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Yes. https://en.m.wikipedia.org/wiki/Post-quantum_cryptography https://en.m.wikipedia.org/wiki/Post-quantum_cryptography Doubled key size does not mean twice a

Yes. https://en.m.wikipedia.org/wiki/Post-quantum_cryptography https://en.m.wikipedia.org/wiki/Post-quantum_cryptography Doubled key size does not mean twice as hard to break. Algorithm weaknesses are a thing. This WP is pretty accurate though. It describes the world we think will exist after legitimate quantum computing.

Retric 10y ago
There is someone evidence that QM will result in weaker signals to the point where you can't use it to break real world crypto. It's something of an open question at this point.
- chimeracoder 10y ago
  Could you elaborate? I'm not sure I follow. It's been a while since my CS Theory classes.
  - Retric 10y ago
    Basically, you can do 64 bit calculations on a 16 bit traditional computer, it just takes more steps and some RAM. However, to do 64 bit quantum calculations you need a 64 quibit quantum computer. Now, we may be able to build a 64 QC, bout even that is useless for real world encryption. Further, it while it does not take more time to run a 64vs 4096 quibit QC, it does become exponentially harder to build. Sort of like trying to measure a building to the nearest inch is harder than nearest foot, and every added digit of accuracy is even harder.
    - smaddox 10y ago
      Good analogy; and quite accurate. It's not just the number of bits that affects signal to noise ratio, though... It's also the complexity of the calculation; more gate operations and longer storage in memory leads to more quantum decoherence. And AFAIK, each type of calculation must be implemented in hardware, because reversible quantum gates must be used. This means you would need a specialized chip for each algorithm. I haven't confirmed this understanding with someone that specializes in QC, but I don't see a way around it, other than to combine many algos onto a single chip, sharing as many gates as possible, but degrading S/N further.
      - andai 10y ago
        Re: need custom hardware for each algorithm Something tells me, for an intelligence agency, building a quantum computer only for the purpose of breaking cryptographic keys would be a worthwhile investment. An investment they have already made: The effort to build “a cryptologically useful quantum computer” -- a machine exponentially faster than classical computers-- is part of a $79.7 million research program called “Penetrating Hard Targets.” article https://www.washingtonpost.com/world/national-security/nsa-seeks-to-build-quantum-computer-that-could-crack-most-types-of-encryption/2014/01/02/8fff297e-7195-11e3-8def-a33011492df2_story.html https://www.washingtonpost.com/world/national-security/nsa-s... leaked document http://apps.washingtonpost.com/g/page/world/a-description-of-the-penetrating-hard-targets-project/691/ http://apps.washingtonpost.com/g/page/world/a-description-of...
    - eru 10y ago
      Yes, that's one of the big questions in QC. If people manage to build good error correction for QC some day, scaling will be less of an issue. Scott Aaronson's blog has some good background information for the layman.

Retric 10y ago

There is someone evidence that QM will result in weaker signals to the point where you can't use it to break real world crypto. It's something of an open question at this point.

chimeracoder 10y ago
Could you elaborate? I'm not sure I follow. It's been a while since my CS Theory classes.
- Retric 10y ago
  Basically, you can do 64 bit calculations on a 16 bit traditional computer, it just takes more steps and some RAM. However, to do 64 bit quantum calculations you need a 64 quibit quantum computer. Now, we may be able to build a 64 QC, bout even that is useless for real world encryption. Further, it while it does not take more time to run a 64vs 4096 quibit QC, it does become exponentially harder to build. Sort of like trying to measure a building to the nearest inch is harder than nearest foot, and every added digit of accuracy is even harder.
  - smaddox 10y ago
    Good analogy; and quite accurate. It's not just the number of bits that affects signal to noise ratio, though... It's also the complexity of the calculation; more gate operations and longer storage in memory leads to more quantum decoherence. And AFAIK, each type of calculation must be implemented in hardware, because reversible quantum gates must be used. This means you would need a specialized chip for each algorithm. I haven't confirmed this understanding with someone that specializes in QC, but I don't see a way around it, other than to combine many algos onto a single chip, sharing as many gates as possible, but degrading S/N further.
    - andai 10y ago
      Re: need custom hardware for each algorithm Something tells me, for an intelligence agency, building a quantum computer only for the purpose of breaking cryptographic keys would be a worthwhile investment. An investment they have already made: The effort to build “a cryptologically useful quantum computer” -- a machine exponentially faster than classical computers-- is part of a $79.7 million research program called “Penetrating Hard Targets.” article https://www.washingtonpost.com/world/national-security/nsa-seeks-to-build-quantum-computer-that-could-crack-most-types-of-encryption/2014/01/02/8fff297e-7195-11e3-8def-a33011492df2_story.html https://www.washingtonpost.com/world/national-security/nsa-s... leaked document http://apps.washingtonpost.com/g/page/world/a-description-of-the-penetrating-hard-targets-project/691/ http://apps.washingtonpost.com/g/page/world/a-description-of...
  - eru 10y ago
    Yes, that's one of the big questions in QC. If people manage to build good error correction for QC some day, scaling will be less of an issue. Scott Aaronson's blog has some good background information for the layman.