微信公众平台安全模式下传输xml数据包时解密方式

前言：

最近一直在搞微信服务（公众）号开发，前面也写过一篇文章，是关于一开始配置、验证token以及接收用户触发关注/取消关注事件时的接口，文章地址：java实现微信服务（公众）号用户关注时，获取openid，安全模式下的加密解密实现

今天将加密解密的工具类汇总整理一下发出来，记录一下。

加密/解密工具类

/**
 * 对公众平台发送给公众账号的消息加解密示例代码.
 * 
 * @copyright Copyright (c) 1998-2014 Tencent Inc.
 */

// ------------------------------------------------------------------------

/**
 * 针对org.apache.commons.codec.binary.Base64，
 * 需要导入架包commons-codec-1.9（或commons-codec-1.8等其他版本）
 * 官方下载地址：http://commons.apache.org/proper/commons-codec/download_codec.cgi
 */
package org.jeecg.modules.utils;

import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

/**
 * 提供接收和推送给公众平台消息的加解密接口(UTF8编码的字符串).
 * <ol>
 *     <li>第三方回复加密消息给公众平台</li>
 *     <li>第三方收到公众平台发送的消息，验证消息的安全性，并对消息进行解密。</li>
 * </ol>
 * 说明：异常java.security.InvalidKeyException:illegal Key Size的解决方案
 * <ol>
 *     <li>在官方网站下载JCE无限制权限策略文件（JDK7的下载地址：
 *      http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html</li>
 *     <li>下载后解压，可以看到local_policy.jar和US_export_policy.jar以及readme.txt</li>
 *     <li>如果安装了JRE，将两个jar文件放到%JRE_HOME%\lib\security目录下覆盖原来的文件</li>
 *     <li>如果安装了JDK，将两个jar文件放到%JDK_HOME%\jre\lib\security目录下覆盖原来文件</li>
 * </ol>
 */
public class WXBizMsgCrypt {
    static Charset CHARSET = Charset.forName("utf-8");
    Base64 base64 = new Base64();
    byte[] aesKey;
    String token;
    String appId;

    /**
     * 构造函数
     * @param token 公众平台上，开发者设置的token
     * @param encodingAesKey 公众平台上，开发者设置的EncodingAESKey
     * @param appId 公众平台appid
     * 
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public WXBizMsgCrypt(String token, String encodingAesKey, String appId) throws AesException {
        if (encodingAesKey.length() != 43) {
            throw new AesException(AesException.IllegalAesKey);
        }

        this.token = token;
        this.appId = appId;
        aesKey = Base64.decodeBase64(encodingAesKey + "=");
    }

    // 生成4个字节的网络字节序
    byte[] getNetworkBytesOrder(int sourceNumber) {
        byte[] orderBytes = new byte[4];
        orderBytes[3] = (byte) (sourceNumber & 0xFF);
        orderBytes[2] = (byte) (sourceNumber >> 8 & 0xFF);
        orderBytes[1] = (byte) (sourceNumber >> 16 & 0xFF);
        orderBytes[0] = (byte) (sourceNumber >> 24 & 0xFF);
        return orderBytes;
    }

    // 还原4个字节的网络字节序
    int recoverNetworkBytesOrder(byte[] orderBytes) {
        int sourceNumber = 0;
        for (int i = 0; i < 4; i++) {
            sourceNumber <<= 8;
            sourceNumber |= orderBytes[i] & 0xff;
        }
        return sourceNumber;
    }

    // 随机生成16位字符串
    String getRandomStr() {
        String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 16; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }

    /**
     * 对明文进行加密.
     * 
     * @param text 需要加密的明文
     * @return 加密后base64编码的字符串
     * @throws AesException aes加密失败
     */
    String encrypt(String randomStr, String text) throws AesException {
        ByteGroup byteCollector = new ByteGroup();
        byte[] randomStrBytes = randomStr.getBytes(CHARSET);
        byte[] textBytes = text.getBytes(CHARSET);
        byte[] networkBytesOrder = getNetworkBytesOrder(textBytes.length);
        byte[] appidBytes = appId.getBytes(CHARSET);

