects.equals(oldState.ephemeralKeyPasscode, newState.ephemeralKeyPasscode)
+                    || oldState.ephemeralKeyExpiryMillis != newState.ephemeralKeyExpiryMillis);
+        }
+
         private void onActiveOperationalDatasetChanged(
                 ActiveOperationalDataset activeDataset, long listenerId) {
             checkOnHandlerThread();
diff --git a/thread/tests/cts/AndroidTest.xml b/thread/tests/cts/AndroidTest.xml
index 34aabe2..e954d3b 100644
--- a/thread/tests/cts/AndroidTest.xml
+++ b/thread/tests/cts/AndroidTest.xml
@@ -56,4 +56,14 @@
         <!-- Ignores tests introduced by guava-android-testlib -->
         <option name="exclude-annotation" value="org.junit.Ignore"/>
     </test>
+
+    <!--
+        This doesn't override a read-only flag, to run the tests locally with `epskc_enabled` flag
+        enabled, set the flag to `is_fixed_read_only: false`. This should be removed after the
+        `epskc_enabled` flag is rolled out.
+    -->
+    <target_preparer class="com.android.tradefed.targetprep.FeatureFlagTargetPreparer">
+        <option name="flag-value"
+                value="thread_network/com.android.net.thread.flags.epskc_enabled=true"/>
+    </target_preparer>
 </configuration>
diff --git a/thread/tests/cts/src/android/net/thread/cts/ThreadNetworkControllerTest.java b/thread/tests/cts/src/android/net/thread/cts/ThreadNetworkControllerTest.java
index c048394..1792bfb 100644
--- a/thread/tests/cts/src/android/net/thread/cts/ThreadNetworkControllerTest.java
+++ b/thread/tests/cts/src/android/net/thread/cts/ThreadNetworkControllerTest.java
@@ -27,11 +27,14 @@
 import static android.net.thread.ThreadNetworkController.DEVICE_ROLE_LEADER;
 import static android.net.thread.ThreadNetworkController.DEVICE_ROLE_ROUTER;
 import static android.net.thread.ThreadNetworkController.DEVICE_ROLE_STOPPED;
+import static android.net.thread.ThreadNetworkController.EPHEMERAL_KEY_DISABLED;
+import static android.net.thread.ThreadNetworkController.EPHEMERAL_KEY_ENABLED;
 import static android.net.thread.ThreadNetworkController.STATE_DISABLED;
 import static android.net.thread.ThreadNetworkController.STATE_DISABLING;
 import static android.net.thread.ThreadNetworkController.STATE_ENABLED;
 import static android.net.thread.ThreadNetworkController.THREAD_VERSION_1_3;
 import static android.net.thread.ThreadNetworkException.ERROR_ABORTED;
+import static android.net.thread.ThreadNetworkException.ERROR_BUSY;
 import static android.net.thread.ThreadNetworkException.ERROR_FAILED_PRECONDITION;
 import static android.net.thread.ThreadNetworkException.ERROR_REJECTED_BY_PEER;
 import static android.net.thread.ThreadNetworkException.ERROR_THREAD_DISABLED;
@@ -72,6 +75,8 @@
 import android.os.HandlerThread;
 import android.os.OutcomeReceiver;
 import android.platform.test.annotations.RequiresFlagsEnabled;
+import android.platform.test.flag.junit.CheckFlagsRule;
+import android.platform.test.flag.junit.DeviceFlagsValueProvider;
 import android.util.SparseIntArray;
 
 import androidx.annotation.NonNull;
@@ -82,6 +87,8 @@
 import com.android.net.thread.flags.Flags;
 import com.android.testutils.FunctionalUtils.ThrowingRunnable;
 
+import kotlin.Triple;
+
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Ignore;
@@ -96,6 +103,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
@@ -134,9 +142,13 @@
                     put(VALID_CHANNEL, VALID_POWER);
                 }
             };
+    private static final Duration EPHEMERAL_KEY_LIFETIME = Duration.ofSeconds(1);
 
