using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace HiTeachCC.Library.Common
{
  public static class WeChatCryptHelper
    {
        public static string AESDecrypt(string encryptedDataStr, string key, string iv)
        {
            RijndaelManaged rijalg = new RijndaelManaged();
            //-----------------    
            //设置 cipher 格式 AES-128-CBC    

            rijalg.KeySize = 128;

            rijalg.Padding = PaddingMode.PKCS7;
            rijalg.Mode = CipherMode.CBC;

            rijalg.Key = Convert.FromBase64String(key);
            rijalg.IV = Convert.FromBase64String(iv);
            byte[] encryptedData = Convert.FromBase64String(encryptedDataStr);
            //解密    
            ICryptoTransform decryptor = rijalg.CreateDecryptor(rijalg.Key, rijalg.IV);
            string result;

            using (MemoryStream msDecrypt = new MemoryStream(encryptedData))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {

                        result= srDecrypt.ReadToEnd();
                    }
                }
            }
            return result;
        }
    }
}
