Android学习之sharedpreferences加密

使用AES对密码进行加密

加密工具类

public class AESEncryptor {
public static String encrypt(String key, String src) throws Exception {
byte[] rawKey = getRawKey(key.getBytes());
byte[] result = encrypt(rawKey, src.getBytes());
return toHex(result);
}

public static String decrypt(String key, String encrypted) throws Exception {
byte[] rawKey = getRawKey(key.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}

private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
// SHA1PRNG 强随机种子算法, 要区别4.2以上版本的调用方法
SecureRandom sr = null;
if (android.os.Build.VERSION.SDK_INT >=  17) {
sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
} else {
sr = SecureRandom.getInstance("SHA1PRNG");
}
sr.setSeed(seed);
kgen.init(256, sr); //256 bits or 128 bits,192bits
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}

private static byte[] encrypt(byte[] key, byte[] src) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(src);
return encrypted;
}

private static byte[] decrypt(byte[] key, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}

public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}

public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}

public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}

测试类

public class MainActivity extends Activity{

private EditText user;
private EditText psw;
private Button bt;
private SharedPreferences sharedPreferences;
private SharedPreferences.Editor editer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
user = (EditText)findViewById(R.id.user1);
psw = (EditText)findViewById(R.id.psw1);
bt = (Button) findViewById(R.id.bt);

//使用私有的方式存储和读取数据
sharedPreferences = getSharedPreferences("test", Context.MODE_PRIVATE);
//使文件处于可编辑状态
editer = sharedPreferences.edit();
//读取数据
user.setText(sharedPreferences.getString("user",""));
if(!sharedPreferences.getString("psw","").isEmpty())
try {
psw.setText(AESEncryptor.decrypt("1111", sharedPreferences.getString("psw","")) );
} catch (Exception e) {
psw.setText("");
}
//点击进行存储
bt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//写入数据
editer.putString("user",user.getText().toString());
try {
editer.putString("psw", AESEncryptor.encrypt("1111",user.getText().toString())) ;
} catch (Exception e) {
e.printStackTrace();
}
editer.commit();//进行保存操作
}
});
}
}