SharedPreferences 在 Android 应用中的常见存储位置是：
/data/data/<package name>/shared_prefs/<filename.xml>
具有 root 权限的用户可以导航到此位置并可以更改其值。需要保护它非常重要。
我们可以通过多少种方式加密整个shared_pref's xml 文件？
我们都知道我们可以在shared_pref's xml 文件中加密和保存数据，但这不仅是 100% 安全的，因此需要使用密钥对整个文件进行加密。在了解加密整个 xml 文件的各种方法方面需要帮助。这是一个通用问题，此处讨论的各种加密方法作为答案可以帮助所有开发人员保护应用程序。
【问题讨论】：
标签： android security encryption sharedpreferences
更新答案：
Android 已在其 Jetpack 库中发布了带有 EncryptedSharedPreferences 的安全库。
编辑：使用 v1.1.0 版本，您可以支持Lollipop (API level 21) 及更高版本
String masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC);
SharedPreferences sharedPreferences = EncryptedSharedPreferences.create(
"secret_shared_prefs",
masterKeyAlias,
context,
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
);
// use the shared preferences and editor as you normally would
SharedPreferences.Editor editor = sharedPreferences.edit();
【讨论】：
Google 已发布 EncryptedSharedPreferences 作为其 androidx 的一部分，我相信这应该是加密偏好的首选方式。
见https://developer.android.com/reference/androidx/security/crypto/EncryptedSharedPreferences
【讨论】：
您需要在 API 23 下处理 Verisons
fun providesSharedPreference(): SharedPreferences {
var sharedPreferences: SharedPreferences
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
sharedPreferences = EncryptedSharedPreferences.create(
application,
Constant.SHARED_PREFERENCE_NAME,
getMasterKey(),
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)
} else {
sharedPreferences =
application.getSharedPreferences(
Constant.SHARED_PREFERENCE_NAME,
Context.MODE_PRIVATE
)
}
return sharedPreferences
}
private fun getMasterKey(): MasterKey {
return MasterKey.Builder(application)
.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
.build()
}
【讨论】：
您应该加密您的数据并写入 SharedPreferences。当您想要获取此数据时，您应该从 SharedPreferences 解密。为此，您需要以下帮助程序类
public class Encryption {
private final Builder mBuilder;
private Encryption(Builder builder) {
mBuilder = builder;
}
public static Encryption getDefault(String key, String salt, byte[] iv) {
try {
return Builder.getDefaultBuilder(key, salt, iv).build();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
}
}
private String encrypt(String data) throws UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException, InvalidKeyException, InvalidKeySpecException, BadPaddingException, IllegalBlockSizeException {
if (data == null) return null;
SecretKey secretKey = getSecretKey(hashTheKey(mBuilder.getKey()));
byte[] dataBytes = data.getBytes(mBuilder.getCharsetName());
Cipher cipher = Cipher.getInstance(mBuilder.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, secretKey, mBuilder.getIvParameterSpec(), mBuilder.getSecureRandom());
return Base64.encodeToString(cipher.doFinal(dataBytes), mBuilder.getBase64Mode());
}
public String encryptOrNull(String data) {
try {
return encrypt(data);
} catch (Exception e) {
e.printStackTrace();
return "";
}
}
public void encryptAsync(final String data, final Callback callback) {
if (callback == null) return;
new Thread(new Runnable() {
@Override
public void run() {
try {
String encrypt = encrypt(data);
if (encrypt == null) {
callback.onError(new Exception("Encrypt return null, it normally occurs when you send a null data"));
}
callback.onSuccess(encrypt);
} catch (Exception e) {
callback.onError(e);
}
}
}).start();
}
private String decrypt(String data) throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidAlgorithmParameterException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
if (data == null) return null;
byte[] dataBytes = Base64.decode(data, mBuilder.getBase64Mode());
SecretKey secretKey = getSecretKey(hashTheKey(mBuilder.getKey()));
