Alexandre recently finished up work adding an opt-in option for flash proxies. Now, clicking on the badge will bring up this page with yes/no buttons:
http://crypto.stanford.edu/flashproxy/options.html
The default model is still opt-out, though this may change in the future. If you want to make the badge on your site opt-in-only, add the cookierequired query parameter to your iframe, and encourage your visitors to visit the options page. The options work by setting a cookie.
<iframe src="//crypto.stanford.edu/flashproxy/embed.html?cookierequired" width="80" height="15" frameborder="0" scrolling="no"></iframe>
To summarize, here is what happens if you use cookierequired or not. The only difference is when the user hasn't set a cookie at all.
Without cookierequired: no cookie cookie=no cookie=yes Will I be a proxy? yes no yes With cookierequired: no cookie cookie=no cookie=yes Will I be a proxy? no no yes
If we switch to opt-in by default in the future, we'll ignore the cookierequired parameter and always use the no/no/yes part of the table. It will also help us switch to opt-in-only if we can get lots of people to opt in in advance.
David Fifield