[extropy-chat] D-Wave premiere of 16 qubit processor

[Eugen Leitl]

On Wed, Feb 14, 2007 at 01:16:49PM +0100, Ricardo Barreira wrote:

> QC gives a quadratic speedup on brute-forcing ciphers, which means

I had to look it up, wasn't aware of Grover's algorithm.
However, one should hasten to add, in theory, in practice
nobody has mapped even a single S-Box to a real QC yet.
Cascading anything classical sequentially, with the output depending
on input with no shortcut would seem to be bad for QC in general,
especially if mapping gates to qubits is expensive.

And I would really really really like to see even a 256 qubit
machine in solid state with a nontrivial amount of iterations
before decoherence, even a cryogenic one.

> that if we want to account for quantum computing, we need to double
> the size of our keys. So QC is not such a big deal for symmetric
> ciphers as far as I know, but it's still useful. I suppose that if
> D-wave's QC design is proven to be scalable, it's surely time do
> starting using AES-256 instead of AES.

Actually, there are already hints that a crack for AES in the works
(similiar applies to SHA-1, there the evidence is already there), 
so running AES-256 today is already a good idea.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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