General checksum question

[mumbl]

Hi Guys, I've been lurking from time to time but now Im ready for my first post .

I heard that after 1.23 maps can not be corrupted. So my question is why is that? Is it related to the return bug or the way the checksum for the map is generated? If yes what did they change?

[KangTooJee]

not too sure but maybe replaced gamecache with hashtable?

[mumbl]

Hm I dont think so. I rather think its because of the checksum algorithm used or the hashed files changed but I'd like to know from someone whos sure.

[haxorico]

I think you are talking about colided maps as I never had trouble corrupting a map regarding any patch. I don't know how. Collision works exactly but it was fixed by blizzard.

[mumbl]

I think you are talking about colided maps as I never had trouble corrupting a map regarding any patch. I don't know how. Collision works exactly but it was fixed by blizzard.

Hm, if colliding means changing stuff without Warcraft noticing that the map changed then Im indeed talking about coliding^^.

Everyone just tells me its not possible anymore but nobody seems to know why actually..

[owner123]

Warcraft III checked if you have the map already by comparing the map checksum to all of your maps checksums. If you don't know what a checksum is, read.

http://en.wikipedia.org/wiki/Checksum

Essentially, people were able to make the two checksums the same while making the 2 maps not the same by adding a lot of commented garbage in the war3map.j.

Blizzard patched this and I believe improved how they check the maps. It now does more than just check the checksum, and therefore makes colliding maps impossible.

[mumbl]

Essentially, people were able to make the two checksums the same while making the 2 maps not the same by adding a lot of commented garbage in the war3map.j.

Blizzard patched this and I believe improved how they check the maps. It now does more than just check the checksum, and therefore makes colliding maps impossible.

Thank you, that is the right direction. Any in detail information about this is appreciated!

[Ken]

WC3 currently uses CRC32 and SHA1 at the same time, so I would imagine collisions are more or less impossible now.

[mumbl]

WC3 currently uses CRC32 and SHA1 at the same time, so I would imagine collisions are more or less impossible now.

Hm interesting, do you know which map files are used for the checksums and whether the checksums are just appended at the end of the .w3x file?

From what owner123 said it is safe to say that the war3map.j file is included but there seem to be other files (like imported models) that either are not included at all or just with their names..

Did Warcraft pre 1.24 not use both algorithms?



Thanks for the answers so far

[owner123]

Warcraft pre 1.24 I believe only used SHA1 algorithms, and it now uses two which is essentially not able to be collided.

I believe that it uses every file but the terrain file. I could be wrong though.