What happens to information?

[vorlon13]

If you want something deleted, ask Hillary.

[Excited Penguin]

The only way to truly "erase" data instantly would be to replace the address space of the data that is being deleted with a seemingly senseless collection of bits simultaneously whilst deletion.
But that would pave way to even move complications and inefficiencies.

Consider this set of bits:
1 0 1 0 1 1 1 0 0 1 0 0 1

Now imagine that you want to delete these bolded bits:
1 0 1 0 1 1 1 0 0 1 0 0 1

Typically,to delete those bits the bits would have to be "shifted" like this:

#1 : 1 0 1 0 1 1 0 0 1 0 0 1 0
#2:  1 0 1 0 1 0 0 1 0 0 1 0 0
#3:  1 0 1 0 0 0 1 0 0 1 0 0 0

As you can see,the previous data has been replaced with even more data,in a particularly inefficient manner which would take a relatively considerable amount of time for huge size's of data,even for 1 or 2 gigabytes of data.So technically speaking,your computer wouldn't be able to free space when you delete something because that particular data would have to be replaced with unrelated bits to actually delete the data.Hence the reason why OS's follow the current method.
I don't know how programs like CCleaner operate but i would never trust them completely.

I think they can overwrite like 36 times over the wiped data - that's an extra option, and if you ask me the best one - so it's basically doing exactly what you're saying except it's not overwriting with meaningless data but with other "meaningful" data - which is serving the same purpose really.

But when I made this thread I wasn't so much talking about information on PCs as about info in general in this technological era. I'm talking about whether future generations will be able to take advantage of our recording capabilities in order to study our times. I was hoping we could banter in that general direction. - And something about the internet. Will future people be able to study internet archives and so on?

[ErGingerbreadMandude]

The only way to truly "erase" data instantly would be to replace the address space of the data that is being deleted with a seemingly senseless collection of bits simultaneously whilst deletion.
But that would pave way to even move complications and inefficiencies.

Consider this set of bits:
1 0 1 0 1 1 1 0 0 1 0 0 1

Now imagine that you want to delete these bolded bits:
1 0 1 0 1 1 1 0 0 1 0 0 1

Typically,to delete those bits the bits would have to be "shifted" like this:

#1 : 1 0 1 0 1 1 0 0 1 0 0 1 0
#2:  1 0 1 0 1 0 0 1 0 0 1 0 0
#3:  1 0 1 0 0 0 1 0 0 1 0 0 0

As you can see,the previous data has been replaced with even more data,in a particularly inefficient manner which would take a relatively considerable amount of time for huge size's of data,even for 1 or 2 gigabytes of data.So technically speaking,your computer wouldn't be able to free space when you delete something because that particular data would have to be replaced with unrelated bits to actually delete the data.Hence the reason why OS's follow the current method.
I don't know how programs like CCleaner operate but i would never trust them completely.

I think they can overwrite like 36 times over the wiped data - that's an extra option, and if you ask me the best one - so it's basically doing exactly what you're saying except it's not overwriting with meaningless data but with other "meaningful" data - which is serving the same purpose really.

But when I made this thread I wasn't so much talking about information on PCs as about info in general in this technological era. I'm talking about whether future generations will be able to take advantage of our recording capabilities in order to study our times. I was hoping we could banter in that general direction. - And something about the internet. Will future people be able to study internet archives and so on?

Yeah sure.Future generations would be able to make use of the information.Information will always be available for everyone what matters is whether they can make use of it i guess

[dyresand]

Most data is not easily recovered you can use shadow copy to recover files but if you use a secure uninstaller or file deletion method said files and data aren't recoverable after that.

[Tartarus Sauce]

Vsauce has an excellent video on just this question.

[Tiberius]

I think they can overwrite like 36 times over the wiped data - that's an extra option, and if you ask me the best one.

I hope not many people do ask you then, because you are completely wrong. The Gutmann method, which is 35 patterns of overwrites was devised in 1996 when both hardware and software was different. Back then, a number of overwrites would be required to make recovery of data highly unlikely. However these days you only need one pass of writing zeroes over the data to make recovery of it highly unlikely.

Even Gutmann himself admits as much. Indeed, people were never supposed to use all 35 patterns of overwrites anyway; they were supposed to select a subset based on the hardware they were using, so the "35 pass" thing is entirely bogus.

So yeah, if you want to irreversibly delete your data, do a single overwrite of zeroes. Anything more is overkill.

