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supernetworks_ | 3 months ago

It would be wise for people to remember that it’s worth doing basic sanity checks before making claims like no backdoors from the NSA. strong encryption has been restricted historically so we had things like DES and 3DES and Crypto AG. In the modern internet age juniper has a bad time with this one https://www.wired.com/2013/09/nsa-backdoor/.

Usually it’s really hard to distinguish intent, and so it’s possible to develop plausible deniability with committees. Their track record isn’t perfect.

With WPA3 cryptographers warned about the known pitfall of standardizing a timing sensitive PAKE, and Harkin got it through anyway. Since it was a standard, the WiFi committee gladly selected it anyway, and then resulted in dragonbleed among other bugs. The techniques for hash2curve have patched that

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tptacek|3 months ago

It's "Dragonblood", not "Dragonbleed". I don't like Harkin's PAKE either, but I'm not sure what fundamental attribute of it enables the downgrade attack you're talking about.

When you're talking about the P-curves, I'm curious how you get your "sanity check" argument past things like the Koblitz/Menezes "Riddle Wrapped In An Enigma" paper. What part of their arguments did you not find persuasive?

supernetworks_|3 months ago

yes dragon blood. I’m not speaking of the downgrade but the timing sidechannels — which were called out very loudly and then ignored during standardization. and then the PAKE showed up in wpa3 of all places, that was the key issue and was extended further in a brain pool curve specific attack for the proposed initial mitigation. It’s a good example of error by committee I do not address that article and don’t know why the NSA advised migration that early.

The riddle paper I’ve not read in a long time if ever, though I don’t understand the question. As Scott Aaronson recently blogged it’s difficult to predict human progress with technology and it’s possible we’ll see shors algorithm running publicly sooner than consensus. It could be that in 2035 the NSA’s call 20 years prior looks like it was the right one in that ECC is insecure but that wouldn’t make the replacements secure by default ofc

UltraSane|3 months ago

The NSA changed the S-boxes in DES and this made people suspicious they had planted a back door but then when differential cryptanalysis was discovered people realized that the NSA changes to S-boxes made them more secure against it.

timschmidt|3 months ago

That was 50 years ago. And since then we have an NSA employee co-authoring the paper which led to Heartbleed, the backdoor in Dual EC DRBG which has been successfully exploited by adversaries, and documentation from Snowden which confirms NSA compromise of standards setting committees.

themafia|3 months ago

The NSA also wanted a 48 bit implementation which was sufficiently weak to brute force with their power. The industry and IBM initially wanted 64 bit. IBM compromised and gave us 56 bit.

cryptonector|3 months ago

Yes, NSA made DES stronger. After first making it weaker. IBM had wanted a 128-bit key, then they decided to knock that down to 64-bit (probably for reasons related to cost, this being the 70s), and NSA brought that down to 56-bit because hey! we need parity bits (we didn't).