利用MD5加密數據庫中的密碼

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--- 利用MD5加密數據庫中的密碼 (http://www.webasp.net/article/15/14403.htm)

-- 作者：未知
-- 發佈日期： 2004-11-01

NET提供了進行數據加密類，下面就用例子進行說明如何使用MD5進行數據加密。

首先，創建一個UserAccount表，字段兩個：UserName和Password，類型分別為varchar(25)和binary(16)，下面的ASP.NET代碼就是創建用戶時的具體實現：

<%@ 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. 創建連接
Const strConnString as String
strConnString= "Data Source=.;Initial Catalog=test;User Id=sa;Password=;"
Dim objConn as New SqlConnection(strConnString)

'2. 創建Command對像
Dim strSQL as String = _
"INSERT INTO UserAccount(Username,Password) " & _
"VALUES(@Username, @Password)"
Dim objCmd as New SqlCommand(strSQL, objConn)

'3. 創建參數
Dim paramUsername as SqlParameter
paramUsername = New SqlParameter("@Username", SqlDbType.VarChar, 25)
paramUsername.Value = txtUsername.Text
objCmd.Parameters.Add(paramUsername)

'加密密碼字段

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)

'插入數據庫
objConn.Open()
objCmd.ExecuteNonQuery()
objConn.Close()

'Redirect 其它頁面
End Sub
</script>

<form runat="server">
<h1>創建帳號：</h1>
用戶名: <asp:TextBox runat="server" id="txtUsername"/>
<br/>
密碼: <asp:TextBox runat="server" id="txtPwd" TextMode="Password"/>
<p><asp:Button runat="server" Text="創建用戶" OnClick="CreateAccount"/></p>
</form>

下面是對用戶進行驗證的ASP.NET代碼：

<%@ 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. 創建連接
Const strConnString as String
strConnString= "Data Source=.;Initial Catalog=test;User Id=sa;Password=;"
Dim objConn as New SqlConnection(strConnString)

'2. 創建Command對像
Dim strSQL as String = "SELECT COUNT(*) FROM UserAccount " & _
"WHERE Username=@Username AND Password=@Password"
Dim objCmd as New SqlCommand(strSQL, objConn)

'3. 創建參數
Dim paramUsername as SqlParameter
paramUsername = New SqlParameter("@Username", SqlDbType.VarChar, 25)
paramUsername.Value = txtUsername.Text
objCmd.Parameters.Add(paramUsername)

'加密密碼
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)

'執行查詢
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>登錄：</h1>
用戶名:<asp:TextBox runat="server" id="txtUsername"/><br/>
密碼:<asp:TextBox runat="server" id="txtPwd" TextMode="Password"/>
<p><asp:Button runat="server" Text="登錄" 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>

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