码，只是一些经过编译后的字符串，以防止数据库管理员利用用户的密码进行非法操作。)
    首先，在c#WinForm程序中引入命名空间,"using System.Web.Security;",此命名空间是专门用来对程序进 

  行安全设置的；
    其次，定义一个string类型的变量，用来接收用输入的密码；
  string passWord = this.textBox1.Text.Trim();
    取到密码之后，接下来便是对密码进行加密处理：
  string pwd = FormsAuthentication.HashPasswordForStoringInConfigFile(pwd, "md5");
    最后，将加密后的密码pwd添加到数据库中去。
  insert into userInfo(uName,pwd) values('{0}','{1}');select @@identity", this.txtUID.Text.Trim   

(),passwrod);
  示例代码：
  using System.Web.Security;

    //取得文本框中的密码
    string pwd = this.txtPwd1.Text.Trim();
    //对密码加密
    string passwrod = FormsAuthentication.HashPasswordForStoringInConfigFile(pwd, "md5");
    //创建SQL语句，将加密后的密码保存到数据库中
    string insCmd =
          string.Format("insert into userInfo(uName,pwd) values('{0}','{1}');select @@identity",  

          this.txtUID.Text.Trim(),passwrod);
    using (SqlCommand cmd = new SqlCommand(insCmd, Form1.Connection))
    {
        int uid = Convert.ToInt32(cmd.ExecuteScalar());
        //int uid = int.Parse(cmd.ExecuteScalar());//error
        if (uid > 0)
        {
            string mess = string.Format("恭喜，注册成功！您的号码是{0}",uid);
            MessageBox.Show(mess);
        }
        else
        {
            MessageBox.Show("对不起，注册失败了！");
        }
    }

  这样加密之后保证了用户密码的安全，但是又出现了一个问题，即用户登录时怎样对密码进行验证，该不会让

 用户去记住加密后的那一长串字符串吧？ 答案当然是否定的，那怎样解决呢？
  应该这样解决：
  在用户登录时，得到用户输入的密码；
  然后，将取到的密码再次进行加密；
  之后，根据用户名取出该用户在数据库中的真实密码；
  最后，将刚刚进行加密的密码与数据库密码进行比对，即可完成用户登录操作。
  示例代码：
  string pwd = this.txtPwd1.Text.Trim();
                string pwd1 = FormsAuthentication.HashPasswordForStoringInConfigFile(pwd, "md5");
                string uid = this.txtUID.Text.Trim();
                string selCmd = string.Format("select pwd from userINfo where uName='{0}'", uid);
                string password = "";
                using (SqlCommand cmd = new SqlCommand(selCmd, Form1.Connection))
                {
                    password= cmd.ExecuteScalar().ToString();
                
                }
                if (password == pwd1)
                {
                    MessageBox.Show("登录成功");
                }
                else
                {
                    MessageBox.Show("密码错误！");
                }
完整实例(复制即可用)：

1.数据库代码：

use tempdb
go
if exists (select * from sysobjects where name = 'UserInfo')
drop table UserInfo
go
create table UserInfo
(
 uId int identity(1,1) not null,
 uName nvarchar(20) not null,
 uAge int not null,
 password nvarchar(200) not null
)
go
alter table UserInfo
add constraint PK_uID primary key (uId)
alter table UserInfo
add constraint CK_uAge check (uAge between 0 and 100)
go
select * from UserInfo

2.c#代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Web.Security;  //安全加密

namespace 密码加密示例
{
    public partial class Form1 : Form
    {
        //创建数据库连接字符串
        static readonly string strConn = "Data Source=.;Initial Catalog=tempdb;Integrated Security=True";
        //创建数据库连接对象
        static SqlConnection connection = null;
        //属性
        public static SqlConnection Connection
        {
            get 
            {
                if (connection == null || connection.State != ConnectionState.Open)
                {
                    connection = new SqlConnection(strConn);  //连接数据库
                    connection.Open();  //打开数据库
                }
                return Form1.connection;  //返回一个连接
            }
            
        }

        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 检查用户输入
        /// </summary>
        /// <returns></returns>
        private bool CheckInput()
        {
            if (string.IsNullOrEmpty(this.txtName.Text))
            {
                this.errorPro.SetError(this.txtName, "用户名不能为空！");
                this.txtName.Focus();
                return false;
            }
            else
            {
                this.errorPro.Dispose();  //终止提示错误
            }
            if (string.IsNullOrEmpty(this.txtAge.Text))
            {
                this.errorPro.SetError(this.txtAge, "姓名不能为空！");
                this.txtAge.Focus();
                return false;
            }
            else
            {
                this.errorPro.Dispose();
            }
            if (string.IsNullOrEmpty(this.txtPass.Text))
            {
                this.errorPro.SetError(this.txtPass, "密码不能为空！");
            }
            else
            {
                this.errorPro.Dispose();
            }
            return true;
        }

        /// <summary>
        /// 添加数据
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAdd_Click(object sender, EventArgs e)
        {
            if (this.CheckInput())
            {
                //获取用户输入的密码
                string password = this.txtPass.Text.Trim();
                //对密码进行加密
                string pwd = FormsAuthentication.HashPasswordForStoringInConfigFile(password, "md5");
                //创建SQL语句,将加密后的密码保存到数据库
                string insCmd = string.Format("insert into UserInfo values ('{0}','{1}','{2}')",
                    this.txtName.Text.Trim(), this.txtAge.Text.Trim(),pwd); 
                using (SqlCommand cmd = new SqlCommand(insCmd,Form1.Connection))
                {
                    if (cmd.ExecuteNonQuery() > 0)
                    {
                        MessageBox.Show("恭喜您，注册成功！");
                    }
                    else
                    {
                        MessageBox.Show("对不起，注册失败···");
                    }
                }
            }
        }
    }
}

完！