/// <summary>
/// ASE加解密
/// </summary>
public class AESHelper
{
    /// <summary>
    /// 獲取密鑰
    /// </summary>
    private static string Key
    {
        get
        {
            return "abcdef1234567890";    ////必須是16位
        }
    }

    //默認密鑰向量
    private static byte[] _key1 = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF, 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

    /// <summary>
    /// AES加密算法
    /// </summary>
    /// <param name="plainText">明文字符串</param>
    /// <returns>將加密后的密文轉換為Base64編碼，以便顯示</returns>
    public static string AESEncrypt(string plainText)
    {
        //分組加密算法
        SymmetricAlgorithm des = Rijndael.Create();
        byte[] inputByteArray = Encoding.UTF8.GetBytes(plainText);//得到需要加密的字節數組
        //設置密鑰及密鑰向量
        des.Key = Encoding.UTF8.GetBytes(Key);
        des.IV = _key1;
        byte[] cipherBytes = null;
        using (MemoryStream ms = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();
                cipherBytes = ms.ToArray();//得到加密后的字節數組
                cs.Close();
                ms.Close();
            }
        }
        return Convert.ToBase64String(cipherBytes);
    }

    /// <summary>
    /// AES解密
    /// </summary>
    /// <param name="cipherText">密文字符串</param>
    /// <returns>返回解密后的明文字符串</returns>
    public static string AESDecrypt(string showText)
    {
        byte[] cipherText = Convert.FromBase64String(showText);

        SymmetricAlgorithm des = Rijndael.Create();
        des.Key = Encoding.UTF8.GetBytes(Key);
        des.IV = _key1;
        byte[] decryptBytes = new byte[cipherText.Length];
        using (MemoryStream ms = new MemoryStream(cipherText))
        {
            using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Read))
            {
                cs.Read(decryptBytes, 0, decryptBytes.Length);
                cs.Close();
                ms.Close();
            }
        }
        return Encoding.UTF8.GetString(decryptBytes).Replace("/0", "");   ///將字符串后尾的'/0'去掉
    }
}