Computer
Forensics:
It is commonly defined as the collection,
preservation, analysis and court presentation of
computer-related evidence. Courts mandate the proper seizure
and analysis of computer evidence in any investigation where
a computer is the means or the instrument of a crime.
The most important tool for a computer forensic investigator
is the software used to perform the investigation. Without
specially designed computer forensic software, there cannot
be a true forensic analysis. FSG has this software.
An important feature of computer forensic software is a
verification process that establishes that the investigator
did not corrupt or tamper with the subject evidence at any
time during the investigation. The software employs a
standard algorithm to generate an image hash value by
calculating a unique numerical value based on the exact
contents of the subject disk drive. If only one single bit
of data changes, such as adding/deleting a character or
changing the case of a character, the hash value is now
different indicating the evidence has been tampered with.
The most common hashing process in use today is the MD5 -
Message Digest number 5 - which is based on a publicly
available algorithm developed by RSA Security. The odds of
two computer files or two images of drives with different
contents having the same MD5 hash value is approximately ten
raised to the 38th power (1 followed by 38 zero's).
For
purposes of comparison, a billion is 1 followed by only 9
zero's.