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One point I think crypto-people need to hammer home to non-crypto audiences is that they should not encrypt and transmit anything that will remain sensitive for more than 5-10 years via any form of encryption relying on factoring, one-way hashes, etc.. (Pretty much everything classical short of one-time-pads exchanged in person.) Credit card transactions? Fine. Affairs? State secrets? Not fine. If you're interesting enough, your coded messages will be archived and cracked within a decade or two (or less).

A lot of crypto algorithm's are theoretically secure for thousands of years (or longer) assuming an eavesdropper has access to existing algorithms and classical hardware with Moore's law scaling. Unfortunately, it's currently non-existing attack algorithms you really need to worry about. Advances are relentless. Then there are things on the horizon like quantum computing...




Quantum computing is overrated. So far all it has told us is that 15 = 3 * 5 with high probability.

While Shor's algorithm demonstrates that integer factorization is in BQP, there are very good reasons to believe that many other problems are not; a large enough quantum computer may break RSA, but it won't break everything.


My point was that you don't need Quantum computing to break all existing crypto algorithms within a couple decades. QC just makes matters that much worse.

(Downplaying Quantum Computing ostrich-style is very popular in classical crypto circles for some reason, but that's a topic for another day!)


Wrong. We have made them do very fast Fourier transforms now. See http://physics.aps.org/pdf/10.1103/PhysRevLett.104.180501.pd... for details.


I once wrote a Crypto plug-in for mIRC that relied on one time pads distributed by floppy disk. (Someone created the masters and mailed them out.)

A floppy disk worth of IRC chat is actually quite a lot but it also had a 'degraded mode' which used the last chunk of the random data as a symmetric cypher key. That would keep things going until the next disk arrived in the post.

This just goes to show that if you are stupid enough to tell a geek what the best answer is then there is a pretty good chance that they will confuse it with the right answer.

My only hope is that our inane chats about movies are, even now, causing cycles to be burned on a NSA supercomputer somewhere :-)


If you were interesting to them, they would just have copied the disks while they were in the mail system. An OTP transmitted over a vulnerable channel like the postal service is not that strong, you have to exchange it in person.


You can just exchange a few floppy disks worth of random bits over various channels, e.g. some postal, some by email, some over the phone, some Diffie-Hellman key exchanges in public and so on. At the end you just XOR them all together, to get the real key. That way all of your channels have to be compromised for your encryption to break.




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