Java之——实现微信小程序加密数据解密算法

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转载请注明出处：http://blog.csdn.net/l1028386804/article/details/79450115

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。

微信小程序提供的加密数据解密算法链接为：https://mp.weixin.qq.com/debug/wxadoc/dev/api/signature.html

我们下载的算法示例如下：

木有Java！！木有Java！！木有Java！！

那么如何解决这个问题，我们一起来实现Java版本的微信小程序加密数据解密算法。

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));
    }
}