[cryptography] Subquantum Crypto Attack

Zack Weinberg zack.weinberg at sv.cmu.edu
Fri Jul 26 12:57:25 EDT 2013


I expect Scott Aaronson would describe this paper as 100% bunk.

On Fri, Jul 26, 2013 at 12:43 PM, John Young <jya at pipeline.com> wrote:
> Has subquantum crypto attack been substantiated?
>
> arXiv:quant-ph/0203049v2 12 Apr 2002
>
> Subquantum Information and Computation
>
> Antony Valentini
>
> It is argued that immense physical resources – for nonlocal communication,
> espionage, and exponentially-fast computation – are hidden from us by
> quantum
> noise, and that this noise is not fundamental but merely a property of an
> equilibrium state in which the universe happens to be at the present time.
> It
> is suggested that ‘non-quantum’ or nonequilibrium matter might exist today
> in
> the form of relic particles from the early universe. We describe how such
> matter
> could be detected and put to practical use. Nonequilibrium matter could be
> used to send instantaneous signals, to violate the uncertainty principle, to
> distinguish
> non-orthogonal quantum states without disturbing them, to eavesdrop
> on quantum key distribution, and to outpace quantum computation (solving
> NP-complete problems in polynomial time). ...
>
> 6 Eavesdropping on Quantum Key Distribution
>
> Alice and Bob want to share a secret sequence of bits that will be used as a
> key for cryptography. During distribution of the key between them, they must
> be able to detect any eavesdropping by Eve. Three protocols for quantum key
> distribution – BB84 [20], B92 [21], and E91 (or EPR) [22] – are known to be
> secure against classical or quantum attacks (that is, against eavesdropping
> based
> on classical or quantum physics) [23]. But these protocols are not secure
> against
> a ‘subquantum’ attack [7]. ...
>
> E91 is particularly interesting for it relies on the completeness of quantum
> theory – that is, on the assumption that there are no hidden ‘elements of
> reality’.
> Pairs of spin-1/2 particles in the singlet state are shared by Alice and
> Bob, who
> perform spin measurements along random axes. For coincident axes the same
> bit
> sequence is generated at each wing, by apparently random quantum outcomes.
> ‘The eavesdropper cannot elicit any information from the particles while in
> transit ..... because there is no information encoded there’ [22]. But our
> Eve has
> access to information outside the domain of quantum theory. She can measure
> the particle positions while in transit, without disturbing the
> wavefunction, and
> so predict the outcomes of spin measurements at the two wings (for the
> publicly
> announced axes).12 Thus Eve is able to predict the key shared by Alice and
> Bob.
>
>
>
>
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