我在我的 android 应用程序中使用了一个外部数据库，它在编译后直接嵌入到 apk 包中。 因为我想在应用程序购买中实现以访问它的一些数据，所以我不想让它没有任何加密。 我使用了 Sqlcipher 库，但它使应用程序太大且太慢。 没有其他方法可以做到这一点吗？例如加密字符串的算法，所以我将加密的文本放入数据库并在应用程序代码中解密？
【问题讨论】：
标签： android sqlite android-studio
以下是一个示例应用程序，它对部分数据进行加密，然后可以打开。它基于我评论中的代码。
首先您需要作为加密数据库基础的数据库（即不包含在应用程序中的MASTER数据库，它的用途是创建加密数据库（或数据库，也许是一个库，如果您想要更高的安全性，每个数据库都有一个唯一的密码/密钥））部分考虑这一点（在整个示例中使用）：-
正如您所见，这将通过一个名为 FreeData 的表和另一个名为 PaidData 的表来工作。除了 PaidData 没有 ID 列之外，表定义相同（此方法的目的是在/如果请求且 SecretKey（密码）有效时将 PaidData 中的行解密为 FreeData。）。
所以 FreeData 表看起来像：-
PaidData 表如下所示：-
第 2 阶段 - 生成加密数据库以与应用程序一起分发
这是由一个应用程序完成的，该应用程序使用与 Encrypt data in SQLite 非常相似的 EncryptDecrypt 类
根据 EncryptDecrypt.java
class EncryptDecrypt {
private Cipher cipher;
private static SecretKeySpec secretKeySpec;
private static IvParameterSpec ivParameterSpec;
private boolean do_encrypt = true;
/**
* Construct EncryptDecrypt instance that does not check user login-in
* mode, thus the assumption is that this user is NOT the special user
* NOUSER that doesn't require a password to login; this constructor
* is designed to ONLY be used when a user has been added by NOUSER,
* and to then encrypt the data using the enccryptForced method solely
* to encrypt any existing card data for the new user that has a password.
*
* @param context The context, required for database usage (user)
* @param skey The secret key to be used to encrypt/decrypt
*/
EncryptDecrypt(Context context, String skey) {
//DBUsersMethods users = new DBUsersMethods(context);
String saltasString = "there is no dark side of the moon it is all dark.";
String paddedskey = (skey + saltasString).substring(0,16);
secretKeySpec = new SecretKeySpec(paddedskey.getBytes(),"AES/CBC/PKCS5Padding");
ivParameterSpec = new IvParameterSpec((saltasString.substring(0,16)).getBytes());
try {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
} catch (Exception e){
//e.printStackTrace();
}
}
/**
* Normal encryption routine that will not encrypt data if the user is
* the special case NOUSER (i.e LOGIN mode is NOUSER), otherwise data
* is encrypted.
*
* @Param toEncrypt The string to be encrypted
* @return The encryted (or not if NOUSER) data as a string
*/
String encrypt(String toEncrypt) {
if (!do_encrypt) {
return toEncrypt;
}
byte[] encrypted;
try {
cipher.init(Cipher.ENCRYPT_MODE,secretKeySpec,ivParameterSpec);
encrypted = cipher.doFinal(toEncrypt.getBytes());
} catch (Exception e) {
//e.printStackTrace();
return null;
}
return Base64.encodeToString(encrypted, Base64.DEFAULT);
}
/**
* Encryption, irrespective of the USER type, noting that this should
* only be used in conjunction with an EncryptDecrypt instance created
* using the 2nd/extended constructor
*
* @param toEncrypt The string to be encrypted
* @return The encrypted data as a string
*/
String encryptForced(String toEncrypt) {
byte[] encrypted;
try {
cipher.init(Cipher.ENCRYPT_MODE,secretKeySpec,ivParameterSpec);
encrypted = cipher.doFinal(toEncrypt.getBytes());
} catch (Exception e) {
//e.printStackTrace();
return null;
}
return Base64.encodeToString(encrypted,Base64.DEFAULT);
}
/**
* Decrypt an encrypted string
* @param toDecrypt The encrypted string to be decrypted
* @return The decrypted string
*/
String decrypt(String toDecrypt) {
if (!do_encrypt) {
return toDecrypt;
}
byte[] decrypted;
try {
cipher.init(Cipher.DECRYPT_MODE,secretKeySpec,ivParameterSpec);
decrypted = cipher.doFinal(Base64.decode(toDecrypt,Base64.DEFAULT));
} catch (Exception e) {
//e.printStackTrace();
return null;
}
return new String(decrypted);
}
}
String saltasString = "there is no dark side of the moon it is all dark."; 硬编码，只要短语长度至少为 16 个字符，就可以更改（仅使用前 16 个字节）。一个类用于满足潜在的灵活性/扩展性，其中可以指定或不指定多个表进行加密，以及可以加密、复制或跳过的多个列（例如，id 可能会被跳过（在示例中它不是甚至定义为列）。）。
