[Cryptography] So please tell me. Why is my solution wrong?

[Ben Tasker]

On Thu, Feb 9, 2017 at 1:59 AM, Salz, Rich <rsalz at akamai.com> wrote:
>
>
> But I can register fidelity.biz, and get a domain-validated certificate
> for that domain.  How will your system prevent Joe from being phished to
> try to login, give their name and password to my site, when they really
> should have gone to fidelity.com?
> __
>

If I was implementing this, I'd probably tie the image to something in the
site's certificate (whether that's a hash of the pub key or whatever), so
the first time you hit a https site you'd need to be prompted to set a
memorable image. So even if I've set for fidelity.com I'd get a prompt when
I hit fidelity.biz

The problem with that, of course, is when people switch browsers, the image
isn't going to be there, and (combined with possible bugs causing you to
have to re-set it) people are going to get complacent and just reset the
image when they hit fidelity.biz, defeating the point.

And that's before the faff of having to set something (or opt not to) every
time you go to a https site you've never visited before. You could avoid
that by having something in the cert to specify whether that auth mechanism
is required (to avoid the prompt on sites that don't require it), but then
fidelity.biz would just omit it from their cert and we'd be back to relying
on the user noticing that something's missing.

I've only skimmed the paper, but to be honest, I think you'd almost get
equal benefit (and setup annoyance) from having the browser inject a big
red "WARNING: YOU'VE NEVER VISITED THIS SITE BEFORE" when you visit a new
https site for the first time. That at least has the advantage of having
something the user can see, rather than the absence of something they
usually see.




-- 
Ben Tasker
https://www.bentasker.co.uk
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