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Old 10-09-2007, 04:04 PM   #1
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Default Recovering Deleted Files

I've been looking up on programs that encrypt the deleted files so that they can't be recovered and I need some help with this question.

You encrypt your deleted files with a program. You delete the program you used to encrypt the files. Someone uses a program that recovers deleted files. Now they know what program you used to encrypt the files.

If they know what program you used to encrypt the information, couldn't they solve the encryption and get the information? Please help me.
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Old 10-09-2007, 09:08 PM   #2
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Default Re: Recovering Deleted Files

using the same program isn't what breaks encryption (unless its a really crappy program), you have to know the key to the encryption to decrypt it.
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Old 10-10-2007, 07:28 AM   #3
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Default Re: Recovering Deleted Files

ok, this is how deleting works,

your disk has several platters,
each platter has sets of cylinders
each cylinder has sectors.

on the disk there is a set of pointers to files,
data is stored on the disk in the sectors, so a file might be made of several sectors,
like this
|1000 0101 1100 1000| |1001 0110 1000 0000|

there is a pointer somewhere on the disk that says that the file is stored in that location, consider it a grid reference,

if you delete a file, it simply marks that are of the disk as free, and doesn't overwrite any data.

when a disk is formatted all that happens is the first bit of each sector is re-written so the above becomes
|0000 0101 1100 1000| |0001 0110 1000 0000|

as you can see the




you don't need to encrypt files to deleted them you need to scrub the disk.

generally accepted *best* method is to do this

basically this involves taking the disk and writing and re-writing ones and zeros to it
|0000 0101 1100 1000| |0001 0110 1000 0000|

then you make it look like this
|0000 0000 0000 0000| |0000 0000 0000 0000|
then
|1111 1111 1111 1111| |1111 1111 1111 1111|
then
|0000 0000 0000 0000| |0000 0000 0000 0000|
then
|1111 1111 1111 1111| |1111 1111 1111 1111|
then
|0000 0000 0000 0000| |0000 0000 0000 0000|

that's a 5 pass disk write/erase and is supposable the best you can do without wasting time.

this is working on the premise that if you took
|0000 0101 1100 1000| |0001 0110 1000 0000|

then you make it look like this
|0000 0000 0000 0000| |0000 0000 0000 0000|

the data is theoretically recoverable with the correct highly sensitive equipment.

(disks store information by arranging a magnetic particle at a different angle,

so 1 = |
0 = _

when you change a 0 to a 0, if it's been a 0 for a long time the particle might end up like this /, that's because the disk has gained some of the magnetic influence of the magnetic particles previous domain.

in theory changing, re changing, changing and re changing will lead to all bits on the disk having the same domain, even if that domain is slightly squiff


so far as encrypting the data goes...

changing

|0000 0101 1100 1000| |0001 0110 1000 0000|
to
|0000 1010 0011 0001| |1000 0110 0001 0000|
(see what I did?) there each word is reversed (a 4 bit number is a word, that's half a byte)

anyway, encrypting something just proves that there was something there in the first place.

securely erasing/scrubbing means that nobody can tell what areas of the disk were, or were not used.
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Old 10-10-2007, 12:31 PM   #4
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Default Re: Recovering Deleted Files

Quote:
your disk has several platters,
each platter has sets of cylinders
each cylinder has sectors.

on the disk there is a set of pointers to files,
data is stored on the disk in the sectors, so a file might be made of several sectors,
like this
|1000 0101 1100 1000| |1001 0110 1000 0000|
The program I used to encrypt files. It lets me choose the "block size" and it's options are small, normal and big. Do you know what this is? When I had first looked up the word block I couldn't find anything related to computers. After you had posted I looked it up again and it said a block could be a cylinder in a set of units.

Can each sector only have four words?




