Completing a 99.8% seedless torrent.

[erKURITA]

Hello,

I have this torrent stuck at 99.8%, no seeds. It's a very important torrent for me but a 1.0 MB piece is amiss.

So, I was wondering: each piece has a hash (to verify its integrity) or if you rather, each file; now, if the missing parts are small enough to be able to "brute force" them to match the hash, it'd be really nice.

And that's the issue: is there any program available to do this? I've been trying to finish this torrent for years (literally) and there are several other people with 99.8%.

Thanks for your time.

[DreadWingKnight]

You have to brute force SHA1 to be able to do that. Specifically a SHA1 for a block that is 1,048,576 bytes in size.

Just pester whoever released the torrent to reseed it. It'll take less time.

[Ultima]

And even if you brute-forced the piece, you're not 100% guaranteed that there was no SHA1 hash collision that resulted in two distinct 1.0 MB pieces having the same hash -- so the data might still not be correct if you brute forced it.

[Switeck]

If it's a video file, you could use a repair program to at least make it usable.

[erKURITA]

Thanks for your replies.

@Ultima

Ugh, SHA1. You're right, I'd be better off asking the original seeder.

@Switeck

It's an audio file (.APE file). And I'd dare say it's one-of-a-kind, since all I've found around are MP3. Lossless music can't beat MP3

[13minus8]

i have this same problem, & i wouldnt be surprised if it was even the same torrent

the last 2 pieces are full of small irrelevant files,

most of which ive found by some serious googling.. all but 3 jpgs & a text file

the only places claiming to have the files are scam sites

i just need 152748 bytes out of two 4mb pieces,

im thinking brute force should be able to regenerate the missing files,

but i have no idea how to do this

i do know that 152748 bytes is 2^(152748*8) possible variations..

which is too big for windows calculator..

but i think its roughly 6.3e+367841 terrabytes of data..

http://www.alpertron.com.ar/BIGCALC.HTM

(smaller if you consider the text file as ascii only

& i could probably get by with just 36469 bytes generated)

most of which will never pass hash, so cant i use the existing fragments

& caculate hash in reverse, generating only passing data..?

theres no way to guess what percent might pass, but id hope its less than 200gb

which should be easy enough to wade through to spot the legitimate files

itd be faster to go with just the 1st junk that passes, but i kinda want to avoid polluting the torrent

contacting the poster is impossible, so im stuck if i cant generate the missing files somehow

ive also tried finding different copies of the torrent & adding their trackers,

that just gives me more peers at 99.8%

[erKURITA]

I'm just missing a single piece, and yeah, the original poster may as well have deleted the file. Ripping off the CD would work just fine, if it wasn't that it's sold in Japan

[13minus8]

well i figured out ive got a different torrent, yours uses 1mb pieces, mine uses 4mb..

did you try finding the same file you need in a different torrent?

i run into incomplete collections alot, & usually you can complete them

by finding the individual files separately (then seed generously)

if your torrent only contains 1 file, then you might still be able to find it with a different piece size

which would give it a different hash, but the same data, then resume in the new torrent

just rename as needed & recheck, then youll have a totally different group of peers

otherwise you could try downloading the same torrent from everywhere you can find it,

just in the hopes that one will have a new tracker & maybe a peer behind it with the missing piece

although i think thats mostly impractical, if a torrent connects to multiple trackers

then any pieces would be shared between them..

so the tracker idea only works in limited circumstances, like if all the existing trackers are bad,

or if whoever added a new tracker, also removed the old ones,

so the trackers would never connect to the same peer simultaneously..