We are very interested in this, but should we be worried about the GDPR? Based on the plugin description it doesn’t seem to collect anything that GAnalytics already does.
How is the data stored? Is it automatically purged at some point of time or can it be purged manually?
Related/Unrelated note: Some browsers are actively working on avoiding fingerprinting. For example Firefox will soon ship with the ability to block this and will be blocked by default soon too.
Unfortunately I am not aware of any big communities that run this plugin. However, in the real world it seems to work pretty well. See https://panopticlick.eff.org/
It depends on how you see it. Every piece of information that is stored cannot be tied to a single individual, which is GDPR compliant. Combining them, you might be able to track individuals.
The plugin uses PluginStore to store at most max_fingerprints fingerprints (default value: 10), purging the oldest to make room for new ones.
I am not sure how their new protection works. In the past, browser extensions were relying on filenames or hashes to do it. Those methods are fragile and minor changes in the fingerprinting script can make them go undetectable.
Big is relative, but I am going to try this in production (tappara.co) when we have our next service break. Could be as soon as next week or one after that.
So it stores 10 most recent prints. Is there a way to purge the prints manually? Are they purged if the user is deleted?
There is no way from the UI, but technically, you could do it from the Rails console. Deleting the user does not purge old Fingerprints, but that is a bug I will have to fix.
user = User.find_by_username("dan")
DiscourseFingerprint::Fingerprint.get_fingerprints(user.id).each do |fp|
DiscourseFingerprint::Fingerprint.remove(user.id, fp)
end
Yes, I believe so. I remember a community had the same problem with mobile devices, especially iPhones due to their build similarity.
I will try and have a look. The news I read said they were using Disconnect’s list which could have been tricked with some little effort.
Should we expect a performance penalty due to this? Our traffic has extreme spikes, based on real time events. Summer time is off-season, so things will be quiet, but during the hockey season we are likely to meet the limits of our server.
One additional idea for fingerprinting the user – what about tagging the users with a unique cookie? That would provide additional information that Harry’s browser has Dan’s cookie? This would obviously happen on shared devices, but might potentially expose trolls that lack technical expertise.
Many thanks for the development efforts and we are most interested in seeing the results.
これは、ユーザーエージェント、画面解像度、タイムゾーン、デバイスメモリなど、20 以上のブラウザ特性を考慮して、各登録ユーザーの一意の識別子（フィンガープリント）を計算することで機能します。
数学の時間: ブラウザ特性が 20 個のみで、それぞれに可能な値が 4 つしかない（注：実際には 20 以上の特性があり、それぞれの値も 4 つ以上あります）と仮定すると、組み合わせ（フィンガープリント）の数は 420 通りになります。つまり、1,099,511,627,776 通りです……地球上の人口はわずか 7,640,175,882 人です。まあ、一部のブラウザ特性は役に立たないかもしれません（例えば、タイムゾーンはローカルコミュニティフォーラムのすべてのユーザーで同じになるなど）……しかし、フォーラムに 76 億人のユーザーがいることはまずありません。