     @Rule public final ThreadFeatureCheckerRule mThreadRule = new ThreadFeatureCheckerRule();
 
+    @Rule
+    public final CheckFlagsRule mCheckFlagsRule = DeviceFlagsValueProvider.createCheckFlagsRule();
+
     private final Context mContext = ApplicationProvider.getApplicationContext();
     private ExecutorService mExecutor;
     private ThreadNetworkController mController;
@@ -164,6 +176,7 @@
 
         setEnabledAndWait(mController, true);
         setConfigurationAndWait(mController, DEFAULT_CONFIG);
+        deactivateEphemeralKeyModeAndWait(mController);
     }
 
     @After
@@ -183,6 +196,7 @@
             }
         }
         mConfigurationCallbacksToCleanUp.clear();
+        deactivateEphemeralKeyModeAndWait(mController);
     }
 
     @Test
@@ -819,6 +833,221 @@
         listener.unregisterStateCallback();
     }
 
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void getMaxEphemeralKeyLifetime_isLargerThanZero() {
+        assertThat(mController.getMaxEphemeralKeyLifetime()).isGreaterThan(Duration.ZERO);
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void activateEphemeralKeyMode_withPrivilegedPermission_succeeds() throws Exception {
+        joinRandomizedDatasetAndWait(mController);
+        CompletableFuture<Void> startFuture = new CompletableFuture<>();
+
+        runAsShell(
+                THREAD_NETWORK_PRIVILEGED,
+                () ->
+                        mController.activateEphemeralKeyMode(
+                                EPHEMERAL_KEY_LIFETIME,
+                                mExecutor,
+                                newOutcomeReceiver(startFuture)));
+
+        startFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS);
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void activateEphemeralKeyMode_withoutPrivilegedPermission_throwsSecurityException()
+            throws Exception {
+        dropAllPermissions();
+
+        assertThrows(
+                SecurityException.class,
+                () ->
+                        mController.activateEphemeralKeyMode(
+                                EPHEMERAL_KEY_LIFETIME, mExecutor, v -> {}));
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void activateEphemeralKeyMode_withZeroLifetime_throwsIllegalArgumentException()
+            throws Exception {
+        grantPermissions(THREAD_NETWORK_PRIVILEGED);
+
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> mController.activateEphemeralKeyMode(Duration.ZERO, mExecutor, v -> {}));
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void activateEphemeralKeyMode_withInvalidLargeLifetime_throwsIllegalArgumentException()
+            throws Exception {
+        grantPermissions(THREAD_NETWORK_PRIVILEGED);
+        Duration lifetime = mController.getMaxEphemeralKeyLifetime().plusMillis(1);
+
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> mController.activateEphemeralKeyMode(lifetime, Runnable::run, v -> {}));
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void activateEphemeralKeyMode_concurrentRequests_secondOneFailsWithBusyError()
+            throws Exception {
+        joinRandomizedDatasetAndWait(mController);
+        CompletableFuture<Void> future1 = new CompletableFuture<>();
+        CompletableFuture<Void> future2 = new CompletableFuture<>();
+
+        runAsShell(
+                THREAD_NETWORK_PRIVILEGED,
+                () -> {
+                    mController.activateEphemeralKeyMode(
+                            EPHEMERAL_KEY_LIFETIME, mExecutor, newOutcomeReceiver(future1));
+                    mController.activateEphemeralKeyMode(
+                            EPHEMERAL_KEY_LIFETIME, mExecutor, newOutcomeReceiver(future2));
+                });
+
+        var thrown =
+                assertThrows(
+                        ExecutionException.class,
+                        () -> {
+                            future2.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS);
+                        });
+        var threadException = (ThreadNetworkException) thrown.getCause();
+        assertThat(threadException.getErrorCode()).isEqualTo(ERROR_BUSY);
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void deactivateEphemeralKeyMode_withoutPrivilegedPermission_throwsSecurityException()
+            throws Exception {
+        dropAllPermissions();
+
+        assertThrows(
+                SecurityException.class,
+                () -> mController.deactivateEphemeralKeyMode(mExecutor, v -> {}));
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void subscribeEpskcState_permissionsGranted_returnsCurrentState() throws Exception {
+        CompletableFuture<Integer> stateFuture = new CompletableFuture<>();
+        CompletableFuture<String> ephemeralKeyFuture = new CompletableFuture<>();
+        CompletableFuture<Instant> expiryFuture = new CompletableFuture<>();
+        StateCallback callback =
+                new ThreadNetworkController.StateCallback() {
+                    @Override
+                    public void onDeviceRoleChanged(int r) {}
+
+                    @Override
+                    public void onEphemeralKeyStateChanged(
