write zeros vs disk wiper
August 6th, 2016
then there is softwares which can wipe disks like ccleaner or slim cleaner , it uses different overwrites starts with 1 goes up to 35 so whats the difference between those , i did a little search , some says writing zeros is equal to 1 pass overwrite , dunno if it is true.
and when using diskwiper whats the optimum overwrite pass to make datas impossible to recover
The more passes, the more difficult it is to recover data theoretically.
About the only way to ‘clean’ a drive to ensure no one can ever get at whatever it held (or history of what it did hold), is to physically destroy it.
The more passes, the more difficult it is to recover data theoretically.
About the only way to 'clean' a drive to ensure no one can ever get at whatever it held (or history of what it did hold), is to physically destroy it.
so i have to overwrite it with hammer for complete security i wondered if there is pass which should be enough for a simple user. and whats the difference between writing zeros and overwriting with pass
Pretty much – but a hammer might not be your best tool. A good ol’fashioned campfire for the disc platters (if a HDD) once the drive was cracked open by the local wildlife.
And quite frankly, I haven’t even had to figure out the best way to make waste of a SSD yet; but the campfire is unlikely to be a good solution as there really is nothing to melt quite as nicely as those HD platters.
For the zeros/passes – Image that the HD platter is a mattress. Now let’s imagine that a Mr. Data, takes a seat on the mattress. Even when he gets off, you can still tell that someone took a seat and where he sat by the impression left.
If you were trying to determine where Mr Data had been, you look for those impressions to reconstruct the file.
The idea behind writing zeros and then 1’s (and then doing it over again – a pass), is that you are covering up the impressions left when Mr. Data took a seat. Like a test mattress at the store …if I was the only one to sit down on it, you would see the impression of my fat backside. After 35 people took a go, you can’t see one butt imprint from the next.
Now with testing, the government and others have determined how many passes it takes (sitting down on the mattress over and over) before a single impression is not discernible. The order of writing, times written, etc. all impacts how the impressions left are affected and that is why you see the different ‘securing profiles’.
Meh .. none of this is as good as the campfire though
uahuauahhau i like hammer u like fire i basically know what overwrite does , what i really wonder is , write zeros with WD software is equal to another third party’s software disk wiper at 1 pass ? or writing zeros , and diskwipers with pass selection , have totally different algorithm? i m trying to choose which one to use
http://www.dban.org/
or format and fill it with crap a couple times if your selling etc, if just disposing a good drill does a bloody good job (done a few times).
http://www.dban.org/
or format and fill it with crap a couple times if your selling etc, if just disposing a good drill does a bloody good job (done a few times).
huauhahuauh this topic has awaken everyone’s violent fantasies with hdds overwriting with 3 pass , should be equal to filling hdd with crap , but what i wonder is the difference between overwrite with a pass and writing zeros , or they somehow equal at a point
The software is basically all the same: The act of writing to the drive is the same regardless of the software. It then comes down to usability. What presets are there so that you have a one-click job rather than a 20 click one. WD write zeros only does that – writes zeros. The software that runs through a pass, writes 1’s and 0’s (lessening the mattress impression).
So is WD write zero = 35 passes by some other software – nope.
i wouldnt use 35 pass it would take days on a 4tb external hdd , even 1 pass takes a very long time , but writing zeros seems very short with WD own software compared to overwriting even a single pass with 3rd party software , if they are doing the same thing , in terms of security , why i would spend a day for 4tb. so basically yes i m actually asking for usability , are there advantages in terms of security , overwriting with 1 pass over writing zeros or vice versa
The theory is that you can tell what was there before because magnetic storage is an analogue system converted to digital.
I mean: Lets say we rate magnetic strength from 0 to 100 – anything below 45 is “0” and anything above 55 is a “1”.
But – lets say we over write a 80 rating with a zero – and the result becomes 45 mag rating – taken as a zero digitally BUT when read magnetically shows “45” and can there mean the previous data there was a “1”.
(if it was a zero, mag rated at 35, and you wrote a zero then it might drop to a magnetic rating of 15 – showing that there was a zero there previously).
Not writing it well, but you follow that?
*****
So – if you want to really be safe, you write random digits over the same spot to scramble the “magnetic rating”.
Why is it that you are wanting to do this anyhow?
Why is it that you are wanting to do this anyhow?
Very good question, before it gets moved to OT
If its just for personal security (not selling etc) a quick wipe will be fine.
The theory is that you can tell what was there before because magnetic storage is an analogue system converted to digital.