Cipher cipher = Cipher.getInstance(mBuilder.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, secretKey, mBuilder.getIvParameterSpec(), mBuilder.getSecureRandom());
byte[] dataBytesDecrypted = (cipher.doFinal(dataBytes));
return new String(dataBytesDecrypted);
}
public String decryptOrNull(String data) {
try {
return decrypt(data);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public void decryptAsync(final String data, final Callback callback) {
if (callback == null) return;
new Thread(new Runnable() {
@Override
public void run() {
try {
String decrypt = decrypt(data);
if (decrypt == null) {
callback.onError(new Exception("Decrypt return null, it normally occurs when you send a null data"));
}
callback.onSuccess(decrypt);
} catch (Exception e) {
callback.onError(e);
}
}
}).start();
}
private SecretKey getSecretKey(char[] key) throws NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeySpecException {
SecretKeyFactory factory = SecretKeyFactory.getInstance(mBuilder.getSecretKeyType());
KeySpec spec = new PBEKeySpec(key, mBuilder.getSalt().getBytes(mBuilder.getCharsetName()), mBuilder.getIterationCount(), mBuilder.getKeyLength());
SecretKey tmp = factory.generateSecret(spec);
return new SecretKeySpec(tmp.getEncoded(), mBuilder.getKeyAlgorithm());
}
private char[] hashTheKey(String key) throws UnsupportedEncodingException, NoSuchAlgorithmException {
MessageDigest messageDigest = MessageDigest.getInstance(mBuilder.getDigestAlgorithm());
messageDigest.update(key.getBytes(mBuilder.getCharsetName()));
return Base64.encodeToString(messageDigest.digest(), Base64.NO_PADDING).toCharArray();
}
public interface Callback {
void onSuccess(String result);
void onError(Exception exception);
}
private static class Builder {
private byte[] mIv;
private int mKeyLength;
private int mBase64Mode;
private int mIterationCount;
private String mSalt;
private String mKey;
private String mAlgorithm;
private String mKeyAlgorithm;
private String mCharsetName;
private String mSecretKeyType;
private String mDigestAlgorithm;
private String mSecureRandomAlgorithm;
private SecureRandom mSecureRandom;
private IvParameterSpec mIvParameterSpec;
public static Builder getDefaultBuilder(String key, String salt, byte[] iv) {
return new Builder()
.setIv(iv)
.setKey(key)
.setSalt(salt)
.setKeyLength(128)
.setKeyAlgorithm("AES")
.setCharsetName("UTF8")
.setIterationCount(1)
.setDigestAlgorithm("SHA1")
.setBase64Mode(Base64.DEFAULT)
.setAlgorithm("AES/CBC/PKCS5Padding")
.setSecureRandomAlgorithm("SHA1PRNG")
.setSecretKeyType("PBKDF2WithHmacSHA1");
}
private Encryption build() throws NoSuchAlgorithmException {
setSecureRandom(SecureRandom.getInstance(getSecureRandomAlgorithm()));
setIvParameterSpec(new IvParameterSpec(getIv()));
return new Encryption(this);
}
private String getCharsetName() {
return mCharsetName;
}
private Builder setCharsetName(String charsetName) {
mCharsetName = charsetName;
return this;
}
private String getAlgorithm() {
return mAlgorithm;
}
private Builder setAlgorithm(String algorithm) {
mAlgorithm = algorithm;
return this;
}
private String getKeyAlgorithm() {
return mKeyAlgorithm;
}
private Builder setKeyAlgorithm(String keyAlgorithm) {
mKeyAlgorithm = keyAlgorithm;
return this;
}
private int getBase64Mode() {
return mBase64Mode;
}
private Builder setBase64Mode(int base64Mode) {
mBase64Mode = base64Mode;
return this;
}
private String getSecretKeyType() {
return mSecretKeyType;
}
private Builder setSecretKeyType(String secretKeyType) {
mSecretKeyType = secretKeyType;
return this;