Quote:
you don't need to encrypt files to deleted them you need to scrub the disk.

generally accepted *best* method is to do this

basically this involves taking the disk and writing and re-writing ones and zeros to it
|0000 0101 1100 1000| |0001 0110 1000 0000|

then you make it look like this
|0000 0000 0000 0000| |0000 0000 0000 0000|
then
|1111 1111 1111 1111| |1111 1111 1111 1111|
then
|0000 0000 0000 0000| |0000 0000 0000 0000|
then
|1111 1111 1111 1111| |1111 1111 1111 1111|
then
|0000 0000 0000 0000| |0000 0000 0000 0000|

that's a 5 pass disk write/erase and is supposable the best you can do without wasting time.

this is working on the premise that if you took
|0000 0101 1100 1000| |0001 0110 1000 0000|

then you make it look like this
|0000 0000 0000 0000| |0000 0000 0000 0000|

the data is theoretically recoverable with the correct highly sensitive equipment.

disks store information by arranging a magnetic particle at a different angle,

so 1 = |
0 = _

when you change a 0 to a 0, if it's been a 0 for a long time the particle might end up like this /, that's because the disk has gained some of the magnetic influence of the magnetic particles previous domain.
in theory changing, re changing, changing and re changing will lead to all bits on the disk having the same domain, even if that domain is slightly squiff

so far as encrypting the data goes...

changing

|0000 0101 1100 1000| |0001 0110 1000 0000|
to
|0000 1010 0011 0001| |1000 0110 0001 0000|
(see what I did?) there each word is reversed (a 4 bit number is a word, that's half a byte)

anyway, encrypting something just proves that there was something there in the first place.

securely erasing/scrubbing means that nobody can tell what areas of the disk were, or were not used.
Over time, will it be like the information was never there? Would you be able to make a guess of how long it would take? I was told that all magnetic objects loss their magnetism after some time(a quick example is a natrual piece of magnetic rock would lose it magetivity in about 10 to 15 years depending on how much it was) and that objects can become magnetic themselfs by being introduced to magetivity over time. If what I had been previously told is true, then marking a | and a _ repeatedly would cover up any trace of the one area at one point to have had more magnetivity in one area over another at a certain point in time.

Do you know why people still make programs that encrypt instead of programs that scrub?

When you said "when you change a 0 to a 0, if it's been a 0 for a long time" did you mean "0 to a 1"?

Is there any writable space on a disk that doesn't have a magnetic | or a _?
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Old 10-10-2007, 06:45 PM   #5
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Default Re: Recovering Deleted Files

Quote:
Eraser
Eraser is a secure data removal tool, which allows you to remove sensitive data from your hard drive by overwriting it with carefully selected patterns.

The program is free software, which means that everyone has access to the source code,
I would just like to add download 'Eraser' to remove data from a hdd. Excellent software which can be found here; http://www.tolvanen.com/eraser/


Nice reply root.
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Old 10-11-2007, 09:09 AM   #6
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Default Re: Recovering Deleted Files

Quote:
Originally Posted by douche.fun View Post
The program I used to encrypt files. It lets me choose the "block size" and it's options are small, normal and big. Do you know what this is? When I had first looked up the word block I couldn't find anything related to computers. After you had posted I looked it up again and it said a block could be a cylinder in a set of units.

Can each sector only have four words?
sectors will have more that four words, i used 4 words sectors in the example because I got bored of typing 1's and 0's.

the information about locks per cylinder can usually be found written on the hard drive

[quote]
Over time, will it be like the information was never there? Would you be able to make a guess of how long it would take?
[quote]Five passes is supposably the least number at least that's what the documentation for DBAN says
Quote:
I was told that all magnetic objects loss their magnetism after some time(a quick example is a natrual piece of magnetic rock would lose it magetivity in about 10 to 15 years depending on how much it was) and that objects can become magnetic themselfs by being introduced to magetivity over time. If what I had been previously told is true, then marking a | and a _ repeatedly would cover up any trace of the one area at one point to have had more magnetivity in one area over another at a certain point in time.
If I get what you're saying then yes that's true... all objects loose magnetivity over time. some quicker than others.

conversely most ferrous metals can gain magnetism as well.and tend to sway to a particular domain. that's why the whole writing/re-writing stuff happens
Quote:
Do you know why people still make programs that encrypt instead of programs that scrub?

When you said "when you change a 0 to a 0, if it's been a 0 for a long time" did you mean "0 to a 1"?

Is there any writable space on a disk that doesn't have a magnetic | or a _?
cause there is still money to be made, some will say that encryption is better than erasing cause the disk is writen with seemingly random data.

yes, too many ones and zeros!

the | and _ were symbolic (but strangly accurate)

the bits on the disk are arranged either longetudinally or traversly by the read/write head whatever the specific domain of the particle then head reads that and knows it as either a 1 or 0
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Old 10-11-2007, 11:48 AM   #7
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Default Re: Recovering Deleted Files

Thank you everyone for your help.
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