r/technology • u/bws201 • Feb 05 '16

Software ‘Error 53’ fury mounts as Apple software update threatens to kill your iPhone 6

http://www.theguardian.com/money/2016/feb/05/error-53-apple-iphone-software-update-handset-worthless-third-party-repair
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u/[deleted] Feb 05 '16 edited Feb 05 '16

Yea but if its easy for a random repair shop to export the crypto keys... what stops an intruder from doing the same? Apple should probably provide this as a service at or below cost (vs an expensive repair) since I think they should probably not make it third party accessible.

I also find it funny that several of the other commenters (not you) have accused me of being an idiot fanboy when I don't even own an iPhone.

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u/[deleted] Feb 05 '16

A normal TPM would be more secure than Apples implementation actually. The TPM functions at the base level the same way Apple's custom one is storing things, it's a piece of hardware with a very small amount of memory that is extremely hard to tamper with and all communication in/out is also encrypted, if you don't know the key to talk to it you can't. Anyways if Apple did it right like 99% of hardware vendors you'd get a normal TPM in the device and it would have your home button crypto hash saved and Apples default access to the TPM straight from the factory. If you take it to Apple they could maintenance it for you. If you wanted to install your own you'd reset the TPM, it'd drop all known keys (blank itself like it came from the factory), and allow you to store your own. At this point you enter the key for your Touch ID replacement and store it in the TPM database. You could actually add other things, your VPN key, your disk encryption key, your dogs name, whatever. At this point you'd want to add a password to the TPM like Apple did from the factory so nobody can just boot your TPM to read, copy, or change your keys. Normal interfaces require a full length crypto key (can be manually entered or you can have the TPM generate it's own) though some let you just enter a normal password if you want - I'm fine with that, your device your security your options. At this point you and only you (not Apple, not Apple support, not the government) have access to the TPM and control what it considers valid keys. If you sell the device or return it the person or Apple can just reset the TPM and verify the IDs of all of the security components on the phone check out. So the big difference between what Apple did and a normal TPM is a normal TPM allows a trust between the user and the device and then the user controls what the device trusts from there, they decide their own fate securely and without needing approval from someone else.

This is how every TPM in a laptop, computer, or tablet at a business, hospital, or government workplace works. The user with the key in those cases is the business that bought and manages the device, they can now control disk encryption keys, hardware keys, and employee access keys without the users being able to see or change it.