}
private String getSalt() {
return mSalt;
}
private Builder setSalt(String salt) {
mSalt = salt;
return this;
}
private String getKey() {
return mKey;
}
private Builder setKey(String key) {
mKey = key;
return this;
}
private int getKeyLength() {
return mKeyLength;
}
public Builder setKeyLength(int keyLength) {
mKeyLength = keyLength;
return this;
}
private int getIterationCount() {
return mIterationCount;
}
public Builder setIterationCount(int iterationCount) {
mIterationCount = iterationCount;
return this;
}
private String getSecureRandomAlgorithm() {
return mSecureRandomAlgorithm;
}
public Builder setSecureRandomAlgorithm(String secureRandomAlgorithm) {
mSecureRandomAlgorithm = secureRandomAlgorithm;
return this;
}
private byte[] getIv() {
return mIv;
}
public Builder setIv(byte[] iv) {
mIv = iv;
return this;
}
private SecureRandom getSecureRandom() {
return mSecureRandom;
}
public Builder setSecureRandom(SecureRandom secureRandom) {
mSecureRandom = secureRandom;
return this;
}
private IvParameterSpec getIvParameterSpec() {
return mIvParameterSpec;
}
public Builder setIvParameterSpec(IvParameterSpec ivParameterSpec) {
mIvParameterSpec = ivParameterSpec;
return this;
}
private String getDigestAlgorithm() {
return mDigestAlgorithm;
}
public Builder setDigestAlgorithm(String digestAlgorithm) {
mDigestAlgorithm = digestAlgorithm;
return this;
}
}}
然后您可以通过如下加密数据来写入 SharedPreferences
Encryption encryption = Encryption.getDefault("Key", "Salt", new byte[16]);
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = preferences.edit();
editor.putString("token", encryption.encryptOrNull(userModel.getToken()));
editor.apply()
您最终可以通过以下方式读取 SharedPreferences 数据。这样，敏感信息将更安全，同时保留在手机的硬件级别上
final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
Encryption encryption = Encryption.getDefault("Key", "Salt", new byte[16]);
String token = encryption.decryptOrNull(preferences.getString("token",""));
【讨论】：
如果您想支持 Android 5.0（API 级别 21）及更高版本
使用以下实现：
implementation "androidx.security:security-crypto:1.0.0-rc04"
或从this source.获取最新消息
那么
首先创建一个主密钥如下：
val masterKey = MasterKey.Builder(context)
.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
.build()
创建shared preferences后如下：
val sharedPreferences = EncryptedSharedPreferences.create(
context,
"secret_shared_prefs",
masterKey,
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)
然后像往常一样使用它，例如：
with(sharedPreferences.edit()) {
putString(Values.SP_USER_ID, personId)
putString(Values.SP_USER_NAME, binding.editTextTextPersonName.text.toString())
apply()
}
【讨论】：
完整答案（api 级别 23+）。首先你需要来自 androidx 的加密。
implementation "androidx.security:security-crypto:1.0.0-alpha02"
Care ：SharedPreferences 和 EncryptedSharedPreferences 之间存在显着的性能差异。 您应该注意到 EncryptedSharedPreferences.create(...) 并没有那么快，所以您必须存储一个实例。
然后您必须使用它来检索 EncryptedSharedPreferences。
public SharedPreferences getEncryptedSharedPreferences(){
String masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC);
SharedPreferences sharedPreferences = EncryptedSharedPreferences.create(
"secret_shared_prefs_file",
masterKeyAlias,
context,
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
);
return sharedPreferences;
}
您只需要使用“标准方式”之类的偏好。保存它：
getEncryptedSharedPreferences().edit()
.putString("ENCRYPTDATA", text)
.apply()
检索偏好值。
getEncryptedSharedPreferences().getString("ENCRYPTDATA", "defvalue")
【讨论】：
Base64 不是加密！不要使用它！是的，“root”用户可以访问该数据。您可以做的一件事是使用 AES 加密该数据或使用单个 NoSQL 数据库文件并加密该文件。当应用程序打开时，您解密数据库并使用它来存储信息或独立加密所有文件。
看这里：https://code.tutsplus.com/tutorials/storing-data-securely-on-android--cms-30558
【讨论】：
