alt Hacker NewsMost of the things you've listed here don't actually seem all that reasonable to me.
User agents as a concept are rather poorly thought out across the board and not all that useful but persist because that's just how technical cruft is.
Fonts should be provided by the website; if not provided the choice should take the form of a spec sent by the website including line height, sarifs or not, monospace or not, etc. There's little to no excuse for the current font situation IMO beyond poor design decisions that became heavily entrenched.
Timezone and other obviously private metadata should never be shared without the user explicitly granting permission on a case by case basis. The status quo here is completely inexcusable as is the continued failure to fix the problem.
Size of the physical screen should never be exposed under any circumstances. The current size of the browser window is reasonable on its face but now that fingerprinting is understood to be an issue should always be heavily letterboxed unless the user consents to sharing the exact value.
Video formats should be provided by the website as a list of offerings and the browser should respond with a choice; the user could optionally intervene. There's no reason to expose the full capabilities to a remote service.
Querying the current time should be gated behind an explicit permission. There's almost never a need for it. However from a fingerprinting perspective you also have to worry about correlating the rate of clock skew across clients. That can be solved by gating access to high resolution time counters behind an explicit permission as (once again) the vast majority of services have no legitimate use for such functionality.
Replies
> if not provided the choice should take the form of a spec sent by the website including line height, sarifs or not, monospace or not, etc.
Width of individual characters would still reveal the browser's choice to some extent. Stick them in an inline-block element and check its width.
> Video formats should be provided by the website as a list of offerings and the browser should respond with a choice
The server still controls what's offered and can see what's supported by offering different combinations. Besides, isn't this how it works now?
> fonts should be provided by the website
Yeah, because I love it when every website I go to downloads 10 megs of fonts to my computer before it starts rendering the page. Fonts should be suggested by the website, and a bog-standard "every computer has this" font should be listed as the fallback.
> Timezone and other obviously private metadata should never be shared without the user explicitly granting permission on a case by case basis
100% agree.
> Size of the physical screen should never be exposed under any circumstances
I mostly agree, but with the understanding that this would cause issues with "modern" web pages having very difficult to format layouts. Responsive design requires a response, after all.
> Video formats should be provided by the website as a list of offerings and the browser should respond with a choice
You're still getting the same feedback with this, that the browser chose to use X format, so you're not increasing privacy with this, only difficulty.
> Querying the current time should be gated behind an explicit permission
100% agree. If there is no active local processing of information that the server relies on, in the format of a game or some other interactivity, then there is no reason why the server needs to know your local time.
> Fonts should be provided by the website
No way!
I don’t ever use any font provided by the website. I don’t even let websites choose which fonts get used. Instead I choose a set of fonts (monospaced and proportional) that are readable and everything uses those.
If you want to see what that looks like, go into the Firefox settings, find the Fonts section, click Advanced, and then uncheck “Allow pages to choose their own fonts, instead of your selections above”. Be sure to adjust the “Minimum font size” while you’re here so that nobody uses text sizes that you cannot read.