[Cryptography] Why prefer symmetric crypto over public key crypto?

[Perry E. Metzger]

On Sat, 07 Sep 2013 13:01:53 -0700
Ray Dillinger <bear at sonic.net> wrote:
> I think we can no longer rule out the possibility that some attacker
> somewhere (it's easy to point a finger at the NSA but it could be
> just as likely pointed at GCHQ or the IDF or Interpol) may have
> secretly developed a functional quantum computer with a qbus wide
> enough to handle key sizes in actual use.

In the same sense that we can no longer rule out the possibility that,
given modern synthetic biology techniques, someone has already come up
with a way to create pigs with wings. I see the possibility of the
quantum computer as slightly smaller, however.

> And IIRC, pretty much every asymmetric ciphersuite (including all
> public- key crypto) is vulnerable to some transformation of Shor's
> algorithm that is in fact practical to implement on such a machine.

To my knowledge, there is no ECC analog of Shor's algorithm.

Perry