// 算法名
publicstaticfinalString KEY_NAME ="AES";
// 加解密算法/模式/填充方式
// ECB模式只用密钥即可对数据进行加密解密，CBC模式需要添加一个iv
publicstaticfinalString CIPHER_ALGORITHM ="AES/CBC/PKCS7Padding";
/**
* 微信 数据解密<br/>
* 对称解密使用的算法为 AES-128-CBC，数据采用PKCS#7填充<br/>
* 对称解密的目标密文:encrypted=Base64_Decode(encryptData)<br/>
* 对称解密秘钥:key = Base64_Decode(session_key),aeskey是16字节<br/>
* 对称解密算法初始向量:iv = Base64_Decode(iv),同样是16字节<br/>
*
*@paramencrypted 目标密文
*@paramsession_key 会话ID
*@paramiv 加密算法的初始向量
*/
publicstaticStringwxDecrypt(String encrypted, String session_key, String iv){
String json =null;
byte[] encrypted64 = Base64.decodeBase64(encrypted);
byte[] key64 = Base64.decodeBase64(session_key);
byte[] iv64 = Base64.decodeBase64(iv);
byte[] data;
try{
init();
json =newString(decrypt(encrypted64, key64, generateIV(iv64)));
}catch(Exception e) {
e.printStackTrace();
}
returnjson;
}
/**
* 初始化密钥
*/
publicstaticvoidinit()throwsException{
Security.addProvider(neworg.bouncycastle.jce.provider.BouncyCastleProvider());
KeyGenerator.getInstance(KEY_NAME).init(128);
}
/**
* 生成iv
*/
publicstaticAlgorithmParametersgenerateIV(byte[] iv)throwsException{
// iv 为一个 16 字节的数组，这里采用和 iOS 端一样的构造方法，数据全为0
// Arrays.fill(iv, (byte) 0x00);
AlgorithmParameters params = AlgorithmParameters.getInstance(KEY_NAME);
params.init(newIvParameterSpec(iv));
returnparams;
}
/**
* 生成解密
*/
publicstaticbyte[] decrypt(byte[] encryptedData,byte[] keyBytes, AlgorithmParameters iv)
throwsException {
Key key =newSecretKeySpec(keyBytes, KEY_NAME);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
// 设置为解密模式
cipher.init(Cipher.DECRYPT_MODE, key, iv);
returncipher.doFinal(encryptedData);
}
/**
* 微信小程序解密
*@paramencryptedData
*@paramsessionKey
*@paramiv
*@return
*/
publicstaticStringgetUserInfo(String encryptedData, String sessionKey, String iv){
String result ="";
// 被加密的数据
byte[] dataByte = Base64.decodeBase64(encryptedData);
// 加密秘钥
byte[] keyByte = Base64.decodeBase64(sessionKey);
// 偏移量
byte[] ivByte = Base64.decodeBase64(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
intbase =16;
if(keyByte.length % base !=0) {
intgroups = keyByte.length / base
+ (keyByte.length % base !=0?1:0);
byte[] temp =newbyte[groups * base];
Arrays.fill(temp, (byte)0);
System.arraycopy(keyByte,0, temp,0, keyByte.length);
keyByte = temp;
}
// 初始化
Security.addProvider(newBouncyCastleProvider());
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding","BC");
SecretKeySpec spec =newSecretKeySpec(keyByte,"AES");
AlgorithmParameters parameters = AlgorithmParameters
.getInstance("AES");
parameters.init(newIvParameterSpec(ivByte));
cipher.init(Cipher.DECRYPT_MODE, spec, parameters);// 初始化
byte[] resultByte = cipher.doFinal(dataByte);
if(null!= resultByte && resultByte.length >0) {
result =newString(resultByte,"UTF-8");
}
}catch(NoSuchAlgorithmException e) {
e.printStackTrace();
}catch(NoSuchPaddingException e) {
e.printStackTrace();
}catch(InvalidParameterSpecException e) {
e.printStackTrace();
}catch(IllegalBlockSizeException e) {
e.printStackTrace();
}catch(BadPaddingException e) {
e.printStackTrace();
}catch(UnsupportedEncodingException e) {
e.printStackTrace();
}catch(InvalidKeyException e) {
e.printStackTrace();
}catch(InvalidAlgorithmParameterException e) {
e.printStackTrace();
}catch(NoSuchProviderException e) {
e.printStackTrace();
}
returnresult;
}
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