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Anonymous #1
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Erasing Sensitive info
#19193478 - 11/26/13 06:28 PM (10 years, 2 months ago) |
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I know very little about this.
Say you had some sensitive info on a comp that you wanted to get rid of permanently, would putting it in the trash and deleting it, then erasing the free space on your computer be good enough? I have the option to do a 35 pass delete, which I think just means it gets encrypted 35 times. Would the info be virtually irretrievable?
Thanks
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Alan Rockefeller
Mycologist

Registered: 03/10/07
Posts: 48,276
Last seen: 9 hours, 34 minutes
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It used to be that you needed to wipe the data 7 times or else it could be recovered with an electron microscope. Due to increased storage capacity, these days the sectors are so small that overwriting it once is enough to make it impossible to recover.
In theory, deleting and wiping free space should do it, but that is not the most effecient way to accomplish this and there is no guarantee that the data is actually gone. Often data you are working with is stored in page / cache / temp files without your knowledge by both the OS and applications.
It would be best to use a secure delete tool that overwrites the file. With unix (and mac), a good tool to do this is srm. There are many free tools for windows that do this as well.
If you want to be sure that your data is gone from all page / cache / temp files, it is smart to use a tool that searches all sectors on your hard drive, whether in use by a file or not. With unix / mac you can accomplish this with a command like "strings -a /dev/hard-drive-device | grep -i "a unique string from your file"". With Windows there are several free tools available that can search an entire drive for a certain string.
Making sure an image is totally gone is more difficult, but the same principle applies. Save a random chunk of data from the middle of your image file, and search the drive for it. If you find it, delete the file with a secure delete tool.
I do computer forensics for a living and would be happy to answer any further questions you may have.
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dontknow
It's all in the reflex


Registered: 07/05/13
Posts: 3,889
Last seen: 7 years, 3 months
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Thanks I'll take you up on that soon too high right now
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The discerning heart seeks knowledge, but the mouth of a fool feeds on folly. -Proverbs 15:14
“Imagination is everything. It is the preview of Life’s coming attractions.” Albert Einstein
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xpl0de
ḆËŦŦЯ_őƑ_Ŧwo ƹvïlz




Registered: 07/14/07
Posts: 2,213
Last seen: 3 years, 10 months
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you'll be fine with 35 passes OP. Like Alan recommended, srm is indeed a great tool.
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blackdust


Registered: 02/28/09
Posts: 8,327
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Re: Erasing Sensitive info [Re: xpl0de]
#19207421 - 11/30/13 05:32 AM (10 years, 2 months ago) |
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I take hammers to my hard drives!
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Alan Rockefeller
Mycologist

Registered: 03/10/07
Posts: 48,276
Last seen: 9 hours, 34 minutes
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Re: Erasing Sensitive info [Re: blackdust]
#19207827 - 11/30/13 09:02 AM (10 years, 2 months ago) |
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Quote:
blackdust said: I take hammers to my hard drives!
Unnecessary, but works.
Just overwriting all the sectors once is enough.
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dontknow
It's all in the reflex


Registered: 07/05/13
Posts: 3,889
Last seen: 7 years, 3 months
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Quote:
If you want to be sure that your data is gone from all page / cache / temp files, it is smart to use a tool that searches all sectors on your hard drive, whether in use by a file or not. With unix / mac you can accomplish this with a command like "strings -a /dev/hard-drive-device | grep -i "a unique string from your file"". With Windows there are several free tools available that can search an entire drive for a certain string.
Hey I know nothing about terminal (I'm on mac) but i replaced "a unique string from your file" with part of the name of the file I've long since deleted and erased over. I'm not sure what a string is though.
The message i got back from terminal was "can't open file: /dev/hard-drive-device (No such file or directory)" This seems good, but is the file name enough to search for? Thanks
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The discerning heart seeks knowledge, but the mouth of a fool feeds on folly. -Proverbs 15:14
“Imagination is everything. It is the preview of Life’s coming attractions.” Albert Einstein
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