ruin it by using iCloud.
That is essentially what Steve Gibson said on Security Now this week.
Apple released a document last week detailing the crypto in the iPhone and iPad OS and, according to Steve Gibson, they do everything right. That, combined with the closed market place makes it a very safe platform to use.
Unfortunately, Apple then went and ruined it with their iCloud implementation, especially the iCloud Keychain, which stores passwords and keys for the user on the cloud, so that they are available on all devices. Here they used one of the algorithms that has since been identified as a probable NSA backdoor. The 2 hour long podcast was very interesting and he provides a very detailed look into what Apple do on iOS. The rest of the analysis follows in next weeks episode.
http://twit.tv/show/security-now/446