Will Clarkson will present his preFPO on Friday October 21 at 2PM in the CITP Conference room (3rd floor). The members of his committee are: Ed Felten, advisor; Adam Finkelstein and Andrew Appel, readers; Rebecca Fiebrink and Brian Kernighan, nonreaders. Everyone is invited to attend his talk. His abstract follows below. --------------------- Title: Breaking Assumptions: Distinguishing Seemingly Identical Objects Using Cheap Sensors Abstract: Many security protocols and procedures implicitly rely on the idea that certain objects are indistinguishable from one another. With the increasing accuracy and availability of cheap sensors, the landscape of what can be measured has changed, forcing us to re-evaluate our preconceptions of what it means for objects to be treated as identical. In many cases, improperly relying on an item’s indistinguishably can have serious implications. In this talk, I will touch on three different examples of commonly held, but ultimately false, assumptions regarding the indistinguishably of seemingly identical items. I’ll discuss how blank sheets of paper, ‘anonymous’ bubble-forms, and your computer’s speakers are not as indistinguishable as you might think. Re-evaluating the assumption of indistinguishability reveals that each of these items has inherent physical features that allow them to be identified with surprisingly high accuracy. In each of these cases the consequences can be positive, providing for new applications, or negative, violating the application's assumption about indistinguishability.