It's getting late and I don't really have the energy to dig into this patent (http://www.google.com/patents/US5412730 http://www.google.com/patents/US5412730),

It's getting late and I don't really have the energy to dig into this patent (http://www.google.com/patents/US5412730 http://www.google.com/patents/US5412730), but on a cursory reading I don't see how it differs from the encryption work that Claude Shannon and Alan Turing were doing during World War 2, later embodied as http://en.wikipedia.org/wiki/SIGSALY http://en.wikipedia.org/wiki/SIGSALY ... is it just because it transmits the data in "blocks"? Pretty low bar for novelty, there.