这个类是 TableColumnConvertList.java 并且是：-
public class TableColumnConvertList {
private ArrayList<TableEntry> tables;
public TableColumnConvertList() {
this.tables = new ArrayList<>();
}
public String[] getTables() {
String[] tableList = new String[tables.size()];
int ix = 0;
for (TableEntry te: this.tables) {
tableList[ix++] = te.getSourceTableName();
}
return tableList;
}
public String[] getTableColumnNamesToEncrypt(String tableName) {
String[] rv = null;
for(TableEntry te: this.tables) {
if (te.getSourceTableName().equals(tableName)) {
rv = new String[te.getColumnNamesToEncrypt().size()];
int ix=0;
for (String s: te.getColumnNamesToEncrypt()) {
rv[ix++] = s;
}
}
}
return rv;
}
public String[] getTableColumnNamesToCopyAsis(String tableName) {
String[] rv = null;
for (TableEntry te: this.tables) {
if (te.getSourceTableName().equals(tableName)) {
rv = new String[te.getColumnNamesToCopyAsis().size()];
int ix=0;
for (String s: te.getColumnNamesToCopyAsis()) {
rv[ix++] = s;
}
}
}
return rv;
}
public String[] getTableColumnNamesToSkip(String tableName) {
String[] rv = null;
for (TableEntry te: this.tables) {
if (te.sourceTableName.equals(tableName)) {
rv = new String[te.getColumnNamesToSkip().size()];
int ix =0;
for (String s: te.getColumnNamesToSkip()) {
rv[ix++] = s;
}
}
}
return rv;
}
public void addTable(
String sourceTableName,
String destinationTableName,
String[] columnNamesToEncrypt,
String[] columnNamesToCopyAsis,
String[] columnNamesToSkip
) {
tables.add(
new TableEntry(
sourceTableName,
destinationTableName,
columnNamesToEncrypt,
columnNamesToCopyAsis,
columnNamesToSkip
)
);
}
private class TableEntry {
private String sourceTableName;
private String destinationTableName;
private ArrayList<String> columnNamesToEncrypt;
private ArrayList<String> columnNamesToCopyAsis;
private ArrayList<String> columnNamesToSkip;
private TableEntry() {}
private TableEntry(String sourceTableName,
String destinationTableName,
String[] columnNamesToEncrypt,
String[] columnNamesToCopyAsis,
String[] columnNamesToSkip
) {
this.sourceTableName = sourceTableName;
this.destinationTableName = destinationTableName;
this.columnNamesToEncrypt = new ArrayList<>();
if (columnNamesToEncrypt != null && columnNamesToEncrypt.length > 0) {
for (String s: columnNamesToEncrypt) {
addColumn(s);
}
}
}
private void addColumn(String s) {
this.columnNamesToEncrypt.add(s);
}
private String getSourceTableName() {
return sourceTableName;
}
public String getDestinationTableName() {
return destinationTableName;
}
public void setSourceTableName(String sourceTableName) {
this.sourceTableName = sourceTableName;
}
public void setDestinationTableName(String destinationTableName) {
this.destinationTableName = destinationTableName;
}
private ArrayList<String> getColumnNamesToEncrypt() {
return columnNamesToEncrypt;
}
public void setColumnNamesToEncrypt(ArrayList<String> columnNamesToEncrypt) {
this.columnNamesToEncrypt = columnNamesToEncrypt;
}
private ArrayList<String> getColumnNamesToCopyAsis() {
return columnNamesToCopyAsis;
}
public void setColumnNamesToCopyAsis(ArrayList<String> columnNamesToCopyAsis) {
this.columnNamesToCopyAsis = columnNamesToCopyAsis;
}
public ArrayList<String> getColumnNamesToSkip() {
return columnNamesToSkip;
}
public void setColumnNamesToSkip(ArrayList<String> columnNamesToSkip) {
this.columnNamesToSkip = columnNamesToSkip;
}
}
}
目前，这个基本应用程序的其余部分都在一个使用两个输入（EditTexts）的单个活动中：-
这个布局xml activiy_main.xml是：-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp"
tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Database EncryptTool" />
<EditText
android:id="@+id/secretkey"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="Secret Key to use to Encrypt the Database."
