Java之——实现微信小程序加密数据解密算法

一、概述

微信推出了小程序，很多公司的客户端应用不仅具有了APP、H5、还接入了小程序开发。但是，小程序中竟然没有提供Java版本的加密数据解密算法。这着实让广大的Java开发人员蛋疼。

二、实现Java版本的微信小程序加密数据解密算法

1、创建项目

这里，我们创建一个Maven工程，具体创建步骤略。

2、配置pom.xml

我们在pom.xml中加入如下配置。

<dependency> <groupId>org.bouncycastle</groupId> <artifactId>bcprov-jdk16</artifactId> <version>1.46</version> </dependency> <dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.4</version> </dependency> <dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.2.3</version> <classifier>jdk15</classifier> </dependency>

3、实现AES类

package com.chwl.medical.crypto.wx; import java.security.AlgorithmParameters; import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import java.security.Key; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.Security; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import org.bouncycastle.jce.provider.BouncyCastleProvider; /** * AES加密 * @author liuyazhuang * */ public class AES { public static boolean initialized = false; /** * AES解密 * * @param content * 密文 * @return * @throws InvalidAlgorithmParameterException * @throws NoSuchProviderException */ public byte[] decrypt(byte[] content, byte[] keyByte, byte[] ivByte) throws InvalidAlgorithmParameterException { initialize(); try { Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); Key sKeySpec = new SecretKeySpec(keyByte, "AES"); cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化 byte[] result = cipher.doFinal(content); return result; } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } catch (NoSuchProviderException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } public static void initialize() { if (initialized) return; Security.addProvider(new BouncyCastleProvider()); initialized = true; } // 生成iv public static AlgorithmParameters generateIV(byte[] iv) throws Exception { AlgorithmParameters params = AlgorithmParameters.getInstance("AES"); params.init(new IvParameterSpec(iv)); return params; } }

4、实现WxPKCS7Encoder类

package com.chwl.medical.crypto.wx; import java.nio.charset.Charset; import java.util.Arrays; /** * 微信小程序加解密 * @author liuyazhuang * */ public class WxPKCS7Encoder { private static final Charset CHARSET = Charset.forName("utf-8"); private static final int BLOCK_SIZE = 32; /** * 获得对明文进行补位填充的字节. * * @param count * 需要进行填充补位操作的明文字节个数 * @return 补齐用的字节数组 */ public static byte[] encode(int count) { // 计算需要填充的位数 int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE); if (amountToPad == 0) { amountToPad = BLOCK_SIZE; } // 获得补位所用的字符 char padChr = chr(amountToPad); String tmp = new String(); for (int index = 0; index < amountToPad; index++) { tmp += padChr; } return tmp.getBytes(CHARSET); } /** * 删除解密后明文的补位字符 * * @param decrypted * 解密后的明文 * @return 删除补位字符后的明文 */ public static byte[] decode(byte[] decrypted) { int pad = decrypted[decrypted.length - 1]; if (pad < 1 || pad > 32) { pad = 0; } return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad); } /** * 将数字转化成ASCII码对应的字符，用于对明文进行补码 * * @param a * 需要转化的数字 * @return 转化得到的字符 */ public static char chr(int a) { byte target = (byte) (a & 0xFF); return (char) target; } }

5、实现WXCore类

这个类主要是对具体算法的封装，统一对外提供方法。

package com.chwl.medical.crypto.wx; import org.apache.commons.codec.binary.Base64; import net.sf.json.JSONObject;

/** * 封装对外访问方法 * @author liuyazhuang * */ public class WXCore { private static final String WATERMARK = "watermark"; private static final String APPID = "appid"; /** * 解密数据 * @return * @throws Exception */ public static String decrypt(String appId, String encryptedData, String sessionKey, String iv){ String result = ""; try { AES aes = new AES(); byte[] resultByte = aes.decrypt(Base64.decodeBase64(encryptedData), Base64.decodeBase64(sessionKey), Base64.decodeBase64(iv)); if(null != resultByte && resultByte.length > 0){ result = new String(WxPKCS7Encoder.decode(resultByte)); JSONObject jsonObject = JSONObject.fromObject(result); String decryptAppid = jsonObject.getJSONObject(WATERMARK).getString(APPID); if(!appId.equals(decryptAppid)){ result = ""; } } } catch (Exception e) { result = ""; e.printStackTrace(); } return result; } public static void main(String[] args) throws Exception{ String appId = "wx4f4bc4dec97d474b"; String encryptedData = "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"; String sessionKey = "tiihtNczf5v6AKRyjwEUhQ=="; String iv = "r7BXXKkLb8qrSNn05n0qiA=="; System.out.println(decrypt(appId, encryptedData, sessionKey, iv)); } }

三、测试

1、运行Java版微信小程序加密数据解密算法

这里我们就直接运行WXcore类的main方法，这里的测试数据都是从Python版微信小程序加密数据解密算法的示例程序中提出来的。我们的运行结果如下：

{"openId":"oGZUI0egBJY1zhBYw2KhdUfwVJJE","nickName":"Band","gender":1,"language":"zh_CN","city":"Guangzhou","province":"Guangdong","country":"CN","avatarUrl":"http://wx.qlogo.cn/mmopen/vi_32/aSKcBBPpibyKNicHNTMM0qJVh8Kjgiak2AHWr8MHM4WgMEm7GFhsf8OYrySdbvAMvTsw3mo8ibKicsnfN5pRjl1p8HQ/0","unionId":"ocMvos6NjeKLIBqg5Mr9QjxrP1FA","watermark":{"timestamp":1477314187,"appid":"wx4f4bc4dec97d474b"}

2、运行Python版微信小程序加密数据解密算法

这里我们在python环境中直接运行微信官方提供的Python版小程序加密数据解密算法，结果如下：

{u'province': u'Guangdong', u'openId': u'oGZUI0egBJY1zhBYw2KhdUfwVJJE', u'language': u'zh_CN', u'city': u'Guangzhou', u'gender': 1, u'avatarUrl': u'http://wx.qlogo.cn/mmopen/vi_32/aSKcBBPpibyKNicHNTMM0qJVh8Kjgiak2AHWr8MHM4WgMEm7GFhsf8OYrySdbvAMvTsw3mo8ibKicsnfN5pRjl1p8HQ/0', u'watermark': {u'timestamp': 1477314187, u'appid': u'wx4f4bc4dec97d474b'}, u'country': u'CN', u'nickName': u'Band', u'unionId': u'ocMvos6NjeKLIBqg5Mr9QjxrP1FA'}

通过对比以上结果可知，我们自行使用Java实现的Java版微信小程序加密数据解密算法与微信官方提供的Python版小程序加密数据解密算法结果一致。