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Re: How is NSA breaking so much crypto?

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On 2015-10-16 20:59:58 +0000, kg said:

> Jeffrey Goldberg  <jeffrey+news@goldmark.org> wrote:
> 
> Which means, if you choose your field to be big enough to resist a
> well-resourced attacker, you are ok.
> 
> Choose big enough primes.

Yep. I do get that.

All of the discussion of "fixes" in the paper were, "use a
bigger group, but if for some reaons you have to use
a 1024 modulus, ..."

>> 1. Does this apply to elliptic curves as as well?
> 
> Well, most algorithms have different optimum parameters when you
> are computing many d.log.s than when you are computing just one, and
> typically, this reduces the per-logarithm cost. But nothing as drastic
> as the number field sieve.

Thanks. This feels counter intuitive to me, but that just illustrates
that I don't have good intuitions about attacks on DH that don't
generally apply to d.logs.

> Choose a big enough curve.

Yeah. I do get that. I was mostly asking to help spur me on to
a better understanding of that some of the attacks on DH
are specific to integer fields.
> 
>> 2. Are there good tools for generating safe primes that are available
>> to developers?
> 
> The problem isn't bad primes. It is too small primes.

I wasn't suggesting that the attacks involve bad primes. Instead
it is that not just any prime (of sufficient size) will do for
a DH group. We want a "safe prime". And so I was asking about
tools for generating a safe prime.

> Choose bigger primes. Problem solved.

I think I am begining to detect a pattern here.

>> 2a. Analogue of question 2 but for ECC parameters?
> 
> Again, choose big enough curves.

Yes. Definitely a hint of a pattern.

> While many people still use 1024 bit fields,

Yes. This is a sad fact.

> I believe few people
> re using less than a 224 bit curve, which is equivalent to 2048 bit
> fields. I believe most people use a 256 bit curve, which is equivalent
> to 3000 bit fields.

Thanks.


So one last question. Is there some simple thing I can do to
avoid the sorts of attacks described in the paper?

> Choose a big enough curve [or primes].

There we go!

Cheers,

-j

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How is NSA breaking so much crypto? Rich <rich@example.invalid> - 2015-10-15 01:44 +0000
  Re: How is NSA breaking so much crypto? "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-10-15 12:04 -0700
    Re: How is NSA breaking so much crypto? wizzofozz <oscxxxxxxxaas@gmail.com> - 2015-10-15 22:24 +0200
      Re: How is NSA breaking so much crypto? William Unruh <unruh@invalid.ca> - 2015-10-15 23:13 +0000
        Re: How is NSA breaking so much crypto? <william@wilbur.25thandClement.com> - 2015-10-16 18:47 -0700
      Re: How is NSA breaking so much crypto? Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2015-10-16 10:09 +0000
    Re: How is NSA breaking so much crypto? Rich <rich@example.invalid> - 2015-10-15 22:38 +0000
    Re: How is NSA breaking so much crypto? William Unruh <unruh@invalid.ca> - 2015-10-15 23:11 +0000
      Re: How is NSA breaking so much crypto? Jakob Bohm <jb-usenet@wisemo.com> - 2015-10-16 02:08 +0200
        Re: How is NSA breaking so much crypto? Rich <rich@example.invalid> - 2015-10-16 00:25 +0000
          Re: How is NSA breaking so much crypto? Jakob Bohm <jb-usenet@wisemo.com> - 2015-10-16 04:04 +0200
  Re: How is NSA breaking so much crypto? Jeffrey Goldberg <nobody@goldmark.org> - 2015-10-16 11:53 -0500
    Re: How is NSA breaking so much crypto? Rich <rich@example.invalid> - 2015-10-16 17:54 +0000
      Re: How is NSA breaking so much crypto? <william@wilbur.25thandClement.com> - 2015-10-16 19:14 -0700
    Re: How is NSA breaking so much crypto? Jakob Bohm <jb-usenet@wisemo.com> - 2015-10-16 20:18 +0200
    Re: How is NSA breaking so much crypto? kg <kristiag+news@math.ntnu.no> - 2015-10-16 20:59 +0000
      Re: How is NSA breaking so much crypto? Jeffrey Goldberg <nobody@goldmark.org> - 2015-10-16 23:19 -0500
        Re: How is NSA breaking so much crypto? kg <kristiag+news@math.ntnu.no> - 2015-10-18 11:37 +0000
          Re: How is NSA breaking so much crypto? Jeffrey Goldberg <nobody@goldmark.org> - 2015-10-19 00:20 -0500
  Re: How is NSA breaking so much crypto? Anonymous <nobody@remailer.paranoici.org> - 2015-10-18 22:53 +0000
    Re: How is NSA breaking so much crypto? Rich <rich@example.invalid> - 2015-10-19 01:18 +0000
  Re: How is NSA breaking so much crypto? Noob <root@127.0.0.1> - 2015-10-30 08:45 +0100

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