1. simulate the generate key

2. add encrypt and decrypt
3. add content provider to store the key

app/build.gradle

@@ -51,4 +51,8 @@ dependencies {
         exclude group: 'com.android.support', module: 'recyclerview-v7'
     }
 
+    // web3j
+    implementation "org.web3j:crypto:4.0.4"
+    implementation 'org.jetbrains:annotations:15.0'
+
 }

app/src/main/AndroidManifest.xml

@@ -7,8 +7,8 @@
     <uses-permission android:name="android.permission.READ_CONTACTS" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
-    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
-    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
     <application
         android:allowBackup="false"
@@ -33,8 +33,7 @@
             android:name=".component.home.HomeActivity"
             android:label="@string/title_home"
             android:screenOrientation="portrait"
-            android:windowSoftInputMode="adjustPan"
-            />
+            android:windowSoftInputMode="adjustPan" />
 
         <activity
             android:name=".component.detail.DetailActivity"
@@ -45,6 +44,10 @@
             android:name=".component.privacy.PrivacyActivity"
             android:label="@string/title_privacy"
             android:screenOrientation="portrait" />
+
+        <provider
+            android:name=".common.tools.UsersProvider"
+            android:authorities="com.example.zxa01.iotclient.common.tools.UserProvider"></provider>
     </application>
 
 </manifest>
\ No newline at end of file

app/src/main/java/com/example/zxa01/iotclient/common/singleton/Config.java → app/src/main/java/com/example/zxa01/iotclient/common/Config.java

-package com.example.zxa01.iotclient.common.singleton;
+package com.example.zxa01.iotclient.common;
 
 import com.example.zxa01.iotclient.common.pojo.Setting;
 import com.example.zxa01.iotclient.common.pojo.auth.LoginMessage;
@@ -15,6 +15,7 @@ public class Config {
     private static Config config = new Config();
     private List<Setting> settings;
     private LoginMessage message;
+    private String key;
 
     private Config() {
         this.reset();
@@ -49,4 +50,11 @@ public class Config {
         this.settings.add(setting);
     }
 
+    public String getKey() {
+        return key;
+    }
+
+    public void setKey(String key) {
+        this.key = key;
+    }
 }

app/src/main/java/com/example/zxa01/iotclient/common/singleton/DefaultData.java → app/src/main/java/com/example/zxa01/iotclient/common/DefaultData.java

-package com.example.zxa01.iotclient.common.singleton;
+package com.example.zxa01.iotclient.common;
 
 import com.example.zxa01.iotclient.common.pojo.auth.LoginMessage;
 

app/src/main/java/com/example/zxa01/iotclient/common/tools/Api.java

@@ -4,7 +4,7 @@ import com.example.zxa01.iotclient.common.pojo.device.Device;
 import com.example.zxa01.iotclient.common.pojo.index.PrivacyChoiceResponse;
 import com.example.zxa01.iotclient.common.pojo.index.PrivacyPolicyReportResponse;
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyChoice;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.google.gson.GsonBuilder;
 
 import java.util.List;

app/src/main/java/com/example/zxa01/iotclient/common/tools/DownloadFile.java

@@ -151,17 +151,14 @@ public class DownloadFile {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
                     == PackageManager.PERMISSION_GRANTED) {
-                Log.v(TAG,"Permission is granted");
                 return true;
             } else {
-                Log.v(TAG,"Permission is revoked");
                 requestPermissions((Activity)context,
                         new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                 return false;
             }
         }
         else {
-            Log.v(TAG,"Permission is granted");
             return true;
         }
     }

