Magnet Link and corrupt Download

[Sonnentier]

I noticed something strange:
I entered a new magnet link to Phex, a file that should be several MBytes big. I had contact with one Peer, then a 23KByte big file was finished downloading, a file that has some DRM in it, definately not the file I requested.

I think the Peer that sent me the data was malicious and sent me content not fitting my SHA1 hashsum (I checked the file after completion, and the key was completely different).

Is it possible that Phex doesnt check the hash after finishing? Somehow, this malicios node has disrupted the download..

perhaps not the primary problem here, but it's not easy to make sure against malicious nodes as you don't have a hash for each chunk, right? One magnet, which you can only check as a whole file. I mean, first the size is unknown, then a filesize appears - which can firstly not be trustworthy.

All these Spambots and stupid nodes are sometimes really annoying.. in other examples they sent results which did not fit my query..

[arne_bab]

There are some magnets, for which Phex isn't able to extract the sha1-urn.

In that case it is very probable, that you won't get the file you search for, but get spam instead.

Could you test the magnet by disconnecting phex, then adding the magnet again and looking, if the download has a sha1-urn assigned?

Thanks for the bug-report!

[Sonnentier]

I could see the correct SHA-1 just after entering, while downloading and after finished. However, the hash of the file was wrong when I externally checked it.

[Hyper-kun]

What do you mean with "externally"? What tool did you use to check the SHA-1? Could you post the magnet with most but not everything after each "param=" Xed out?

For example

magnet:?xs=http:*****&xt=ABCDEFXXXXX

dn= shouldn't matter, drop that.

and also show the complete magnet with all values removed like this:

magnet:?xs=REMOVED&dn=REMOVED&xl=REMOVED&kt=REMOVE D

so that one can see the structure of the magnet. It might help if you contacted the developers directly because not seeing the magnet in full, is a pain in the rear but gnutellaforums are pedantically strict on these matters even if the magnet doesn't point to anything questionable ... oh well ...

[Sonnentier]

Oh Ok I see..

I used Hashcalc.

Overview:
magnet:?xt=REMOVED&dn=REMOVED

Xed
magnet:?xt=urn:sha1:7LOMUVZETDMJSV2CB7ZXXXXXXXXXXX XX

[Hyper-kun]

I've looked at features overview and the screenshot. They mention SHA-1 but the screenshot shows only hex output for it. Gnutella uses base32 encoding for SHA-1 instead of hex because it's shorter and case-insensitive.

urn:sha1:7LOMUVZETDMJSV2CB7ZXXXXXXXXXXX
becomes
fadcca572498d89957420ff37XXXXXXXXXXX

Does the SHA-1 as shown by HashCalc match this or not?