tielset attributes file
 

There should be a human-readable file one can create to use with custom tilesets, that allows for custom placements of tile-types. e.g.
(0 = Water,
1 = Grass,
2 = Dirt,
3 = Lava,)

11110111011
00111111011
01111011001
10122111222
21111122122
22210102120
22211022213 etc...

It would greatly expand the use of tilesets if we could just issue a command like addtiledef imagefile,textfile,levels;

Except that Joe ScriptKiddie could easily edit his files such that he's able to walk over walls.

Wouldn't a checksum work here?

*shrugs*

It would help, but it wouldn't guarantee security.

Would work well if it's a serverside option.

I've found checksums to be pretty secure. I don't know a lot about computer security, but I know a lot of programs use checksums to check on game data. I guess it is just the matter of finding the right one for what you want to do.