Re: [Fed-Talk] Really, Truly Wiping an Iphone
Re: [Fed-Talk] Really, Truly Wiping an Iphone
- Subject: Re: [Fed-Talk] Really, Truly Wiping an Iphone
- From: Jeffrey Walton <email@hidden>
- Date: Wed, 12 Sep 2012 14:56:24 -0400
On Wed, Sep 12, 2012 at 2:40 PM, Marcus, Allan B <email@hidden> wrote:
> OK, Apple answered my question:
>
> http://support.apple.com/kb/HT2110?viewlocale=en_US&locale=en_US
>
>
> * Devices that support hardware encryption: Erases user settings and
> information by removing the encryption key that protects the data. This
> process takes just a few minutes.
> * Devices that overwrite memory: Overwrites user settings and information,
> writing a series of ones to the data partition. This process can take
> several hours, depending on the storage capacity of your iPhone or iPod
> touch. During this time, the device displays the Apple logo and a progress
> bar.
>
> So now the question remains: is just moving the keys good enough? Is there
> any way to recreate the keys, or is iErase the way to go?
Removing the keys is OK if the device supports hardware encryption
(and the PRNG used to generate the keys was in good working order). In
this configurations the keys (more correctly, the keybag) are stored
in Effaceable Storage and the storage is overwritten. Effaceable
Storage does *not* reside in bulk storage (such as SSDs and NAND
Flash).
Details: http://esec-lab.sogeti.com/dotclear/public/publications/11-hitbamsterdam-iphonedataprotection.pdf.
> * Devices that overwrite memory: Overwrites user settings and information,
> writing a series of ones to the data partition.
I suspect this is defective due to on-controller compression. There
will be tail bytes that are not overwritten because the string of 1's
will be compressed and less than the hardware's native block size.
In the past, I tried to get specs on the compression algorithm to make
sure it was being defeated - no joy (even when searching through
patents). I think the best bet is to write a random [incompressible]
string.
Jeff
> On 9/12/12 12:38 PM, "Marcus, Allan B" <email@hidden> wrote:
>
>>How long does this secure erase take? (on say a 32GB device)
>>
>>I was under the impression the Erase All Content just deletes the
>>encryption keys. If it's just the encryption keys, couldn't the content be
>>resurrected?
>>
>>I looked into product called iErase (by Zdziarski, so you know it's
>>good).Do you think that is needed, or is the "Erase All Content and
>>Settings" truly and overwrite erase?
>>
>>On 9/12/12 5:56 AM, "Dave Schroeder" <email@hidden> wrote:
>>
>>>On Sep 12, 2012, at 6:08 AM, "Villano, Paul Mr CIV USA TRADOC"
>>><email@hidden> wrote:
>>>
>>>> All the talk of the highest number of resales of phones in history in
>>>>anticipation of today's Iphone 5* announcement has me wondering what the
>>>>absolutely best way to wipe Iphones is without a gun. :0)
>>>>
>>>> Yes, I've googled it but based on who's running/on this list I thought
>>>>you might have tips/tricks that aren't commonly known.
>>>
>>>Secure Erase was implemented in iPhone Software (now called iOS,
>>>obviously) 2.0 and newer.
>>>
>>>Settings -> General -> Reset -> Erase All Content and Settings. This is a
>>>Secure Erase.
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