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[liberationtech] Quantum computation & communication

Jacob Appelbaum jacob at appelbaum.net
Wed Dec 19 09:30:39 PST 2012


Gregory Foster:
> After reading Assange, et. al.'s "Cypherpunks: Freedom and the Future of
> the Internet", wherein classical encryption is presented as a panacea
> for ensuring privacy in an age of mass surveillance, I found the
> following article succinct in questioning the long-term viability of
> that narrative (or at least insisting on some qualifications).  Quantum
> computation and communication is still a long distance away, but this
> article provides the outlines of how that technology will be used (and
> abused) by the institutions that will be able to afford it.
> 

We didn't state that "classical encryption" is a "panacea." Frankly, we
didn't event present crypto in general as a panacea - rather, we
presented it as a tactical solution that buys time for the social issues
that crop up with a surveillance society, amongst other points.

We discussed strong cryptography but we were hardly limiting it to RSA
or DSA. In any case, most block ciphers aren't thought to be impacted by
quantum computers. DJB (Bernstein_-_Post_Quantum_Cryptography.pdf) has a
great book on the topic.

We tried to state the importance of understanding the threats, the
reality and the world wide market for such technology. Obviously, a lack
of crypto is itself a threat when spying is essentially free. And while
I generally agree that "classical" crypto is only buying time from
specific attackers in the long run, we argued that part of attacking is
targeting - so to blend in with lots of other ciphertext makes the
attacker's job much harder to locate a person.

If you have a specific passage where you feel that we state that
classical encryption is a panacea to the problem of mass surveillance,
I'd hope it is considered in the context of all the social discussion
that has almost nothing to do with cryptography per se.

(In any case, thanks for reading the book, I hope you enjoyed it!)

All the best,
Jacob

> Aerospace & Defense News (Dec 19) - "Army Researchers Seek Secure
> Quantum Communications":
> http://www.asdnews.com/news-46753/Army_Researchers_Seek_Secure_Quantum_Communications.htm
> 
> 
>> For the U.S. Army, a secure quantum communications network is a
>> technology investment worth making. Meyers said physicists around the
>> world are pursuing quantum teleportation research.
>>
>> "One day we will have communication over worldwide distances with
>> quantum repeaters as mediators at nodes in between," Meyers said.
>> "We'll be able to teleport information globally. What we'll have is
>> tamper-resistant security."
>>
>> Cyber-security is a major concern for military and civilian sectors.
>>
>> "This is important," he said. "The greatest potential that a quantum
>> communications network holds for the Army is secure communications."
>>
>> As quantum computing takes hold in the coming decades, the potential
>> for hacking exponentially increases.
>>
>> "Quantum computers will be able to easily decrypt communications that
>> are currently secure," Meyers said. "We're talking decryption in
>> seconds instead of years. That's one reason why it's vital for us to
>> explore quantum encryption."
> 
> 
> To understand the assertion that a sufficiently large quantum computer
> can (hypothetically) decrypt classically encrypted communications---from
> any time---see:
> http://en.wikipedia.org/wiki/Shor's_algorithm
> 
> Will the economic effects of Moore's Law apply to quantum computers,
> facilitating the mass distribution and use of this technology for
> popular quantum cryptography?  Probably not for some period of time, a
> time which may recapitulate the big iron power dynamics of the mainframe
> priesthood.  It is that interim time period when there is likely to be a
> disparity in access to quantum computation that gives me pause.
> 
> However, in researching this post I was happy to learn that this threat
> is understood and research is underway into post-Quantum cryptography,
> which looks like it can be implemented on classical computers.  So
> predictable future problems may be mitigated by avoiding reliance on
> particular cryptographic techniques that are known to be breakable by
> quantum computers, such as the RSA algorithm used by many contemporary
> public-key cryptography systems:
> http://en.wikipedia.org/wiki/Post-quantum_cryptography
> 
> I'll readily admit that I am about out of my depth here and welcome
> corrections and clarifications.  If we see this probability emerging,
> then it seems like liberationtechnicians should be advocating review and
> redesign of the algorithms used in popular public-key cryptosystems.
> 
> HT @ASDNewsCom via @MrKoot:
> http://twitter.com/ASDNewscom/status/281018815276539904
> 
> gf
> 




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