        // randomStr + networkBytesOrder + text + appid
        byteCollector.addBytes(randomStrBytes);
        byteCollector.addBytes(networkBytesOrder);
        byteCollector.addBytes(textBytes);
        byteCollector.addBytes(appidBytes);

        // ... + pad: 使用自定义的填充方式对明文进行补位填充
        byte[] padBytes = PKCS7Encoder.encode(byteCollector.size());
        byteCollector.addBytes(padBytes);

        // 获得最终的字节流, 未加密
        byte[] unencrypted = byteCollector.toBytes();

        try {
            // 设置加密模式为AES的CBC模式
            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            SecretKeySpec keySpec = new SecretKeySpec(aesKey, "AES");
            IvParameterSpec iv = new IvParameterSpec(aesKey, 0, 16);
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, iv);

            // 加密
            byte[] encrypted = cipher.doFinal(unencrypted);

            // 使用BASE64对加密后的字符串进行编码
            String base64Encrypted = base64.encodeToString(encrypted);

            return base64Encrypted;
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.EncryptAESError);
        }
    }

    /**
     * 对密文进行解密.
     * 
     * @param text 需要解密的密文
     * @return 解密得到的明文
     * @throws AesException aes解密失败
     */
    String decrypt(String text) throws AesException {
        byte[] original;
        try {
            // 设置解密模式为AES的CBC模式
            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            SecretKeySpec key_spec = new SecretKeySpec(aesKey, "AES");
            IvParameterSpec iv = new IvParameterSpec(Arrays.copyOfRange(aesKey, 0, 16));
            cipher.init(Cipher.DECRYPT_MODE, key_spec, iv);

            // 使用BASE64对密文进行解码
            byte[] encrypted = Base64.decodeBase64(text);

            // 解密
            original = cipher.doFinal(encrypted);
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.DecryptAESError);
        }

        String xmlContent, from_appid;
        try {
            // 去除补位字符
            byte[] bytes = PKCS7Encoder.decode(original);

            // 分离16位随机字符串,网络字节序和AppId
            byte[] networkOrder = Arrays.copyOfRange(bytes, 16, 20);

            int xmlLength = recoverNetworkBytesOrder(networkOrder);

            xmlContent = new String(Arrays.copyOfRange(bytes, 20, 20 + xmlLength), CHARSET);
            from_appid = new String(Arrays.copyOfRange(bytes, 20 + xmlLength, bytes.length),
                    CHARSET);
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.IllegalBuffer);
        }

        // appid不相同的情况
        if (!from_appid.equals(appId)) {
            throw new AesException(AesException.ValidateAppidError);
        }
        return xmlContent;

    }

    /**
     * 将公众平台回复用户的消息加密打包.
     * <ol>
     *     <li>对要发送的消息进行AES-CBC加密</li>
     *     <li>生成安全签名</li>
     *     <li>将消息密文和安全签名打包成xml格式</li>
     * </ol>
     * 
     * @param replyMsg 公众平台待回复用户的消息，xml格式的字符串
     * @param timeStamp 时间戳，可以自己生成，也可以用URL参数的timestamp
     * @param nonce 随机串，可以自己生成，也可以用URL参数的nonce
     * 
     * @return 加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String encryptMsg(String replyMsg, String timeStamp, String nonce) throws AesException {
        // 加密
        String encrypt = encrypt(getRandomStr(), replyMsg);

        // 生成安全签名
        if (timeStamp == "") {
            timeStamp = Long.toString(System.currentTimeMillis());
        }

        String signature = SHA1.getSHA1(token, timeStamp, nonce, encrypt);

        // System.out.println("发送给平台的签名是: " + signature[1].toString());
        // 生成发送的xml
        String result = XMLParse.generate(encrypt, signature, timeStamp, nonce);
        return result;
    }