>
</EditText>
<EditText
android:id="@+id/databasename"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="MyDatabase"
android:hint="Database Name"
>
</EditText>
<Button
android:id="@+id/encrypt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ENCRYPT"
android:visibility="gone"
>
</Button>
</LinearLayout>
MainActivity.java 工作完成的地方是：-
public class MainActivity extends AppCompatActivity {
public static final String ASSETDB_NAME = "basedb.db";
public static final int ASSETDB_NOT_FOUND = -10;
public static final int ASSETFILE_OPEN_ERROR = -11;
public static final int ASSETDB_OPEN_ERROR = -12;
public static final int ASSETDB_COPY_ERROR = -13;
public static final int ASSETDB_FLUSH_ERROR = -14;
public static final int ASSETDB_CLOSE_ERROR = -15;
public static final int ASSETFILE_CLOSE_ERROR = -16;
public static final int ASSETDB_CREATED_SUCCESSFULLY = 0;
public static final int BUFFERSIZE = 1024 * 4;
EditText mSecretKey, mDBName;
Button mEncryptButton;
TableColumnConvertList mTCCL = new TableColumnConvertList();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDBName = this.findViewById(R.id.databasename);
mSecretKey = this.findViewById(R.id.secretkey);
mEncryptButton = this.findViewById(R.id.encrypt);
//<<<<<<<<< set what data to encrypt i.e. table(s) and the column(s) in the table >>>>>>>>>
mTCCL.addTable(
"PaidData",
"FreeData",
new String[]{"theData"},
new String[]{},
new String[]{"id"}
);
if (getDBFromAsset() >= 0) {
mEncryptButton.setVisibility(View.VISIBLE);
mEncryptButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mDBName.getText().toString().length() < 1) {
Toast.makeText(
v.getContext(),
"The Database Name cannot be blank.",
Toast.LENGTH_LONG
).show();
mDBName.requestFocus();
return;
}
if (mDBName.getText().toString().equals(ASSETDB_NAME)) {
Toast.makeText(
v.getContext(),
"Database Name cannot be "
+ ASSETDB_NAME
+ ". Please change the name.",
Toast.LENGTH_LONG
).show();
mDBName.requestFocus();
return;
}
if (mSecretKey.getText().toString().length() < 1) {
Toast.makeText(
v.getContext(),
"The Secret Key cannot be blank.",
Toast.LENGTH_LONG
).show();
mSecretKey.requestFocus();
return;
}
if (createEncryptedDatabase(mTCCL,
mDBName.getText().toString(),
mSecretKey.getText().toString()
) == 0) {
Toast.makeText(v.getContext(),"Successfully Encrypted Database " + mDBName + " using Secret Key " + mSecretKey,Toast.LENGTH_LONG).show();
}
}
});
}
}
private boolean checkIfDataBaseExists(String databaseName) {
File dbFile = new File(this.getDatabasePath(databaseName).getPath());
if (dbFile.exists()) {
return true;
} else {
if (!dbFile.getParentFile().exists()) {
dbFile.getParentFile().mkdirs();
}
}
return false;
}
private boolean checkIfAssetDBExists() {
try {
InputStream is = this.getAssets().open(ASSETDB_NAME);
is.close();
return true;
} catch (IOException e) {
return false;
}
}
private int getDBFromAsset() {
int rv = ASSETDB_NOT_FOUND;
File dbFile = new File(this.getDatabasePath(ASSETDB_NAME).getPath());
InputStream is;
FileOutputStream os;
int read_length;
byte[] buffer = new byte[BUFFERSIZE];
if (!checkIfAssetDBExists()) {
return ASSETDB_NOT_FOUND;
}
if (checkIfDataBaseExists(ASSETDB_NAME)) {
dbFile.delete();
}
try {
rv = ASSETFILE_OPEN_ERROR;
is = this.getAssets().open(ASSETDB_NAME);
rv = ASSETDB_OPEN_ERROR;
os = new FileOutputStream(dbFile);
rv = ASSETDB_COPY_ERROR;
