Is it possible to make a checksum?

I have had issues recently with people put cheats into my games. Therefore, I would like to include a checksum trigger if possible, counting the number of lines or something. Is this possible? If so, how would I do it?

You could optimize your map with Vexorian's map optimizer. It has the ability to change your maps code into gibberish and will not allow world editor to load it. When a map is in that state, only mappers who know what they are doing can crack it. I doubt people like that would want to go to the trouble of it to insert a few cheats.

As for an actual checksum, its not possible.

Another thing:
You can get the map name and (I believe) description with a bit of Jass. From there you can compare if there are any changes, and then quit the game if there is.

You can do the equivilent with handle counts.

A better idea is yes to use Vex's optimizer, but not to delete files that are needed for WE to open it.
Just optimize it normally, and your triggers will become Jass, and your Jass will become as optimized as possible.
For example, if you had something like:
set Player[MyIntLolol+WelcomeVar[kk]*MyOtherInt[LargeNumber]] = Wtf

That will get converted to:

set a[b+c[d]*e[f]] = g

As you can see, nobody is gonna understand that. Nobody can edit it, aslong as you have the original map which you can read and optimize your map each time you want to release it your gonna be fine.
If you really wanted, you could add some sort of protection method such as corrupting your map so only Wc3 can open it and not the WE.

Think of ways of recognizing if there are more handles than usual in some position.

Handle count is deterministic, you can't add cheats without changing the handle count.

I can't give more details since giving them would also be giving out the ways to 'unlock' it

The best way to deal with this is to have an official download location and tell players to only download from there.

I know this sucks and makes it hard to promote new maps, blame blizzard for letting this happen.

I was writing this before the 2 last posts appeared.