/// <summary>
    /// 文件加密类
    /// </summary>
    public class FileEncryptTool
    {
        /// <summary>
        /// 加密文件内容并写入-AES加密
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <param name="content">加密内容</param>
        /// <param name="pwd">加密密匙</param>
        public void EncryptFile(string path, byte[] content, string pwd)
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            byte[] result;

            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                result = AESTool.AESEncrypt(content, pwd);
                fs.Position = 0;
                fs.Write(result, 0, result.Length);
                fs.Flush();
            }

            result = null;
        }

        /// <summary>
        /// 解密文件内容-AES解密
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <param name="pwd">加密密匙</param>
        public ReturnModel DecryptFile(string path, string pwd)
        {
            ReturnModel returnModel = new ReturnModel();
            byte[] read;

            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                if (fs.Length < 1)
                {
                    return returnModel;
                }

                read = new byte[fs.Length];
                fs.Position = 0;
                fs.Read(read, 0, read.Length);
                returnModel.MessageOrString = Encoding.UTF8.GetString(AESTool.AESDecrypt(read, pwd));
                read = null;

                return returnModel;
            }
        }
    }

/// <summary>
    /// AES操作类
    /// </summary>
    public class AESTool
    {
        static byte[] rd_buffer;
        static IBufferedCipher cipher;

        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="input"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        public static string AESEncrypt(string input, string key)
        {
            byte[] plainText = Encoding.UTF8.GetBytes(input);

            cipher = CipherUtilities.GetCipher("AES/ECB/PKCS5Padding");
            cipher.Init(true, GetKeyBySeed(key));

            string re = Convert.ToBase64String(cipher.DoFinal(plainText));
            plainText = null;
            cipher = null;

            return re;
        }

        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="input"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        public static byte[] AESEncrypt(byte[] plainText, string key)
        {
            cipher = CipherUtilities.GetCipher("AES/ECB/PKCS5Padding");
            cipher.Init(true, GetKeyBySeed(key));

            return cipher.DoFinal(plainText);
        }

        public static KeyParameter GetKeyBySeed(string strKey)
        {
            byte[] seed = Encoding.UTF8.GetBytes(strKey);

            using (SHA1CryptoServiceProvider nd = new SHA1CryptoServiceProvider())
            {
                rd_buffer = nd.ComputeHash(SHA1.Create().ComputeHash(seed));
                seed = null;

                return new KeyParameter(rd_buffer.Take(16).ToArray());
            }
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="cipherText"></param>
        /// <returns></returns>
        public static byte[] AESDecrypt(byte[] cipherText, string pwd)
        {
            cipher = CipherUtilities.GetCipher("AES/ECB/PKCS5Padding");
            cipher.Init(false, GetKeyBySeed(pwd));

            return cipher.DoFinal(cipherText);
        }
    }