java微信小程序步数encryptedData和开放数据解密的实现

前提：

三个参数，
1.sessionKey（拿openId的时候可以得到）
2.encryptedData(前端提供)
3.iv(前端提供)

一个类，一个方法。

1.类：

import java.nio.charset.Charset;
import java.util.Arrays;

public class WxPKCS7Encoder {
  private static final Charset CHARSET = Charset.forName("utf-8");
  private static final int BLOCK_SIZE = 32;
 
  
  public static byte[] encode(int count) {
    // 计算需要填充的位数
    int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE);
    if (amountToPad == 0) {
      amountToPad = BLOCK_SIZE;
    }
    // 获得补位所用的字符
    char padChr = chr(amountToPad);
    String tmp = new String();
    for (int index = 0; index < amountToPad; index++) {
      tmp += padChr;
    }
    return tmp.getBytes(CHARSET);
  }
 
  
  public static byte[] decode(byte[] decrypted) {
    int pad = decrypted[decrypted.length - 1];
    if (pad < 1 || pad > 32) {
      pad = 0;
    }
    return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad);
  }
 
  
  public static char chr(int a) {
    byte target = (byte) (a & 0xFF);
    return (char) target;
  }
}

2.方法：

import java.io.UnsupportedEncodingException;
import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
import java.security.spec.InvalidParameterSpecException;
import java.util.HashMap;

import javax.annotation.Resource;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.base64;
import org.apache.commons.lang3.StringUtils;
import org.bouncycastle.jce.provider.BouncyCastleProvider;


import lombok.extern.slf4j.Slf4j;
@Slf4j
public class AesCbcUtil {

  static {
     //BouncyCastle是一个开源的加解密解决方案，主页在http://www.bouncycastle.org/
     Security.addProvider(new BouncyCastleProvider());
   }
 
   
   public static String decrypt(String data, String key, String iv, String encodingFormat,Integer type) throws Exception {
//     initialize();
   if(StringUtils.isEmpty(data)||StringUtils.isEmpty(key)||StringUtils.isEmpty(iv))
    throw new SkyParamNullException("小程序获取用户信息参数不能为空");
     //被加密的数据
     byte[] dataByte = base64.decodebase64(data);
     //加密秘钥
     byte[] keyByte = base64.decodebase64(key);
     //偏移量
     byte[] ivByte = base64.decodebase64(iv);
 
 
     try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
 
SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
 
AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
parameters.init(new IvParameterSpec(ivByte));
 
cipher.init(Cipher.DECRYPT_MODE, spec, parameters);// 初始化
 
byte[] resultByte = cipher.doFinal(dataByte);
if (null != resultByte && resultByte.length > 0) {
if (type==1){
   return new String(WxPKCS7Encoder.decode(resultByte));

   }else {
   return new String(resultByte, encodingFormat);

   }


}
return null;
     } catch (NoSuchAlgorithmException e) {
e.printStackTrace();
log.error("小程序解析出错1{}",e.getMessage());
     } catch (NoSuchPaddingException e) {
e.printStackTrace();
log.error("小程序解析出错2{}",e.getMessage());
     } catch (InvalidParameterSpecException e) {
e.printStackTrace();
log.error("小程序解析出错3{}",e.getMessage());
     } catch (InvalidKeyException e) {
e.printStackTrace();
log.error("小程序解析出错4{}",e.getMessage());
     } catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
log.error("小程序解析出错5{}",e.getMessage());
     } catch (IllegalBlockSizeException e) {
e.printStackTrace();
log.error("小程序解析出错6{}",e.getMessage());
     } catch (BadPaddingException e) {
e.printStackTrace();
log.error("小程序解析出错7{}",e.getMessage());
     }
  catch (UnsupportedEncodingException e) {
  e.printStackTrace();
  log.error("小程序解析出错8{}",e.getMessage());
  }
     return null;
   }
}

实现

@ApiOperation(value = "wx步数解密")
  @PostMapping(value = "/decode")
  public ResultModel