编辑代码

using System;
using System.Security.Cryptography;
using System.Text;

public class HelloWorld
{
    public static void Main()
    {
        string res = AesDecryptBase64("zzzzzz", "123456"); //参数：密文，KEY
        Console.WriteLine("解密结果：" + res);
    }

    public static string AesDecryptBase64(string decryptStr, string key)
    {
        try
        {
            if (string.IsNullOrEmpty(key)) key = "888888";
            byte[] keyArray = Convert.FromBase64String(key);
            byte[] toEncryptArray = Convert.FromBase64String(decryptStr);

            RijndaelManaged rDel = new RijndaelManaged();
            rDel.Key = keyArray;
            rDel.Mode = CipherMode.ECB;
            rDel.Padding = PaddingMode.PKCS7;

            ICryptoTransform cTransform = rDel.CreateDecryptor();
            byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

            return Encoding.UTF8.GetString(resultArray);
        }
        catch
        {
            return null;
        }
    }
    
}