+                            int state, String ephemeralKey, Instant expiry) {
+                        stateFuture.complete(state);
+                        ephemeralKeyFuture.complete(ephemeralKey);
+                        expiryFuture.complete(expiry);
+                    }
+                };
+
+        runAsShell(
+                ACCESS_NETWORK_STATE,
+                THREAD_NETWORK_PRIVILEGED,
+                () -> mController.registerStateCallback(mExecutor, callback));
+
+        try {
+            assertThat(stateFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS))
+                    .isEqualTo(EPHEMERAL_KEY_DISABLED);
+            assertThat(ephemeralKeyFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS)).isNull();
+            assertThat(expiryFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS)).isNull();
+        } finally {
+            runAsShell(ACCESS_NETWORK_STATE, () -> mController.unregisterStateCallback(callback));
+        }
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void subscribeEpskcState_withoutThreadPriviledgedPermission_returnsNullEphemeralKey()
+            throws Exception {
+        CompletableFuture<Integer> stateFuture = new CompletableFuture<>();
+        CompletableFuture<String> ephemeralKeyFuture = new CompletableFuture<>();
+        CompletableFuture<Instant> expiryFuture = new CompletableFuture<>();
+        StateCallback callback =
+                new ThreadNetworkController.StateCallback() {
+                    @Override
+                    public void onDeviceRoleChanged(int r) {}
+
+                    @Override
+                    public void onEphemeralKeyStateChanged(
+                            int state, String ephemeralKey, Instant expiry) {
+                        stateFuture.complete(state);
+                        ephemeralKeyFuture.complete(ephemeralKey);
+                        expiryFuture.complete(expiry);
+                    }
+                };
+        joinRandomizedDatasetAndWait(mController);
+        activateEphemeralKeyModeAndWait(mController);
+
+        runAsShell(
+                ACCESS_NETWORK_STATE, () -> mController.registerStateCallback(mExecutor, callback));
+
+        try {
+            assertThat(stateFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS))
+                    .isEqualTo(EPHEMERAL_KEY_ENABLED);
+            assertThat(ephemeralKeyFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS)).isNull();
+            assertThat(
+                            expiryFuture
+                                    .get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS)
+                                    .isAfter(Instant.now()))
+                    .isTrue();
+        } finally {
+            runAsShell(ACCESS_NETWORK_STATE, () -> mController.unregisterStateCallback(callback));
+        }
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void subscribeEpskcState_ephemralKeyStateChanged_returnsUpdatedState() throws Exception {
+        EphemeralKeyStateListener listener = new EphemeralKeyStateListener(mController);
+        joinRandomizedDatasetAndWait(mController);
+
+        try {
+            activateEphemeralKeyModeAndWait(mController);
+            deactivateEphemeralKeyModeAndWait(mController);
+
+            listener.expectThreadEphemeralKeyMode(EPHEMERAL_KEY_DISABLED);
+            listener.expectThreadEphemeralKeyMode(EPHEMERAL_KEY_ENABLED);
+            listener.expectThreadEphemeralKeyMode(EPHEMERAL_KEY_DISABLED);
+        } finally {
+            listener.unregisterStateCallback();
+        }
+    }
+
+    @Test
+    @RequiresFlagsEnabled({Flags.FLAG_EPSKC_ENABLED})
+    public void subscribeEpskcState_epskcEnabled_returnsSameExpiry() throws Exception {
+        EphemeralKeyStateListener listener1 = new EphemeralKeyStateListener(mController);
+        Triple<Integer, String, Instant> epskc1;
+        try {
+            joinRandomizedDatasetAndWait(mController);
+            activateEphemeralKeyModeAndWait(mController);
+            epskc1 = listener1.expectThreadEphemeralKeyMode(EPHEMERAL_KEY_ENABLED);
+        } finally {
+            listener1.unregisterStateCallback();
+        }
+
+        EphemeralKeyStateListener listener2 = new EphemeralKeyStateListener(mController);
+        try {
+            Triple<Integer, String, Instant> epskc2 =
+                    listener2.expectThreadEphemeralKeyMode(EPHEMERAL_KEY_ENABLED);
+
+            assertThat(epskc2.getSecond()).isEqualTo(epskc1.getSecond());
+            assertThat(epskc2.getThird()).isEqualTo(epskc1.getThird());
+        } finally {
+            listener2.unregisterStateCallback();
+        }
+    }
+
     // TODO (b/322437869): add test case to verify when Thread is in DISABLING state, any commands
     // (join/leave/scheduleMigration/setEnabled) fail with ERROR_BUSY. This is not currently tested
     // because DISABLING has very short lifecycle, it's not possible to guarantee the command can be
@@ -1274,6 +1503,71 @@
         setFuture.get(SET_CONFIGURATION_TIMEOUT_MILLIS, MILLISECONDS);
     }
 
