making code to check hashes

[sPlOrYgOn]

I need help making a code to check hashes but I don't understand y we can't just send the data without having hashes.  If anyone can tell me how to check for hashes and y we can't just send data i'd like it.

[iago]

The reason for the hash is to prove that you are really using the game client.  

[sPlOrYgOn]

but y can't u just send them fake info?

[Camel]

One must calculate the checksum based on a string provided by battle.net; the value is dynamic and therefore cannot be spoofed.

[iago]

They didn't want to make it easy to write a bot

[Mesiah / haiseM]

One must calculate the checksum based on a string provided by battle.net; the value is dynamic and therefore cannot be spoofed.

Don't forget the mpq version, thats plays a role too.

[DarkMinion]

Camel apparently thinks they're both sent in the same string  

Woe is VB users.  

[Camel]

I was referring to the equation. The first 3 values in the string are seeds, and so is the mpq version.

[c0ol]

less seed, more random initalizations of the variables. basicly the equations, initalized with the values sent, are done for each dword in the collective set of hash files, the resulting "proof" is having a value that matches the value that was calculated serverside for the same files/equation set.

[CoLdFeAr]

You could make it check the file sizes.

[Noodlez]

and what if someone created files with the exact same size?

[Camel]

and what if someone created files with the exact same size?

The checksum would still be wrong.