Wild Speculation on iPhone 3G S Hardware Encryption

2009-06-08 20:00:00 -0400

At the WWDC yesterday Apple announced the upcoming availability of their iPhone 3G S. In addition to a host of speed optimizations and new OS features Apple announced some new security features for the 3G S models: “Hardware Encryption” and remote wipe.

Ostensibly, the plan is that if your phone were lost or stolen you could issue a remote wipe and be confident that your data couldn’t be accessed. This is a feature that security conscious companies expect based on their experiences with BlackBerry’s “Erase Data and Disable Handheld” feature.

It’s interesting, however, to take a close look at careful wording Apple has used in their communications about the feature:

“iPhone 3G S offers highly secure hardware encryption that enables instantaneous remote wipe. You can even encrypt your iTunes backups.”

It almost sounds like the “whole device” encryption is primarily used to drive the remote wipe feature, not as an active security measure in its own right. If the encryption were used behind the scenes to secure the data on flash, then the remote wipe operation may not delete data. It could just remove the key and the device would “instantaneously” be rendered inoperable.

If that is the approach used there are some potential security implications:

  • If the encryption is fully in hardware, is it really securing the device while running, or is it just enabling remote wipe? Will a strong passphrase (> 4 digits) be required to unlock the key? It’s not likely if background operations and software are running.
  • Next up – the remote wipe trigger. It stands to reason that the device would need cell or network connectivity to initiate a remote wipe. Could you effectively disable remote wipe on an unlocked device by putting it into airplane mode and shutting off networking? What happens if you pop out and replace the SIM card?
  • Finally, there is the matter of the encrypted backups. The statement that you can even encrypt your iTunes backups implies that the feature is optional and that backups wouldn’t normally be encrypted. This may in turn imply that iPhone application data is unencrypted when read off the device during a backup and re-encrypted for storage by iTunes. This lends credence to the idea that the scope of the encryption is limited.

This is all wild speculation of course, since very few substantive details have been released. While there is no doubt that the encryption features will enhance iPhone device security, it remains to be seen how the practical improvements will compare to the launch hype. I strongly suspect that highly sensitive information storage will still require dedicated security applications.

Zetetic is the creator of the encrypted iPhone data vault and password manager Strip and the open source encryption-enhanced database engine SQLCipher.

blog comments powered by Disqus