I mean: Lets say we rate magnetic strength from 0 to 100 - anything below 45 is "0" and anything above 55 is a "1".
But - lets say we over write a 80 rating with a zero - and the result becomes 45 mag rating - taken as a zero digitally BUT when read magnetically shows "45" and can there mean the previous data there was a "1".
(if it was a zero, mag rated at 35, and you wrote a zero then it might drop to a magnetic rating of 15 - showing that there was a zero there previously).
Not writing it well, but you follow that?
*****
So - if you want to really be safe, you write random digits over the same spot to scramble the "magnetic rating".
it is hell of a technical explanation , but in basic you say , using overwrite with a few pass , 3 for example , is always better than writing zeros due to writing zeros just gives you 2 options 0 and 1 or did i get wrong
Why is it that you are wanting to do this anyhow?
i will give my external hdd to a friend of mine , so basically even a format would be enough for me. but i always did 1 pass overwrite until today. i know what overwrite does basically , like the mattress example you given , u try to hide mark of the first person’s butt on matress by making sit another person on it after and after which is equal to passes , then accidently came with the concept writing zeros. made a little search and actually couldnt find an answer whats the difference between overwriting and writing zeros , at least understandable at novice level, i wanna learn it as a knowledge for future uses which should be useful
Writing the 1’s and 0’s .. you absolutely know that all places on the ‘mattress’ are being sat upon. Overwriting with other data – you may hit most of the mattress, but it won’t be consistent with some parts getting no writes and others getting more. @: I had a good laugh when combining the mattress analogy to the magnetic strength – somehow I ended up pondering what the magnetic field strength around a backside might be
hauhahuahua how many passes are required to overwrite j.lop butt by taking into consideration of magnetic field theory basically i got the answers what i needed thank you very much , , and , really appreciate it.
but i m not marking this as solved , since there may be some who want to add additional information also topic have good technical explanations which are rare to find. i even dont mention , harddrive destruction techniques and magnetic field
Oh poor old Gutmann… one random pass over the drive is quite enough actually.
Gutmann is 35 pass as i remember i always wondered if he is really a person who found it
Oh poor old Gutmann... one random pass over the drive is quite enough actually.
With all due respect , would you pass on a drive after one random pass, I’m quite sure you wouldn’t.
The rational side in me says I would, the paranoid says I wouldn’t.
That’s where we agree, although I would never pass a drive on family wise or as part of a PC sale anyway, and I’m pretty sure you wouldn’t either.
That's where we agree, although I would never pass a drive on family wise or as part of a PC sale anyway, and I'm pretty sure you wouldn't either.
what would you do , 3 or 7 pass ?
The question is are you keeping the drive or moving it on to someone else, if moving it on I would fill it with crap, format, repeat, run DBan a few times and still feel worried, and then keep it…..
Nah, I’ve given drives away before… one pass, you seems a bit superstitious
then the question should be , what you were keeping in the drive, for me nothing serious or personal , if it is something like corporate secrets , it should be better to destroy it physically. always one obsessive side of people cant be satisfied but when i think about , if i sell drive to someone a simple person after 3 pass or 7 pass. that person will buy it, then send it to a data recovery firm , then pay hundreds or thousands of dollar for recovery which is still not certain that it will be recovered. the chance of happening this seems same to me with the chance of meteor falls to my head while walking on the road
Nah, I've given drives away before... one pass, you seems a bit superstitious
Maybe, however I’m in a position I don’t need to sell drives, if I sell a used system I would put new in, but that has come about due to working hard in the past (I know not everyone is as fortunate, building for family DBAN it), as for where our OP is coming from I am mystified and to be honest past giving a ~ censored ~!
only a ONE PASS wipe is needed on modern hard drives. the Gutmann method was developed years ago, when hard drives were tiny.. http://itknowledgeexchange.techtarget.com/security-corner/the-great-drive-wiping-controversy-settled-at-last/ one pass defeats even electron microscopy, so, that ‘s the end of it..
The theory is that you can tell what was there before because magnetic storage is an analogue system converted to digital.
I mean: Lets say we rate magnetic strength from 0 to 100 - anything below 45 is "0" and anything above 55 is a "1".
But - lets say we over write a 80 rating with a zero - and the result becomes 45 mag rating - taken as a zero digitally BUT when read magnetically shows "45" and can there mean the previous data there was a "1".
(if it was a zero, mag rated at 35, and you wrote a zero then it might drop to a magnetic rating of 15 - showing that there was a zero there previously).
