[philh]

Not 100% unbreakable in general, but I think it does pretty well in the real world. There are plenty of messages that Eve simply can't decrypt with complete confidence. For example, she can't tell ATTACK WILL AT DAWN from ATTACK DAWN AT WILL. She'd have to resort to priors to guess which of those was intended.

[aparent]

It is so good that even Alice can't decrypt those with confidence! :)

[wanderfowl]

It's the newest, hottest thing in Crypto: Perfect Backwards Secrecy!