EDENWAITH  Hello:

When Mac OS X's Secure Empty Trash erases, it will write over the same location on the hard drive 7 times, which is sort of like "scribbling" over the area so it makes it increasingly difficult to read what was originally on the hard drive.

Permanent Eraser makes use of a method (the Gutmann Method) to erase a file up to 35 times. This will not cause your hard drive to fill up or anything of the like.   
(Version 2.3.5)

EDENWAITH  Yes, if the warning doesn't appear, delete the Permanent Eraser preference file (~/Library/Preferences/com.edenwaith.permanenteraser.plist) and that will reset any settings.  
(Version 2.3.4)

EDENWAITH  What is meant by "traditional means" are specialized software programs and techniques which can scan a drive and retrieve data from files which were deleted, but not fully erased.

If someone is looking for a way to overwrite their files, then things like Secure Empty Trash, Permanent Eraser, or Disk Utility can be used to erase files or zero out an entire drive.

But if you want to make sure that no one will ever be able to retrieve your data, about the only fully secure method is to grind and incinerate your drive.  
(Version 2.3.2)

BELINE  Grind... Hmmm... Yeah...

No, I understand what you are saying, and I think I have found a fairly secure (maybe even over-board) method...

I am using Permanent Eraser for file deletion (I trust the Gutman (sp?) Method over the other options) and then I have ShredIt X run on free-space nightly.

From what I understand about magnetics and how data recovery works, it actually works by sampling the polarity of the plater area near the bit, and not the actual bit it's self. The is because the polarity "leaks" out over time.

Permanent Eraser (while great as an initial step) only writes random data real quick to one spot. Unfortunately, this doesn't effect the nearby area that much, and in the end is about as effective as writing to the spot only once.

I use Permanent Eraser for short-term security, and the nightly wipes of ShredIt to randomize the "spilt" polarities, as they are done over time...

From my research, this is the next best thing to grinding the plater to a fine dust... :-D  
(Version 2.3.2)

BELINE  Having trouble wiping folders containing a large number of files... Hangs...

It also hung while wiping an ISO file... Something about large file sizes?  
(Version 2.3.2)

EDENWAITH  How large of an ISO file were you trying to delete?  
(Version 2.3.2)

BELINE  It happens with any thing/group of size.

Ex: Around 200 JPG files. It will get through about 150 or so of them, and start to slow down, eventually just stopping on one.

Again, I understand how this all works, and that large files (the ISO was 300+ Megs) take a long time to write over 35+ times. But progress should be steady (I think)... Shouldn't it?

Shouldn't a similar size JPG wipe at the same speed no matter if it is the first of the 300th file?  
(Version 2.3.2)

BELINE  I forgot to mention:

MacBook Pro - 10.4.9

Intel 2.33 C2D - 2 GB Ram  
(Version 2.3.2)

EDENWAITH  The largest slow downs I've seen while deleting is deleting an application (which often contains a lot of smaller files inside it), yet a single file of the same size can be deleted relatively quickly.

I will need to test deleting a large iso file and see if I encounter the same problems that you've been having.  
(Version 2.3.2)

EDENWAITH  The problem with Permanent Eraser hanging has been reproduced. This only seems to happen at times when a large batch of files is being erased.

I created a folder of 3000 files, then started to erase them using PE 2.3.2. Around the 250th file, PE stopped erasing. I ran another test, and it had similar results where it had problems around the 250th file (it wasn't the same exact number, but it was close).

However, this test was run a third time on another computer (a recent Mac mini), and it never had encountered any problems.

I will investigate this issue further to solve this issue.  
(Version 2.3.2)

BELINE  Very nice, thank you for still looking into this, as it has been quite a while since I posted this problem.

Very nice.  
(Version 2.3.2)

EDENWAITH  The problem with Permanent Eraser hanging after deleting 250 files has been resolved. The fix will be in the next release of Permanent Eraser.  
(Version 2.3.2)

EDENWAITH  Permanent Eraser 2.3.3 fixes this issue where PE would stall after erasing around 250 files.  
(Version 2.3.3)

EDENWAITH  Secure Empty Trash uses the 7-pass DoD algorithm to erase over the data in your Trash.

Permanent Eraser ups this level by using the 35-pass Gutmann Method when overwriting your data. Permanent Eraser's other advantages over using the Secure Empty Trash are that PE can erase selected files, instead of only those in the Trash and it can also erase CD-RWs and DVD-RWs.  
(Version 2.3.2)

EDENWAITH  If you launched Permanent Eraser by clicking on it, its default action is to erase the Trash.

However, if you are trying to delete certain files which are not in the Trash, drag the file(s) onto the PE icon to delete the selected file(s).

