Update: Facebook started to show the announced prompt and ask for user consent.
Almost a year after it removed the option for 90% of its members, Facebook informed on Wednesday the remaining 10% that they’ll remove the “Who can search my timeline by name” setting in a few days. Removing this setting si likely a violation of the 2011 FTC settlement.
Timeline concealed to the public
A month ago Facebook announced that they’ll prompt user to get their consent before removing the setting  but they finally decided to just inform users with an email and a very short notice displayed above the News Feed.
In the mail sent to its members, Facebook argues that when they created this setting “the only way to find [them] on Facebook was to search for [their ]specific name. Now, people can come across [their] Timeline in other ways: for example if a friend tags [them] in a photo, which links to [their]Timeline, or if people search for phrases like “People who like The Beatles,” or “People who live in Seattle,” in Graph Search”. However, I’m confident that some users – including me — are not tagged in public photo, do not like public content and have no friend whose “friends list” is public.
Timelines of these users will not appear in public Graph Search results Facebook and there is no public link that could be used to find them. As a matter of fact, people who are not my friends (or friends of friends) can’t even know if I have a Facebook account. As for today, the only solution to find my Facebook Timeline is to test the 1.2 billion userID numbers. In addition to be time consuming, this exhaustive search would violate Facebook Terms of Services.
Private vs Nonpublic
A Timeline page is public because any user can load its content but Timelines URLs (i.e. usernames) are not public since not anyone can find them: without the search functionality, it is not possible to retrieve the Timeline associated to a specific user. Timelines URLs are like unlisted phone numbers or Google Docs shared with “anyone with the link”. These documents may not be seen as private but I would not define them as public (i.e. I’d be unpleasantly surprised to see them used in an endorsed advertisement). I do not claim that Timelines are private, only that they are “nonpublic user information” .
Why Facebook could violate the FTC settlement
The FTC settlement does not focus on user private information but cover the entire nonpublic user information (e.g. a user ID to which access is restricted by a privacy setting). Indeed, Section II-A of the 2011 settlement requires that Facebook “prior to any sharing of a user’s nonpublic user information by [Facebook] with any third party, which materially exceeds the restrictions imposed by a user’s privacy setting (s), shall […] obtain the user’s affirmative express consent”.
Facebook will not only remove the possibility to select who can look-up timelines, they will set the setting to its default values “Everyone”. Hence, Facebook will modify settings of users who set it to a more restricted audience. Obviously the two lines message Facebook displayed and the email they sent to the affected members does not offer a valid solution to get an affirmative express consent. So Facebook will certainly violate the FTC settlement in a few days.
According to Facebook, Graph Search not only helps people finding information about their friends, it also helps them to know what information they reveal about themself. I find this objective questionable especially in France where many people are still not aware that Graph Search even exist  and yet have their profiles searchable by anyone in the US. Yet, Graph Search is certainly very useful and educative about what could go wrong with tagging and shared content.
Last July update of Graph Search makes it even simpler to retrieve list of friends of people who hide it. Indeed, Graph Search now allows you to search who liked or commented on photos. Since some content is only visible to my friends, only they can comment or like my pictures. Having a list of people who liked or commented on my photos is like having a list of my friends with who I share things on Facebook. Some people that I do not know commented on my photos, but that’s a negligible fraction.
Unwanted side effects
Surprisingly, it seems that you can even know if someone liked a photo you don’t have access to. Indeed, in some circumstances, you cannot see which picture has been liked; you only know that someone liked a picture (see bellow). It goes against Facebook claim that Graph Search only gives you access to information you already had.
Update: In fact, the person who liked the picture is not searchable but she appears in the search results because she liked a public photo.
Another annoying effect is that queries like “People who liked photos by me” returns a list of people with who I’m no longer friend. And it’s pretty easy to spot these people because they are systematically at the end of the result list.
How bad is it?