    /**
     * 检验消息的真实性，并且获取解密后的明文.
     * <ol>
     *     <li>利用收到的密文生成安全签名，进行签名验证</li>
     *     <li>若验证通过，则提取xml中的加密消息</li>
     *     <li>对消息进行解密</li>
     * </ol>
     * 
     * @param msgSignature 签名串，对应URL参数的msg_signature
     * @param timeStamp 时间戳，对应URL参数的timestamp
     * @param nonce 随机串，对应URL参数的nonce
     * @param postData 密文，对应POST请求的数据
     * 
     * @return 解密后的原文
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String decryptMsg(String msgSignature, String timeStamp, String nonce, String postData)
            throws AesException {

        // 密钥，公众账号的app secret
        // 提取密文
        Object[] encrypt = XMLParse.extract(postData);

        // 验证安全签名
        String signature = SHA1.getSHA1(token, timeStamp, nonce, encrypt[1].toString());

        // 和URL中的签名比较是否相等
        // System.out.println("第三方收到URL中的签名：" + msg_sign);
        // System.out.println("第三方校验签名：" + signature);
        if (!signature.equals(msgSignature)) {
            throw new AesException(AesException.ValidateSignatureError);
        }

        // 解密
        String result = decrypt(encrypt[1].toString());
        return result;
    }

    /**
     * 验证URL
     * @param msgSignature 签名串，对应URL参数的msg_signature
     * @param timeStamp 时间戳，对应URL参数的timestamp
     * @param nonce 随机串，对应URL参数的nonce
     * @param echoStr 随机串，对应URL参数的echostr
     * 
     * @return 解密之后的echostr
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String verifyUrl(String msgSignature, String timeStamp, String nonce, String echoStr)
            throws AesException {
        String signature = SHA1.getSHA1(token, timeStamp, nonce, echoStr);

        if (!signature.equals(msgSignature)) {
            throw new AesException(AesException.ValidateSignatureError);
        }

        String result = decrypt(echoStr);
        return result;
    }

}

官方提供的测试类：

package org.jeecg.modules.utils;

import static org.junit.Assert.*;

import java.io.IOException;
import java.io.StringReader;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;


import org.junit.*;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class WXBizMsgCryptTest {
    String encodingAesKey = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFG";
    String tokeN = "";
    String timestamp = "1409304348";
    String nonce = "xxxxxx";
    String appId = "wxb11529c136998cb6";
    String replyMsg = "我是中文abcd123";
    String xmlFormat = "<xml><><![CDATA[toUser]]></ToUserName><Encrypt><![CDATA[%1$s]]></Encrypt></xml>";
    String afterAesEncrypt = "jn1L23DB+6ELqJ++3bnyg5K55bgVtVzd832WzZGMhkP72vVOfg==";
    String randomStr = "aaaabbbbccccdddd";

    String replyMsg2 = "<xml><ToUserName><![CDATA[oia2Tj我是中文jewbmiOUlr6X-1crbLOvLw]]></ToUserName><FromUserName><![CDATA[gh_7f083739789a]]></FromUserName><CreateTime>1407743423</CreateTime><MsgType><![CDATA[video]]></MsgType><Video><MediaId><![CDATA[eYJ1MbwPRJtOvIEabaxHs7TX2D-HV71s79GUxqdUkjm6Gs2Ed1KF3ulAOA9H1xG0]]></MediaId><Title><![CDATA[testCallBackReplyVideo]]></Title><Description><![CDATA[testCallBackReplyVideo]]></Description></Video></xml>";
    String afterAesEncrypt2 = "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";

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
    }

    @Before
    public void setUp() throws Exception {

    }

    @After
    public void tearDown() throws Exception {
    }

    @Test
    public void testNormal() throws ParserConfigurationException, SAXException, IOException {
        try {
            WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
            String afterEncrpt = pc.encryptMsg(replyMsg, timestamp, nonce);

