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I am under the impression that, unlike magnetic storage, once data has been deleted from a flash drive it is gone for good but I'm looking to confirm this.

This is actually relating to my smart phone, not my computer, but I figured it would be the same for any flash type memory. Basically, I have done a "Factory Reset" on the phone, which wipes the Flash ROM clean but I'm wondering is it really clean or is the next person that has my phone, if they are savvy enough going to be able to get all my passwords and what not?

And yes, I am wearing my tinfoil hat so the CIA satellites can't read my thoughts, so I'm covered there.

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+1 for the tinfoil hat – Nifle Sep 19 '10 at 15:48
up vote 2 down vote accepted

Yes. Their behavior is identical. Essentially is the same thing.

Files aren't physically sorted in the way you "see" them: files are not located "inside" folders. In fact the're all around the drive. Then you have a folders and that folder is a file which list the locations of the files "inside the folder". When you delete a file, it's deleted from it's location in that file, physically the file remains stored.

Think in a book: the index says where the page is located. If you remove an entry from the index page that chapter doesn't get removed from the book.

So, data deleted can be recovered.

In another hand you're almost right: after deleting a file stored in a traditional magnetic storage it can be recovered at least it's overwritten. After several write passes it can't be recovered. Think in a notebook: when you write the pen prints the shape to the sheet below, and the another below that, etc. That's a traditional magnetic storage. Your question refers to flash memory which doesn't work so. After one pass overwritten there's no data recoverable; so if you delete and overwrite the entire disk you won't need seven passes to secure it.

Now getting more complex: since flash memory are limited in the number of writes they have algorithms to avoid overwrite a once and again over the same piece. They write where have less writes accumulated.

Final and simple recommendation: Format the device then get it full loaded with mp3 or video, then format again. zero index available after that.

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Not quite. There's a tool called Bad Copy which is known for the ability to recover deleted files from flash cards and USB flash drives.

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Note: These tools only work if the drive hasn't been zeroed. Quick formats do not zero the drive. If you perform a long format or zero the drive, these tools are rendered useless. – Maxx Daymon Aug 30 '14 at 21:36

To retrieve deleted data off of a cell phone, it would be necessary to either:

  • desolder the flash chip from the phone's circuit board. As all chips on modern cell phones are BGAs, this is extremely difficult.

  • use exposed JTAG pins to possibly access the flash chip. This is also extremely difficult.

  • install a modified operating system that provides direct access to the flash device. This is generally impossible on Blackberries, somewhat possible on many Windows Mobile phones, and certainly possible on Android or PalmOS phones. Probably also possible on a jailbroken iPhone. Android and PalmOS phones are easy to "jailbreak" and run simple Linux commands that can check free space on the flash. I'm unsure if Windows Mobile allows applications direct access to flash, but it's possible on many models to create custom ROMs, or even run Linux, and do the same.

If you have a Blackberry, I do believe the security wipe feature does zero out the flash.

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Why to reinvent the wheel? It's easier to write a simple app which read the drive sectors. In fact all recovery programs work in that way. On the other hand most mobile phones can mount their sotrage memory as flash drive via USB cable. – Melvyn Sep 19 '10 at 19:05
That is correct, but many phones have additional flash storage that is not exposed as a mass storage device. The Blackberry 8330, for example, will expose an installed SD card as a mass storage device, but not the internal flash holding the address book, installed apps, etc. It only does that through the Blackberry Desktop Manager. – LawrenceC Sep 19 '10 at 20:07

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