+    private void deactivateEphemeralKeyModeAndWait(ThreadNetworkController controller)
+            throws Exception {
+        CompletableFuture<Void> clearFuture = new CompletableFuture<>();
+        runAsShell(
+                THREAD_NETWORK_PRIVILEGED,
+                () ->
+                        controller.deactivateEphemeralKeyMode(
+                                mExecutor, newOutcomeReceiver(clearFuture)));
+        clearFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS);
+    }
+
+    private void activateEphemeralKeyModeAndWait(ThreadNetworkController controller)
+            throws Exception {
+        CompletableFuture<Void> startFuture = new CompletableFuture<>();
+        runAsShell(
+                THREAD_NETWORK_PRIVILEGED,
+                () ->
+                        controller.activateEphemeralKeyMode(
+                                EPHEMERAL_KEY_LIFETIME,
+                                mExecutor,
+                                newOutcomeReceiver(startFuture)));
+        startFuture.get(CALLBACK_TIMEOUT_MILLIS, MILLISECONDS);
+    }
+
+    private class EphemeralKeyStateListener {
+        private ArrayTrackRecord<Triple<Integer, String, Instant>> mEphemeralKeyStates =
+                new ArrayTrackRecord<>();
+        private final ArrayTrackRecord<Triple<Integer, String, Instant>>.ReadHead mReadHead =
+                mEphemeralKeyStates.newReadHead();
+        ThreadNetworkController mController;
+        StateCallback mCallback =
+                new ThreadNetworkController.StateCallback() {
+                    @Override
+                    public void onDeviceRoleChanged(int r) {}
+
+                    @Override
+                    public void onEphemeralKeyStateChanged(
+                            int state, String ephemeralKey, Instant expiry) {
+                        mEphemeralKeyStates.add(new Triple<>(state, ephemeralKey, expiry));
+                    }
+                };
+
+        EphemeralKeyStateListener(ThreadNetworkController controller) {
+            this.mController = controller;
+            runAsShell(
+                    ACCESS_NETWORK_STATE,
+                    THREAD_NETWORK_PRIVILEGED,
+                    () -> controller.registerStateCallback(mExecutor, mCallback));
+        }
+
+        // Expect that EphemeralKey has the expected state, and return a Triple of <state,
+        // passcode, expiry>.
+        public Triple<Integer, String, Instant> expectThreadEphemeralKeyMode(int state) {
+            Triple<Integer, String, Instant> epskc =
+                    mReadHead.poll(
+                            ENABLED_TIMEOUT_MILLIS, e -> Objects.equals(e.getFirst(), state));
+            assertThat(epskc).isNotNull();
+            return epskc;
+        }
+
+        public void unregisterStateCallback() {
+            runAsShell(ACCESS_NETWORK_STATE, () -> mController.unregisterStateCallback(mCallback));
+        }
+    }
+
     private CompletableFuture joinRandomizedDataset(
             ThreadNetworkController controller, String networkName) throws Exception {
         ActiveOperationalDataset activeDataset = newRandomizedDataset(networkName, controller);
diff --git a/thread/tests/unit/src/android/net/thread/ThreadNetworkControllerTest.java b/thread/tests/unit/src/android/net/thread/ThreadNetworkControllerTest.java
index 0423578..62801bf 100644
--- a/thread/tests/unit/src/android/net/thread/ThreadNetworkControllerTest.java
+++ b/thread/tests/unit/src/android/net/thread/ThreadNetworkControllerTest.java
@@ -17,6 +17,8 @@
 package android.net.thread;
 
