1404017 - Pref for fingerprinting resistance in private browsing mode

Status: RESOLVED DUPLICATE of bug 1450398

(Firefox :: Private Browsing, enhancement, P3)

Description

[Arthur Edelstein [:arthur]]

== Proposal ==

I would like to propose a boolean pref, "privacy.resistFingerprinting.pbm". When true, this pref would enable Fingerprinting Resistance in Private Browsing windows only.

privacy.resistFingerprinting.pbm:
* true: All Private Browsing windows resist fingerprinting; all non-PB windows do not.
* false (default): Normal behavior

== Background ==

Firefox currently has a boolean pref called "privacy.resistFingerprinting". The Fingerprinting Resistance mechanism spoofs or hides numerous characteristics of the user's system from content pages, such as screen dimensions, installed fonts, etc.

privacy.resistFingerprinting has two values:
* true: All content pages resist fingerprinting
* false (default): Normal behavior

== Purpose ==

Users expect Private Browsing windows should protect their privacy. According to a recent survey by DuckDuckGo (https://duckduckgo.com/download/Private_Browsing.pdf):
"""
  • 41.0 ±2.5% believe that Private Browsing “Prevents websites from tracking me.”
  • 39.1 ±2.6% believe that Private Browsing “Prevents ads from tracking me.”
"""

Providing an option to enable Fingerprinting Resistance in Private Browsing windows will help to meet these user expectations. In the future (not in this ticket), we might consider enabling the proposed pref by default.

(See also bug 1397264, where I proposed a pref to lets user enable First-Party Isolation in Private Browsing windows.)

Comment 1

[Arthur Edelstein [:arthur]]

Another alternative would be to convert privacy.resistFingerprinting to an integer. Then the integer could have three values:

0: Fingerprinting Resistance off
1: Fingerprinting Resistance on in all windows
2: Fingerprinting Resistance on in Private-Browsing windows only

Comment 2

[Simon Mainey]

I favor the integer approach (and I think this should be the same for the FPI ticket: Bug 1397624)

Comment 3

[Ethan Tseng [:ethan]]

(In reply to Arthur Edelstein (Tor Browser dev) [:arthuredelstein] from comment #0)
> (See also bug 1397264, where I proposed a pref to lets user enable
> First-Party Isolation in Private Browsing windows.)

A typo here. Arthur meant bug 1397624.

Comment 4

[Ethan Tseng [:ethan]]

(In reply to Simon Mainey from comment #2)
> I favor the integer approach (and I think this should be the same for the
> FPI ticket: Bug 1397624)

+1 for the integer approach.
One less preference means less complexity to me.
For example, we don't have to deal with the case when "privacy.resistFingerprinting" and
"privacy.resistFingerprinting.pbm" are both true.

Comment 5

[Tom Ritter [:tjr] (OOTO until 4/30 at least)]

The next step for this bug is to investigate the callsites of ShouldResistFingerprinting and make a list of the sites where adding OriginAttributes into the callsite will be difficult (because it is not readily available.)  This investigation will also inform us of the feasibility of a "Disable ResistFingerprinting for this Origin" feature.

Hopefully of the difficult callsites, there is some handy boolean hanging around that tells us if we are in a Private Browsing window or not. (That won't solve the 'for this Origin' problem but let's get the list and evaluate it from there.)

I'm passing this bug to Tim for now for the investigation, and when he's able to complete that we can unassign or reassign it.

Comment 6

[nicholas_j]

Any progress on this, please? It is evident that it would be a significant improvement and indeed in an area that Mozilla claims to care greatly about.

Comment 7

[Simon Mainey]

(In reply to nicholas_j from comment #6)

Any progress on this, please?

See Bug 1635603

Comment 8

[William O'Connell]

Bug 1635603 looks to be resolved, is this still being considered/worked on?

Comment 9

[Tom Ritter [:tjr] (OOTO until 4/30 at least)]

We are slowly cutting over callsites in sub-bugs on Bug 1450398 - I'm going to dupe this there. But we are not very close to the finish line, so contributions welcome :) Feel free to reach out if interested.