Patrick Wilken, <patrickw@cs.monash.edu.au>, writes regarding factoring breakthroughs not being a concern:
> But presumably only until we develop reasonable quantum computing. How long
> is that going to take? <20years? Are their any encryption schemes that will
> hold up to a QCs assault?
I am skeptical that it will turn out to be possible to extend quantum computers to the size necessary to factor numbers of interest (hundreds or thousands of qubits). I made a posting on July 8 about what the alternatives would be for cryptographers if that should happen. See the archives at
http://www.lucifer.com/exi-lists/extropians/2755.html
Hal