Back in 2008 researchers did a single pass overwrite of a hard drive containing a few files. They sent the hard drive to three top data recovery companies and asked whether they could recover the data. All three refused to even take a look, because they knew it would be impossible: http://www.hostjury.com/blog/view/195/th...unaccepted

[Excited Penguin]

I was asumming it worked when I said it was the best one. I don't know squat about this, though, nor do I pretend to. Not sure you got that.

This was a different kind of question overall but no one seemed to pick up on it so I'll just let it go. Maybe I didn't phrase it right. I'm sorry about that. Good to learn a few things about deleting software though.

So what kind of apps do that? Is CCleaner overwriting zeroes, or what? Does anyone know?

[Napoléon]

They sent the hard drive to three top data recovery companies and asked whether they could recover the data. All three refused to even take a look, because they knew it would be impossible: http://www.hostjury.com/blog/view/195/th...unaccepted

You sure it wasn't just because the prize is a paltry 40 bucks?

[Tartarus Sauce]

I think they can overwrite like 36 times over the wiped data - that's an extra option, and if you ask me the best one.

I hope not many people do ask you then, because you are completely wrong. The Gutmann method, which is 35 patterns of overwrites was devised in 1996 when both hardware and software was different. Back then, a number of overwrites would be required to make recovery of data highly unlikely. However these days you only need one pass of writing zeroes over the data to make recovery of it highly unlikely.

Even Gutmann himself admits as much. Indeed, people were never supposed to use all 35 patterns of overwrites anyway; they were supposed to select a subset based on the hardware they were using, so the "35 pass" thing is entirely bogus.

So yeah, if you want to irreversibly delete your data, do a single overwrite of zeroes. Anything more is overkill.

Back in 2008 researchers did a single pass overwrite of a hard drive containing a few files. They sent the hard drive to three top data recovery companies and asked whether they could recover the data. All three refused to even take a look, because they knew it would be impossible: http://www.hostjury.com/blog/view/195/th...unaccepted

I'm a tech nub so excuse me for my ignorance, but what's the difference between a pass overwrite and a normal overwrite (the typical "data delete" where the markers are switched to empty instead of occupied)?

[Tiberius]

I was asumming it worked when I said it was the best one. I don't know squat about this, though, nor do I pretend to. Not sure you got that.

This was a different kind of question overall but no one seemed to pick up on it so I'll just let it go. Maybe I didn't phrase it right. I'm sorry about that. Good to learn a few things about deleting software though.

So what kind of apps do that? Is CCleaner overwriting zeroes, or what? Does anyone know?

I believe CCleaner has an option to do a single pass overwrite. I'm not sure whether they zero the data or write random bits, or even all ones. In an ideal world, any three of those methods would be enough to wipe the data, however writing zeroes or ones is realistically better than random bits, because random number generators are not perfect and could potentially leave patterns in the data.

They sent the hard drive to three top data recovery companies and asked whether they could recover the data. All three refused to even take a look, because they knew it would be impossible: http://www.hostjury.com/blog/view/195/th...unaccepted

You sure it wasn't just because the prize is a paltry 40 bucks?

The prize for people applying was $40. They contacted three top data recovery companies and asked whether they would be able to do it; I don't believe a prize was mentioned to them, and the correspondence quoted on that site ended with the saleperson offering a quote. The fact that all three companies rejected the job demonstrates that the likelihood of data recovery in this instance is close to impossible, if not entirely impossible.

I'm a tech nub so excuse me for my ignorance, but what's the difference between a pass overwrite and a normal overwrite (the typical "data delete" where the markers are switched to empty instead of occupied)?

There's no difference at all. The language is just very abstract to allow people to talk about storage without having to actually talk about what happens on the disk. On regular HDDs (not solid state), the data is stored in magnetized regions on the disk. The regions have a polarity which is either N/S (North then South) or S/N (South then North). One of these is considered a "1", the other a "0". Nothing gets overwritten or "switched to empty", but rather the polarities of the regions get changed. If you wanted the "zero" the disk, you would just set all the regions to the same polarity (e.g. N/S).

Now there is a difference between a multi-pass overwrite and a single overwrite. The difference being that instead of writing over the data once, you do it multiple times, and often you change what is being written with each pass. A popular (but again, ultimately unnecessary) 3-pass overwrite involves first writing 0's over the data, then writing 1's over the data, and then finally writing random 1's and 0's. This is the method used by the DOD, but you only have to Google "DOD 3 pass wipe" and most of the articles are debunking it.