diff --git a/Android.bp b/Android.bp
index 53b74dc..c5fcd65 100644
--- a/Android.bp
+++ b/Android.bp
@@ -232,7 +232,7 @@
     required: [
         "e2fsdroid.recovery",
         "librecovery_ui_ext",
-        "mke2fs.conf",
+        "mke2fs.conf.recovery",
         "mke2fs.recovery",
         "recovery_deps",
     ],
diff --git a/recovery_main.cpp b/recovery_main.cpp
index 99f9650..020a531 100644
--- a/recovery_main.cpp
+++ b/recovery_main.cpp
@@ -97,8 +97,13 @@
   }
   stage = std::string(boot.stage);
 
+  std::string boot_command;
   if (boot.command[0] != 0) {
-    std::string boot_command = std::string(boot.command, sizeof(boot.command));
+    if (memchr(boot.command, '\0', sizeof(boot.command))) {
+      boot_command = std::string(boot.command);
+    } else {
+      boot_command = std::string(boot.command, sizeof(boot.command));
+    }
     LOG(INFO) << "Boot command: " << boot_command;
   }
 
@@ -149,6 +154,12 @@
     LOG(ERROR) << "Failed to set BCB message: " << err;
   }
 
+  // Finally, if no arguments were specified, check whether we should boot
+  // into fastboot.
+  if (args.size() == 1 && boot_command == "boot-fastboot") {
+    args.emplace_back("--fastboot");
+  }
+
   return args;
 }
 
diff --git a/updater_sample/README.md b/updater_sample/README.md
index 69e8e24..f9c3fb8 100644
--- a/updater_sample/README.md
+++ b/updater_sample/README.md
@@ -220,7 +220,7 @@
 - [x] Add Sample app update state (separate from update_engine status)
 - [x] Add smart update completion detection using onStatusUpdate
 - [x] Add pause/resume demo
-- [ ] Verify system partition checksum for package
+- [x] Verify system partition checksum for package
 
 
 ## Running tests
diff --git a/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java b/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java
index 1e0fadc..61872a6 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/UpdateConfig.java
@@ -25,6 +25,7 @@
 
 import java.io.File;
 import java.io.Serializable;
+import java.util.ArrayList;
 import java.util.Optional;
 
 /**
@@ -67,31 +68,28 @@
                 throw new JSONException("Invalid type, expected either "
                         + "NON_STREAMING or STREAMING, got " + o.getString("ab_install_type"));
         }
-        if (c.mAbInstallType == AB_INSTALL_TYPE_STREAMING) {
-            JSONObject meta = o.getJSONObject("ab_streaming_metadata");
-            JSONArray propertyFilesJson = meta.getJSONArray("property_files");
-            PackageFile[] propertyFiles =
-                    new PackageFile[propertyFilesJson.length()];
-            for (int i = 0; i < propertyFilesJson.length(); i++) {
-                JSONObject p = propertyFilesJson.getJSONObject(i);
-                propertyFiles[i] = new PackageFile(
-                        p.getString("filename"),
-                        p.getLong("offset"),
-                        p.getLong("size"));
-            }
-            String authorization = null;
-            if (meta.has("authorization")) {
-                authorization = meta.getString("authorization");
-            }
-            c.mAbStreamingMetadata = new StreamingMetadata(
-                    propertyFiles,
-                    authorization);
-        }
 
         // TODO: parse only for A/B updates when non-A/B is implemented
         JSONObject ab = o.getJSONObject("ab_config");
         boolean forceSwitchSlot = ab.getBoolean("force_switch_slot");
-        c.mAbConfig = new AbConfig(forceSwitchSlot);
+        boolean verifyPayloadMetadata = ab.getBoolean("verify_payload_metadata");
+        ArrayList<PackageFile> propertyFiles = new ArrayList<>();
+        if (ab.has("property_files")) {
+            JSONArray propertyFilesJson = ab.getJSONArray("property_files");
+            for (int i = 0; i < propertyFilesJson.length(); i++) {
+                JSONObject p = propertyFilesJson.getJSONObject(i);
+                propertyFiles.add(new PackageFile(
+                        p.getString("filename"),
+                        p.getLong("offset"),
+                        p.getLong("size")));
+            }
+        }
+        String authorization = ab.optString("authorization", null);
+        c.mAbConfig = new AbConfig(
+                forceSwitchSlot,
+                verifyPayloadMetadata,
+                propertyFiles.toArray(new PackageFile[0]),
+                authorization);
 
         c.mRawJson = json;
         return c;
@@ -112,9 +110,6 @@
     /** non-streaming (first saves locally) OR streaming (on the fly) */
     private int mAbInstallType;
 