while ((read_length = is.read(buffer)) > 0) {
os.write(buffer,0,read_length);
}
rv = ASSETDB_FLUSH_ERROR;
os.flush();
rv = ASSETDB_CLOSE_ERROR;
os.close();
rv = ASSETFILE_CLOSE_ERROR;
is.close();
rv = ASSETDB_CREATED_SUCCESSFULLY;
} catch (IOException e) {
e.printStackTrace();
}
return rv;
}
private int createEncryptedDatabase(TableColumnConvertList tableColumnConvertList, String databaseName, String key) {
File copiedAssetDB = new File(this.getDatabasePath(ASSETDB_NAME).getPath());
File encryptedDB = new File(this.getDatabasePath(databaseName).getPath());
if (encryptedDB.exists()) {
encryptedDB.delete();
}
try {
byte[] buffer = new byte[BUFFERSIZE];
int read_length;
InputStream is = new FileInputStream(copiedAssetDB);
OutputStream os = new FileOutputStream(encryptedDB);
while ((read_length = is.read(buffer)) > 0) {
os.write(buffer,0,read_length);
}
os.flush();
os.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
return -1;
}
SQLiteDatabase db = SQLiteDatabase.openDatabase(encryptedDB.getPath(),null,SQLiteDatabase.OPEN_READWRITE);
EncryptDecrypt ed = new EncryptDecrypt(this,key);
int errorcount = 0;
db.beginTransaction();
for (String t: tableColumnConvertList.getTables()) {
ContentValues cv = new ContentValues();
String[] columnsToEncrypt = tableColumnConvertList.getTableColumnNamesToEncrypt(t);
String[] columnOriginalValues = new String[columnsToEncrypt.length];
Cursor c = db.query(true,t,columnsToEncrypt,null,null,null,null,null, null);
int totalRows = c.getCount();
int updatedRows = 0;
while (c.moveToNext()) {
cv.clear();
int ovix=0;
StringBuilder whereClause = new StringBuilder();
for (String s: c.getColumnNames()) {
for (String ec: columnsToEncrypt ) {
if (s.equals(ec)) {
cv.put(s,ed.encrypt(c.getString(c.getColumnIndex(s))));
columnOriginalValues[ovix++] = c.getString(c.getColumnIndex(s));
if (whereClause.length() > 0) {
whereClause.append(" AND ");
}
whereClause.append(s).append("=?");
}
}
}
updatedRows += db.update(t,cv,whereClause.toString(),columnOriginalValues);
}
c.close();
Log.d("ENCRYPTRESULT","Read " + totalRows + " DISTINCT ROWS. Updated " + updatedRows);
errorcount += totalRows - updatedRows;
}
if (errorcount == 0) {
db.setTransactionSuccessful();
} else {
Toast.makeText(
this,
"Errors encountered Encrypting Database. Rolled back (not changed)",
Toast.LENGTH_LONG
).show();
}
db.endTransaction();
return errorcount;
}
}
这一行/代码很重要：-
TableColumnConvertList mTCCL = new TableColumnConvertList();
..........
//<<<<<<<<< set what data to encrypt i.e. table(s) and the column(s) in the table >>>>>>>>>
mTCCL.addTable(
"PaidData",
"FreeData",
new String[]{"theData"},
new String[]{},
new String[]{"id"}
);
这会将一个表添加到要加密的表列表中。它的参数是：-
最终结果是根据 assets 文件夹中的数据库（名为 basedb.db）的数据库，该数据库已加密 PaidData 表的 theData 列中的数据，但 FreeData 表是不变。然后可以复制该数据库（例如使用设备资源管理器），然后将其作为资产包含在要分发的应用程序中。该应用程序可能包括使用密钥和 EncryptDecrypt 类的解密部分来反转加密。
例如
FreeData 表：-
付费数据表：-
当应用程序启动时，如果从 assets 文件夹中复制数据库（硬编码为 basedb.db），则它存在并使 Encrypt 按钮可见。 p>
如果出现“加密”按钮，则只需点击该按钮即可进行加密。
点击按钮后，createEncryptedDatabase 方法被调用。
这将创建一个副本，这将是加密数据库，该副本是从资产文件夹复制的数据库，方法是将文件复制到它的新名称（根据给定的数据库名称，该名称必须与资产的文件名不同）。
使用复制的数据库查询在 mTCCL 中定义的表（TableColumnConvertList 类的一个实例）。
查询将仅提取已指定为要加密的列的数据。查询仅获取不同的行（即，如果存在多行且列中具有相同数据，则仅提取其中一行）。
对于每个提取的行：-
cv.put(s,ed.encrypt(c.getString(c.getColumnIndex(s)))); 完成的
数据库将位于 data/data/package_name/databases 文件夹中，例如:-
【讨论】：
