Encrypt passwords in a database using MD5

Encryption | data | Database NET provides a class for data encryption, and the following examples illustrate how to use MD5 for data encryption.

First, create a UserAccount table, the fields two: username and password, the types are varchar (25) and binary (16), and the following ASP.net code is the specific implementation when creating the user:

<%@ 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. Create a connection
Const strconnstring as String
strconnstring= "Data source=.;i Nitial catalog=test; User Id=sa; password=; "
Dim objconn as New SqlConnection (strconnstring)

' 2. Create Command object
Dim strSQL as String = _
"INSERT into UserAccount (Username,password)" & _
"VALUES (@Username, @Password)"
Dim objcmd as New SqlCommand (strSQL, objconn)

' 3. Create parameters
Dim Paramusername as SqlParameter
Paramusername = New SqlParameter ("@Username", SqlDbType.VarChar, 25)
Paramusername.value = txtUsername.Text
OBJCMD.PARAMETERS.ADD (Paramusername)


' Encrypt password field '

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)


' Insert Database
objConn.Open ()
Objcmd.executenonquery ()
Objconn.close ()

' Redirect other pages
End Sub
</script>

<form runat= "Server" >
User name: <asp:textbox runat= "Server" id= "txtUserName"/>
<br/>
Password: <asp:textbox runat= "Server" id= "txtpwd" textmode= "Password"/>
<p><asp:button runat= "Server" text= "Create user" onclick= "CreateAccount"/></p>
</form>

The following is the ASP.net code that validates the user:


<%@ 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. Create a connection
Const strconnstring as String
strconnstring= "Data source=.;i Nitial catalog=test; User Id=sa; password=; "
Dim objconn as New SqlConnection (strconnstring)

' 2. Create Command object
Dim strSQL as String = "SELECT COUNT (*) from UserAccount" & _
"WHERE username= @Username and password= @Password"
Dim objcmd as New SqlCommand (strSQL, objconn)

' 3. Create parameters
Dim Paramusername as SqlParameter
Paramusername = New SqlParameter ("@Username", SqlDbType.VarChar, 25)
Paramusername.value = txtUsername.Text
OBJCMD.PARAMETERS.ADD (Paramusername)


' Encrypt password
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)


' Execute Query
objConn.Open ()
Dim iresults as Integer = Objcmd.executescalar ()
Objconn.close ()

If iresults = 1 Then
' Legal
Else
' Not legal
End If
End Sub
</script>

<form runat= "Server" >
User name: <asp:textbox runat= "Server" id= "txtUserName"/><br/>
Password: <asp:textbox runat= "Server" id= "txtpwd" textmode= "Password"/>
<p><asp:button runat= "Server" text= "login" onclick= "Login"/>
</form>

The following is an example of MD5CryptoServiceProvider directly generated:
<%@ 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/> Results are into" & _
"An array of bytes. These 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 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>