import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.AlgorithmParameters;
import java.security.Key;
import java.security.Security;

public class AES {
  // 算法名
  public static final String KEY_NAME = "AES";
  // 加解密算法/模式/填充方式
  // ECB模式只用密鑰即可對(duì)數(shù)據(jù)進(jìn)行加密解密，CBC模式需要添加一個(gè)iv
  public static final String CIPHER_ALGORITHM = "AES/CBC/PKCS7Padding";

  /**
   * 微信 數(shù)據(jù)解密<br/>
   * 對(duì)稱解密使用的算法為 AES-128-CBC，數(shù)據(jù)采用PKCS#7填充<br/>
   * 對(duì)稱解密的目標(biāo)密文:encrypted=Base64_Decode(encryptData)<br/>
   * 對(duì)稱解密秘鑰:key = Base64_Decode(session_key),aeskey是16字節(jié)<br/>
   * 對(duì)稱解密算法初始向量:iv = Base64_Decode(iv),同樣是16字節(jié)<br/>
   *
   * @param encrypted 目標(biāo)密文
   * @param session_key 會(huì)話ID
   * @param iv 加密算法的初始向量
   */
  public static String wxDecrypt(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 = new String(decrypt(encrypted64, key64, generateIV(iv64)));
    } catch (Exception e) {
      e.printStackTrace();
    }
    return json;
  }

  /**
   * 初始化密鑰
   */
  public static void init() throws Exception {
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    KeyGenerator.getInstance(KEY_NAME).init(128);
  }

  /**
   * 生成iv
   */
  public static AlgorithmParameters generateIV(byte[] iv) throws Exception {
    // iv 為一個(gè) 16 字節(jié)的數(shù)組，這里采用和 iOS 端一樣的構(gòu)造方法，數(shù)據(jù)全為0
    // Arrays.fill(iv, (byte) 0x00);
    AlgorithmParameters params = AlgorithmParameters.getInstance(KEY_NAME);
    params.init(new IvParameterSpec(iv));
    return params;
  }

  /**
   * 生成解密
   */
  public static byte[] decrypt(byte[] encryptedData, byte[] keyBytes, AlgorithmParameters iv)
      throws Exception {
    Key key = new SecretKeySpec(keyBytes, KEY_NAME);
    Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
    // 設(shè)置為解密模式
    cipher.init(Cipher.DECRYPT_MODE, key, iv);
    return cipher.doFinal(encryptedData);
  }

}

public String decodeUserInfo(String encrypted, String session_key, String iv) throws IOException {

  String json = wxDecrypt(encrypted, session_key, iv);
  System.out.println(json);
  return json;
}