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Enhancing security and privacy in online social networks
Sonia Jahid

Social networks have traditionally had some strange ways of dealing with security and privacy, and bring new challenges. How do we handle it if you leave a comment on a private photo and that later becomes public? Right now many networks would make the comment public, but does that make sense?

Sonia Jahid notes that one of the oddities of the social network is that traditionally we don't go through a 3rd party to talk to our friends, and some of the challenges towards a private and secure social network stem from that change. She proposes looking at a more decentralized model, but this forces us to make new decisions and answer new questions. For example, where is data going to be stored? (will I keep it myself? what if I'm offline?) What does access control mean for social networks? How do those models change if the network is decentralized? How can one efficiently provide something like a news feed for a distributed network?

I think one of the key insights of this talk is that while these questions may not seem that urgent for a facebook status update (what if you don't care about those?), many of these questions come up in other applications. For example, medical record sharing can be likened to a social network, where patients, doctors, hospitals, specialists, etc. all want to share some data while keeping other data private. And bringing the problem into the healthcare space brings other challenges: what if we need a "in case of emergency break glass" policy where if the patient is hospitalized while traveling, her medical data can still be accessed by the hospital that admits her. What if the patient wishes to see an audit listing everyone who has accessed her data? (How can we make that possible while keeping that information private from other folk?)

There's clearly some really interesting problems in this space!

Securing Online Reputation Systems
Yuhong Liu


Trust exists between people who know each other, but what if we want to trust people we may not know? This is the goal of reputation systems, but these ratings can be easily manipulated. Yuhong Liu points out a movie rating that was exceptionally high while the movie was during its promotional period, but fell rapidly once it had been out a while. Her research includes detecting such ratings manipulation.

For a single attacker, common strategies include increasing the cost of obtaining single userids, investigating statistically aberrant ratings, or giving users trust values, but all of these can be worked around, so Yuhong Liu's research includes a defense where she builds a statistical model based on the idea that items have intrinsic quality which is unlikely to change rapidly. She found that colluding users often share statistical patterns, making it possible to detect them.

One of the interesting things about this talk was a question from the audience about the complexity of this model: Because the first pass of the model uses a threshold to determine areas of interest in the ratings, we can avoid doing larger checks constantly and can focus only on regions of interest, making this much more feasible as far as run time goes. Handy!

On Detecting Deception
Sadia Afroz


Deception: adversarial behaviour that disrupts regular behaviour of a system

Sadia Afroz's work involves detecting deception three areas:
1. in writing where an author pretends to be another author.
2. websites pretending to be other webites (phishing)
3. blog comments (are the legit or are they spam?)

All of these are interesting cases, but I was most fascinated by the fact that her algorithm was fairly good at detecting short-term detection (e.g. a single article aping someone else's style) but had more difficulty detecting long-term deception like in the case of Amina/Thomas MacMaster. (This might be interesting to [personal profile] badgerbag?) Are long-term personas actually a different type of "deception" ?


All in all, lots of food for thought in this session. I've also uploaded my raw notes to the GHC12 wiki in case anyone wants a bit more detail than in this blog post.

Note: If you're one of the speakers and feel I accidentally mis-represented your talk or want me to remove a photo of you for any reason, please contact me at terri(a)zone12.com and I'd be happy to get things fixed for you!

Date: October 4th, 2012 12:19 pm (UTC)
altamira16: A sailboat on the water at dawn or dusk (Default)
From: [personal profile] altamira16
Thank you for writing about the talks.

Date: October 5th, 2012 08:41 pm (UTC)
ivy: Two strands of ivy against a red wall (Default)
From: [personal profile] ivy
This was really interesting to me -- thanks for the writeup! I've never been to GHC, but now I'm thinking that maybe I ought to make the time. (I have been really burned out on conferences lately.)

Date: October 11th, 2012 10:02 pm (UTC)
From: [personal profile] gailcarmichael
I know what you mean about GHC having high quality speakers. Even if some of them are what I consider "status quo" (which I think could be better), the general high quality even of these speakers really hit home after attending another conference this week. I was starting to feel like I was the only person there who knew how to give a decent talk. Ugh.

Date: October 13th, 2012 12:06 am (UTC)
From: [personal profile] gailcarmichael
Looks like it! I'll ponder a good title. We've got some time. ;)


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