Two-factor authentication requires a user of FaceTime or iMessage to enter a separate application-specific password after logging in with their usual username and password.
This means another layer of security, as the application-specific passcode can only be obtained by using an Apple ID account on the web. Even if the username and password of an account holder is compromised, their iMessage and FaceTime apps cannot be used by attackers without access to their Apple ID account.
If users of FaceTime or iMessage log out of these applications or try to log in on other machines, two-factor authentication will require them to enter a second passcode to successfully log in.
Two-factor authentication is an optional service that tightens security for Apple Inc. (NASDAQ:AAPL) account holders which means users can opt not to use it. It was first rolled out by Apple Inc. (NASDAQ:AAPL) in March 2013 for Apple ID accounts.
Apple Inc. (NASDAQ:AAPL) also expanded the coverage of two-factor verification for iCloud last September after iCloud accounts of some certain celebrities were compromised. The attack leaked private photos of these celebrities.
Carl Icahn’s Icahn Capital LP owned over 52.76 million Apple Inc. (NASDAQ:AAPL) shares by the end of the third quarter of 2014. Worth then at about $5.32 billion, the stake made up 15.8% of Icahn Capital’s whole portfolio.