C#文本字符串加密 解密

#region 加密 解密
        /// <summary>
        /// 加密字符串
        /// </summary>
        /// <param name="str">待加密字符串</param>
        /// <param name="encryptKey">密钥(注意：密钥只能是4位)</param>
        /// <returns>返回文本</returns>
        public static string 文本加密(string str, string encryptKey)
        {//加密字符串
            try
            {
                byte[] key = Encoding.Unicode.GetBytes(encryptKey);//密钥
                byte[] data = Encoding.Unicode.GetBytes(str);//待加密字符串
                DESCryptoServiceProvider descsp = new DESCryptoServiceProvider();//加密、解密对象
                MemoryStream MStream = new MemoryStream();//内存流对象
                //用内存流实例化加密流对象
                CryptoStream CStream = new CryptoStream(MStream, descsp.CreateEncryptor(key, key), CryptoStreamMode.Write);
                CStream.Write(data, 0, data.Length);//向加密流中写入数据
                CStream.FlushFinalBlock();//将数据压入基础流
                byte[] temp = MStream.ToArray();//从内存流中获取字节序列
                CStream.Close();//关闭加密流
                MStream.Close();//关闭内存流
                return Convert.ToBase64String(temp);//返回加密后的字符串
            }
            catch
            {
                return str;
            }
        }
        /// <summary>
        /// 解密字符串
        /// </summary>
        /// <param name="str">待解密字符串</param>
        /// <param name="encryptKey">密钥(注意：密钥只能是4位)</param>
        /// <returns>返回文本</returns>
        public string 文本解密(string str, string encryptKey)
        {//解密字符串
            try
            {
                byte[] key = Encoding.Unicode.GetBytes(encryptKey);//密钥
                byte[] data = Convert.FromBase64String(str);//待解密字符串
                DESCryptoServiceProvider descsp = new DESCryptoServiceProvider();//加密、解密对象
                MemoryStream MStream = new MemoryStream();//内存流对象
                //用内存流实例化解密流对象
                CryptoStream CStream = new CryptoStream(MStream, descsp.CreateDecryptor(key, key), CryptoStreamMode.Write);
                CStream.Write(data, 0, data.Length);//向加密流中写入数据
                CStream.FlushFinalBlock();//将数据压入基础流
                byte[] temp = MStream.ToArray();//从内存流中获取字节序列
                CStream.Close();//关闭加密流
                MStream.Close();//关闭内存流
                return Encoding.Unicode.GetString(temp);//返回解密后的字符串
            }
            catch
            {
                return str;
            }
        }
        #region md5加密 解密
        /// <summary>
        /// MD5字符串加密
        /// </summary>
        /// <param name="txt"></param>
        /// <returns>加密后字符串</returns>
        public static string MD5Generate(string txt)
        {
            using (MD5 mi = MD5.Create())
            {
                byte[] buffer = Encoding.Default.GetBytes(txt);
                //开始加密
                byte[] newBuffer = mi.ComputeHash(buffer);
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < newBuffer.Length; i++)
                {
                    sb.Append(newBuffer[i].ToString("x2"));
                }
                return sb.ToString();
            }
        }
        /// <summary>
        /// MD5流加密
        /// </summary>
        /// <param name="inputStream"></param>
        /// <returns></returns>
        public static string MD5Generate(Stream inputStream)
        {
            using (MD5 mi = MD5.Create())
            {
                //开始加密
                byte[] newBuffer = mi.ComputeHash(inputStream);
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < newBuffer.Length; i++)
                {
                    sb.Append(newBuffer[i].ToString("x2"));
                }
                return sb.ToString();
            }
        }
        #endregion
        #endregion