WeChatDecryptUtils.java

package com.boco.nbd.wios.wx.utils;

import com.boco.nbd.cams.core.constant.CamsConstant;
import com.ihidea.component.pay.ail.Base64;
import com.ihidea.core.util.JSONUtilsEx;
import com.ihidea.core.util.StringUtilsEx;
import org.apache.commons.lang.StringUtils;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.AlgorithmParameters;
import java.security.Security;
import java.util.Arrays;
import java.util.Map;

/**
 * 微信解密工具类
 *
 * @author lvpeng
 * @version [版本号]
 * @date  2017年11月6日
 */
public class WeChatDecryptUtils {

	private static final Logger logger = LoggerFactory.getLogger(WeChatDecryptUtils.class);

	 public static Map<String, Object> decode(String sessionKey, String encryptedData, String iv) {

	        //转义字符处理
	        encryptedData = StringUtilsEx.unescapeXss(encryptedData);
	        iv = StringUtilsEx.unescapeXss(iv);
	        sessionKey = StringUtilsEx.unescapeXss(sessionKey);
	        byte[] decrypted = decrypt(sessionKey, encryptedData, iv);
	        if (null != decrypted && decrypted.length > 0) {
	            String jsonStr = new String(decodeForWxPKCS7(decrypted));
	            if (StringUtils.isNotBlank(jsonStr)) {
	                return JSONUtilsEx.deserialize(jsonStr, Map.class);
	            }
	        }
	        return null;
	    }


	 /**
	     * AES解密
	     *
	     * @author lvpeng
	     * @date 2017年9月7日
	     * @param sessionKey    密钥
	     * @param encryptedData 加密内容
	     * @param iv 加密算法的偏移量
	     * @return
	     */
	    public static byte[] decrypt(String sessionKey, String encryptedData, String iv) {
//	    	  logger.error("sessionKey:{},encryptedData:{},iv:{}", new String[]{sessionKey, encryptedData, iv});
	        byte[] aesKey = Base64.decode(sessionKey);
	        byte[] aesData = Base64.decode(encryptedData);
	        byte[] aesIv = Base64.decode(iv);
	        Security.addProvider(new BouncyCastleProvider());
	        try {
	            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
	            SecretKeySpec keyspec = new SecretKeySpec(aesKey, "AES");
	            IvParameterSpec ivspec = new IvParameterSpec(aesIv);
	            cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
	            byte[] original = cipher.doFinal(aesData);
	            return original;
	        } catch (Exception e) {
	            logger.error("解密失败");
	            return null;
	        }
	    }

	    /**
	     * 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
	     */
	    private static byte[] decodeForWxPKCS7(byte[] decrypted) {
	        int pad = decrypted[decrypted.length - 1];
	        if (pad < 1 || pad > 32) {
	            pad = 0;
	        }
	        return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad);
	    }

	    /**
	     * 解密微信用户数据
	     * @param sessionkey
	     * @param encryptedData
	     * @param iv
	     * @return
	     */
	    @SuppressWarnings("unchecked")
		public static String decryptWxUser(String sessionkey, String encryptedData, String iv) {
	    	if(StringUtils.isEmpty(sessionkey) || StringUtils.isEmpty(encryptedData) || StringUtils.isEmpty(iv)){
	    		return null;
	    	}
	        // 被加密的数据
	        byte[] dataByte = Base64.decode(encryptedData);
	        // 加密秘钥
	        byte[] keyByte = Base64.decode(sessionkey);
	        // 偏移量
	        byte[] ivByte = Base64.decode(iv);
	        try {
	               // 如果密钥不足16位,那么就补足.  这个if 中的内容很重要
	            int base = 16;
	            if (keyByte.length % base != 0) {
	                int groups = keyByte.length / base + (keyByte.length % base != 0 ? 1 : 0);
	                byte[] temp = new byte[groups * base];
	                Arrays.fill(temp, (byte) 0);
	                System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
	                keyByte = temp;
	            }
	            // 初始化
	            Security.addProvider(new BouncyCastleProvider());
	            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding","BC");
	            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
	            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
	            parameters.init(new IvParameterSpec(ivByte));
	            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
	            byte[] resultByte = cipher.doFinal(dataByte);
	            if (null != resultByte && resultByte.length > 0) {
	                String result = new String(resultByte, StandardCharsets.UTF_8);
	                Map<String, String> resultMap = JSONUtilsEx.deserialize(result, Map.class);
	                return resultMap!=null && resultMap.get("purePhoneNumber")!=null? resultMap.get("purePhoneNumber") : null;
	            }
	        } catch (Exception e) {
	            e.printStackTrace();
	        }
	        return null;
	    }
}