MD5加密在軟件開發中經常使用, 由于是單向加密也稱作不可逆加密, 經常用來做為校驗使用, 可以用來校驗用戶密碼, 文件校驗

        /// <summary>
        /// MD5字符串加密
        /// </summary>
        /// <param name="input">需要加密的字符串</param>
        /// <returns>返回32位大寫字符串</returns>  
        public static string MD5(string input)
        {
            try
            {
                using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider())
                {
                    string result = "";
                    byte[] btInput = System.Text.Encoding.UTF8.GetBytes(input);
                    byte[] btOut = md5.ComputeHash(btInput);
                    for (int i = 0; i < btOut.Length; i++)
                    {
                        result += btOut[i].ToString("X2");
                    }
                    return result;
                }
            }
            catch
            {
                throw;
            }
        }

        /// <summary>
        /// MD5文件流加密
        /// </summary>
        /// <param name="input">文件流</param>
        /// <returns>返回32位大寫字符串</returns>  
        public static string MD5(Stream input)
        {
            try
            {
                using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider())
                {
                    string result = "";
                    byte[] btOut = md5.ComputeHash(input);
                    for (int i = 0; i < btOut.Length; i++)
                    {
                        result += btOut[i].ToString("X2");
                    }
                    return result;
                }
            }
            catch
            {
                throw;
            }
        }