-    /** metadata is required only for streaming update */
-    private StreamingMetadata mAbStreamingMetadata;
-
     /** A/B update configurations */
     private AbConfig mAbConfig;
 
@@ -127,7 +122,6 @@
         this.mName = in.readString();
         this.mUrl = in.readString();
         this.mAbInstallType = in.readInt();
-        this.mAbStreamingMetadata = (StreamingMetadata) in.readSerializable();
         this.mAbConfig = (AbConfig) in.readSerializable();
         this.mRawJson = in.readString();
     }
@@ -154,10 +148,6 @@
         return mAbInstallType;
     }
 
-    public StreamingMetadata getStreamingMetadata() {
-        return mAbStreamingMetadata;
-    }
-
     public AbConfig getAbConfig() {
         return mAbConfig;
     }
@@ -185,43 +175,11 @@
         dest.writeString(mName);
         dest.writeString(mUrl);
         dest.writeInt(mAbInstallType);
-        dest.writeSerializable(mAbStreamingMetadata);
         dest.writeSerializable(mAbConfig);
         dest.writeString(mRawJson);
     }
 
     /**
-     * Metadata for streaming A/B update.
-     */
-    public static class StreamingMetadata implements Serializable {
-
-        private static final long serialVersionUID = 31042L;
-
-        /** defines beginning of update data in archive */
-        private PackageFile[] mPropertyFiles;
-
-        /**
-         * SystemUpdaterSample receives the authorization token from the OTA server, in addition
-         * to the package URL. It passes on the info to update_engine, so that the latter can
-         * fetch the data from the package server directly with the token.
-         */
-        private String mAuthorization;
-
-        public StreamingMetadata(PackageFile[] propertyFiles, String authorization) {
-            this.mPropertyFiles = propertyFiles;
-            this.mAuthorization = authorization;
-        }
-
-        public PackageFile[] getPropertyFiles() {
-            return mPropertyFiles;
-        }
-
-        public Optional<String> getAuthorization() {
-            return mAuthorization == null ? Optional.empty() : Optional.of(mAuthorization);
-        }
-    }
-
-    /**
      * Description of a file in an OTA package zip file.
      */
     public static class PackageFile implements Serializable {
@@ -269,14 +227,48 @@
          */
         private boolean mForceSwitchSlot;
 
-        public AbConfig(boolean forceSwitchSlot) {
+        /**
+         * if set true device will boot to new slot, otherwise user manually
+         * switches slot on the screen.
+         */
+        private boolean mVerifyPayloadMetadata;
+
+        /** defines beginning of update data in archive */
+        private PackageFile[] mPropertyFiles;
+
+        /**
+         * SystemUpdaterSample receives the authorization token from the OTA server, in addition
+         * to the package URL. It passes on the info to update_engine, so that the latter can
+         * fetch the data from the package server directly with the token.
+         */
+        private String mAuthorization;
+
+        public AbConfig(
+                boolean forceSwitchSlot,
+                boolean verifyPayloadMetadata,
+                PackageFile[] propertyFiles,
+                String authorization) {
             this.mForceSwitchSlot = forceSwitchSlot;
+            this.mVerifyPayloadMetadata = verifyPayloadMetadata;
+            this.mPropertyFiles = propertyFiles;
+            this.mAuthorization = authorization;
         }
 
         public boolean getForceSwitchSlot() {
             return mForceSwitchSlot;
         }
 
+        public boolean getVerifyPayloadMetadata() {
+            return mVerifyPayloadMetadata;
+        }
+
+        public PackageFile[] getPropertyFiles() {
+            return mPropertyFiles;
+        }
+
+        public Optional<String> getAuthorization() {
+            return mAuthorization == null ? Optional.empty() : Optional.of(mAuthorization);
+        }
     }
 
