Take a look at this blackhat talk from Apple's head of security Ivan Krstic, where he explains the mechanism they use to secure credentials stored in the cloud:

Take a look at this blackhat talk from Apple's head of security Ivan Krstic, where he explains the mechanism they use to secure credentials stored in the cloud: https://youtu.be/BLGFriOKz6U?t=22m31s https://youtu.be/BLGFriOKz6U?t=22m31s