            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            StringReader sr = new StringReader(afterEncrpt);
            InputSource is = new InputSource(sr);
            Document document = db.parse(is);

            Element root = document.getDocumentElement();
            NodeList nodelist1 = root.getElementsByTagName("Encrypt");
            NodeList nodelist2 = root.getElementsByTagName("MsgSignature");

            String encrypt = nodelist1.item(0).getTextContent();
            String msgSignature = nodelist2.item(0).getTextContent();
            String fromXML = String.format(xmlFormat, encrypt);

            // 第三方收到公众号平台发送的消息
            String afterDecrpt = pc.decryptMsg(msgSignature, timestamp, nonce, fromXML);
            assertEquals(replyMsg, afterDecrpt);
        } catch (AesException e) {
            fail("正常流程，怎么就抛出异常了？？？？？？");
        }
    }

    @Test
    public void testAesEncrypt() {
        try {
            WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
            assertEquals(afterAesEncrypt, pc.encrypt(randomStr, replyMsg));
        } catch (AesException e) {
            e.printStackTrace();
            fail("no异常");
        }
    }

    @Test
    public void testAesEncrypt2() {
        try {
            WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
            assertEquals(afterAesEncrypt2, pc.encrypt(randomStr, replyMsg2));

        } catch (AesException e) {
            e.printStackTrace();
            fail("no异常");
        }
    }

    @Test
    public void testIllegalAesKey() {
        try {
            new WXBizMsgCrypt(token, "abcde", appId);
        } catch (AesException e) {
            assertEquals(AesException.IllegalAesKey, e.getCode());
            return;
        }
        fail("错误流程不抛出异常？？？");
    }

    @Test
    public void testValidateSignatureError() throws ParserConfigurationException, SAXException,
            IOException {
        try {
            WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
            String afterEncrpt = pc.encryptMsg(replyMsg, timestamp, nonce);
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            StringReader sr = new StringReader(afterEncrpt);
            InputSource is = new InputSource(sr);
            Document document = db.parse(is);

            Element root = document.getDocumentElement();
            NodeList nodelist1 = root.getElementsByTagName("Encrypt");

            String encrypt = nodelist1.item(0).getTextContent();
            String fromXML = String.format(xmlFormat, encrypt);
            pc.decryptMsg("12345", timestamp, nonce, fromXML); // 这里签名错误
        } catch (AesException e) {
            assertEquals(AesException.ValidateSignatureError, e.getCode());
            return;
        }
        fail("错误流程不抛出异常？？？");
    }

    @Test
    public void testVerifyUrl() throws AesException {
        WXBizMsgCrypt wxcpt = new WXBizMsgCrypt("QDG6eK",
                "jWmYm7qr5nMoAUwZRjGtBxmz3KA1tkAj3ykkR6q2B2C", "wx5823bf96d3bd56c7");
        String verifyMsgSig = "5c45ff5e21c57e6ad56bac8758b79b1d9ac89fd3";
        String timeStamp = "1409659589";
        String nonce = "263014780";
        String echoStr = "P9nAzCzyDtyTWESHep1vC5X9xho/qYX3Zpb4yKa9SKld1DsH3Iyt3tP3zNdtp+4RPcs8TgAE7OaBO+FZXvnaqQ==";
        wxcpt.verifyUrl(verifyMsgSig, timeStamp, nonce, echoStr);
        // 只要不抛出异常就好
    }
}

我的解密测试

这个是我写的解密测试类，其实也差不多，只是我为了后面维护方便，将共用的信息提取到了常量类中：

package org.jeecg.modules.utils;

import org.jeecg.modules.config.WeChatContant;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.StringReader;