Not writing it well, but you follow that?
*****
So - if you want to really be safe, you write random digits over the same spot to scramble the "magnetic rating".
it is hell of a technical explanation , but in basic you say , using overwrite with a few pass , 3 for example , is always better than writing zeros due to writing zeros just gives you 2 options 0 and 1 or did i get wrong
If you only overwrite once with a zero then FBI MIGHT be able to reconstruct what was there “under” the zeros written – they do this by measuring the magnetic flux rather than ones and zeros.
If you overwrite 3 times with random data then it destroys any residual “sub-data” that can be retrieved by magnetic measurements.
Think like this:
Drive data bits: 1 0 1
BUT represented by magnetic readings of 85 35 85 (remember, under 45 is treated as zero)
Now you write 0 0 0 there.
BUT the magnetic readings only change to 40 05 40
Now some “spook” agent reads your drive, records the 60 05 60 and recovers the 1 0 1, NOT the 0 0 0 you actually wrote. (Lets assume they know you wrote zeros there). If you had written 1 1 1 then the reading might become 99 60 99
And they will still be able to recover the 1 0 1 (the 60 representing a previous “0” with a “1” magnetic flux change added)
If you do a 3 or 5 pass random write, those magnetic readings become scrambled.
Does that make better sense? It’s a little bit simplistic.
Writing the 1's and 0's .. you absolutely know that all places on the 'mattress' are being sat upon. Overwriting with other data - you may hit most of the mattress, but it won't be consistent with some parts getting no writes and others getting more. @: I had a good laugh when combining the mattress analogy to the magnetic strength - somehow I ended up pondering what the magnetic field strength around a backside might be
The gravitational well depends on the mass and volume of the body at the centre.. LOL!
Now you have me wondering – do our bum cheeks stay together by gravitational attraction?
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As an aside – a far simpler method is to keep two installation dvds of two different types of Linux – say Debian and Mandrake (age is irrelevant).
Then format to Linux drive format (ext2 ?), install one, Reformat to ntfs, then repeat (with the Linux format) with the next version of linux.
The original data should be pretty well scrambled after that!
And you have a legitimate response to “why did you secure scramble your drive if you have nothing to hide” – “I didn’t, I only wanted to try out these Linux versions, Mr. FedSpook.”
Or… microwave the hard drive…
Now you have me wondering - do our bum cheeks stay together by gravitational attraction?
Reverse cowgirl answers that perfectly …….although there could be anti-gravity involved too, so now you have me wondering
Leaving the question of the cosmic forces aside for a second, my general advice when thinking about selling (and worse giving away) any computer equipment to a friend is DON’T. Wiped or not.
No good deed goes unpunished!
You KNOW that if something happens to the drive, lost files, dead, slow, not recognized by his computer and so forth, YOU will be getting the support call!
For the $ you will receive, it never is enough for the aggravation later on.
It’s said, never lend or sell to friends or family – either say no or give it away…
Leaving the question of the cosmic forces aside for a second, my general advice when thinking about selling (and worse giving away) any computer equipment to a friend is DON'T. Wiped or not.
No good deed goes unpunished!
You KNOW that if something happens to the drive, lost files, dead, slow, not recognized by his computer and so forth, YOU will be getting the support call!
For the $ you will receive, it never is enough for the aggravation later on.
you are also making good deeds here on forum by helping people , what will happen to you
@ , i got what you meant but i also read what posted , it also made sense , maybe they didnt consider magnetic thing. i , as a simple person with a simple harddrive started this topic , which goes at a level of cryptography , far beyond my knowledge. so i should set aside and let big boys talk and again thanks for detailed explanation , you r wasting yourself here
(Electron micrography can actually visualise the magnetic spin of the disk bits – it’s the same thing just a different way of seeing it.
If a zero is “-” and a one is “|” then a “\” might mean the original data was a one that has been overwritten with a zero)
At the end of the day – if you’re giving/selling it to people then a one-pass zero will do.
The average person doesn’t have the tech or the desire to recover “sub-deleted” files.
Some, out of some perverse sticky-beak desire might try an undelete program to maybe find nude girlfriend or wife photos.. but a zero pass wipe will remove any chance of undelete programs working.
If you worry about “feds” then you probably have the technology to erase a drive properly – super-strength magnets or microwave killing the drive.. maybe even Thermite charges as they do in the films !!
A guy I knew decades ago used to cook his drives in an electric oven – 220 C for 30 mins will totally bugger the magnetics up.
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