Kotlin 使用 anrdoidx 的 security-crypto 库（最低 API 23）的双重用途加密和未加密共享首选项示例。
我使用 Dagger2 在需要的地方将其作为@Singleton 注入。
使用 Dagger 模块中的 @Name 注释来区分 SharedPreferences 实例，您可以有 2 个单独的 .xml 文件（1 个加密，1 个未加密）来读取/写入/写入。
在 build.gradle 中添加依赖项：
implementation "androidx.security:security-crypto:1.0.0-beta01"
import android.content.Context
import android.content.SharedPreferences
import androidx.security.crypto.EncryptedSharedPreferences
class Prefs(prefsName: String, context: Context) {
private lateinit var ANDX_SECURITY_KEY_KEYSET: String
private lateinit var ANDX_SECURITY_VALUE_KEYSET: String
private lateinit var cntext: Context
private lateinit var prefName: String
private lateinit var prefs: SharedPreferences
constructor(
prefsName: String,
context: Context,
masterKeyAlias: String,
prefKeyEncryptionScheme: EncryptedSharedPreferences.PrefKeyEncryptionScheme,
prefValueEncryptionScheme: EncryptedSharedPreferences.PrefValueEncryptionScheme
): this(prefsName, context) {
ANDX_SECURITY_KEY_KEYSET = "__androidx_security_crypto_encrypted_prefs_key_keyset__"
ANDX_SECURITY_VALUE_KEYSET = "__androidx_security_crypto_encrypted_prefs_value_keyset__"
cntext = context
prefName = prefsName
prefs =
EncryptedSharedPreferences.create(
prefsName,
masterKeyAlias,
context,
prefKeyEncryptionScheme,
prefValueEncryptionScheme
)
}
init {
if (!::ANDX_SECURITY_KEY_KEYSET.isInitialized) {
prefs =
context.getSharedPreferences(
prefsName,
Context.MODE_PRIVATE
)
}
}
companion object {
const val INVALID_BOOLEAN: Boolean = false
const val INVALID_FLOAT: Float = -11111111111F
const val INVALID_INT: Int = -1111111111
const val INVALID_LONG: Long = -11111111111L
const val INVALID_STRING: String = "INVALID_STRING"
val INVALID_STRING_SET: Set<String> = setOf(INVALID_STRING)
}
/**
* OnChangeListener
* */
fun registerOnSharedPreferenceChangeListener(
listener: SharedPreferences.OnSharedPreferenceChangeListener) =
prefs.registerOnSharedPreferenceChangeListener(listener)
fun unregisterOnSharedPreferenceChangeListener(
listener: SharedPreferences.OnSharedPreferenceChangeListener) =
prefs.unregisterOnSharedPreferenceChangeListener(listener)
/**
* Read Shared Prefs
* */
fun contains(key: String): Boolean =
prefs.contains(key)
fun getAll(): Map<String, *> =
prefs.all
// Returns null if the Boolean value is not in
// Shared Preferences
fun read(key: String): Boolean? =
if (contains(key)) {
read(key, INVALID_BOOLEAN)
} else {
null
}
// Boolean
fun read(key: String, returnIfInvalid: Boolean): Boolean =
prefs.getBoolean(key, returnIfInvalid)
// Float
fun read(key: String, returnIfInvalid: Float): Float =
prefs.getFloat(key, returnIfInvalid)
// Int
fun read(key: String, returnIfInvalid: Int): Int =
prefs.getInt(key, returnIfInvalid)
// Long
fun read(key: String, returnIfInvalid: Long): Long =
prefs.getLong(key, returnIfInvalid)
// Set<String>
fun read(key: String, returnIfInvalid: Set<String>): Set<String>? =
prefs.getStringSet(key, returnIfInvalid)
// String
fun read(key: String, returnIfInvalid: String): String? =
prefs.getString(key, returnIfInvalid)
/**
* Modify Shared Prefs
* */
fun clear() {
if (::ANDX_SECURITY_KEY_KEYSET.isInitialized) {
val clearTextPrefs = cntext.getSharedPreferences(prefName, Context.MODE_PRIVATE)
val keyKeyset = clearTextPrefs.getString(ANDX_SECURITY_KEY_KEYSET, INVALID_STRING)
val valueKeyset = clearTextPrefs.getString(ANDX_SECURITY_VALUE_KEYSET, INVALID_STRING)
if (keyKeyset != null && keyKeyset != INVALID_STRING
&& valueKeyset != null && valueKeyset != INVALID_STRING) {
if (!clearTextPrefs.edit().clear().commit()) {
clearTextPrefs.edit().clear().apply()
