将 sqlite 转换为加密数据库：

Question

我的应用程序中有一个现有的 sqlite 数据库。它运行成功。现在我需要使用 sqlcipher 加密数据库。我的问题是在将 sqlite 转换为加密时出现以下异常。

net.sqlcipher.database.SQLiteException: table android_metadata already exists
 at net.sqlcipher.database.SQLiteDatabase.native_rawExecSQL(Native Method)
 at net.sqlcipher.database.SQLiteDatabase.rawExecSQL(SQLiteDatabase.java:1851)
 at com.x.y.convert_sqlite_to_sqlcipher(Practitioner_menu.java:2626)
 at com.x.y$AdminProcess.doInBackground(Practitioner_menu.java:1659)
 at com.x.y$AdminProcess.doInBackground(Practitioner_menu.java:1)
 at android.os.AsyncTask$2.call(AsyncTask.java:287)
 at java.util.concurrent.FutureTask.run(FutureTask.java:234)
 at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
 at java.lang.Thread.run(Thread.java:856)

我的转换代码：

File old_sqliteFile = getDatabasePath("old_db.sqlite");
File databaseFile = getDatabasePath("new_db.db");
        databaseFile.mkdirs();
        databaseFile.delete();
    database = SQLiteDatabase.openOrCreateDatabase(databaseFile,
                    "password", null);
database.rawExecSQL(String.format(
                    "ATTACH DATABASE '%s' AS encrypted KEY '%s'",
                    databaseFile.getAbsolutePath(), "password");
            database.rawExecSQL("select sqlcipher_export('encrypted')");
            database.rawExecSQL("DETACH DATABASE encrypted");
            database.close();

请任何人帮助我找出我做错了什么？

Answer 1

您使用了两次databaseFile。你的openOrCreateDatabase() 应该被称为old_sqliteFile，而不是databaseFile。

这是一种将未加密的数据库文件替换为加密替换的方法：

  public static void encrypt(Context ctxt, String dbName,
                             String passphrase) throws IOException {
    File originalFile=ctxt.getDatabasePath(dbName);

    if (originalFile.exists()) {
      File newFile=
          File.createTempFile("sqlcipherutils", "tmp",
                              ctxt.getCacheDir());
      SQLiteDatabase db=
          SQLiteDatabase.openDatabase(originalFile.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=
          SQLiteDatabase.openDatabase(newFile.getAbsolutePath(),
                                      passphrase, null,
                                      SQLiteDatabase.OPEN_READWRITE);
      db.setVersion(version);
      db.close();

      originalFile.delete();
      newFile.renameTo(originalFile);
    }
  }

Answer 2

谢谢，效果很好。 我添加了这段代码来加密、解密和更改密码。

@Override
public synchronized SQLiteDatabase getWritableDatabase(String password) {
    SQLiteDatabase sqLiteDatabase;
    try{
        sqLiteDatabase = super.getWritableDatabase(password);
    }catch(Exception e){
        try {
            encrypt(context,DATABASE_NAME,PWOLD,PWNEW);
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        sqLiteDatabase = super.getWritableDatabase(password);
    }
    return sqLiteDatabase;
}

@Override
public synchronized SQLiteDatabase getReadableDatabase(String password) {
    SQLiteDatabase sqLiteDatabase;
    try{
        sqLiteDatabase = super.getReadableDatabase(password);
    }catch(Exception e){
        try {
            encrypt(context, DATABASE_NAME, PWOLD, PWNEW);
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        sqLiteDatabase = super.getReadableDatabase(password);
    }
    return sqLiteDatabase;
}

public static void encrypt(Context context, String dbName,
                           String oldPass, String newPass) throws IOException {
    if(!newPass.isEmpty()) Log.d(TAG,"Encrypt DB...");
    else Log.d(TAG,"Decrypt DB...");

    File originalFile=context.getDatabasePath(dbName);

    if (originalFile.exists()) {
        File newFile = File.createTempFile("sqlcipherutils", "tmp",
                        context.getCacheDir());
        SQLiteDatabase db = SQLiteDatabase.openDatabase(originalFile.getAbsolutePath(),
                oldPass, null,
                SQLiteDatabase.OPEN_READWRITE);

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

        int version=db.getVersion();

        db.close();

        db = SQLiteDatabase.openDatabase(newFile.getAbsolutePath(),
                newPass, null,
                SQLiteDatabase.OPEN_READWRITE);
        db.setVersion(version);
        db.close();

        originalFile.delete();
        newFile.renameTo(originalFile);
    }
}