Comments on: GNU Shred https://pthree.org/2008/12/02/gnu-shred/ Linux. GNU. Freedom. Mon, 09 Oct 2017 10:42:05 +0000 hourly 1 https://wordpress.org/?v=4.9-alpha-41547 By: John https://pthree.org/2008/12/02/gnu-shred/#comment-109369 Wed, 14 Jan 2009 03:00:25 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-109369 Little late here but, I was searching for clues about how to speed up shred and found something you might find interesting.

There is a new version of corutils being used these days, 6.x. It uses a different source for it's PRNG and that seems to be what makes it so slow.

In around 2.5 hours with 6.x I only had 20% of 1 pass of a 180 gig partition finished. I booted an older distribution using 5.x coreutils and in around 2.5 hours it had finished 2 complete passes. Big difference.

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By: ronc https://pthree.org/2008/12/02/gnu-shred/#comment-109051 Tue, 16 Dec 2008 12:19:30 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-109051 Hey Aaron what is the differences between shred and srm?

Thanks

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By: Aaron https://pthree.org/2008/12/02/gnu-shred/#comment-108945 Sat, 06 Dec 2008 16:32:30 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108945 On a filesystem level, any journaled filesystem will have the journal before the available blocks for your data. As such, if you are inside the filesystem, then yes- wiping data on journaled filesystems is a bit more difficult. However, if you back out to the disk level, and blow away the filesystem, as well as the data, then it doesn't matter what the filesystem was underneath.

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By: Damien https://pthree.org/2008/12/02/gnu-shred/#comment-108943 Fri, 05 Dec 2008 01:05:00 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108943 Hey, I was wondering if you had any suggestions for wiping a drive that has an ext3 partition and ReiserFS partition?

The shred man page mentions that it isn't effective on file systems like reiser, but does that apply if i am shred'ing the whole drive?

Any thoughts greatly appreciated!

Also, sorry to hear about your job situation!

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By: DavidM https://pthree.org/2008/12/02/gnu-shred/#comment-108941 Wed, 03 Dec 2008 19:10:29 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108941 I would agree that zero'ing out the drive is more than enough in most cases. I think more drastic measures are only taken due to pure paranoia and mis-information. However there's no harm other than time and perhaps some wear and tear to doing these multiple pass techniques.

I don't know if you've seen this but here's a link to a group that issued a challenge to data recovery firms to recover the data on a drive that had been zero'ed out using dd.

http://16systems.com/zero/index.html

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By: ThaddeusQ https://pthree.org/2008/12/02/gnu-shred/#comment-108940 Wed, 03 Dec 2008 17:42:20 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108940 I like to use:
shred -n 0 -v -z /dev/sdc
I don't know why I prefer this way to just using /dev/zero, maybe it's because I get the progress report.

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By: Mike Rushton https://pthree.org/2008/12/02/gnu-shred/#comment-108939 Wed, 03 Dec 2008 15:39:49 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108939 This is a good article/challenge related to this same idea of data recovery and the assumptions of how easy it is to recover data:
http://16systems.com/zero/

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By: Aaron https://pthree.org/2008/12/02/gnu-shred/#comment-108938 Wed, 03 Dec 2008 12:46:54 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108938 In my experience, USB 2.0 suffers from speed burst. It fills up the cache, the slows down considerably. FireWire 400 doesn't suffer from this. So, even though technically speaking, USB 2.0 is theoretically faster, my experience has generally been that FireWire 400 is faster.

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By: Aaron https://pthree.org/2008/12/02/gnu-shred/#comment-108937 Wed, 03 Dec 2008 12:45:16 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108937 Exactly. Again, as I mentioned in the post, there's no proof that data can be recovered after a single pass of /dev/zero. If they want your data that bad, as you mentioned, there's other ways to get it.

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By: Aaron https://pthree.org/2008/12/02/gnu-shred/#comment-108936 Wed, 03 Dec 2008 12:43:24 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108936 Thanks man. I hope to be back on my feet in no time.

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By: Peter Gutmann https://pthree.org/2008/12/02/gnu-shred/#comment-108933 Wed, 03 Dec 2008 06:42:08 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108933 http://www.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/

[WORDPRESS HASHCASH] The poster sent us '0 which is not a hashcash value.

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By: ethana2 https://pthree.org/2008/12/02/gnu-shred/#comment-108932 Wed, 03 Dec 2008 06:10:35 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108932 ...I noted that you said you used firewire, I bought an external enclosure recently that's USB.. It seems USB 2 is faster than firewire 400, does firewire have a solid advantage in anything other than cpu usage?

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By: Roger https://pthree.org/2008/12/02/gnu-shred/#comment-108931 Wed, 03 Dec 2008 03:42:48 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108931 If an organization has hundreds of thousands of dollars for scanning electron microscopes in order to get at your deleted data then they can just as easily spy on you in other ways. Or pay someone to put a gun to your head!

What the conspiracy theorists do is not look at the big picture. Using attack trees is a good way to work out effective and efficient ways of getting at the data.

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By: boredandblogging https://pthree.org/2008/12/02/gnu-shred/#comment-108930 Wed, 03 Dec 2008 03:25:04 +0000 http://pthree.org/2008/12/02/gnu-shred/#comment-108930 That sucks man. Hope it works out soon for you.

nick

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