Firstly, congratulations on working out how to save!
I guess that depends on what your save file is. If you stick all your data to be saved into a large array (e.g. SaveArray(x,y)) then use the SAVE ARRAY command then the file that is produced isn't readable (I think, can't check at the minute) in notepad.
Alternatively, if you have simply outputed to text to a .txt file then before you save each variable you could alter it.
For example, you could simply square root each numerical value or raise it to the power 1/5 or something similar and then save that value. Or if it's a string that you want to save, you could convert each character in the string to it's ASCII value, add 1 (or another number) to it then save the resultant string to your .txt file.
Although this isn't encrypting as such, it means that when you perform the reverse upon loading, any weird values, etc can be recognised and you could code it so that your game engine would recognise that the file had been tampered with.
When I get home, i'll see if I can dig out my old XOR encryption algorithm I toyed with in VB.....
I hope this makes some sense.
