Schneier on Security

Second SHB Workshop Liveblogging (8)

The penultimate session of the conference was “Privacy,” moderated by Tyler Moore.

Alessandro Acquisti, Carnegie Mellon University (suggested reading: What Can Behavioral Economics Teach Us About Privacy?; Privacy in Electronic Commerce and the Economics of Immediate Gratification), presented research on how people value their privacy. He started by listing a variety of cognitive biases that affect privacy decisions: illusion of control, overconfidence, optimism bias, endowment effect, and so on. He discussed two experiments. The first demonstrated a “herding effect”: if a subject believes that others reveal sensitive behavior, the subject is more likely to also reveal sensitive behavior. The second examined the “frog effect”: do privacy intrusions alert or desensitize people to revealing personal information? What he found is that people tend to set their privacy level at the beginning of a survey, and don’t respond well to being asked easy questions at first and then sensitive questions at the end. In the discussion, Joe Bonneau asked him about the notion that people’s privacy protections tend to ratchet up over time; he didn’t have conclusive evidence, but gave several possible explanations for the phenomenon.

Adam Joinson, University of Bath (suggested reading: Privacy, Trust and Self-Disclosure Online; Privacy concerns and privacy actions), also studies how people value their privacy. He talked about expressive privacy—privacy that allows people to express themselves and form interpersonal relationships. His research showed that differences between how people use Facebook in different countries depend on how much people trust Facebook as a company, rather than how much people trust other Facebook users. Another study looked at posts from Secret Tweet and Twitter. He found 16 markers that allowed him to automatically determine which tweets contain sensitive personal information and which do not, with high probability. Then he tried to determine if people with large Twitter followings post fewer secrets than people who are only twittering to a few people. He found absolutely no difference.

Peter Neumann, SRI (suggested reading: Holistic systems; Risks; Identity and Trust in Context), talked about lack of medical privacy (too many people have access to your data), about voting (the privacy problem makes the voting problem a lot harder, and the end-to-end voting security/privacy problem is much harder than just securing voting machines), and privacy in China (the government is requiring all computers sold in China to be sold with software allowing them to eavesdrop on the users). Any would-be solution needs to reflect the ubiquity of the threat. When we design systems, we need to anticipate what the privacy problems will be. Privacy problems are everywhere you look, and ordinary people have no idea of the depth of the problem.

Eric Johnson, Dartmouth College (suggested reading: Access Flexibility with Escalation and Audit; Security through Information Risk Management), studies the information access problem from a business perspective. He’s been doing field studies in companies like retail banks and investment banks, and found that role-based access control fails because companies can’t determine who has what role. Even worse, roles change quickly, especially in large complex organizations. For example, one business group of 3000 people experiences 1000 role changes within three months. The result is that organizations do access control badly, either over-entitling or under-entitling people. But since getting the job done is the most important thing, organizations tend to over-entitle: give people more access than they need. His current work is to find the right set of incentives and controls to set access more properly. The challege is to do this without making people risk averse. In the discussion, he agreed that a perfect access control system is not possible, and that organizations should probably allow a certain amount of access control violations—similar to the idea of posting a 55 mph speed limit but not ticketing people unless they go over 70 mph.

Christine Jolls, Yale Law School (suggested reading: Rationality and Consent in Privacy Law, Employee Privacy), made the point that people regularly share their most private information with their intimates—so privacy is not about secrecy, it’s more about control. There are moments when people make pretty big privacy decisions. For example, they grant employers the rights to monitor their e-mail, or test their urine without notice. In general, courts hold that blanket signing away of privacy rights—”you can test my urine on any day in the future”—are not valid, but immediate signing away of privacy of privacy rights—”you can test my urine today”—are. Jolls believes that this is reasonable for several reasons, such as optimism bias and an overfocus on the present at the expense of the future. Without realizing it, the courts have implemented the system that behavioral economics would find optimal. During the discussion, she talked about how coercion figures into this; the U.S. legal system tends not to be concerned with it.

Andrew Adams, University of Reading (suggested reading: Regulating CCTV), also looks at attitudes of privacy on social networking services. His results are preliminary, and based on interviews with university students in Canada, Japan, and the UK, and are very concordant with what danah boyd and Joe Bonneau said earlier. From the UK: People join social networking sites to increase their level of interaction with people they already know in real life. Revealing personal information is okay, but revealing too much is bad. Even more interestingly, it’s not okay to reveal more about others than they reveal themselves. From Japan: People are more open to making friends online. There’s more anonymity. It’s not okay to reveal information about others, but “the fault of this lies as much with the person whose data was revealed in not choosing friends wisely.” This victim responsibility is a common theme with other privacy and security elements in Japan. Data from Canada is still being compiled.

Great phrase: the “laundry belt”—close enough for students to go home on weekends with their laundry, but far enough away so they don’t feel as if their parents are looking over their shoulder—typically two hours by public transportation (in the UK).

Adam Shostack’s liveblogging is here. Ross Anderson’s liveblogging is in his blog post’s comments. Matt Blaze’s audio is here.

Posted on June 12, 2009 at 3:01 PM • View Comments