"I Saw Images I Didn't Even Know I Had": Understanding User Perceptions of Cloud Storage Privacy.

More than a billion people use cloud-based storage for personal files. While many are likely aware of the extent to which they store information in the cloud, it is unclear whether users are fully aware of what they are storing online. We recruited 30 research subjects from Craigslist to investigate how users interact with and understand the privacy issues of cloud storage. We studied this phenomenon through surveys, an interview, and custom software which lets users see and delete their photos stored in the cloud. We found that a majority of users stored private photos in the cloud that they did not intend to upload, and a large portion also chose to permanently delete some of the off ending images. We believe our study highlights a mismatch between user expectation and reality. As cloud storage is plentiful and ubiquitous, effective tools for enabling risk self-assessment are necessary to protect users' privacy.