/**
 * @author: muxiongxiong
 * @date: 2022年08月17日 下午 9:21
 * 公众号：雄雄的小课堂
 * 博客：https://blog.csdn.net/qq_34137397
 * 个人站：http://www.穆雄雄.com
 * 个人站：http://www.muxiongxiong.cn
 * @Description: 官方提供的加解密demo类
 */
public class Program {
    // 需要加密的明文
    String encodingAesKey = WeChatContant.ENCODINGAESKEY;
    String token = WeChatContant.TOKEN;
    String timestamp = "1409304348";
    String nonce = "xxxxxx";
    String appId = WeChatContant.APPID;

    /**
     * main方法
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        Program program = new Program();
        program.decode();
    }

    /**
     * 解密测试
     */
    public  void decode() throws AesException {
        //构造函数
        WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
        String miwen = "5Fhy9chrfcshHmeCrAKLBZmJdYWm1RwDNYOyCfbVC6L1MUAUto5xOimdotgLBSCKRyt+yys+o+5aO0nRdO4XfS9CAhYK50NeO6O/M8woX0fanUn/DjYGJV4Mm/Zfg7KmpkXXxwguo5RJrYweglVOHZ96tLWZppAA5/LDl26YF2TmaBWAwPZU1n8R1Wg8jCaSolXBOYZ90lE3854n/+GV27xtpNy1+a+lPs5YPmyauL6wCCU2g2H71g4iYyz4ifi1afxmZsI6vkmKv0sncQMfkOYgX7g0pOZaQ/rnwjmnGfFpmY3DJe7ufmSyd+LA/5r93PIW0vW7j/Bf7xbw77ElrSghvA/Ro6U+xEZHNF3ZUqb5ce1P+62qPakC0r23RlJfMhTVF1yqKL0W/fM1pNbCfJC7KBX9IHja9bxPuN7QiWs=";
        String jiemi = pc.decrypt(miwen);
        System.out.println("解密后的内容是："+jiemi);

    }


    /**
     * 官方提供的示例代码
     * @throws Exception
     */
    public  void authorityDemo() throws Exception{

        String replyMsg = " 中文<xml><ToUserName><![CDATA[oia2TjjewbmiOUlr6X-1crbLOvLw]]></ToUserName><FromUserName><![CDATA[gh_7f083739789a]]></FromUserName><CreateTime>1407743423</CreateTime><MsgType><![CDATA[video]]></MsgType><Video><MediaId><![CDATA[eYJ1MbwPRJtOvIEabaxHs7TX2D-HV71s79GUxqdUkjm6Gs2Ed1KF3ulAOA9H1xG0]]></MediaId><Title><![CDATA[testCallBackReplyVideo]]></Title><Description><![CDATA[testCallBackReplyVideo]]></Description></Video></xml>";
        //构造函数
        WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);
        String mingwen = pc.encryptMsg(replyMsg, timestamp, nonce);
        System.out.println("加密后: " + mingwen);

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
        dbf.setFeature("http://xml.org/sax/features/external-general-entities", false);
        dbf.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
        dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
        dbf.setXIncludeAware(false);
        dbf.setExpandEntityReferences(false);

        DocumentBuilder db = dbf.newDocumentBuilder();
        StringReader sr = new StringReader(mingwen);
        InputSource is = new InputSource(sr);
        Document document = db.parse(is);

        Element root = document.getDocumentElement();
        NodeList nodelist1 = root.getElementsByTagName("Encrypt");
        NodeList nodelist2 = root.getElementsByTagName("MsgSignature");

        String encrypt = nodelist1.item(0).getTextContent();
        String msgSignature = nodelist2.item(0).getTextContent();

        String format = "<xml><ToUserName><![CDATA[toUser]]></ToUserName><Encrypt><![CDATA[%1$s]]></Encrypt></xml>";
        String fromXML = String.format(format, encrypt);

        //
        // 公众平台发送消息给第三方，第三方处理
        //

        // 第三方收到公众号平台发送的消息
        String result2 = pc.decryptMsg(msgSignature, timestamp, nonce, fromXML);
        System.out.println("解密后明文: " + result2);

        //pc.verifyUrl(null, null, null, null);
    }





}

然后就可以了。