What if two files have the same digital thumbprint?
Abtrusion Protector uses digital thumbprints of files to determine which
files are allowed to execute. What if a hacker sends me a file with the same
digital thumbprint as one I already have installed? Well, this will never
happen. Although theoretically two different files can have the same digital
thumbprint this is so unlikely that it will never occur.
Abtrusion Protector uses the SHA-1 algorithm to generate its digital
thumbprints (also known as cryptographic checksums or hash values). It is
one of the best studied hash algorithms and is considered very safe. It is
the basis of almost all digital certificates and encryption protocols in
general use today.
Here are some statistics for you:
It would take about 30000 computers, each generating a million different
files a second for a million years to come up with two different files with
the same thumbprint.
To come up with a file that has the same thumbprint as one of the
executable files already on your hard disk, it would take ten billion
computers, each generating a billion files each micro-second for at least
ten billion years.