利用MD5加密数据库中的密码
作者：孟宪会 出自：【孟宪会之精彩世界】 发布日期：2003年4月26日 4点57分50秒
.NET提供了进行数据加密类，下面就用例子进行说明如何使用MD5进行数据加密。
首先，创建一个UserAccount表，字段两个：UserName和Password，类型分别为varchar(25)和binary(16)，下面的ASP.NET代码就是创建用户时的具体实现：
<%@ Import Namespace="System.Security.Cryptography" %>
<%@ Import Namespace="System.Text" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat="server" language="VB">
Sub CreateAccount(sender as Object, e as EventArgs)
'1. 创建连接
Const strConnString as String
strConnString= "Data Source=.;Initial Catalog=test;User Id=sa;Password=;"
Dim objConn as New SqlConnection(strConnString)
'2. 创建Command对象
Dim strSQL as String = _
"INSERT INTO UserAccount(Username,Password) " & _
"VALUES(@Username, @Password)"
Dim objCmd as New SqlCommand(strSQL, objConn)
'3. 创建参数
Dim paramUsername as SqlParameter
paramUsername = New SqlParameter("@Username", SqlDbType.VarChar, 25)
paramUsername.Value = txtUsername.Text
objCmd.Parameters.Add(paramUsername)
'加密密码字段
Dim md5Hasher as New MD5CryptoServiceProvider()
Dim hashedBytes as Byte()
Dim encoder as New UTF8Encoding()
hashedBytes = md5Hasher.ComputeHash(encoder.GetBytes(txtPwd.Text))
Dim paramPwd as SqlParameter
paramPwd = New SqlParameter("@Password", SqlDbType.Binary, 16)
paramPwd.Value = hashedBytes
objCmd.Parameters.Add(paramPwd)
'插入数据库
objConn.Open()
objCmd.ExecuteNonQuery()
objConn.Close()
'Redirect 其它页面
End Sub
</script>
<form runat="server">
<h1>创建帐号：</h1>
用户名: <asp:TextBox runat="server" id="txtUsername"/>
<br/>
密码: <asp:TextBox runat="server" id="txtPwd" TextMode="Password"/>
<p><asp:Button runat="server" Text="创建用户" OnClick="CreateAccount"/></p>
</form>
下面是对用户进行验证的ASP.NET代码：
<%@ Import Namespace="System.Security.Cryptography" %>
<%@ Import Namespace="System.Text" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat="server" language="VB">
Sub Login(sender as Object, e as EventArgs)
'1. 创建连接
Const strConnString as String
strConnString= "Data Source=.;Initial Catalog=test;User Id=sa;Password=;"
Dim objConn as New SqlConnection(strConnString)
'2. 创建Command对象
Dim strSQL as String = "SELECT COUNT(*) FROM UserAccount " & _
"WHERE Username=@Username AND Password=@Password"
Dim objCmd as New SqlCommand(strSQL, objConn)
'3. 创建参数
Dim paramUsername as SqlParameter
paramUsername = New SqlParameter("@Username", SqlDbType.VarChar, 25)
paramUsername.Value = txtUsername.Text
objCmd.Parameters.Add(paramUsername)
'加密密码
Dim md5Hasher as New MD5CryptoServiceProvider()
Dim hashedDataBytes as Byte()
Dim encoder as New UTF8Encoding()
hashedDataBytes = md5Hasher.ComputeHash(encoder.GetBytes(txtPwd.Text))
Dim paramPwd as SqlParameter
paramPwd = New SqlParameter("@Password", SqlDbType.Binary, 16)
paramPwd.Value = hashedDataBytes
objCmd.Parameters.Add(paramPwd)
'执行查询
objConn.Open()
Dim iResults as Integer = objCmd.ExecuteScalar()
objConn.Close()
If iResults = 1 then
'合法
Else
'不合法
End If
End Sub
</script>
<form runat="server">
<h1>登录：</h1>
用户名:<asp:TextBox runat="server" id="txtUsername"/><br/>
密 码:<asp:TextBox runat="server" id="txtPwd" TextMode="Password"/>
<p><asp:Button runat="server" Text="登录" OnClick="Login"/>
</form>
下面是MD5CryptoServiceProvider直接生成的例子： <%@ Import Namespace="System.Security.Cryptography" %>
<%@ Import Namespace="System.Text" %>
<script language="VB" runat="server">
Sub DisplayEncryptedText(sender as Object, e as EventArgs)
If Page.IsValid then
Dim md5Hasher as New MD5CryptoServiceProvider()
Dim hashedDataBytes as Byte()
Dim encoder as New UTF8Encoding()
hashedDataBytes = md5Hasher.ComputeHash(encoder.GetBytes(txtPassword.Text))
ltlResults.Text = "<b>Encrypted Results</b><br /> The results are encrypted into " & _
"an array of 16 bytes. These 16 bytes contain the values:<p><ul>"
Dim b as Byte
For Each b in hashedDataBytes
ltlResults.Text &= "<li>" & b & "</li>"
Next b
ltlResults.Text &= "</ul>"
End If
End Sub
</script>
<form runat="server">
Enter a string:
<asp:TextBox id="txtPassword" runat="server" />
<asp:RequiredFieldValidator runat="server" ControlToValidate="txtPassword"
Display="Dynamic" ErrorMessage="<i>You must provide a value here...</i>" />
<asp:RegularExpressionValidator runat="server" ControlToValidate="txtPassword"
Display="Dynamic" ErrorMessage="<i>The string must be 20 characters or less...</i>"
ValidationExpression="^.{1,20}$" />
<br />
<asp:Button runat="server" Text="View the String as Encrypted Text"
OnClick="DisplayEncryptedText" />
<p>
<asp:Literal runat="server" id="ltlResults" />
</form>
