com.riversoft.weixin.common.decrypt.MessageDecryption Maven / Gradle / Ivy
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package com.riversoft.weixin.common.decrypt;
import org.apache.commons.codec.binary.Base64;
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.Charset;
import java.util.Arrays;
import java.util.Random;
/**
* Created by exizhai on 10/1/2015.
*/
public class MessageDecryption {
static Charset CHARSET = Charset.forName("utf-8");
private static Logger logger = LoggerFactory.getLogger(MessageDecryption.class);
Base64 base64 = new Base64();
byte[] aesKey;
String token;
String clientId;
/**
* 构造函数
*
* @param token 公众平台上，开发者设置的token
* @param aes 公众平台上，开发者设置的EncodingAESKey
* @param clientId 企业的corpId或者服务号的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 MessageDecryption(String token, String aes, String clientId) throws AesException {
if (aes.length() != 43) {
logger.error("MessageDecryption constructs failed, aesKey size is not 43.");
throw new AesException(AesException.IllegalAesKey);
}
this.token = token;
this.clientId = clientId;
aesKey = Base64.decodeBase64(aes + "=");
}
// 生成4个字节的网络字节序
private 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
private 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
private 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
*/
private 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[] corpidBytes = clientId.getBytes(CHARSET);
// randomStr + networkBytesOrder + text + corpid
byteCollector.addBytes(randomStrBytes);
byteCollector.addBytes(networkBytesOrder);
byteCollector.addBytes(textBytes);
byteCollector.addBytes(corpidBytes);
// ... + 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
return base64.encodeToString(encrypted);
} catch (Exception e) {
logger.error("MessageDecryption encrypt failed.", e);
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
*/
private 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) {
logger.error("MessageDecryption decrypt failed.", e);
throw new AesException(AesException.DecryptAESError);
}
String xmlContent, from_corpid;
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corpId
byte[] networkOrder = Arrays.copyOfRange(bytes, 16, 20);
int xmlLength = recoverNetworkBytesOrder(networkOrder);
xmlContent = new String(Arrays.copyOfRange(bytes, 20, 20 + xmlLength), CHARSET);
from_corpid = new String(Arrays.copyOfRange(bytes, 20 + xmlLength, bytes.length),
CHARSET);
} catch (Exception e) {
logger.error("MessageDecryption decrypt failed.", e);
throw new AesException(AesException.IllegalBuffer);
}
// corpid不相同的情况
if (!from_corpid.equals(clientId)) {
logger.error("MessageDecryption decrypt failed, corpid mismatches.");
throw new AesException(AesException.ValidateCorpidError);
}
return xmlContent;
}
/**
* 将公众平台回复用户的消息加密打包.
*
* - 对要发送的消息进行AES-CBC加密
* - 生成安全签名
* - 将消息密文和安全签名打包成xml格式
*
*
* @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 encrypt(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);
// 生成发送的xml
return XMLParse.generate(encrypt, signature, timeStamp, nonce);
}
/**
* 检验消息的真实性，并且获取解密后的明文.
*
* - 利用收到的密文生成安全签名，进行签名验证
* - 若验证通过，则提取xml中的加密消息
* - 对消息进行解密
*
*
* @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 decrypt(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
return decrypt(encrypt[1].toString());
}
/**
* 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 decryptEcho(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);
}
return decrypt(echoStr);
}
}