 }
diff --git a/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java b/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
index a9783e7..12a8f3f 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
@@ -324,7 +324,7 @@
             if (code == PrepareStreamingService.RESULT_CODE_SUCCESS) {
                 builder.setPayload(payloadSpec);
                 builder.addExtraProperty("USER_AGENT=" + HTTP_USER_AGENT);
-                config.getStreamingMetadata()
+                config.getAbConfig()
                         .getAuthorization()
                         .ifPresent(s -> builder.addExtraProperty("AUTHORIZATION=" + s));
                 updateEngineApplyPayload(builder.build());
diff --git a/updater_sample/src/com/example/android/systemupdatersample/services/PrepareStreamingService.java b/updater_sample/src/com/example/android/systemupdatersample/services/PrepareStreamingService.java
index ac6e223..9314048 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/services/PrepareStreamingService.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/services/PrepareStreamingService.java
@@ -173,7 +173,7 @@
     }
 
     /**
-     * Downloads files defined in {@link UpdateConfig#getStreamingMetadata()}
+     * Downloads files defined in {@link UpdateConfig#getAbConfig()}
      * and exists in {@code PRE_STREAMING_FILES_SET}, and put them
      * in directory {@code dir}.
      * @throws IOException when can't download a file
@@ -185,7 +185,7 @@
             Files.deleteIfExists(Paths.get(OTA_PACKAGE_DIR, file));
         }
         Log.d(TAG, "Downloading files to " + dir);
-        for (UpdateConfig.PackageFile file : config.getStreamingMetadata().getPropertyFiles()) {
+        for (UpdateConfig.PackageFile file : config.getAbConfig().getPropertyFiles()) {
             if (PRE_STREAMING_FILES_SET.contains(file.getFilename())) {
                 Log.d(TAG, "Downloading file " + file.getFilename());
                 FileDownloader downloader = new FileDownloader(
diff --git a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java
index 5080cb6..bbefcaf 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/util/UpdateConfigs.java
@@ -83,7 +83,7 @@
 
     /**
      * @param filename searches by given filename
-     * @param config searches in {@link UpdateConfig#getStreamingMetadata()}
+     * @param config searches in {@link UpdateConfig#getAbConfig()}
      * @return offset and size of {@code filename} in the package zip file
      *         stored as {@link UpdateConfig.PackageFile}.
      */
@@ -91,7 +91,7 @@
             final String filename,
             UpdateConfig config) {
         return Arrays
-                .stream(config.getStreamingMetadata().getPropertyFiles())
+                .stream(config.getAbConfig().getPropertyFiles())
                 .filter(file -> filename.equals(file.getFilename()))
                 .findFirst();
     }
diff --git a/updater_sample/tests/res/raw/update_config_001_stream.json b/updater_sample/tests/res/raw/update_config_001_stream.json
index be51b7c..b024ad9 100644
--- a/updater_sample/tests/res/raw/update_config_001_stream.json
+++ b/updater_sample/tests/res/raw/update_config_001_stream.json
@@ -2,7 +2,9 @@
     "name": "streaming-001",
     "url": "http://foo.bar/update.zip",
     "ab_install_type": "STREAMING",
-    "ab_streaming_metadata": {
+    "ab_config": {
+        "verify_payload_metadata": true,
+        "force_switch_slot": true,
         "property_files": [
             {
                 "filename": "payload.bin",
@@ -10,8 +12,5 @@
                 "size": 8
             }
         ]
-    },
-    "ab_config": {
-        "force_switch_slot": true
     }
 }
diff --git a/updater_sample/tests/res/raw/update_config_002_stream.json b/updater_sample/tests/res/raw/update_config_002_stream.json
index 40c8fe1..12c18bb 100644
--- a/updater_sample/tests/res/raw/update_config_002_stream.json
+++ b/updater_sample/tests/res/raw/update_config_002_stream.json
@@ -1,10 +1,8 @@
 {
     "__": "*** Generated using tools/gen_update_config.py ***",
     "ab_config": {
-        "force_switch_slot": false
-    },
-    "ab_install_type": "STREAMING",
-    "ab_streaming_metadata": {
+        "verify_payload_metadata": true,
+        "force_switch_slot": false,
         "property_files": [
             {
                 "filename": "payload_metadata.bin",
@@ -38,6 +36,7 @@
             }
         ]
     },
+    "ab_install_type": "STREAMING",
     "name": "S ota_002_package",
     "url": "file:///data/my-sample-ota-builds-dir/ota_002_package.zip"
 }
\ No newline at end of file
diff --git a/updater_sample/tests/res/raw/update_config_003_nonstream.json b/updater_sample/tests/res/raw/update_config_003_nonstream.json
index 7c78b9d..2011f76 100644
--- a/updater_sample/tests/res/raw/update_config_003_nonstream.json
+++ b/updater_sample/tests/res/raw/update_config_003_nonstream.json
@@ -1,7 +1,15 @@
 {
     "__": "*** Generated using tools/gen_update_config.py ***",
     "ab_config": {
-        "force_switch_slot": false
+        "verify_payload_metadata": true,
+        "force_switch_slot": false,
+        "property_files": [
+            {
+                "filename": "payload.bin",
+                "offset": 195,
+                "size": 8
+            }
+        ]
     },
     "ab_install_type": "NON_STREAMING",
     "name": "S ota_002_package",
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java
index 1cbd860..48d0e42 100644
--- a/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/UpdateConfigTest.java
@@ -44,10 +44,12 @@
 @SmallTest
 public class UpdateConfigTest {
 
