When using public computers at MIT your privacy is ensured, in part, by the security mechanisms in place. However do not conflate security and privacy. There are important notes to consider when using cluster computers:

• Do not store files locally as these can be read, edited, deleted by cron and others. (They are also routinely deleted without warning)
• cron have management tools which allow for the remote observation/control of public computers. Though we never do so without user consent, we do have that capability
• All files stored on AFS and DFS are, technically, available for viewing to IS&T staff (though not cron). Law enforcement would contact MIT for access. Some requests, such as National Security Letters, would keep you from learning of such requests
• All files you store in the cloud storage services listed here are viewable by the companies providing said services. Further, these are subject to law enforcement requests, including National Security Letters with their accompanying gag-orders: iCloud, Dropbox, OneDrive, Google Drive, Facebook and more than you care to know. Note that some of these (Google and Facebook specifically) are in the business of mining information you store with them and selling it to third parties