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
            }
        });
    }
}