Storing multiple CAPTCHA solutions in a session

Question

I'm implementing a 3D CAPTCHA for my website.

My original idea was to store the expected captcha solution in a session variable. After a user submits a form, I'd compare it with their response.

What happens if the user opens my website in multiple tabs though? For each tab a new CAPTCHA challenge is generated and the expected response variable in the session is overwritten.

Now consider the user submits a form in an "old" tab. Since the expected response variable in the session has been overwritten, they won't pass the test.

Should I worry about this? How would you deal with it?

don't worry about it. you can't reliably identify WHERE a page request came from (different tab? different window?). At most a person will simply get failures on the "earlier" windows because the "last" window's captcha overwrote the setup. They load up another captcha and off they go. — Marc B
@MarcB: Thanks, just wanted to make sure it's not a bad practice. — packet

Iesus Sonesson Iesus Sonesson · Accepted Answer · 2013-02-15T15:34:52

That is the general approach for captchas and sometimes a reason why they do not validate.

This is a goood read http://www.sitepoint.com/captcha-inaccessible-to-everyone/ why not to use captcha

You could however add them in an array instead and see if the answer exists in array. You are not stating which language you are using otherwise i could provide some code.

Storing multiple CAPTCHA solutions in a session

1 Answers