package com.nuvole.util;

import java.security.AlgorithmParameters;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

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

/**
 * 微信加解密工具类
 *
 * @author liujun
 * @Date 2019/5/27 17:36
 */
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());
    }

    /**
     * AES解密
     *
     * @param data
     *            //密文，被加密的数据
     * @param key
     *            //秘钥
     * @param iv
     *            //偏移量
     * @param encodingFormat
     *            //解密后的结果需要进行的编码
     * @return
     * @throws Exception
     */
    public static String decrypt(String data, String key, String iv, String encodingFormat) throws Exception {
        // initialize();
        // 被加密的数据
        byte[] dataByte = Base64.decodeBase64(data.getBytes());
        // 加密秘钥
        byte[] keyByte = Base64.decodeBase64(key.getBytes());
        // 偏移量
        byte[] ivByte = Base64.decodeBase64(iv.getBytes());
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
        SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
        AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
        parameters.init(new IvParameterSpec(ivByte));
        // 初始化
        cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
        byte[] resultByte = cipher.doFinal(dataByte);
        if (null != resultByte && resultByte.length > 0) {
            String result = new String(resultByte, encodingFormat);
            return result;
        }
        return null;
    }
}