}
if (!clearTextPrefs.edit().putString(ANDX_SECURITY_KEY_KEYSET, keyKeyset).commit()) {
clearTextPrefs.edit().putString(ANDX_SECURITY_KEY_KEYSET, keyKeyset).apply()
}
if (!clearTextPrefs.edit().putString(ANDX_SECURITY_VALUE_KEYSET, valueKeyset).commit()) {
clearTextPrefs.edit().putString(ANDX_SECURITY_VALUE_KEYSET, valueKeyset).apply()
}
}
} else {
if (!prefs.edit().clear().commit()) {
prefs.edit().clear().apply()
}
}
}
fun remove(key: String) {
if (!prefs.edit().remove(key).commit()) {
prefs.edit().remove(key).apply()
}
}
// Boolean
fun write(key: String, value: Boolean) {
if (!prefs.edit().putBoolean(key, value).commit()) {
prefs.edit().putBoolean(key, value).apply()
}
}
// Float
fun write(key: String, value: Float) {
if (!prefs.edit().putFloat(key, value).commit()) {
prefs.edit().putFloat(key, value).apply()
}
}
// Int
fun write(key: String, value: Int) {
if (!prefs.edit().putInt(key, value).commit()) {
prefs.edit().putInt(key, value).apply()
}
}
// Long
fun write(key: String, value: Long) {
if (!prefs.edit().putLong(key, value).commit()) {
prefs.edit().putLong(key, value).apply()
}
}
// Set<String>
fun write(key: String, value: Set<String>) {
if (!prefs.edit().putStringSet(key, value).commit()) {
prefs.edit().putStringSet(key, value).apply()
}
}
// String
fun write(key: String, value: String) {
if (!prefs.edit().putString(key, value).commit()) {
prefs.edit().putString(key, value).apply()
}
}
}
using Dagger2 to inject as a @Singleton 的替代选项可以是：
AppPrefs.kt
object AppPrefs {
lateinit var encryptedPrefs: Prefs
lateinit var prefs: Prefs
// Add your key strings here...
fun initEncryptedPrefs(context: Context) {
encryptedPrefs =
Prefs(
"ENCRYPTED_PREFS",
context,
MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)
}
fun initPrefs(context: Context) {
prefs = Prefs("PREFS", context)
}
}
Application.kt
class Application: Application() {
override fun onCreate() {
super.onCreate()
AppPrefs.initEncryptedPrefs(this.applicationContext)
AppPrefs.initPrefs(this.applicationContext)
}
}
然后从任何地方拨打电话AppPrefs.prefs 或AppPrefs.encryptedPrefs
【讨论】：
public class NodeCrypto {
private String iv = "fedcba9876543210";//Dummy iv (CHANGE IT!)
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "0123456789abcdef";//Dummy secretKey (CHANGE IT!)
public void doKey(String key)
{
ivspec = new IvParameterSpec(iv.getBytes());
key = padRight(key,16);
Log.d("hi",key);
keyspec = new SecretKeySpec(key.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text,String key) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
doKey(key);
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code,String key) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
doKey(key);
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] data)
{
if (data==null)
{
return null;
}
int len = data.length;
String str = "";
for (int i=0; i<len; i++) {
if ((data[i]&0xFF)<16)
str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
else
str = str + java.lang.Integer.toHexString(data[i]&0xFF);
}
return str;
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
public static String padRight(String s, int n) {
return String.format("%1$-" + n + "s", s);
}
}
-----------------------------------------------
from your activity or class call encrypt or decrypt method before saving or retriving from SharedPreference
【讨论】：
Array#toString() 只返回数组类型和哈希。
对于 API 23 以下，请查看 Datum 库。它对数据进行异步加密：
StringDatum stringDatum = provider.new StringDatum("string_key", "default");
stringDatum.setValue("new value");
stringDatum.getValue(value->{
//got value
});
【讨论】：