-    private static final String JSON_NON_STREAMING =
-            "{\"name\": \"vip update\", \"url\": \"file:///builds/a.zip\", "
-                    + " \"ab_install_type\": \"NON_STREAMING\","
-                    + " \"ab_config\": { \"force_switch_slot\": false } }";
+    private static final String JSON_NON_STREAMING = "{"
+            + " \"name\": \"vip update\", \"url\": \"file:///my-builds/a.zip\","
+            + " \"ab_install_type\": \"NON_STREAMING\","
+            + " \"ab_config\": {"
+            + "     \"force_switch_slot\": false,"
+            + "     \"verify_payload_metadata\": false } }";
 
     @Rule
     public final ExpectedException thrown = ExpectedException.none();
@@ -71,7 +73,7 @@
         assertSame("type is parsed",
                 UpdateConfig.AB_INSTALL_TYPE_NON_STREAMING,
                 config.getInstallType());
-        assertEquals("url is parsed", "file:///builds/a.zip", config.getUrl());
+        assertEquals("url is parsed", "file:///my-builds/a.zip", config.getUrl());
     }
 
     @Test
@@ -81,9 +83,9 @@
         assertEquals("http://foo.bar/update.zip", config.getUrl());
         assertSame(UpdateConfig.AB_INSTALL_TYPE_STREAMING, config.getInstallType());
         assertEquals("payload.bin",
-                config.getStreamingMetadata().getPropertyFiles()[0].getFilename());
-        assertEquals(195, config.getStreamingMetadata().getPropertyFiles()[0].getOffset());
-        assertEquals(8, config.getStreamingMetadata().getPropertyFiles()[0].getSize());
+                config.getAbConfig().getPropertyFiles()[0].getFilename());
+        assertEquals(195, config.getAbConfig().getPropertyFiles()[0].getOffset());
+        assertEquals(8, config.getAbConfig().getPropertyFiles()[0].getSize());
         assertTrue(config.getAbConfig().getForceSwitchSlot());
     }
 
@@ -96,9 +98,12 @@
 
     @Test
     public void getUpdatePackageFile_throwsErrorIfNotAFile() throws Exception {
-        String json = "{\"name\": \"upd\", \"url\": \"http://foo.bar\","
+        String json = "{"
+                + " \"name\": \"upd\", \"url\": \"http://foo.bar\","
                 + " \"ab_install_type\": \"NON_STREAMING\","
-                + " \"ab_config\": { \"force_switch_slot\": false } }";
+                + " \"ab_config\": {"
+                + "     \"force_switch_slot\": false,"
+                + "     \"verify_payload_metadata\": false } }";
         UpdateConfig config = UpdateConfig.fromJson(json);
         thrown.expect(RuntimeException.class);
         config.getUpdatePackageFile();
@@ -107,7 +112,7 @@
     @Test
     public void getUpdatePackageFile_works() throws Exception {
         UpdateConfig c = UpdateConfig.fromJson(JSON_NON_STREAMING);
-        assertEquals("/builds/a.zip", c.getUpdatePackageFile().getAbsolutePath());
+        assertEquals("/my-builds/a.zip", c.getUpdatePackageFile().getAbsolutePath());
     }
 
     private String readResource(int id) throws IOException {
diff --git a/updater_sample/tools/gen_update_config.py b/updater_sample/tools/gen_update_config.py
index b43e49d..f2cb1a8 100755
--- a/updater_sample/tools/gen_update_config.py
+++ b/updater_sample/tools/gen_update_config.py
@@ -46,11 +46,17 @@
     AB_INSTALL_TYPE_STREAMING = 'STREAMING'
     AB_INSTALL_TYPE_NON_STREAMING = 'NON_STREAMING'
 
