As I suspected. But another question is how quickly can they do that? If I want to jump the wife of an FBI agent, how much time would I have to get the hell out?
>> If I want to jump the wife of an FBI agent, how much time would I have to get the hell out?
Oh, THAT’S it! I might have known; I was a sailor, too ;-). Yeah, I hear those FBI wives are lonely, what with hubby working late breaking codes and such.
Well, look at it this way: the more complex you make your code, the longer you can tie up her FBI hubby, so the more “jumping time” you have.
Things are not so bad. As an example, OTP encryption can not be broken at all:
The Vernam-Mauborgne one-time pad was recognized early on as difficult to break, but its special status was only established by Claude Shannon some 25 years later. He proved, using information theory considerations, that the one-time pad has a property he termed perfect secrecy; that is, the ciphertext C gives absolutely no additional information about the plaintext. (link)
OTP's flaw is in lack of secure key exchange mechanism. Diplomats usually send OTP keys with a trusted courier. Also, each OTP can be used only once. As long as you do that, they are unbreakable, in theory and in practice.
AES is one of the newer ciphers that is seen as fairly secure. As matter of fact, there is no viable attack on it so far (except if you can run your own program on the encrypting computer... and then you don't need to bother cracking the code.)
If you are interested in highest security then you must use open source encryption software (such as GnuPG) because it is widely peer-reviewed. Closed source software, like today's PGP, may contain security flaws that nobody knows about (and those who do have means of breaking the code.) Also, as other people mentioned, keep the private key password-protected, on a USB disk, and do encryption only on a computer that is never connected to the Internet. Windows or Linux - that does not matter in this case.
High security of modern encryption is the reason why UK has a law that every UK subject must reveal their private encryption key upon demand by authorities, or go to jail. They would not need to do that if they could crack AES on their quantum computers. (They can't, and they don't have quantum computers either.) In most scenarios your privacy will be very well protected if you use modern ciphers; the attacker would have a much better chance of getting the plaintext by beating you with a rubber hose until you provide the key.
But security of your message also depends on the recipient. If you send a super-secret message to Alice, and she then proceeds to decrypt it, print it, and leave on her desk in front of the window that faces the street, or save as plaintext on her Internet-connected, insecure computer, then your message is revealed to anyone who cares to have it.