app/src/main/java/com/example/zxa01/iotclient/common/tools/ECCGenerate.java

+package com.example.zxa01.iotclient.common.tools;
+
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.KeyGenerator;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+
+public class ECCGenerate {
+
+    private static final String ALGORITHM = "AES";
+
+    public ECCGenerate() {
+    }
+
+    public String generate() throws NoSuchAlgorithmException {
+        KeyGenerator keyGen = KeyGenerator.getInstance(ALGORITHM);
+        keyGen.init(new SecureRandom());
+        return encodeKey(keyGen.generateKey());
+    }
+
+    public String encrypt(String message, String secretKey) throws NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException, InvalidKeyException {
+        Cipher cipher = Cipher.getInstance(ALGORITHM);
+        cipher.init(cipher.ENCRYPT_MODE, decodeKey(secretKey));
+        return Base64.getEncoder().encodeToString(cipher.doFinal(message.getBytes()));
+    }
+
+    public String decrypt(String message, String secretKey) throws NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException, InvalidKeyException {
+        Cipher cipher = Cipher.getInstance(ALGORITHM);
+        cipher.init(Cipher.DECRYPT_MODE, decodeKey(secretKey));
+        byte[] decryptedText = cipher.doFinal(Base64.getDecoder().decode(message));
+        return new String(decryptedText);
+    }
+
+    private SecretKey decodeKey(String key) {
+        byte[] decodedKey = Base64.getDecoder().decode(key);
+        return new SecretKeySpec(decodedKey, 0, decodedKey.length, ALGORITHM);
+    }
+
+    private String encodeKey(SecretKey secretKey) {
+        return Base64.getEncoder().encodeToString(secretKey.getEncoded());
+    }
+}

app/src/main/java/com/example/zxa01/iotclient/common/tools/UsersProvider.java

+package com.example.zxa01.iotclient.common.tools;
+
+import android.content.ContentProvider;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.UriMatcher;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteException;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.database.sqlite.SQLiteQueryBuilder;
+import android.net.Uri;
+
+import java.util.HashMap;
+
+public class UsersProvider extends ContentProvider {
+
+    public static final String PROVIDER_NAME = "com.example.zxa01.iotclient.common.tools.UserProvider";
+    public static final String URL = "content://" + PROVIDER_NAME + "/users";
+    public static final Uri CONTENT_URI = Uri.parse(URL);
+
+    public static final String id = "id";
+    public static final String name = "name";
+    public static final String secret_key = "secret_key";
+    public static final int uriCode = 1;
+    static final UriMatcher uriMatcher;
+    static final String DATABASE_NAME = "iotclient.db";
+    static final String TABLE_NAME = "user";
+    static final int DATABASE_VERSION = 1;
+    static final String CREATE_DB_TABLE = " CREATE TABLE " + TABLE_NAME
+            + " (id INTEGER PRIMARY KEY AUTOINCREMENT, "
+            + " name TEXT NOT NULL,"
+            + " secret_key TEXT )";
+    private static HashMap<String, String> values;
+
+    static {
+        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        uriMatcher.addURI(PROVIDER_NAME, "users", uriCode);
+        uriMatcher.addURI(PROVIDER_NAME, "users/*", uriCode);
+    }
+
+    private SQLiteDatabase db;
+
+    @Override
+    public String getType(Uri uri) {
+        switch (uriMatcher.match(uri)) {
+            case uriCode:
+                return "vnd.android.cursor.dir/users";
+            default:
+                throw new IllegalArgumentException("Unsupported URI: " + uri);
+        }
+    }
+
+    @Override
+    public boolean onCreate() {
+        Context context = getContext();
+        DatabaseHelper dbHelper = new DatabaseHelper(context);
+        db = dbHelper.getWritableDatabase();
+        if (db != null) {
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection,
+                        String[] selectionArgs, String sortOrder) {
+        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
+        qb.setTables(TABLE_NAME);
+
+        switch (uriMatcher.match(uri)) {
+            case uriCode:
+                qb.setProjectionMap(values);
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        if (sortOrder == null || sortOrder == "") {
+            sortOrder = id;
+        }
+        Cursor c = qb.query(db, projection, selection, selectionArgs, null,
+                null, sortOrder);
+        c.setNotificationUri(getContext().getContentResolver(), uri);
+        return c;
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        long rowID = db.insert(TABLE_NAME, "", values);
+        if (rowID > 0) {
+            Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
+            getContext().getContentResolver().notifyChange(_uri, null);
+            return _uri;
+        }
+        throw new SQLiteException("Failed to add a record into " + uri);
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection,
+                      String[] selectionArgs) {
+        int count = 0;
+        switch (uriMatcher.match(uri)) {
+            case uriCode:
+                count = db.update(TABLE_NAME, values, selection, selectionArgs);
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+        return count;
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0;
+        switch (uriMatcher.match(uri)) {
+            case uriCode:
+                count = db.delete(TABLE_NAME, selection, selectionArgs);
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+        return count;
+    }
+
+    private static class DatabaseHelper extends SQLiteOpenHelper {
+        DatabaseHelper(Context context) {
+            super(context, DATABASE_NAME, null, DATABASE_VERSION);
+        }
+
+        @Override
+        public void onCreate(SQLiteDatabase db) {
+            db.execSQL(CREATE_DB_TABLE);
+        }
+
+        @Override
+        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
+            onCreate(db);
+        }
+    }
+}

