[guardian-dev] Is a secure wipe possible on Android?

Adrian-Ken Rueegsegger rueegsegger at swiss-it.ch
Thu Jan 27 12:43:21 EST 2011


Hi,

Am 27.01.2011 06:18, wrote Nathan Freitas:
> Please tell me why this won't work[1], is a bad idea, or why this very
> simple app doesn't exist yet for Android devices with 'dd' on them. For
> most people, I could see this as a way to just zero out memory from time
> to time after they delete sensitive data. The most extreme case is a
> full wipe and zero/random of both internal and external memory.

As I understand it, the issue with current SD cards and most flash
memory for this use case is, that they perform wear-leveling [1]
internally. This means that writes will be spread out over the free
blocks on the flash medium.  There is an interesting paper on secure
deletion for NAND flash file systems [2]. This might be an option to
explore...

Just my two cents,
Adrian

[1] - http://en.wikipedia.org/wiki/Wear_leveling
[2] - http://eoslab.ssu.ac.kr/pdf/2008-5.pdf


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