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Question about Data recovery prevention in Nexus 5

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rachel_taylor
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Default Question about Data recovery prevention in Nexus 5

Hello,
I have decided to replace my nexus 5 because it has developed dead pixels. But i have my personal data like videos, photos and other sensitive information on the device. After doing some research I've realized that its very easy to recover data even after Factory Resetting the N5 or formatting in recovery with help of Disk Digger and other similar sorta apps.
So my question is how will i be able to prevent the recovery of my data if Google employee decides to recover it ? [Because on phone the customer care executive told me my phone will go through a thorough inspection]
I don't want my data to be recovered.
Please suggest me a surefire way to prevent the recovery of my data on nexus device.

PS: Nexus is rooted and running on Android L dev preview
 
rootSU
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Data is recovered because data is never deleted. It just empties the index for the data in the file system (more details on that in my n5 data loss and recovery thread via signature)

Data is only gone for ever when you actually overwrite it.

So factory reset then put say 12 GB of video on there. That will overwrite old data. Then delete that.

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rachel_taylor
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(Last edited by rachel_taylor; 29th August 2014 at 07:35 AM.)
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Quote:
Originally Posted by rootSU View Post
Data is recovered because data is never deleted. It just empties the index for the data in the file system (more details on that in my n5 data loss and recovery thread via signature)

Data is only gone for ever when you actually overwrite it.

So factory reset then put say 12 GB of video on there. That will overwrite old data. Then delete that.

Sent from my Nexus 5 using Tapatalk
thank you so much. I just need a little clarification about overwriting the data, Do i need to overwrite and delete data just once or should i do it several times to be completely sure?
 
Wakamatsu
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Theoretically, there is no surefire method of deletion short of physical destruction of the storage medium. But overwriting the data, even once, will make it too costly and difficult for most people to even bother.
Current phone: something with Android 4.something-something
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rootSU
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thank you so much. I just need a little clarification about overwriting the data, Do i need to overwrite and delete data just once or should i do it several times to be completely sure?
When you write a file to your device, it is written to a block. Let's say you write a file to block 1 then another to block 2. The file system knows which file is in block 1 and 2. When you open the file, the file system tells the is where the file is and retrieves it. If you delete the file in block 1 and 2, the data remains but the file system forgets ota location so it appears gone. Most data recovery methods involve scanning the actual block s and record what it finds to allow access.

If you then write a file to block 1, what used to be there is gone. Standard recovery methods cannot retrieve it.

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rachel_taylor
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Originally Posted by Wakamatsu View Post
Theoretically, there is no surefire method of deletion short of physical destruction of the storage medium. But overwriting the data, even once, will make it too costly and difficult for most people to even bother.
So if i erase (format) and fill up the storage with random data like 10-15 times it would be impossible to restore even for a expert? right?
Im sorry ive become really paranoid about this
 
kilowatt95
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So if i erase (format) and fill up the storage with random data like 10-15 times it would be impossible to restore even for a expert? right?
Im sorry ive become really paranoid about this
Not impossible per se, but it becomes prohibitively expensive (in terms of time and cost) to do so. You don't need to do it 10-15 times though...3 to 5 should be sufficient (and I'm talking really paranoid here, 3 to 5).

kwPhone6: Google Nexus 5 D821: Android 4.4.4 Stock ROM, Franco kernel r61, PhilZ touch recovery
kwPad2: LG G Pad 8.3 V500: SlimKat 4.4.2 Linaro (Infected_ build), PhilZ touch recovery
kwPhone5: Galaxy S III i9305: SlimKat 4.4.4, PhilZ touch Recovery
kwPad ASUS Transformer Eee Pad TF101: SlimKat 4.4.2, TWRP

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Wakamatsu
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Quote:
Originally Posted by rachel_taylor View Post
So if i erase (format) and fill up the storage with random data like 10-15 times it would be impossible to restore even for a expert? right?
Im sorry ive become really paranoid about this
If a person had a million dollars, he could rent electron microscope time and have a trained tech scan your flash media sector by sector and hope to get something useful. I just say, if a dude wants to spend that kind of money to find out the PIN to my bank account with next month's rent in it, he can have at it.

In short, a person has to be SURE that it's worth it or he won't even bother.
Current phone: something with Android 4.something-something
 
rootSU
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Jeez.

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