请注意，数据库（MyDatabase）是从应用程序的data/data/package_name/databases从上一个答案（即加密数据库）复制到此应用程序的资产文件夹中
以下是一个非常基本的应用程序，最初只有免费数据，但作为一个编辑文本和一个按钮，允许解密和检索付费数据。可用数据（最初是免费数据）列在 ListView 中；解密后，已复制到 FreeData 的付费数据可以使用并列出。
EncryptDEcrypt.java 与 Encrypt 工具中使用的相同。
数据库助手是：-
public class DBHelper extends SQLiteOpenHelper {
public static final String DBNAME = "MyDatabase";
public static final int DBVERSION = 1;
public static final String TBL_FREEDATA = "FreeData";
public static final String COL_FREEDATA_ID = "id";
public static final String COL_THEDATA = "theData";
SQLiteDatabase mDB;
public DBHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
loadDBFromAssets(context);
mDB = this.getWritableDatabase();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public long insertFreeDataRow(String theData) {
ContentValues cv = new ContentValues();
cv.put(COL_THEDATA,theData);
return mDB.insert(TBL_FREEDATA,null,cv);
}
public Cursor getAllAvialableData() {
return mDB.query(TBL_FREEDATA,new
String[]{"*",COL_FREEDATA_ID + " AS " + BaseColumns._ID},
null,null,null,null,null
);
}
public void decryptAndLoadPaidData(Context context, String secretKey) {
EncryptDecrypt ed = new EncryptDecrypt(context,secretKey);
mDB.beginTransaction();
Cursor c = mDB.query("PaidData",null,null,null,null,null,null);
while (c.moveToNext()) {
String decrypted_data = ed.decrypt(c.getString(c.getColumnIndex(COL_THEDATA)));
if (decrypted_data != null) {
insertFreeDataRow(decrypted_data);
} else {
Toast.makeText(context,"Naughty, that's not the password.",Toast.LENGTH_LONG).show();
}
}
c.close();
mDB.setTransactionSuccessful();
mDB.endTransaction();
}
private boolean loadDBFromAssets(Context context) {
File dbFile = new File(context.getDatabasePath(DBNAME).getPath());
byte[] buffer = new byte[1024 * 4];
int read_length = 0;
if (dbFile.exists()) return true;
if (!dbFile.getParentFile().exists()) {
dbFile.getParentFile().mkdirs();
}
try {
InputStream assetdb = context.getAssets().open(DBNAME);
OutputStream realdb = new FileOutputStream(dbFile);
while ((read_length = assetdb.read(buffer)) > 0) {
realdb.write(buffer,0,read_length);
}
realdb.flush();
realdb.close();
assetdb.close();
} catch (IOException e) {
e.printStackTrace();
return false;
}
return true;
}
}
MainActivity.java 是：-
public class MainActivity extends AppCompatActivity {
ListView mListView;
EditText mSecretKeyInput;
Button mDecrypt;
SimpleCursorAdapter mSCA;
Cursor mAllTheData;
DBHelper mDBhlpr;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListView = this.findViewById(R.id.list);
mSecretKeyInput = this.findViewById(R.id.secretKey);
mDecrypt = this.findViewById(R.id.decrypt);
mDBhlpr = new DBHelper(this);
manageListView();
manageDecryptButton();
}
private void manageListView() {
mAllTheData = mDBhlpr.getAllAvialableData();
if (mSCA == null) {
mSCA = new SimpleCursorAdapter(
this,android.R.layout.simple_list_item_1,mAllTheData,new String[]{DBHelper.COL_THEDATA},new int[]{android.R.id.text1},0);
mListView.setAdapter(mSCA);
} else {
mSCA.swapCursor(mAllTheData);
}
}
private void manageDecryptButton() {
mDecrypt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mSecretKeyInput.getText().toString().length() > 0) {
mDBhlpr.decryptAndLoadPaidData(v.getContext(),mSecretKeyInput.getText().toString());
manageListView();
}
}
});
}
}
第一次运行时，应用程序仅显示免费数据：-
如果输入正确的密码/密钥并按下“获取付费数据”按钮，则会添加额外数据：-
如果提供的密码不正确，则不会加载数据，并会出现提示密码错误的提示。
【讨论】：