Bruce Schneier disses quantum cryptography

Update: Wow, I’m absent-minded.  Not only did The Pontiff cover this story already, but I commented on it.

Cryptography guru Bruce Schneier, creator of the solitaire algorithm (among others), has dissed quantum cryptography as ultimately pointless. As someone who works in this area I was more than a little curious as to why. I understand that, at present, it is fairly useless since most current encryption algorithms are secure against attacks from classical computers. For example, when properly implemented, RSA is essentially unbreakable by classical methods (note that by ‘properly implemented’ I mean one chooses sufficiently large prime numbers). But, as Peter Shor showed nearly fifteen years ago, RSA is vulnerable to an attack by a quantum computer. Schneier’s reply is that “[i]f one were built — and we’re talking science fiction here — then it could factor numbers and solve discrete-logarithm problems very quickly.” He maintains that even if one were built, symmetric cryptography (which I admittedly know very little about) would not be completely compromised. The question then seems to boil down to the practical reality of quantum computers. While I am among the many who are somewhat skeptical of D-Wave’s claims of a 16-qubit quantum computer, I have no doubt actual quantum computers are on the near horizon and thus I think Schneier’s comments are premature to say the least. (Note: I first heard about Schneier’s comments from the Quantiki message board.)

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