13. Dispose of the body.pdf

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Chapter 13

Dispose of the body

on’t

get scared. I won’t teach you anything criminal. I’ll only discuss the necessity of

disposing electronic documents. Not everybody knows that if they delete a document

from the disk, by highlighting and pressing

Delete

key, this document isn’t physically

erased yet. The ﬁle with the document is moved to the

Trash

, where it can be restored at any

time. This is not a disposal! This is just the process of careful moving of the document from the

desktop to the waste basket under the desk, where they’ll be accessible to everyone.

Of course, you can empty the

Trash

, and its contents won’t be accessible by standard means

anymore. But you need to understand one thing: Even in this case ﬁles are not erased physically.

Operating systems work in such a way that when they receive the command to delete a ﬁle,

they, roughly speaking, mark appropriate disk space as empty. It is like an apartment for rent:

previous tenants are still there, packing their belongings, but the sign “For rent” is already posted,

and the apartment is available for new tenants.

The same happens with the “deleted” ﬁles. And the basic problem with them is that before

new “tenants” (that is ﬁles) occupy “empty” space, “deleted” ﬁles can be restored. There are

software tools to accomplish that. And what is particularly interesting, the way ﬁles are recorded

on the disks makes it possible to restore ﬁles days, weeks, and even months after they were

“deleted”.

Every now and then you may hear about situations when people buy second-hand “empty”

disks, and on closer examination ﬁnd there quite interesting information.

Therefore, you need to distinguish delete from safe delete. Safe delete doesn’t just free some

parts of the disk, but also ﬁlls that space with zeroes, or other characters. So, if intruders manage

to restore deleted ﬁles, all they will get will be some garbage. This technique is called

data erasure

(sometimes referred to as data clearing or data wiping). It is implemented in a number of small

but efﬁcient programs, many of which are distributed for free, like, for example,

BleachBit.

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