Criticism of Dropbox centers around various forms of security and privacy controversies surrounding Dropbox, an American company specializing in cloud storage and file synchronization. Issues include a June 2011 authentication problem that let accounts be accessed for several hours without passwords, a July 2011 Privacy Policy update with language suggesting Dropbox had ownership of users' data, concerns about Dropbox employee access to users' information, July 2012 email spam with reoccurrence in February 2013, leaked government documents in June 2013 with information that Dropbox was being considered for inclusion in the National Security Agency's PRISM surveillance program, a July 2014 comment from NSA whistleblower Edward Snowden criticizing Dropbox's encryption, the leak of 68 million account passwords on the Internet in August 2016, and a January 2017 accidental data restoration incident where years-old supposedly deleted files reappeared in users' accounts.