-    def __init__(self, package, url, ab_install_type, ab_force_switch_slot):
+    def __init__(self,
+                 package,
+                 url,
+                 ab_install_type,
+                 ab_force_switch_slot,
+                 ab_verify_payload_metadata):
         self.package = package
         self.url = url
         self.ab_install_type = ab_install_type
         self.ab_force_switch_slot = ab_force_switch_slot
+        self.ab_verify_payload_metadata = ab_verify_payload_metadata
         self.streaming_required = (
             # payload.bin and payload_properties.txt must exist.
             'payload.bin',
@@ -71,29 +77,24 @@
 
     def run(self):
         """Generates config."""
-        streaming_metadata = None
-        if self.ab_install_type == GenUpdateConfig.AB_INSTALL_TYPE_STREAMING:
-            streaming_metadata = self._gen_ab_streaming_metadata()
-
         self._config = {
             '__': '*** Generated using tools/gen_update_config.py ***',
             'name': self.ab_install_type[0] + ' ' + os.path.basename(self.package)[:-4],
             'url': self.url,
-            'ab_streaming_metadata': streaming_metadata,
+            'ab_config': self._gen_ab_config(),
             'ab_install_type': self.ab_install_type,
-            'ab_config': {
-                'force_switch_slot': self.ab_force_switch_slot,
-            }
         }
 
-    def _gen_ab_streaming_metadata(self):
-        """Builds metadata for files required for streaming update."""
+    def _gen_ab_config(self):
+        """Builds config required for A/B update."""
         with zipfile.ZipFile(self.package, 'r') as package_zip:
-            metadata = {
-                'property_files': self._get_property_files(package_zip)
+            config = {
+                'property_files': self._get_property_files(package_zip),
+                'verify_payload_metadata': self.ab_verify_payload_metadata,
+                'force_switch_slot': self.ab_force_switch_slot,
             }
 
-        return metadata
+        return config
 
     @staticmethod
     def _get_property_files(package_zip):
@@ -135,6 +136,11 @@
                         action='store_true',
                         help='if set device will boot to a new slot, otherwise user '
                               'manually switches slot on the screen')
+    parser.add_argument('--ab_verify_payload_metadata',
+                        default=False,
+                        action='store_true',
+                        help='if set the app will verify the update payload metadata using '
+                             'update_engine before downloading the whole package.')
     parser.add_argument('package',
                         type=str,
                         help='OTA package zip file')
@@ -154,7 +160,8 @@
         package=args.package,
         url=args.url,
         ab_install_type=args.ab_install_type,
-        ab_force_switch_slot=args.ab_force_switch_slot)
+        ab_force_switch_slot=args.ab_force_switch_slot,
+        ab_verify_payload_metadata=args.ab_verify_payload_metadata)
     gen.run()
     gen.write(args.out)
     print('Config is written to ' + args.out)
diff --git a/updater_sample/tools/test_gen_update_config.py b/updater_sample/tools/test_gen_update_config.py
index c907cf2..8b77cb2 100755
--- a/updater_sample/tools/test_gen_update_config.py
+++ b/updater_sample/tools/test_gen_update_config.py
@@ -32,7 +32,7 @@
     def test_ab_install_type_streaming(self):
         """tests if streaming property files' offset and size are generated properly"""
         config, package = self._generate_config()
-        property_files = config['ab_streaming_metadata']['property_files']
+        property_files = config['ab_config']['property_files']
         self.assertEqual(len(property_files), 6)
         with open(package, 'rb') as pkg_file:
             for prop in property_files:
@@ -56,6 +56,8 @@
                                    '../tests/res/raw/ota_002_package.zip')
         gen = GenUpdateConfig(ota_package,
                               'file:///foo.bar',
-                              GenUpdateConfig.AB_INSTALL_TYPE_STREAMING)
+                              GenUpdateConfig.AB_INSTALL_TYPE_STREAMING,
+                              True,  # ab_force_switch_slot
+                              True)  # ab_verify_payload_metadata
         gen.run()
         return gen.config, ota_package