android中AES加解密的使用方法

今天在android项目中使用AES对数据进行加解密，遇到了很多问题，网上也找了很多资料，也不行。不过最后还是让我给搞出来了，这里把这个记录下来，不要让别人走我的弯路，因为网上绝大多数的例子都是行不通的。好了，接下来开始讲解

1、Aes工具类

package com.example.cheng.aesencrypt;
import android.text.TextUtils;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class Aes {
 private static final String SHA1PRNG = "SHA1PRNG"; // SHA1PRNG 强随机种子算法, 要区别4.2以上版本的调用方法
 private static final String IV = "qws871bz73msl9x8";
 private static final String AES = "AES"; //AES 加密
 private static final String CIPHERMODE = "AES/CBC/PKCS5Padding"; //algorithm/mode/padding
 
 public static String encrypt(String key, String cleartext) {
 if (TextUtils.isEmpty(cleartext)) {
  return cleartext;
 }
 try {
  byte[] result = encrypt(key, cleartext.getBytes());
  return parseByte2HexStr(result);
 } catch (Exception e) {
  e.printStackTrace();
 }
 return null;
 }
 
 public static byte[] encrypt(String key, byte[] clear) throws Exception {
 byte[] raw = getRawKey(key.getBytes());
 SecretKeySpec skeySpec = new SecretKeySpec(raw, AES);
 Cipher cipher = Cipher.getInstance(CIPHERMODE);
 cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()]));
 byte[] encrypted = cipher.doFinal(clear);
 return encrypted;
 }
 
 public static String decrypt(String key, String encrypted) {
 if (TextUtils.isEmpty(encrypted)) {
  return encrypted;
 }
 try {
  byte[] enc = parseHexStr2Byte(encrypted);
  byte[] result = decrypt(key, enc);
  return new String(result);
 } catch (Exception e) {
  e.printStackTrace();
 }
 return null;
 }
 
 public static byte[] decrypt(String key, byte[] encrypted) throws Exception {
 byte[] raw = getRawKey(key.getBytes());
 SecretKeySpec skeySpec = new SecretKeySpec(raw, AES);
 Cipher cipher = Cipher.getInstance(CIPHERMODE);
 cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()]));
 byte[] decrypted = cipher.doFinal(encrypted);
 return decrypted;
 }
 
 public static String generateKey() {
 try {
  SecureRandom secureRandom = SecureRandom.getInstance(SHA1PRNG);
  byte[] key = new byte[20];
  secureRandom.nextBytes(key);
  return toHex(key);
 } catch (NoSuchAlgorithmException e) {
  e.printStackTrace();
 }
 return null;
 }
 
 public static byte[] getRawKey(byte[] seed) throws Exception {
 KeyGenerator kgen = KeyGenerator.getInstance(AES);
 //for android
 SecureRandom sr = null;
 // 在4.2以上版本中，SecureRandom获取方式发生了改变
 if (android.os.Build.VERSION.SDK_INT >= 17) {
  sr = SecureRandom.getInstance(SHA1PRNG, "Crypto");
 } else {
  sr = SecureRandom.getInstance(SHA1PRNG);
 }
 // for Java
 // secureRandom = SecureRandom.getInstance(SHA1PRNG);
 sr.setSeed(seed);
 kgen.init(128, sr); //256 bits or 128 bits,192bits
 //AES中128位密钥版本有10个加密循环，192比特密钥版本有12个加密循环，256比特密钥版本则有14个加密循环。
 SecretKey skey = kgen.generateKey();
 byte[] raw = skey.getEncoded();
 return raw;
 }
 
 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 static void appendHex(StringBuffer sb, byte b) {
 sb.append(IV.charAt((b >> 4) & 0x0f)).append(IV.charAt(b & 0x0f));
 }
 
 public static String parseByte2HexStr(byte buf[]) {
 StringBuilder sb = new StringBuilder();
 for (int i = 0; i < buf.length; i++) {
  String hex = Integer.toHexString(buf[i] & 0xFF);
  if (hex.length() == 1) {
  hex = '0' + hex;
  }
  sb.append(hex.toUpperCase());
 }
 return sb.toString();
 }
 
 public static byte[] parseHexStr2Byte(String hexStr) {
 if (hexStr.length() < 1)
  return null;
 byte[] result = new byte[hexStr.length() / 2];
 for (int i = 0; i < hexStr.length() / 2; i++) {
  int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
  int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
   16);
  result[i] = (byte) (high * 16 + low);
 }
 return result;
 }
}

2、mainActivity和layout文件如下：

package com.example.cheng.aesencrypt;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
 private EditText mInputET;
 private TextView mShowEncryputTV;
 private TextView mShowInputTV;
 private static final String PASSWORD_STRING = "12345678";
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 mInputET = (EditText) findViewById(R.id.ase_input);
 mShowEncryputTV = (TextView) findViewById(R.id.show_oringe_encrypt);
 mShowInputTV = (TextView) findViewById(R.id.show_ase_encrypt);
 }
 
 public void encrypt(View view) {
 String inputString = mInputET.getText().toString().trim();
 if (inputString.length() == 0) {
  Toast.makeText(this, "请输入要加密的内容", Toast.LENGTH_SHORT).show();
  return;
 }
 String encryStr = Aes.encrypt(PASSWORD_STRING, inputString);
 mShowInputTV.setText(encryStr);
 }
 
 public void decrypt(View view) {
 String encryptString = mShowInputTV.getText().toString().trim();
 if (encryptString.length() == 0) {
  Toast.makeText(this, "解密字符串不能为空", Toast.LENGTH_SHORT).show();
  return;
 }
 String decryStr = Aes.decrypt(PASSWORD_STRING, encryptString);
 mShowEncryputTV.setText(decryStr);
 }
}

layout文件

<?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:id="@+id/activity_main"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:gravity="center_vertical"
 android:orientation="vertical"
 android:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin"
 tools:context="com.example.cheng.aesencrypt.MainActivity">
 <EditText
 android:id="@+id/ase_input"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:hint="输入要加密的内容" />
 <Button
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:onClick="encrypt"
 android:text="点击进行ASE加密" />
 <TextView
 android:id="@+id/show_ase_encrypt"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_marginTop="10dp"
 android:text="显示加密后的内容" />
 <Button
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:onClick="decrypt"
 android:text="点击进行ASE解密" />
 <TextView
 android:id="@+id/show_oringe_encrypt"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginTop="10dp"
 android:text="显示加密后的内容" />
</LinearLayout>

3、最后的效果如下：

1）、是一个输入框，输入钥加密的字符串；

2）、点击“AES加密”按钮后生产的加密字符串；

3）、点击“AES解密”按钮后，对加密字符串进行解密，然后在3处看到解密后的字符串，可以看到加密字符串和解密字符串相同，所以AES加解密成功了

4、总结

要用真机测试，模拟器是不行的，具体原因没去研究；
点击获取本例的github地址：
也可以通过android studio直接git下来，git地址为https://github.com/chenguo4930/AndroidAES.git
其中也还有DES、RSA的加解密demo的github地址为https://github.com/chenguo4930/EncodeDemo
git地址为： https://github.com/chenguo4930/EncodeDemo.git

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