MD5加密在Net framework 4.5下面会警告过时

//4.0,4.5中过时（编译器警告）

users.Password = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(txt_pwd.Value.ToString().Trim(), "SHA1").ToUpper(); //SHA1加密，40位
users.Password = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(txt_pwd.Value.ToString().Trim(), "MD5").ToUpper(); //MD5加密，32位

解决方案：

        users.Password = Md5Hash(txt_Phone.Value.ToString().Trim());  
        public String Md5Hash(String pwd) 
        {
            MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
            byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(pwd));
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < data.Length; i++)
            {
             sb.Append(data[i].ToString("x2"));
            }
            return sb.ToString();
        }