ウィーチャットウィジェットAES復号化ツールクラス

ウィーチャットウィジェットAES復号化
注:復号に使用するセッション_keyは、微信ユーザ情報を取得する前に取得する必要があります.そうしないと、復号化に失敗します.

encryptedData:復号化されたデータ

iv:オフセット

session_key:復号用key

package com.sy430.common.utils.security.mini;


import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.*;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.*;
import java.security.spec.InvalidParameterSpecException;
import java.util.Arrays;

/**
 * Created by Yipw on 2018/8/8 0008.
 */
public class MiniAESUtil {

    //    
    public static final String KEY_NAME = "AES";
    //      /  /    
    // ECB                 ，CBC        iv
    public static final String CIPHER_ALGORITHM = "AES/CBC/PKCS7Padding";

    /**
     *        

     *            AES-128-CBC，    PKCS#7  

     *          :encrypted=Base64_Decode(encryptData)

     *       :key = Base64_Decode(session_key),aeskey 16  

     *           :iv = Base64_Decode(iv),   16  

     *
     * @param encrypted     
     * @param session_key   ID
     * @param iv          
     */
    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;
    }

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

    /**
     *   iv
     */
    public static AlgorithmParameters generateIV(byte[] iv) throws Exception {
        // iv     16      ，      iOS         ，    0
        // Arrays.fill(iv, (byte) 0x00);
        AlgorithmParameters params = AlgorithmParameters.getInstance(KEY_NAME);
        params.init(new IvParameterSpec(iv));
        return params;
    }

    /**
     *     
     */
    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);
        //        
        cipher.init(Cipher.DECRYPT_MODE, key, iv);
        return cipher.doFinal(encryptedData);
    }

    public static void main(String[] args) {
        String encryptedData = "33fZhF8F6/GOIIv+s6Cyrvqt43DQUhAAqvU1oro4DLTAWCE9tmPGSPXz67WrAoLd/WqTwUuL2bLP+WIfXc/y6alTTiv+ApM1d3FPDELcMnVi/M2QYcoqxiAJXeHOWknzobOSBkwfpDglRzl0YzrGp9rj/WPbukqMeXJaExzUUQiYDuYBG/lb1BvZ4NYuUR+SJdADuVlhJgWjW2BAyeESZg==";
        String iv = "dtzfyZmCe3ccIqw78pVXTg==";
        String session_key = "VrLEvceeizQl7+5qxMZBrA==";
        String json = getUserInfo(encryptedData, session_key, iv);
        String wxDecrypt = wxDecrypt(encryptedData, session_key, iv);

        System.out.println(json);
    }


    /**
     *        
     * @param encryptedData
     * @param sessionKey
     * @param iv
     * @return
     */
    public static String getUserInfo(String encryptedData, String sessionKey, String iv) {
        String result = "";
        //       
        byte[] dataByte = Base64.decodeBase64(encryptedData);
        //     
        byte[] keyByte = Base64.decodeBase64(sessionKey);
        //    
        byte[] ivByte = Base64.decodeBase64(iv);
        try {
            //       16 ，     .   if        
            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;
            }
            //    
            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) {
                result = new String(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();
        }
        return result;
    }

}