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


public class AESUtil
{

    /// <summary>
    /// AES加密
    /// </summary>
    /// <param name="str">需要加密的字串</param>
    /// <param name="key">32位金鑰</param>
    /// <param name="iv">向量（一定要問問對面要用什麼向量）</param>
 

    /// <returns>加密後的字串</returns>
    public static string Encrypt(string str, string key, string iv)
    {
        byte[] keyArray = Encoding.UTF8.GetBytes(key);
        byte[] toEncryptArray = Encoding.UTF8.GetBytes(str);
        var rijndael = new RijndaelManaged();
        rijndael.Key 
 
= keyArray;
        rijndael.Mode = CipherMode.CBC;
        rijndael.Padding = PaddingMode.PKCS7;
        rijndael.IV = Encoding.UTF8.GetBytes(iv);
        ICryptoTransform cTransform = rijndael.CreateEncryptor();
        byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
        
 
return Convert.ToBase64String(resultArray, 0, resultArray.Length);
    }

    /// <summary>
    /// AES解密
    /// </summary>
    /// <param name="str">需要解密的字串</param>
    /// <param name="key">32位金鑰</param>
    /// <param name="iv">向量（一定要問問對面要用什麼向量）</param>
    /// <returns>解密後的字串</returns>
    public static string Decrypt(string str, string key, string iv)
    {
        byte[] keyArray = Encoding.UTF8.GetBytes(key);
        byte[] toEncryptArray = Convert.FromBase64String(str);
        var rijndael = new RijndaelManaged();
        rijndael.Key = keyArray;
        rijndael.Mode = CipherMode.CBC;
        rijndael.Padding = PaddingMode.PKCS7;
        rijndael.IV = Encoding.UTF8.GetBytes(iv);
        ICryptoTransform cTransform = rijndael.CreateDecryptor();
        byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
        return Encoding.UTF8.GetString(resultArray);
    }
}

程式碼賦值黏貼直接用，樓主已經和對應的java對比了無數遍了，加密後的字串是一樣的