Private Browsing

Good news… Adobe Flash Player 10.1 can tie into the “Private Browsing Mode” of some browsers, meaning that any local storage is flushed at the end of each session.

I haven’t worked with it across browsers myself yet, but it already tests successfully within Microsoft Internet Explorer 8.0, Mozilla FireFox 3.5, and Google Chrome 1.0. Apple Safari is also reported to be supporting it in the future. (I’m not sure about Opera’s Private Mode, especially in light of their quotes about plugins, but I hope it will also work in Opera.)

This won’t matter for most of us, but is good protection on shared screens (libraries, hotels, etc)… if we enter a password on a public computer, this could clean out all traces in both the browser’s cache and Flash’s Local Storage.

The Flash Player’s local storage options have existed since Player 6 in 2002, possibly earlier. They’re necessary for storing application state across sessions, and also for synching with servers. Back then browsers rarely offered interfaces for managing their own local storage, so Player offered a mini-UI on a context-click, and a larger Settings interface on an webpage to expose your local data store. Now that browsers are offering more mature privacy controls — and ones with which plugins can connect! — it’s great to see many control aspects united in a common interface.

This may cause complications for content developers, however. While “Private Mode” makes most sense for public screens, their alternate name of “Porn Mode” implies use on family machines too. If someone returns to a game after entering Private Mode, then the game may not recognize their previous levels of accomplishment. Even within the same Private Mode session, browsers vary in how they handle inter-page communication, so it may be difficult to retain app-state across HTML refreshes. The last half of the Developer Connection article has more info on potential new support costs.

If you’re working in this area of local storage, then you might also want to check into “3rd-Party Cookies, DOM Storage and Privacy”, a recent survey of how different browsers deal with different third-party storage requests in different user-modes.

Cooperation on “Private Mode” settings is a positive step, but there’s still more work to do… as Adobe’s Brad Arkin recently explained: “For a long time we have been trying to work with the web browser vendors for them to open up the API, so that when the user clicks ‘clear browser cookies,’ this will also clear the Flash Player Local Shared Objects. But the browsers don’t expose those APIs today. That’s something that we’ve been working with the browser vendors, because if they can open up that API ability then we can hook into that as Flash Player, so that when the user clicks ‘clear’ it will clear LSOs as well as the browser cookies. Our goal is to make it as easy and as intuitive as possible for the users to manage Local Shared Objects. There’s a lot of study going on right now around the user interface and the integration at the browser level of how we can best support that.”

(btw, I do not agree with pundits’ speech that “privacy is really, really dead”… most of these arguments are of the form “privacy is not absolute; therefore it does not exist”. Just as with protection from crime or disease, the goal is to minimize your exposure to risk. In this case it’s prudent to minimize the effect of web trackers to create proprietary databases which are then potentially vulnerable to internal or external breaches. Just because we likely cannot resist a highly determined privacy attack does not imply that we should fail to protect against all other privacy risks.)

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