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suggesting that NSA knew about differential cryptoanalysis way ahead of time and were suggesting ways to protect the public against its eventual discovery The

by Flenser 14y ago

suggesting that NSA knew about differential cryptoanalysis way ahead of time and were suggesting ways to protect the public against its eventual discovery The NSA may also have know who else knew about differential cryptoanalysis, and didn't want it to be weak in ways that others could break it, but left it weak in ways that they could.

dalke 14y ago
You would think that after this many decades any such built-in weakness to DES would have been discovered. Do you think the NSA crypto knowledge (or rather, IBM crypto knowledge, since that's where differential cryptanalysis was developed) back in the 1970s was better than the modern crypto knowledge?
- DanBC 14y ago
  To give one small example: Clifford Cocks invented RSA about 3 years before RSA did. But he did it by himself, and he did it in his head. Cocks' version was revealed 25 years after he created it; 22 years after RSA was revealed. They're only just released some of the stuff that Turing did. They keep things secret, and they use things hard. There's not really anyway to know what they know about your system, which is why cryptography likes systems that seem secure even when you know everything about that system. (http://www.youtube.com/watch?v=a-xEiOvXux4 http://www.youtube.com/watch?v=a-xEiOvXux4)
  - trhtrsh 14y ago
    "3 years" in not quite the same secret head start that "30 years" is.
    - DanBC 14y ago
      The point is that even though PKI had been independently developed, and made public, 3 years after Cocks did it they still kept it secret for 22 years. So imagine what they do with the secrets that are still secret - the secrets not independently developed and made public.
      - geofft 14y ago
        I think of all the public crypto that we know duplicated intelligence-agency crypto, the public was only behind by a handful of years. We haven't heard of anything that was like "Oh yeah, the NSA had this twenty years ago." (Differential cryptanalysis is probably the biggest of these gaps, and its timeframe is something of an outlier.) So either the public is doing a decent job of keeping up with the spooks, there's a massive misinformation campaign where intelligence agencies only admit to having discovered things that the public discovered soon afterwards, or there's a strange bimodal property where the public replicates private results either five years later or fifty. Also, the NSA is not _fundamentally smarter_ than the rest of the world; they're just possibly more focused on it. So exactly how a clever idea would occur to them in the 1970s and 1980 and have occurred to nobody in academia since then needs some explanation.
tedunangst 14y ago
If that's true, then the NSA is 40 years ahead of the public.
- kps 14y ago
  Some information about computers from the early '50s is still classified — http://www.governmentattic.org/4docs/NSAgenSpecComputers_1986.pdf http://www.governmentattic.org/4docs/NSAgenSpecComputers_198... . That plus http://www.governmentattic.org/3docs/NSA-HGPEDC_1964.pdf http://www.governmentattic.org/3docs/NSA-HGPEDC_1964.pdf are interesting reads for anyone interested in the early development of computing.

by Flenser 14y ago

dalke 14y ago

You would think that after this many decades any such built-in weakness to DES would have been discovered. Do you think the NSA crypto knowledge (or rather, IBM crypto knowledge, since that's where differential cryptanalysis was developed) back in the 1970s was better than the modern crypto knowledge?

DanBC 14y ago
To give one small example: Clifford Cocks invented RSA about 3 years before RSA did. But he did it by himself, and he did it in his head. Cocks' version was revealed 25 years after he created it; 22 years after RSA was revealed. They're only just released some of the stuff that Turing did. They keep things secret, and they use things hard. There's not really anyway to know what they know about your system, which is why cryptography likes systems that seem secure even when you know everything about that system. (http://www.youtube.com/watch?v=a-xEiOvXux4 http://www.youtube.com/watch?v=a-xEiOvXux4)
- trhtrsh 14y ago
  "3 years" in not quite the same secret head start that "30 years" is.
  - DanBC 14y ago
    The point is that even though PKI had been independently developed, and made public, 3 years after Cocks did it they still kept it secret for 22 years. So imagine what they do with the secrets that are still secret - the secrets not independently developed and made public.
    - geofft 14y ago
      I think of all the public crypto that we know duplicated intelligence-agency crypto, the public was only behind by a handful of years. We haven't heard of anything that was like "Oh yeah, the NSA had this twenty years ago." (Differential cryptanalysis is probably the biggest of these gaps, and its timeframe is something of an outlier.) So either the public is doing a decent job of keeping up with the spooks, there's a massive misinformation campaign where intelligence agencies only admit to having discovered things that the public discovered soon afterwards, or there's a strange bimodal property where the public replicates private results either five years later or fifty. Also, the NSA is not _fundamentally smarter_ than the rest of the world; they're just possibly more focused on it. So exactly how a clever idea would occur to them in the 1970s and 1980 and have occurred to nobody in academia since then needs some explanation.

tedunangst 14y ago

If that's true, then the NSA is 40 years ahead of the public.

kps 14y ago
Some information about computers from the early '50s is still classified — http://www.governmentattic.org/4docs/NSAgenSpecComputers_1986.pdf http://www.governmentattic.org/4docs/NSAgenSpecComputers_198... . That plus http://www.governmentattic.org/3docs/NSA-HGPEDC_1964.pdf http://www.governmentattic.org/3docs/NSA-HGPEDC_1964.pdf are interesting reads for anyone interested in the early development of computing.