Apple on Tuesday began offering an additional security protection for iCloud account users, following the theft of nude photos from several celebrities’ accounts last month. The company added a two-step verification process, which involves entering a numerical passcode that is sent by SMS to users’ phones after they’ve entered their username and password.

Apple has already applied a two-step verification feature for iTunes and App Store accounts.

The celebrity iCloud accounts were thought to have been accessed after hackers guessed their usernames and passwords, possibly by answering the security questions Apple poses if someone loses their password.

Apple came under pressure after the nude photos were published on various websites.

Apple says that third-party applications will still be able to access data in iCloud, but users will have to set up application-specific passwords no later than Oct. 1.