Quote (irimi @ 27 Aug 2012 06:33)

well, I'm sure there are ways to do that (as pointed out above).

but i'm kind of assuming that the OP's program is dead simple - that is, the dictionary can be loaded fully into memory and used as such, and that the text file is really there for persistence more than anything else... in which case, you don't need to be able to decrypt it piecewise.

and if readable by user isn't actually a big deal (you just dont want them to modify it), you don't even need all that jazz.  all you really need to do is to validate the file's checksum.