The most popular one on this site for GUI users is the following ->
http://www.hiveworkshop.com/forums/...0-2-a-177395/?prev=d=list&r=20&u=TriggerHappy
If you want to use something that produces even smaller code, you gotta go
to vJASS =).
There is also a 100-part interactive tutorial on writing your own save/load systems.
There are also 2 codeless save/load systems. The good one needs to have the Network library be updated for much faster synchronization though. The codeless one also supports GUI : P, but once again, the Network library is way too slow in its current form, so it can't be used.
For security, the codeless ones use MD5 and AES-128. The non-codeless vJASS one uses Scrambler (dated, needs to be on AES-128) and Knuth Checksum. The GUI one I linked doesn't use any of that fancy stuff =).
A lot of people on the site know a lot about save/load, so if you're curious about improving the way your data is stored, let everyone know and we can show you the most awesome techniques ever to minimize the size of your code ; D.