Laura,

Up until recently, I was using RetroGuard (http://www.retrologic.com/)
It was an outstanding tool, and easily integrated into Eclipse through
means of External Tools.  But then when I hit their website for the
latest update, I found that they now charge $139/yr for the
non-commercial version. Well... I'm cheap, and I knew Open Source would
come through.

This lead me to ProGuard which was actually spawned from RetroGuard.
And, seeing as it's licensed under GPL it also fits within my budget
constraints.

You can find it at :
http://proguard.sourceforge.net/

You definitely want to read the documentation, and decompile the end
result yourself until you feel "safer" about what you've done.  I say
"safer", because a reverse engineer with a keg of coffee, and nothing
better to do with their time is going to be able to make out what you've
done.  But, hey, I wouldn't know anything about that.... heheheh.

And, no, provided you do it right, the client doesn't need to know about
the obfuscator.

Regards,
Pavel

<INSERT PLUG HERE> : Special thanks to Mark Welsh, Dirk Schnelle, Eric
Lafortune, and anyone else that maintains and donates to the ProGuard
project.  Open Source would be 10000 times better if there were more
donations.

for a list of candidates see
http://mindprod.com/jgloss/obfuscator.html

That "doesn't compute". I'll tell you why.

You should not rely on an obfuscator for security. Maybe for protection of your
code (IP), but even that is just walking on thin ice. Security should be dealt
with in a different way. You should use cryptosystems for this purpose.
Cryptosystems don't rely on privacy/secrecy of algorithms (that's sometimes
called security through obscurity:
http://en.wikipedia.org/wiki/Security_through_obscurity ), but rather on
privacy/secrecy of a key (or keys) used.

(Some might argue that keys are a part of an algorithm, but for the sake of this
argument, let's say keys are input for an algorithm.)

Don't get me wrong, though. You don't have to open source your ( super duper ;-)
) code/algorithm. But you shouldn't take it for granted that nobody will ever
figure it out, either.