In speaking with an associate, he mentioned in passing that PGP had been broken a few weeks ago in San Diego by the DoD using a Cray. All questioning about said subject was ended immediately as he felt that he might have said too much how it was. Was PGP "broken"?

There's a store here in Chicago that sells surveillance equipment. I had driven by it for years and never gone in, and a few weeks ago I finally gave in to curiosity and checked it out. One of the things they were selling was a $100 floppy disk labeled "public key encryption". Is that like PGP? "No, this is much better. PGP can be broken, this uses DES." (DES isn't a public key algorithm, of course, and it's no longer considered secure.) There have been hundreds of reports like yours throughout PGP's short history. They're always second hand, and there's never any information about the specifics of the attack. It's hard to take such reports seriously. What do you mean when you speak of "breaking PGP"? Decrypting a single message? Forging a single signature? Producing a private key from a public one? Figuring out a way to make one of those other problems easier by exploiting a weakness in PGP's implementation? A new attack on RSA, IDEA, or MD5? Coming up with a technique for factoring big numbers? I'd be willing to bet that most people -- literally, more than half -- who use PGP have made the mistake of picking a weak passphrase. If I'm right about that, it would mean that an awful lot of people who think they have security don't. If you pick a weak passphrase, your key could fall to a dictionary attack. But that's a problem with the user, not PGP. It's most likely that the person who told you that PGP had been broken was mistaken. If there's anything at all to the story, chances are overwhelming that he was referring to a successful dictionary attack against a single key. A lot of people seem to feel a little uneasy about MD5, which PGP uses to make signatures; perhaps some super spook has put a dent in that. Anything is possible. It's only "Pretty Good" privacy. But you can rest assured that if credible evidence that PGP has been compromised ever emerges, you won't have to go digging around for it. It will be all over the net and the traditional media.

Although there is always the possibility that PGP could be broken, it is highly unlikely that the program as a whole has been broken. I would think that it would be much easier to attempt to guess someone's passphrase than to brute-force the crypto in the program. Also, if it is the DoD that is purporting this supposed break, I doubt the public will ever hear about it. It would be interesting to know "how" PGP was supposedly broken. Was a cryptographic routine broken, or was it a user interface break? I.e., was a signature forged or a message decrypted? Or was an old message replayed as a new one? Also, it could be that a small PGP key has been broken. A 384-bit PGP key has already been broken by a factoring attack. That is neither surprising nor alarming to say the least. Without more information it really is impossible to analyze what happened. -derek