 import static android.net.thread.ThreadNetworkController.DEVICE_ROLE_CHILD;
+import static android.net.thread.ThreadNetworkException.ERROR_FAILED_PRECONDITION;
+import static android.net.thread.ThreadNetworkException.ERROR_INTERNAL_ERROR;
 import static android.net.thread.ThreadNetworkException.ERROR_UNAVAILABLE;
 import static android.net.thread.ThreadNetworkException.ERROR_UNSUPPORTED_CHANNEL;
 import static android.net.thread.ThreadNetworkException.ERROR_UNSUPPORTED_FEATURE;
@@ -26,6 +28,7 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.doAnswer;
 
@@ -134,6 +137,16 @@
         return (IOperationalDatasetCallback) invocation.getArguments()[0];
     }
 
+    private static IOperationReceiver getActivateEphemeralKeyModeReceiver(
+            InvocationOnMock invocation) {
+        return (IOperationReceiver) invocation.getArguments()[1];
+    }
+
+    private static IOperationReceiver getDeactivateEphemeralKeyModeReceiver(
+            InvocationOnMock invocation) {
+        return (IOperationReceiver) invocation.getArguments()[0];
+    }
+
     @Test
     public void registerStateCallback_callbackIsInvokedWithCallingAppIdentity() throws Exception {
         setBinderUid(SYSTEM_UID);
@@ -440,4 +453,88 @@
         assertThat(callbackUid.get()).isNotEqualTo(SYSTEM_UID);
         assertThat(callbackUid.get()).isEqualTo(Process.myUid());
     }
+
+    @Test
+    public void activateEphemeralKeyMode_callbackIsInvokedWithCallingAppIdentity()
+            throws Exception {
+        setBinderUid(SYSTEM_UID);
+        AtomicInteger successCallbackUid = new AtomicInteger(0);
+        AtomicInteger errorCallbackUid = new AtomicInteger(0);
+        Duration lifetime = Duration.ofSeconds(100);
+        doAnswer(
+                        invoke -> {
+                            getActivateEphemeralKeyModeReceiver(invoke).onSuccess();
+                            return null;
+                        })
+                .when(mMockService)
+                .activateEphemeralKeyMode(anyLong(), any(IOperationReceiver.class));
+        mController.activateEphemeralKeyMode(
+                lifetime, Runnable::run, v -> successCallbackUid.set(Binder.getCallingUid()));
+        doAnswer(
+                        invoke -> {
+                            getActivateEphemeralKeyModeReceiver(invoke)
+                                    .onError(ERROR_FAILED_PRECONDITION, "");
+                            return null;
+                        })
+                .when(mMockService)
+                .activateEphemeralKeyMode(anyLong(), any(IOperationReceiver.class));
+        mController.activateEphemeralKeyMode(
+                lifetime,
+                Runnable::run,
+                new OutcomeReceiver<>() {
+                    @Override
+                    public void onResult(Void unused) {}
+
+                    @Override
+                    public void onError(ThreadNetworkException e) {
+                        errorCallbackUid.set(Binder.getCallingUid());
+                    }
+                });
+
+        assertThat(successCallbackUid.get()).isNotEqualTo(SYSTEM_UID);
+        assertThat(successCallbackUid.get()).isEqualTo(Process.myUid());
