Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Tor at the Heart: Firefox

blog.torproject.org

Post reply on HN
Print view View original

21–30 of 77 posts

Re: Tor at the Heart: Firefox

#21

Post by muizelaar »

noja wrote: post #19
SamBam wrote: post #17

Earlier quoted context omitted.

How accurate is canvas fingerprinting? And could it be used in the courts (which would seem a pertinent question for many Tor users)?

Someone else can answer better than me, but https://panopticlick.eff.org claims the canvas fingerprint provides 17 bits of identifying information (click detailed results after testing)

I think this is an over-estimation of the amount of entropy. If canvas hardware acceleration is disabled, the only things that can really have an impact on the output of the panopticlick canvas fingerprint are OS version, user-agent and available cpu vectorization instructions.

Re: Tor at the Heart: Firefox

#22

Post by [deleted] »

noja wrote: post #19
SamBam wrote: post #17

Earlier quoted context omitted.

How accurate is canvas fingerprinting? And could it be used in the courts (which would seem a pertinent question for many Tor users)?

Someone else can answer better than me, but https://panopticlick.eff.org claims the canvas fingerprint provides 17 bits of identifying information (click detailed results after testing)

[deleted]

Re: Tor at the Heart: Firefox

#23

Post by hsivonen »

mburns wrote: post #5
saurik wrote: post #3

Why did they make up this term "uplift" instead of just saying "upstream"?

https://wiki.mozilla.org/Release_Management/Uplift_rules

That page doesn't explain the use of "uplift" to mean what's commonly called "upstreaming". That page refers to "uplift" meaning a patch being added to an older Firefox branch ahead of normal whole-branch promotion. (I.e. cherry pickin from the Nightly channel to Aurora, Beta or even Release ahead of Nightly as a whole becoming the new Aurora, etc.)

Re: Tor at the Heart: Firefox

#24

Post by bzbarsky »

mburns wrote: post #5
saurik wrote: post #3

Why did they make up this term "uplift" instead of just saying "upstream"?

https://wiki.mozilla.org/Release_Management/Uplift_rules

That's not the same thing. "uplift" for that page means "backport from development trunk to a more-stable branch".

Re: Tor at the Heart: Firefox

#25

Post by w8rbt »

niftich wrote: post #20
SamBam wrote: post #17

Earlier quoted context omitted.

How accurate is canvas fingerprinting? And could it be used in the courts (which would seem a pertinent question for many Tor users)?

The 2012 UCSD paper [1] claims they observed 5.73 bits of entropy in their admittedly non-representative population. As with everything, it depends on the user's threat model. In a court setting, it'd depend on how individual pieces of evidence stack up against a user to make them look bad, and whether there is enough reasonable doubt. [1] https://cseweb.ucsd.edu/~hovav/papers/ms12.html

That's less than picking one character randomly from a keyboard. Seems pretty small to me.

    >>> import math
    >>> print math.log(95) / math.log(2)
    6.56

Re: Tor at the Heart: Firefox

#26

Post by selenamarie »

leojackson wrote: post #10
akavel wrote: post #6

Earlier quoted context omitted.

Truth said, I can't find an explanation/definition of what actually an "uplift" means there?

It looks like this page is designed for people who already know what an "uplift" is, but wish to implement it properly. That being said, it also appears that "uplifts" will include bug fixes made in Tor Browser and sent upstream to Firefox, rather than just features added (but disabled by default) as was implied in the OP article. I would have assumed that bug fixes made in a downstream product would already have a m…

Uplift to us is bringing the patches into mozilla-central pref'd off so that Tor developers can just pref features on, rather than re-merge patches for each major and dot release. We also add tend to add tests.

Re: Tor at the Heart: Firefox

#27

Post by bifurcation »

noja wrote: post #8

I'd like to see the canvas fingerprinting dealt with in Firefox mainline, it's used everywhere.

Fingerprinting (in general) is the next thing on the agenda after First Party Isolation. Addressing canvas fingerprinting is in the plan:

https://wiki.mozilla.org/Security/Fingerprinting

https://bugzilla.mozilla.org/show_bug.cgi?id=1041818

Re: Tor at the Heart: Firefox

#28

Post by bifurcation »

kebolio wrote: post #13
saurik wrote: post #3

Why did they make up this term "uplift" instead of just saying "upstream"?

"uplift" in this context seemed to mean to me that they were not upstreaming the patches verbatim but neutering them for Firefox.

It's a mix. Some patches are just getting rebased and landed. For others, the Firefox and Tor Browser teams are working together to re-implement the feature in a way that makes more sense in the broader Firefox architecture.

For example, for First Party Isolation, we took the "origin attributes" feature that we built to support containers (user-specified tracking limitations) and reused it for isolation. In the containers case, origins get tagged with a user-specified label; with First Party Isolation, they get tagged with the top-level origin.

And to be clear, there's no "neutering" going on here. We're adding the full features that Tor Browser has, since the whole point of this exercise is to let Tor Browser user preference changes instead of patches. That means that the full capability of the Tor Browser features are in Firefox if users want to enable them.

Re: Tor at the Heart: Firefox

#29

Post by drvdevd »

muizelaar wrote: post #21
noja wrote: post #19

Earlier quoted context omitted.

Someone else can answer better than me, but https://panopticlick.eff.org claims the canvas fingerprint provides 17 bits of identifying information (click detailed results after testing)

I think this is an over-estimation of the amount of entropy. If canvas hardware acceleration is disabled, the only things that can really have an impact on the output of the panopticlick canvas fingerprint are OS version, user-agent and available cpu vectorization instructions.

Interesting. I wonder to what extent one could trap vectorization instructions in e.g. KVM. Presumably they are unprivileged instructions on x86?
Post reply on HN