The nice thing about any strong crypto is that it should stand up to attack even if you know the algorithm and implementation.
Of course if you find a flaw.... it can make anything easier to crack, especially if you have known text to work with.
You might want to check out GPG, the GNU open source version of PGP.
I would rather plant spyware on the Hotmail page that loads to any computer that accesses it from Pakistan, and pings the CIA computer from there...
Look at all the Phishing exploits going on now....and how many people are unaware!