using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ShwasherSys
{
    public class WxDecryptHelper
    {
        public static string Decrypt(string encryptedData, string sessionKey, string iv)
        {
            try
            {
                // Base64解码
                var encryptedDataBytes = Convert.FromBase64String(encryptedData);
                var keyBytes = Convert.FromBase64String(sessionKey);
                var ivBytes = Convert.FromBase64String(iv);

                // 创建AES解密器
                var cipher = CipherUtilities.GetCipher("AES/CBC/PKCS7Padding");
                var keyParam = new KeyParameter(keyBytes);
                var keyParameters = new ParametersWithIV(keyParam, ivBytes);

                cipher.Init(false, keyParameters);
                var resultBytes = cipher.DoFinal(encryptedDataBytes);

                // 返回解密后的JSON字符串
                return Encoding.UTF8.GetString(resultBytes);
            }
            catch (Exception ex)
            {
                throw new Exception("解密失败", ex);
            }
        }
    }
}