I was left with the impression that if "good" random number generators exist, then this is not a problem: you use your small key as a seed to make the big key.

I was left with the impression that if "good" random number generators exist, then this is not a problem: you use your small key as a seed to make the big key. And we do not have a reason yet to doubt the existence of such RNGs. Did I get this wrong? Edit: I think I was right, as the mathematical term "perfect secrecy" from the theorem is not particularly practical (lack of perfect secrecy does not imply the existence of a way to break the cypher). http://www.cs.miami.edu/home/burt/learning/Csc609.011/Perfect/ http://www.cs.miami.edu/home/burt/learning/Csc609.011/Perfec...