7、Android AES加密

1、AES加密工具类

java不支持PKCS7Padding，只支持PKCS5Padding。我们知道加密算法由算法+模式+填充组成，下一篇介绍iOS和Android通用的AES加密，本篇文章使用PKCS5Padding加密方式。

package com.example.aesdemo;

import java.io.UnsupportedEncodingException;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

///** AES对称加密解密类 **/
public class AESHelper {

//  /** 算法/模式/填充 **/
private static final String CipherMode = "AES/ECB/PKCS5Padding";

///** 创建密钥 **/
private static SecretKeySpec createKey(String password) {
byte[] data = null;
if (password == null) {
password = "";
}
StringBuffer sb = new StringBuffer(32);
sb.append(password);
while (sb.length() < 32) {
sb.append("0");
}
if (sb.length() > 32) {
sb.setLength(32);
}

try {
data = sb.toString().getBytes("UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return new SecretKeySpec(data, "AES");
}

// /** 加密字节数据 **/
public static byte[] encrypt(byte[] content, String password) {
try {
SecretKeySpec key = createKey(password);
System.out.println(key);
Cipher cipher = Cipher.getInstance(CipherMode);
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] result = cipher.doFinal(content);
return result;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

///** 加密(结果为16进制字符串) **/
public static String encrypt(String content, String password) {
byte[] data = null;
try {
data = content.getBytes("UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
data = encrypt(data, password);
String result = byte2hex(data);
return result;
}

//  /** 解密字节数组 **/
public static byte[] decrypt(byte[] content, String password) {
try {
SecretKeySpec key = createKey(password);
Cipher cipher = Cipher.getInstance(CipherMode);
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] result = cipher.doFinal(content);
return result;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

///** 解密16进制的字符串为字符串 **/
public static String decrypt(String content, String password) {
byte[] data = null;
try {
data = hex2byte(content);
} catch (Exception e) {
e.printStackTrace();
}
data = decrypt(data, password);
if (data == null)
return null;
String result = null;
try {
result = new String(data, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return result;
}

// /** 字节数组转成16进制字符串 **/
public static String byte2hex(byte[] b) { // 一个字节的数，
StringBuffer sb = new StringBuffer(b.length * 2);
String tmp = "";
for (int n = 0; n < b.length; n++) {
// 整数转成十六进制表示
tmp = (java.lang.Integer.toHexString(b
& 0XFF));
if (tmp.length() == 1) {
sb.append("0");
}
sb.append(tmp);
}
return sb.toString().toUpperCase(); // 转成大写
}

//  /** 将hex字符串转换成字节数组 **/
private static byte[] hex2byte(String inputString) {
if (inputString == null || inputString.length() < 2) {
return new byte[0];
}
inputString = inputString.toLowerCase();
int l = inputString.length() / 2;
byte[] result = new byte[l];
for (int i = 0; i < l; ++i) {
String tmp = inputString.substring(2 * i, 2 * i + 2);
result[i] = (byte) (Integer.parseInt(tmp, 16) & 0xFF);
}
return result;
}
}

2、使用

新建Android工程

package com.example.aesdemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.util.Log;

public class MainActivity extends Activity {

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

String masterPassword = "a";
String originalText = "于";

try {
String encryptingCode = AESHelper.encrypt(originalText,masterPassword);
//	          System.out.println("加密结果为 " + encryptingCode);
Log.i("加密结果为 ",encryptingCode);
String decryptingCode = AESHelper.decrypt(encryptingCode,masterPassword);
//	            System.out.println("解密结果为 " + decryptingCode);
Log.i("解密结果",decryptingCode);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

3、打印结果

09-19 10:41:05.467: I/加密结果为(707): E55C24701F6380478E1940ADDFD08D22
09-19 10:41:05.467: I/解密结果(707): 于