[ASP.NET]验证码的实现以及用户密码的简单加密

namespace jingdong.Verification_code
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (Request.QueryString["mathmod"] != null)
            {
                if (Request.QueryString["mathmod"] == "reg")
                {
                    string temp = GenerateCheckCode();
                    Session["Verification_code"] = temp;
                    this.CreateCheckCodeImage(temp);
                }
                else if (Request.QueryString["mathmod"] == "repwd")
                {
                    string temp = GenerateCheckCode();
                    Session["repwd_Verification_code"] = temp;
                    this.CreateCheckCodeImage(temp);
                }
            }
        }

        private string GenerateCheckCode()
        {
            int number;
            char code;
            string checkCode = String.Empty;

            System.Random random = new Random();

            for (int i = 0; i < 5; i++)
            {
                number = random.Next();

                if (number % 2 == 0)
                    code = (char)('0' + (char)(number % 10));
                else
                    code = (char)('A' + (char)(number % 26));

                checkCode += code.ToString();
            }

            Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));

            return checkCode;
        }

        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;

            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
            Graphics g = Graphics.FromImage(image);

            try
            {
                //生成随机生成器
                Random random = new Random();

                //清空图片背景色
                g.Clear(Color.White);

                //画图片的背景噪音线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);

                    g.DrawLine(new Pen(Color.GreenYellow), x1, y1, x2, y2);
                }

                Font font = new System.Drawing.Font("Verdana", 10, (System.Drawing.FontStyle.Bold));
                System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(checkCode, font, brush, 2, 2);

                //画图片的前景噪音点
                for (int i = 0; i < 80; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);

                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }

                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Red), 0, 0, image.Width - 1, image.Height - 1);

                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
    }
}

　　用户密码加密实现:

namespace jingdong
{
    public class Myencrypt : __encrypt__
    {
        public string GetSha1(string str)
        {
            return Encryptions(str);
        }
    }


    public class __encrypt__
    {
        /// <summary>
        /// 加密接口
        /// </summary>
        /// <param name="str">要加密的字符串</param>
        /// <returns>返回加密以后的密文</returns>
        public string Encryptions(string str)
        {
            return encryptions(str);
        }

        /// <summary>
        /// 加密实现
        /// </summary>
        /// <param name="str">要加密的字符串</param>
        /// <returns>如果加密成功，返回密文；否则返回空</returns>
        private string encryptions(string str)
        {
            if (!String.IsNullOrEmpty(str))
            {
                return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "SHA1").ToLower();
            }
            else
            {
                return string.Empty;
            }
        }
    }
}