Re: [cryptography] Deleting data on a flash?

2013-09-23 Thread Trevor Perrin
On Mon, Sep 23, 2013 at 1:25 AM, Adam Back wrote: > > For wear-leveling its more tricky, but it I think the trick to deletion > would be to delete and temporarily fill the disk - even wear leveling has to > delete then. Reardon et al have some good analysis of this [1,2]. They propose keeping th

Re: [cryptography] Deleting data on a flash?

2013-09-23 Thread Peter Gutmann
Adam Back writes: >Apparently or so I've heard claim SSDs also offer lower level APIs to >actually wipe physical (not logically wear-level mapped) cells, to reliably >wipe working cells. Anyone know about those? They could be used where >available and to the extent they are trusted. What you'r

Re: [cryptography] Deleting data on a flash?

2013-09-23 Thread Moritz
On 09/23/2013 10:02 AM, ianG wrote: >> The issue is that it's pretty much impossible to delete data securely >> from a flash device. > Why is that? The flash memory controller hides the real storage cells from you and spreads writes across all cells equally for wear-leveling. You cannot directly a

Re: [cryptography] Deleting data on a flash?

2013-09-23 Thread Adam Back
While I get wear leveling is a problem, I'm not sure if the flash in a phone is even going to use wear-leveling, but say for the sake of argument it does. It is however not a completely brand-new problem, relatedly spinning disks now and then suffer sector failures, and the failed sectors are rem

Re: [cryptography] Deleting data on a flash?

2013-09-23 Thread Eugen Leitl
On Mon, Sep 23, 2013 at 11:02:45AM +0300, ianG wrote: > On 23/09/13 07:12 AM, Dev Random wrote: > >I've been thinking about this for a while now and I don't see a way to > >do this with today's mobile devices without some external help. > > > >The issue is that it's pretty much impossible to delete

[cryptography] Deleting data on a flash?

2013-09-23 Thread ianG
On 23/09/13 07:12 AM, Dev Random wrote: I've been thinking about this for a while now and I don't see a way to do this with today's mobile devices without some external help. The issue is that it's pretty much impossible to delete data securely from a flash device. Why is that? That means