If the application responded in a manner other than how you expected, please elaborate further on how you were using PE.  
(Version 2.3)

JEEPEE  Here is some information: http://rixstep.com/2/20030314,00.shtml .  
(Version 2.2.3)

FERRUCCIO BUSONI  So, then, they're saying it is possible to store 8.75TB on a 250GB drive, provided you overwrite 35 times and then use fancy forensic hardware to recover the rewrites.

Is that really true? It would be far to slow to actually use, but it's still surprising that after 35 random rewrites, you can recover all, or even most, of anything coherent from each layer.  
(Version 2.3.1)

JEEPEE  Where did you read that?

With the Gutmann-method it's, as far as I know, impossible to recover the data.  
(Version 2.3.1)

FERRUCCIO BUSONI  Yes -- I'm saying if you don't use the Gutmann method. If you just overwrite thirty-five times. The Gutmann method is supposedly necessary because even after thirty-five rewrites, your data can be recovered.  
(Version 2.3.1)

JEEPEE  I think that's because you overwrite it 35 times exactly the same way. Gutmann overwrites them using specific patterns and random. Well it's complicated... :-)  
(Version 2.3.1)

EDENWAITH  These are some good points that have been brought up. An option should be present so the warning message appears each time Permanent Eraser is run.  
(Version 2.2.2)

AESCHYLUS  Thanks for being so responsive. I would trust Guttman to keep my ex wife out of my files :)

This could make life a lot more pleasant.  
(Version 2.2.2)

EDENWAITH  Yes, file names are mangled before the file is fully erased.  
(Version 2.2)

JEEPEE  Permanent Eraser uses the Gutmann-method instead of the DoD-method used by Secure Empty trash.

The Gutmann-method uses 35 special passes, which makes it absolutely impossible to recover data. The DoD-method uses 7 special passes, enough to make it extremely difficult (if not impossible) to retreive shredded data.

The Panther-beta had 3 options to choose from: Empty trash, Shred 7 times and Shred 35 times. The last choice was removed, I guess it took too long. :-)  
(Version 2.2)

EDENWAITH  The problem most likely is a result of decompressing the .sit file with StuffIt Expander 8 or higher. There have been problems with StuffIt Expander properly expanding .sit files created with an earlier version of StuffIt.

An alternate download for Permanent Eraser can be found here:

http://www.edenwaith.com/downloads/permanenteraser.dmg.gz  
(Version 2.1.1)

JEEPEE  Panther has it built in, but it can only be done by Terminal. Secure Delete in Panther overwrites 7 times.

It works in all versions of Panther and also in Tiger.  
(Version 2.1.1)

JEEPEE  Works great here on both my iBook and iMac under 10.3.8.

Does srm show up in the Activity Monitor? Try downloading again.  
(Version 2.1)

JEEPEE  Tiger also loves Permanent Eraser 2.1.1  
(Version 2.1.1)

MIKE  Had the same problem when I downloaded it. Problem turned out to be with Stuffit Expander. Downloading disk image from http://www.edenwaith.com/downloads/permanenteraser.dmg.gz solved the problem.  
(Version 2.1.1)

JEEPEE  It uses srm (unix) so it really uses the Gutmann method. You can find more info here: http://www.opensource.apple.com/darwinsource/10.3.7/ and by using Google for example.  
(Version 2.1)

EDENWAITH  Permanent Eraser 2.0 uses the Guttmann Method, which writes over files 35 times, the same procedure that Mac OS 10.3 uses. I do not know how SecretShredder works, so I cannot comment on that.  
(Version 2.0)

HERAGLIO  A. It's Gutmann, not Guttmann. Peter would prefer you spelled his name correctly.

B. Panther does not use Gutmann. It uses Unix purge, exactly 'rm -P'.

C. Gutmann is slower than NISPOM or any other 'pseudo' method, but the speed is in the disk access, not so much in the algorithm. Remember median accesses are measured in milliseconds; internal clock speeds etc in micro- and nanoseconds. The hard drive is always the bottleneck.

D. Different ways to write and flush data can have slight variances in results - in speeds. If a program goes after too much memory at once, this might put a burden on the system's VM. Still, it is important to flush data to disk.

E. If this program flushes data to disk it cannot be faster than the other product mentioned (which is not an authentic shredder anyway), leading me to suspect it does not flush data to disk. When data is not flushed to disk the shredding is no more effective than a simple single overwrite - that is, not effective at all.  
(Version 2.0)

EDENWAITH  A clarification:

Per the Apple's Mac OS X site:

"Securely Delete Files.

You can securely delete files — they’re overwritten with the same 7-pass algorithm approved by the Department of Defense — by choosing “Secure Empty Trash” in the Finder preferences."

This command is performed by using the command srm -m [some_files]

The -m option overwrites the file(s) with 7 US DoD compliant passes (0xF6, 0x00, 0xFF, random, 0x00, 0xFF, random). Early demonstrations of Panther showed several options for securely erasing the Trash, up to 35 times. However, it appears that Apple decided to limit it to just 7 times, instead of 35.  
(Version 2.0)