ASP.Net using a RegularExpressionValidator to make sure there's at least one special character

Question

I'm working on an ASP.Net application and I need to make sure my password field contains at least one special character.

This is what I have:

<asp:TextBox ID="Password" runat="server" TextMode="Password" />
<asp:RequiredFieldValidator ID="rfvPassword" runat="server" ForeColor="Red"
    ErrorMessage="Password Required" ValidationGroup="vgErrors" 
    ControlToValidate="Password" Display="Dynamic" Text="*" />

Then I need to add an <asp:RegularExpressionValidator > to this field as well which needs to take the following special characters: (including a space)

 !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

I'm struggling to implement this because I'm not too familiar with the <asp:RegularExpressionValidator > control, and I'm having some issues since they're special characters.

Answer 1

You can use the following regular expression to match a password containing between 8 and 16 characters, including one special character from your list. You can change at your need the range of total characters allowed:

^(?=.*\w)(?=.*[ !"#$%&'()*+,-./:;<=>?@[\]\^_`\{\|\}\~]).{8,16}$

In your aspx page, add a RegularExpressionValidator:

<asp:RegularExpressionValidator ID="revPassword" ControlToValidate="Password"
     ForeColor="Red" ValidationGroup="vgErrors" runat="server" ErrorMessage="Error Message"/>

In the code-behind of your aspx page, you can set the ValidationExpression of your RegularExpressionValidator:

revPassword.ValidationExpression =
    "^(?=.*\\w)(?=.*[ !\"#$%&'()*+,-./:;<=>?@[\\]\\^_`\\{\\|\\}\\~]).{8,16}$";