app/src/main/java/com/example/zxa01/iotclient/component/detail/DetailModel.java

@@ -6,10 +6,9 @@ import android.support.annotation.NonNull;
 import android.util.Log;
 
 import com.example.zxa01.iotclient.common.pojo.index.PrivacyPolicyReportResponse;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.example.zxa01.iotclient.common.tools.Api;
 import com.example.zxa01.iotclient.common.pojo.device.Device;
-import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyPolicyReport;
 
 import retrofit2.Call;
 import retrofit2.Callback;

app/src/main/java/com/example/zxa01/iotclient/component/detail/DetailViewModel.java

 package com.example.zxa01.iotclient.component.detail;
 
 import com.example.zxa01.iotclient.common.pojo.device.Device;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.example.zxa01.iotclient.common.tools.DownloadFile;
 import com.example.zxa01.iotclient.component.privacy.PrivacyActivity;
 import android.arch.lifecycle.MutableLiveData;

app/src/main/java/com/example/zxa01/iotclient/component/home/record/RecordModel.java

@@ -5,7 +5,7 @@ import android.databinding.BaseObservable;
 import android.support.annotation.NonNull;
 import android.util.Log;
 
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.example.zxa01.iotclient.common.tools.Api;
 import com.example.zxa01.iotclient.common.pojo.index.PrivacyChoiceResponse;
 

app/src/main/java/com/example/zxa01/iotclient/component/home/setting/SettingModel.java

@@ -4,7 +4,7 @@ import android.arch.lifecycle.MutableLiveData;
 import android.databinding.BaseObservable;
 
 import com.example.zxa01.iotclient.common.pojo.Setting;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 
 import java.util.List;
 

app/src/main/java/com/example/zxa01/iotclient/component/home/setting/SettingViewModel.java

@@ -8,7 +8,7 @@ import android.databinding.ObservableBoolean;
 
 import com.example.zxa01.iotclient.R;
 import com.example.zxa01.iotclient.common.pojo.Setting;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.example.zxa01.iotclient.component.login.LoginActivity;
 
 import java.util.List;

app/src/main/java/com/example/zxa01/iotclient/component/login/LoginModel.java

 package com.example.zxa01.iotclient.component.login;
+
 import com.example.zxa01.iotclient.common.pojo.Setting;
-import com.example.zxa01.iotclient.common.pojo.auth.User;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 import com.example.zxa01.iotclient.common.pojo.auth.LoginMessage;
-import com.example.zxa01.iotclient.common.singleton.DefaultData;
-import com.example.zxa01.iotclient.component.home.device.DeviceFragment;
+import com.example.zxa01.iotclient.common.DefaultData;
+import com.example.zxa01.iotclient.common.tools.ECCGenerate;
+import com.example.zxa01.iotclient.common.tools.UsersProvider;
 
 import android.arch.lifecycle.MutableLiveData;
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
 import android.databinding.BaseObservable;
 import android.support.annotation.NonNull;
 
