Android 數據庫加密 SQLCipher使用方法

Android 數據庫加密 SQLCipher使用方法

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最近在做數據庫加密，遇到了些問題,特此記錄

greendao 支持數據庫加密
網址http://greenrobot.org/greendao/documentation/database-encryption/

SQLCipher 網址：https://www.zetetic.net/sqlcipher/

SQLCipher 如何依賴在Android
網址：https://www.zetetic.net/sqlcipher/sqlcipher-for-android/

AS依賴 compile ‘net.zetetic:android-database-sqlcipher:3.5.9@aar’

每次在操作數據庫前，初始化SQLCipher 所以我放在了Application下

SQLiteDatabase.loadLibs(APPApplication.this);

• 在操作數據庫時與SQLiteDatabase 基本一樣，唯一的區別就是打開數據庫，需要密碼
• 首先打開一個加密的數據庫

---

sqlcipher 打開加密數據庫

---

net.sqlcipher.database.SQLiteDatabase  sqLiteDatabase = net.sqlcipher.database.SQLiteDatabase.openDatabase(file.getAbsolutePath(), password, null,
                        SQLiteDatabase.OPEN_READWRITE
                                | SQLiteDatabase.CREATE_IF_NECESSARY
                                | SQLiteDatabase.NO_LOCALIZED_COLLATORS, new SQLiteDatabaseHook() {
                            @Override
                            public void preKey(net.sqlcipher.database.SQLiteDatabase sqLiteDatabase) {

                            }

                            @Override
                            public void postKey(net.sqlcipher.database.SQLiteDatabase sqLiteDatabase) {
                               //操作數據與 Android SQLiteDatabase 用法一致
                            }
                        });


//greendao 操作數據庫時 用這個方法 打開加密的庫
openHelper.getEncryptedWritableDb(Contents.DB_KEY);
openHelper.getEncryptedReadableDb(Contents.DB_KEY);

---

greendao 中結合 sqlcipher 用法：

---

    /**
     * 獲取可讀數據庫
     */
    private Database getReadableDatabase() {
        if (Contents.DB_RELEASE) {
            DBencrypt.getInstences().encrypt(UIUtil.getContext(), Contents.DB_KEY);
            return openHelper.getEncryptedReadableDb(Contents.DB_KEY);
        } else {
            return openHelper.getReadableDb();
        }
    }

    /**
     * 獲取可寫數據庫
     */
    private Database getWritableDatabase() {
        if (Contents.DB_RELEASE) {
            DBencrypt.getInstences().encrypt(UIUtil.getContext(), Contents.DB_KEY);
            return openHelper.getEncryptedWritableDb(Contents.DB_KEY);
        } else {
            return openHelper.getReadableDb();
        }
    }

---

做完後遇到一個尷尬的問題，第一次進去時確實能顯示，沒毛病，當把進程殺死後在進去，都報錯。。。

net.sqlcipher.database.SQLiteException: file is not a database: , while compiling: select count(*) from sqlite_master;

查詢多次後發現 是加密 解密時出問題,當數據庫原來未加密時用此方法打開，會報錯。所以在查詢數據之前，先把未加密的數據庫加密，再去查詢

代碼附上：

    /**
     * 加密數據庫
     * Created by Han on 2018/4/10
     * Email:[email protected]
     * CSDN:http://blog.csdn.net/yin13753884368/article
     * Github:https://github.com/yin13753884368
     */

    public class DBencrypt {
        public static DBencrypt dBencrypt;
        private Boolean isOpen = true;

        public static DBencrypt getInstences() {
            if (dBencrypt == null) {
                synchronized (DBencrypt.class) {
                    if (dBencrypt == null) {
                        dBencrypt = new DBencrypt();
                    }
                }
            }
            return dBencrypt;
        }

        /**
         * 如果有舊錶 先加密數據庫
         *
         * @param context
         * @param passphrase
         */
        public void encrypt(Context context, String passphrase) {
            File file = new File("/data/data/" + context.getPackageName() + "/databases/db_name");
            if (file.exists()) {
                if (isOpen) {
                    try {
                        File newFile = File.createTempFile("sqlcipherutils", "tmp", context.getCacheDir());

                        net.sqlcipher.database.SQLiteDatabase db = net.sqlcipher.database.SQLiteDatabase.openDatabase(
                                file.getAbsolutePath(), "", null, SQLiteDatabase.OPEN_READWRITE);

                        db.rawExecSQL(String.format("ATTACH DATABASE '%s' AS encrypted KEY '%s';",
                                newFile.getAbsolutePath(), passphrase));
                        db.rawExecSQL("SELECT sqlcipher_export('encrypted')");
                        db.rawExecSQL("DETACH DATABASE encrypted;");

                        int version = db.getVersion();
                        db.close();

                        db = net.sqlcipher.database.SQLiteDatabase.openDatabase(newFile.getAbsolutePath(),
                                passphrase, null,
                                SQLiteDatabase.OPEN_READWRITE);

                        db.setVersion(version);
                        db.close();
                        file.delete();
                        newFile.renameTo(file);
                        isOpen = false;
                    } catch (Exception e) {
                        isOpen = false;
                    }
                }
            }
        }
    }

官網文檔地址：https://www.zetetic.net/sqlcipher/sqlcipher-api/#attach