To measure the fraction of the friend list that could be retrieved through Graph Search, I listed the number of results that were listed when I search for:
Q1 :“People who liked photos by X”
Q2:“People who commented on photos by X”
Q3:”People who uploaded photos liked by X”
Q4: “People who uploaded photos of X”
Unfortunately, Graph Search does not (yet?) support ‘OR’ queries so there is no easy way to quantify the overlap between these four queries . I reported numbers of confirmed retrieved friends (using the “mutual friend” filter) and the total number of retrieved people because it also includes former friends. I compare that to the number of friends I have (and I thank my friends who did not hide their friends list).
59 ( 73)
I made some tests on a few friends and I obtained similar results , queries Q1 and Q3 are the more effective queries in general. On average, Graph Search returns 30% of friends, plus some former friends. I guess I could retrieve up to 40-50% by combining the four queries. It’s problematic because many people assume that their friend’s lists are safe, but this safety goes away when they share likable photos or when they like photos.
Since “Like” visibility is public, you can even retrieve some friends of people with who you have no connection. I can imagine many circumstances where having your list of friends publicly available is very problematic.
What can you do?
Unfortunately, you cannot prevent your friends from liking content you share with them. Likes are not like tag or comments: they cannot be removed. The only current solution is to not share “likeable” content or to ask to people to not like it, but that’s very counter intuitive on Facebook. In the end, you can only hide friends who don’t “like” you.
Another solution is to obfuscate the list of people who liked your pictures. I probably rely too much on obfuscation, but asking people you don’t know to like your photos is currently the only technical solution to prevent stalkers from quickly retrieving your friends.
Acknowledgements: Thanks to my stalked friends who do not share their friends lists, they motivated this post. Thanks to those who do share their list, they helped me to make this post relevant.
 If you have not yet enabled “Graph Search”, I recommand you to do so. See http://www.fredzone.org/comment-activer-le-graph-search-de-facebook-929
 I’ll post more results when I’ll get their consent
When Facebook announced Graph Search, they emphasized that they designed it with privacy in mind and yet made two different statements. First, M. Zuckerberg said that it’ll give access only to « things that people have shared with you » while T. Stocky said that «[you] can only search for what [you] can already see on Facebook».
I define the « content I share with you» as the content you can see on my timeline which is in fact a subset of the content you could see about me on Facebook. But Facebook has a different definition and considers « content shared » as everything about me that is visible, even if it normally requires a considerable effort to find it.
Finding pictures with Graph Search
Facebook made it clear that hiding photos on your timeline is no longer enough to prevent people from seeing them. With graph search, it’s now very simple to find all the photos of someone that are visible to you.
For instance, if one of your friends is tagged on pictures that he decided to remove from its timeline, these “hidden” photos will appear in graph search if you have access to them.
It was already possible to find « hidden » pictures a friend was tagged on but it required a considerable amount of time and effort: you had to go through the list of all his friends and check their pictures in case your friend might appear on some of them. Unless you were really creepy, your friends were safe to assume that most of their « hidden » pictures would not be viewed by you. That’s no longer the case and to control who can see your “hidden” pictures you’ll have to delete tags or ask your friends to limit the pictures visibility .
Removing tag is not the solution
Tags is not only a feature used to annotate content, it’s also used to know when someone comments a picture you appear on. If you delete the tag, you lose the possibility to quickly know how people react to a photo. Not removing a tag is different than sharing a picture. Assuming that people want to share every picture they’re tagged on is wrong, especially when they’re a « share » button that allows them to do precisely that.
Unlike posts on your timeline, tags don’t have to be reviewed before they appear in Graph Search. To control photos of you that will appear in graph search, you have to frequently visit Facebook and remove unwanted tags. You have no option to proactively control your image on Facebook other than relying on your friends to not tag you without your consent.
The case of friends list
Strangely Facebook did not adopt the same definition of “sharing” with the “Friends list”. Assuming we’re friends; if you’ve decided to hide yourfriend list from your timeline, I can try to recompose it by visiting each of your friend’s timeline and check that you appear as a mutual friend. It would require knowing some of your friends first, but that’s fairly easy if they posted something on your timeline. By iterating this process, I could retrieve a subset of your friends. Like photos you are tagged on, this subset is presumably shared by you but won’t appear if I search for the list of your friends.