signature for a file ?

[Paul Rubin]

"Shagshag13" <shagshag13 at yahoo.fr> writes:
> > same MD5 checksum, it's basically certain that the files are
> > identical.
> 
> thanks for this, (so no need to use SHA or CRC ?)

SHA and MD5 do pretty much the same thing.  SHA is a little newer and
preferred for high security uses, but that's not really what you're doing,
so it doesn't matter much.  MD5 is a bit faster.  

CRC's are sort of the same idea, but they're easier to fool.  If you
use a 32-bit CRC and have a lot of files (say 100 thousand), chances
are some two different files (i.e. contents not the same) will have
the same CRC.