+        assertThat(errorCallbackUid.get()).isNotEqualTo(SYSTEM_UID);
+        assertThat(errorCallbackUid.get()).isEqualTo(Process.myUid());
+    }
+
+    @Test
+    public void deactivateEphemeralKeyMode_callbackIsInvokedWithCallingAppIdentity()
+            throws Exception {
+        setBinderUid(SYSTEM_UID);
+        AtomicInteger successCallbackUid = new AtomicInteger(0);
+        AtomicInteger errorCallbackUid = new AtomicInteger(0);
+        doAnswer(
+                        invoke -> {
+                            getDeactivateEphemeralKeyModeReceiver(invoke).onSuccess();
+                            return null;
+                        })
+                .when(mMockService)
+                .deactivateEphemeralKeyMode(any(IOperationReceiver.class));
+        mController.deactivateEphemeralKeyMode(
+                Runnable::run, v -> successCallbackUid.set(Binder.getCallingUid()));
+        doAnswer(
+                        invoke -> {
+                            getDeactivateEphemeralKeyModeReceiver(invoke)
+                                    .onError(ERROR_INTERNAL_ERROR, "");
+                            return null;
+                        })
+                .when(mMockService)
+                .deactivateEphemeralKeyMode(any(IOperationReceiver.class));
+        mController.deactivateEphemeralKeyMode(
+                Runnable::run,
+                new OutcomeReceiver<>() {
+                    @Override
+                    public void onResult(Void unused) {}
+
+                    @Override
+                    public void onError(ThreadNetworkException e) {
+                        errorCallbackUid.set(Binder.getCallingUid());
+                    }
+                });
+
+        assertThat(successCallbackUid.get()).isNotEqualTo(SYSTEM_UID);
+        assertThat(successCallbackUid.get()).isEqualTo(Process.myUid());
+        assertThat(errorCallbackUid.get()).isNotEqualTo(SYSTEM_UID);
+        assertThat(errorCallbackUid.get()).isEqualTo(Process.myUid());
+    }
 }
diff --git a/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java b/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
index d8cdbc4..b97e2b7 100644
--- a/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
+++ b/thread/tests/unit/src/com/android/server/thread/ThreadNetworkControllerServiceTest.java
@@ -838,4 +838,26 @@
 
         verify(mockReceiver, times(1)).onError(eq(ERROR_INTERNAL_ERROR), anyString());
     }
+
+    @Test
+    public void activateEphemeralKeyMode_succeed() throws Exception {
+        mService.initialize();
+        final IOperationReceiver mockReceiver = mock(IOperationReceiver.class);
+
+        mService.activateEphemeralKeyMode(1_000L, mockReceiver);
+        mTestLooper.dispatchAll();
+
+        verify(mockReceiver, times(1)).onSuccess();
+    }
+
+    @Test
+    public void deactivateEphemeralKeyMode_succeed() throws Exception {
+        mService.initialize();
+        final IOperationReceiver mockReceiver = mock(IOperationReceiver.class);
+
+        mService.deactivateEphemeralKeyMode(mockReceiver);
+        mTestLooper.dispatchAll();
+
+        verify(mockReceiver, times(1)).onSuccess();
+    }
 }