but again, what compares the checksums?

if it's on the sender's computer, they'll just write a hack to get around it, and then people will be less careful because they assume 'the network is protecting us'.

if it's on the receivers' computer, we need to store a checksum for.. well.. every file limewire/gnutella has ever seen. will limewire be shipping with a new HDD to store that on now? "new limewire, better compression, only a 5gig dowload". and thats still the same as it being on the senders' computer anyways. plus what keep the list itself safe from hacking thru a virus obtained elsewhere?

and if we put it on the limewire central server -- oh wait, there still isn't one.

i hope i'm not coming off condescending here, i'm certainly not trying to. it would be a perfectly acceptable method of protection in a more limited, client/server type setup. like an MMO style game sending patches to the clients. in a peer-to-peer system, where thousands of new files a day might be seen, theres just no way to keep up.

every time limewiere started up it would have to scan & compare every file against its database, to make sure it hasn't changed. that might take hours if you're sharing say 1000 files, and need to scan, hash, then compare against the 100,000,000 files in the database.

if you edit an mp3 to clip 2-3 seconds of silence off at the end, guess what, it's a "new file".

and then if it finds say 1 or 2 files you added that aren't catalogued what does it do? send a report and ban you till they get processed?
or risk lettng you onto the network to share these potentially dangerous viruses? (even tho it's just your shopping list in a txt file, that you saved in the wrong directory).

and then on top of that.. who catalogues all these tens of hundreds of thousands of files? by my guessing, you'd need a handful of people working full time jobs, just to keep the database up to date.


and then from there, you still need to get that database out to the users. every limewire user downloading an update every time they start limewire that might potentially be larger than the installer itself.

coz sooner or later someone's going to accidentally shar their c:\windows\ folder, and 50- to 100,000 files go on the pile in one dump.