+import java.security.NoSuchAlgorithmException;
+
 public class LoginModel extends BaseObservable {
 
     private MutableLiveData<Boolean> isAuthorized;
+    private Context context;
 
-    public LoginModel() {
+    public LoginModel(Context context) {
+        this.context = context;
         isAuthorized = new MutableLiveData<>();
         isAuthorized.setValue(false);
     }
@@ -28,10 +36,45 @@ public class LoginModel extends BaseObservable {
         if (verification(message)) {
             settingConfig(message);
             isAuthorized.setValue(true);
+            checkKey();
+        }
+
+    }
+
+    private void checkKey() {
+        Cursor cursor = context.getContentResolver().query(
+                UsersProvider.CONTENT_URI, null, null, null, null);
+        if(cursor.moveToFirst()) {
+            boolean found = false;
+            while (!cursor.isAfterLast()) {
+                if(cursor.getString(cursor.getColumnIndex(UsersProvider.name)).equals(Config.getConfig().getMessage().getAccount())){
+                    Config.getConfig().setKey(cursor.getString(cursor.getColumnIndex(UsersProvider.secret_key)));
+                    found = true;
+                    break;
+                }
+                cursor.moveToNext();
+            }
+            if (!found) {
+                generateKey();
+            }
+        } else{
+            generateKey();
         }
 
     }
 
+    private void generateKey() {
+        try {
+            Config.getConfig().setKey(new ECCGenerate().generate());
+            ContentValues values = new ContentValues();
+            values.put(UsersProvider.name,Config.getConfig().getMessage().getAccount());
+            values.put(UsersProvider.secret_key,Config.getConfig().getKey());
+            context.getContentResolver().insert(UsersProvider.CONTENT_URI, values);
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        }
+    }
+
     private boolean verification(@NonNull LoginMessage message) {
         return message.getAccount() != null &&
                 message.getPassword() != null &&

app/src/main/java/com/example/zxa01/iotclient/component/login/LoginViewModel.java

 package com.example.zxa01.iotclient.component.login;
 
-import com.example.zxa01.iotclient.common.singleton.DefaultData;
+import com.example.zxa01.iotclient.common.DefaultData;
 import com.example.zxa01.iotclient.component.home.HomeActivity;
 import com.example.zxa01.iotclient.common.pojo.auth.LoginMessage;
 import android.arch.lifecycle.MutableLiveData;
@@ -12,13 +12,14 @@ import android.databinding.ObservableField;
 public class LoginViewModel extends ViewModel {
 
     public ObservableField<LoginMessage> loginMessage = new ObservableField<>();
-    private LoginModel loginModel = new LoginModel();
+    private LoginModel loginModel;
     private Context context;
 
     public LoginViewModel(Context context) {
-        this.context = context;
         // default
-        loginMessage.set(DefaultData.getDefaultData().getLoginMessage());
+        this.loginMessage.set(DefaultData.getDefaultData().getLoginMessage());
+        this.context = context;
+        loginModel = new LoginModel(context);
     }
 
     public void login() {

app/src/main/java/com/example/zxa01/iotclient/component/privacy/PrivacyModel.java

@@ -12,7 +12,7 @@ import com.example.zxa01.iotclient.common.tools.Api;
 import com.example.zxa01.iotclient.common.pojo.index.PrivacyChoiceResponse;
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyChoice;
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyContent;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 
 import retrofit2.Call;
 import retrofit2.Callback;

app/src/main/java/com/example/zxa01/iotclient/component/privacy/PrivacyViewModel.java

@@ -6,7 +6,7 @@ import com.example.zxa01.iotclient.common.pojo.index.PrivacyPolicyReportResponse
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyContent;
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyPolicy;
 import com.example.zxa01.iotclient.common.pojo.privacy.PrivacyPolicyReport;
-import com.example.zxa01.iotclient.common.singleton.Config;
+import com.example.zxa01.iotclient.common.Config;
 
 import android.arch.lifecycle.MutableLiveData;
 import android.arch.lifecycle.ViewModel;